Discectomía mínimamente invasiva versus microdiscectomía / discectomía abierta para la herniación discal lumbar sintomática
Resumen
Antecedentes
La microdiscectomía o discectomía abierta (MD/DA) son los procedimientos estándar para la herniación discal lumbar sintomática e incluyen la extracción de la porción del disco intervertebral que comprime la raíz nerviosa o la médula espinal (o ambas) con o sin la ayuda de lupa binocular o magnificación con microscopio. Las ventajas potenciales de los procedimientos más nuevos de discectomía mínimamente invasiva (DMI) sobre la MD/DA estándar incluyen menor pérdida sanguínea, menor dolor posoperatorio, una hospitalización más corta y el retorno al trabajo de forma más temprana.
Objetivos
Comparar los efectos beneficiosos y perjudiciales de la DMI versus MD/DA para el tratamiento de la discopatía intervertebral lumbar.
Métodos de búsqueda
Se hicieron búsquedas en el Registro Cochrane Central de Ensayos Controlados (Cochrane Central Register of Controlled Trials) (CENTRAL) (noviembre 2013), MEDLINE (1946 hasta noviembre 2013) y en EMBASE (1974 hasta noviembre 2013) y no se aplicaron restricciones de idioma. También se estableció contacto con expertos en el tema para obtener estudios adicionales y se revisaron las listas de referencias de los estudios relevantes.
Criterios de selección
Se seleccionaron los ensayos controlados aleatorios (ECA) y los ensayos controlados cuasialeatorios (ECCA) que compararon la MD/DA con una DMI (discectomía lumbar percutánea endoscópica interlaminar o transforaminal, microdiscectomía tubular transmuscular y discectomía lumbar percutánea automatizada) para el tratamiento de la radiculopatía lumbar secundaria a la discopatía en adultos. Se evaluaron los siguientes resultados primarios: dolor relacionado con la ciática o dolor lumbar (DL) según lo medido en una escala analógica visual, resultados específicos de la ciática como el déficit neurológico de la extremidad inferior o la incontinencia fecal/urinaria y los resultados funcionales (incluida la actividad diaria o el retorno al trabajo). También se evaluaron los siguientes resultados secundarios: complicaciones de la intervención quirúrgica, duración de la estancia hospitalaria, uso de opioides posoperatorios, calidad de vida y satisfacción general del participante. Dos autores examinaron los resúmenes de datos y los artículos para su inclusión. Las discrepancias se resolvieron mediante consenso.
Obtención y análisis de los datos
Se utilizaron los procedimientos metodológicos estándar previstos por La Colaboración Cochrane. Se utilizaron los formularios desarrollados previamente para extraer los datos y dos autores evaluaron de forma independiente el riesgo de sesgo. Para el análisis estadístico, se utilizaron los cocientes de riesgos (CR) para los resultados dicotómicos y las diferencias de medias (DM) para los resultados continuos con intervalos de confianza (IC) del 95% para cada resultado.
Resultados principales
Se identificaron 11 estudios (1172 participantes). Se evaluaron siete de cada 11 estudios como de riesgo general de sesgo alto. Hubo pruebas de baja calidad de que la DMI se asoció con mayor dolor de la pierna que la MD/DA al momento del seguimiento que varió de seis meses a dos años (p.ej. un año más tarde: DM 0,13; IC del 95%: 0,09 a 0,16), aunque las diferencias fueron pequeñas (menos de 0,5 puntos en una escala de 0 a 10) y no alcanzaron los umbrales estándar para una diferencia clínicamente significativa. Hubo pruebas de baja calidad de que la DMI se asoció con mayor DL que la MD/DA a los seis meses de seguimiento (DM 0,35; IC del 95%: 0,19 a 0,51) y a los dos años (DM 0,54; IC del 95%: 0,29 a 0,79). No hubo diferencias significativas un año más tarde (escala de 0 a 10: DM 0,19; IC del 95%: ‐0,22 a 0,59). La heterogeneidad estadística fue pequeña a alta (estadística I2 = 35% a los seis meses, 90% un año más tarde y 65% a los dos años). No hubo diferencias claras entre las técnicas de DMI y de MD/DA en otros resultados primarios relacionados con la discapacidad funcional (Oswestry Disability Index mayor que seis meses después de la cirugía) y la persistencia de déficits neurológicos motores y sensoriales, aunque las pruebas sobre los déficits neurológicos fueron limitadas por los números pequeños de participantes en los ensayos con déficits neurológicos al inicio. Hubo sólo un estudio para cada uno de los resultados específicos de la ciática incluido el Sciatica Bothersomeness Index y el Sciatica Frequency Index, que no necesitó análisis adicional. Para los resultados secundarios, la DMI se asoció con un riesgo menor de infección del sitio quirúrgico y otras infecciones, aunque se relacionó con un riesgo mayor de nueva hospitalización debido a la herniación discal recurrente. Además, la DMI se asoció con una calidad de vida levemente inferior (menos de 5 puntos en una escala de 100 puntos) en algunas medidas de la calidad de vida, como algunas subclases físicas del Short Form de 36 ítems. Algunos ensayos encontraron que la DMI se asoció con una duración más corta de la hospitalización que la MD/DA, aunque los resultados fueron inconsistentes.
Conclusiones de los autores
La DMI puede ser inferior en cuanto al alivio del dolor de la pierna, el DL y la nueva hospitalización; sin embargo, las diferencias en el alivio del dolor parecieron ser pequeñas y pueden no ser clínicamente importantes. Las ventajas potenciales de la DMI son el menor riesgo de infección del sitio quirúrgico y otras infecciones. La DMI puede asociarse con una estancia hospitalaria más corta aunque las pruebas fueron inconsistentes. Teniendo en cuenta estas ventajas potenciales, se necesita más investigación para definir las indicaciones apropiadas para la DMI como una alternativa a la MD/DA estándar.
PICO
Resumen en términos sencillos
Cirugía para el dolor de la pierna y espalda causado por daño a los discos espinales
Antecedentes
Cuando los discos ubicados entre las vértebras de la columna presentan daños (herniación), el gel blando dentro de ellos empuja la pared del disco y presiona contra los nervios o la médula espinal, lo cual causa un dolor urente en las piernas y dolor en la espalda. Cuando este trastorno sucede en la zona lumbar de la espalda, el mismo se conoce como herniación discal lumbar.
Pregunta de la revisión
El tratamiento principal para este trastorno es la discectomía lumbar, que incluye la extracción de la parte del disco que ejerce presión en los nervios. Existen dos tipos principales de esta cirugía. El primer tipo es la microdiscectomía estándar, que puede realizarse con la ayuda de magnificación con microscopio o lupa binocular, o la discectomía abierta en la cual los cirujanos no utilizan microscopio ni lupa (MD/DA). Sin embargo, todos los pasos de las cirugías son similares. El segundo tipo de cirugía incluye los procedimientos de discectomía mínimamente invasiva (DMI). La DMI incluye una incisión más pequeña y menos daño al tejido circundante. Se examinaron las pruebas para observar si un tipo de intervención quirúrgica es más efectiva que el otro tipo de cirugía en cuanto a los resultados después de la intervención quirúrgica incluido el dolor en las piernas, el dolor lumbar, los problemas con la movilidad o el adormecimiento y la discapacidad.
Características de los estudios
Se encontraron 11 estudios hasta noviembre de 2013 que examinaron a 1172 personas, con estudios que variaron de 22 a 325 participantes y de edades entre 12 y 70 años. Todos habían probado tratamientos no quirúrgicos y todos presentaban dolor en la pierna que era peor que el dolor de espalda. El período de seguimiento después de la cirugía varió entre cinco días y 56 meses.
Resultados clave
Los pacientes sometidos a la MD/DA presentaron menos dolor en las piernas, y menos dolor lumbar, aunque la diferencia fue pequeña. Presentaron menor probabilidad de necesitar una segunda cirugía debido a que la primera no había sido exitosa. Se sintieron levemente mejor en algunos aspectos físicos de la calidad de vida, aunque nuevamente la diferencia fue demasiado pequeña para ser significativa. En cuanto a las complicaciones, las dos cirugías fueron similares, aunque los pacientes sometidos a una MD/DA presentaron mayor probabilidad de tener infecciones de la herida.
Calidad de la evidencia
Muchos de los estudios se realizaron en un número pequeño de pacientes y presentaron un riesgo alto de sesgo, por lo cual la calidad general de las pruebas sobre el dolor de la pierna y el dolor lumbar fue baja.
Authors' conclusions
Summary of findings
| Minimal invasive discectomy compared with micro/discectomy for lumbar disc herniation | ||||||
| Participant or population: participants with lumbar disc herniation Settings: operated lumbar disc herniation Intervention: minimally invasive discectomy Comparison: micro/discectomy | ||||||
| Outcomes# | Illustrative comparative risks* (95% CI) | Relative effect | No of participants | Quality of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| Micro/discectomy | Minimal invasive discectomy | |||||
| Mean leg pain intensity on a numerical scale, e.g. 0 (no pain) to 10 (maximum pain) ‐ 1‐year post operative | Mean leg pain score ranged across control groups from 0.1 to 1 | Mean leg pain score in the intervention groups was 0.13 higher (0.09 to 0.16) | Not applicable | 599 (4 studies) | ⊕⊕⊝⊝ | There was a difference between the groups that was small in magnitude. However, the difference was not clinically important (< 1.5 out of 10 points) |
| Mean LBP intensity on a numerical scale, e.g. 0 (no pain) to 10 (maximum pain) ‐ 6‐month post operative | Mean LBP score ranged across control groups from 1 to 1.77 | Mean LBP score in the intervention groups was 0.35 higher (0.19 to 0.51) | Not applicable | 577 (3 studies) | ⊕⊕⊝⊝ | There was a difference between the groups that was small in magnitude. However, the difference was not clinically important (<1.5 out of 10 points) |
| Mean LBP intensity on a numerical scale, e.g. 0 (no pain) to 10 (maximum pain) ‐ 1‐year post operative | Mean LBP score ranged across control groups from 0 to 1.75 | Mean LBP score in the intervention groups was 0.19 higher (‐0.22 to 0.59) | Not applicable | 577 (3 studies) | ⊕⊝⊝⊝ | There was no statistically significant difference |
| Mean LBP intensity on a numerical scale, e.g. 0 (no pain) to 10 (maximum pain) ‐ 2‐year post operative | Mean LBP score ranged across control groups from 0 to 1.94 | Mean LBP score in the intervention groups was 0.54 higher (0.29 to 0.79) | Not applicable | 577 (3 studies) | ⊕⊕⊝⊝ | There was a difference between the groups that was small in magnitude. However, the difference was not clinically important (< 1.5 out of 10 points) |
| Persistent motor deficits post operative | Study population 343.7 per 1000 | Study population 338.7 per 1000 | Not applicable | 126 (4 studies) | ⊕⊕⊝⊝ | There was no statistically significant difference |
| Persistent sensory deficits post operative | Study population 550 per 1000 | Study population 459 per 1000 | Not applicable | 165 (4 studies) | ⊕⊕⊝⊝ | There was no statistically significant difference |
| Persistent reflex deficit post operative (12 months) | Study population 737 per 1000 | Study population 500 per 1000 | Not applicable | 47 (2 studies) | ⊕⊕⊝⊝ | There was a difference between the groups. However, the difference was not clinically important |
| Disability (higher ratings mean greater disability). Various instruments were used, e.g. in Oswestry Disability Index > 6 months' post operative 0% (no disability) to 100% (bedridden) | Mean disability score ranged across control groups from 10 to 13 | Mean disability score in the intervention groups was 0.84 higher (‐0.21 to 1.88) | Not applicable | 312 (3 studies) | ⊕⊕⊝⊝ | There was no statistically significant difference |
| Side effects ‐ surgical site and other infections > 6 months' follow‐up | Study population 32 per 1000 | Study population 2.3 per 1000 | RR 0.23 (0.07 to 0.79) | 931 (6 studies) | ⊕⊕⊕⊝ | There was a difference between the groups that was small in magnitude. However, the difference was not clinically important (< 10%) |
| Side effects ‐ re‐hospitalisation due to recurrent disc herniation ≥ 6 months' follow‐up | Study population 43 per 1000 | Study population 75 per 1000 (43 to 103) | RR 1.74 (1.03 to 2.94) | 949 (6 studies) | ⊕⊕⊕⊝ | The magnitude of this difference was small to moderate. However, the difference was not clinically important (< 10%) |
| SF‐36 Physical Functioning subclass > 6 months' follow‐up ‐ on a numerical scale (higher ratings mean higher quality of life), e.g. 0 (the worst) and 100 (the highest) quality | Mean HRQoL score ranged across control groups from 80.4 to 84 | Mean HRQoL score in the intervention group was 4.7 lower (‐5.05 to ‐4.35) | Not applicable | 385 (2 studies) | ⊕⊕⊝⊝ | The magnitude of this difference was in the range of small to moderate. However, this difference was not clinically important (< 10%) |
| The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). GRADE Working Group grades of evidence | ||||||
| # Persistent bladder dysfunction > six months' follow‐up, sciatica‐specific outcomes including the Sciatica Bothersomeness Index (SBI) and the Sciatica Frequency Index (SFI) have been written in the text but did not mention in the 'Summary of finding' table because there was only one study for each and no need for further evaluation and meta‐analysis. 1 Two trials had unclear risk of bias due to non‐adequate randomisation, no allocation concealment and no blinding (Huang 2005; Mayer 1993). Meanwhile, Huang 2005 had no clear intention‐to‐treat analysis and Mayer 1993 had unclear co‐intervention. One other trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had unclear allocation concealment and high risk of bias for blinding (Teli 2010). We downgraded the level of evidence due to the high risk of bias and low precision due to the small number of trials for specific minimally invasive techniques. The analysis was consistent with no heterogeneity (I2 = 0%). 2 One trial had high risk of bias due to non‐adequate randomisation, no allocation concealment, no blinding, group differences at baseline and no clear intention‐to‐treat analysis (Righesso 2007). One other trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had unclear allocation concealment and high risk of bias for blinding (Teli 2010). We downgraded the level of evidence due to the high risk of bias and low precision because of the small number of trials for specific minimally invasive techniques. The analysis was almost consistent with small heterogeneity (I2 = 35%). 3 One trial had high risk of bias due to non‐adequate randomisation, no allocation concealment, no blinding, group differences at baseline and no clear intention‐to‐treat analysis (Righesso 2007). One other trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had unclear allocation concealment and high risk of bias for blinding (Teli 2010). We downgraded the level of evidence due to the high risk of bias, low precision because of the small number of trials for specific minimally invasive techniques and high heterogeneity (I2 = 90%). 4 One trial had high risk of bias due to non‐adequate randomisation, no allocation concealment, no blinding, group differences at baseline and no clear intention‐to‐treat analysis (Righesso 2007). One other trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had unclear allocation concealment and high risk of bias for blinding (Teli 2010). We downgraded the level of evidence due to the high risk of bias and low precision because of the small number of trials for specific minimally invasive techniques. The analysis was almost consistent with small heterogeneity (I2 = 65%). 5 Two trials had high risk of bias due to non‐adequate randomisation, allocation concealment and no blinding (Ryang 2008; Righesso 2007). One trial had unclear risk of bias due to non‐adequate randomisation, no allocation concealment, no blinding and unclear co‐intervention (Mayer 1993). In another trial, there was no blinding of participants, care provider and outcome assessor; and authors did not mention whether there was any co‐intervention or not (Hermantin 1999). The analysis was consistent with small heterogeneity (I2 = 15%). 6 Two trials had high risk of bias due to non‐adequate randomisation, allocation concealment and no blinding (Ryang 2008; Righesso 2007). One trial had unclear risk of bias due to non‐adequate randomisation, no allocation concealment, no blinding and unclear co‐intervention (Mayer 1993). In another trial, there was no blinding of participants, care provider and outcome assessor; and authors did not mention whether there was any co‐intervention or not (Hermantin 1999). The analysis was consistent with no heterogeneity (I2 = 0%). 7 One trial had unclear risk of bias due to non‐adequate randomisation, no allocation concealment, no blinding and unclear co‐intervention (Mayer 1993). In another trial, there was no blinding of participants, care provider and outcome assessor; and authors did not mention whether there was any co‐intervention or not (Hermantin 1999). There was statistically significant difference between minimally invasive discectomy and microdiscectomy/open discectomy. However, we downgraded the evidence because of high risk of bias and low precision due to small sample size. The analysis was consistent with no heterogeneity (I2 = 0%). 8 Only one trial had overall low risk of bias (Teli 2010). Both other trials had high risk of bias due to non‐adequate randomisation, allocation concealment and no blinding (Ryang 2008; Righesso 2007). There was no statistically significant difference between different types of minimally invasive discectomy (microendoscopic discectomy and minimal access trocar microdiscectomy) versus microdiscectomy. However, we downgraded the evidence because of high risk of bias and low precision due to small sample size. The analysis was consistent with no heterogeneity (I2 = 0%). 9 Six trials evaluated side effects of postoperative surgical infection. One trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had unclear allocation concealment and high risk of bias for blinding (Teli 2010). One trial had high risk of bias due to no clear randomisation method, no clear allocation concealment, no clear blinding of participants and personnel, no clear selective reporting and no clear intention‐to‐treat analysis (Garg 2011). One trial had high risk of bias due to no clear randomisation, no clear allocation concealment, no clear blinding and no clear intention‐to‐treat analysis (Huang 2005). One trial had high risk of bias because of non‐randomisation, no allocation, no blinding, no clear group similarity at baseline and no clear intention‐to‐treat analysis (Ruetten 2008). However, there was no blinding of participants, care provider and outcome assessor. Authors did not mention whether there was any co‐intervention or not. Lack of blindness, and unclear co‐intervention were major problems of the one trial that had no other risk of bias (Hermantin 1999). We downgraded the evidence due to the high risk of bias. One participant out of 431 had infection following minimally invasive discectomy versus 16 out of 500 participants in microdiscectomy/open discectomy. The analysis was almost consistent with small heterogeneity (I2 = 34%). 10 One trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had unclear allocation concealment and high risk of bias for blinding (Teli 2010). However, four other trials had high risk of bias because of non‐randomisation, no allocation and no blinding of participants and personnel (Garg 2011; Mayer 1993; Ruetten 2008; Ryang 2008). We downgraded the evidence to the low level due to high risk of bias and imprecision (wide 95% confidence intervals). The analysis was consistent with no heterogeneity (I2 = 0%). 11 One trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had high overall risk of bias because of non‐randomisation, no allocation concealment, no blinding, unclear group similarity at baseline and no clear intention‐to‐treat analysis (Ryang 2008). We downgraded the level of evidence due to the high risk of bias and low precision because of small number of trials. The analysis was consistent with no heterogeneity (I2 = 0%). | ||||||
Background
Lumbar discectomy involves removal of all or part of one or more intervertebral discs. Intervertebral discs separate and cushion the spinal vertebral bodies. In people with a protruded or herniated disc, the soft gel inside pushes through the wall of the disc. Pathophysiology of lumbar discopathy suggests that probably inflammation is more important than pressure. By removing part of the intervertebral disc, lumbar discectomy can relieve symptoms.
The lumbar discectomy procedure remained basically unchanged until the operating microscope enhanced the visualisation of the operative field in 1978. This new operation was described as lumbar microdiscectomy because it was performed through a smaller incision, with less dissection than open lumbar discectomy (Arts 2008). Microdiscectomy is generally regarded as a technical modification of standard discectomy, rather than a distinct procedure (Koebbe 2002). In one systematic review by Gibson and Waddell, results of microdiscectomy for treatment of lumbar disc prolapse were "broadly comparable" to results of open lumbar discectomy (Gibson 2007). Microdiscectomy is now the most common surgical procedure for lumbar disc herniation (Koebbe 2002).
More recently, several minimally invasive surgical approaches have been introduced for the surgical management of symptomatic lumbar disc herniation, utilising technologies to reduce incision size and the area of dissection further (Deen 2003). Systematic reviews have compared specific types of minimally invasive lumbar surgery for the management of lumbar disc herniation and radiculopathy (Dasenbrock 2012; Jacobs 2012; Nellensteijn 2010; Singh 2009a; Singh 2009b), but did not yield conclusive results, in part due to limited evidence. Given the availability of newer evidence, we performed a systematic review of the literature to evaluate the benefits and harms of minimally invasive discectomy (MID) versus microdiscectomy/open discectomy (MD/OD).
Description of the condition
Lumbar discopathy (disc herniation) often presents clinically as radiculopathy (sciatica), which results from compression of one or more spinal nerve roots, and manifests as radiating leg pain and paraesthesias (a sensation of tingling, burning and numbness), with or without a neurological deficit. Approximately 3% to 4% of people presenting with low back pain (LBP) have lumbar radiculopathy. Lumbar disc herniation, defined as displacement of central disc material (nucleus) beyond the margins of the intervertebral disc space, is considered to be the most common cause (90%) of radiculopathy (Hahne 2010; Koes 2007). In people who have severe symptoms refractory to conservative management for six to eight weeks, imaging studies are often indicated. If imaging demonstrates correlative disc pathology, the person may be a surgical candidate (Koes 2007). Progressive or severe neurological deficits is an indication for more urgent surgery. Neurological symptoms can manifest as progressive lower extremity muscle weakness or urinary or bowel (or both) incontinence. Surgical intervention for radiculopathy (discectomy) is based on removal of herniated disc materials to relieve nerve root irritation or compression or both (Gibson 2007).
Description of the intervention
Although the first lumbar disc surgery was performed in 1934 by Mixter and Barr (Mixter 1934), few technical changes occurred in this field until the 1970s, when the operating microscope and subsequent microdiscectomy were introduced. The use of an operating microscope allowed a smaller incision, with outcomes generally comparable to open discectomy (Gibson 2007). Microdiscectomy, or discectomy that is performed under microscope, is now a common procedure for the management of lumbar radiculopathy resulting from lumbar disc herniation (Arts 2008; Gibson 2007; Haines 2002; Thomé 2005; Tullberg 1993). Since the mid‐1970s, several minimally invasive procedures have been developed as alternatives to standard MD/OD. Minimally invasive spine surgeries use technologies to reduce incision size and the area of tissue dissection further (Krappel 2001), potentially resulting in reduced recovery time and better cosmetic results (Jaikumar 2002).
The first generation of minimally invasive procedures involved blind percutaneous techniques including chemonucleolysis, percutaneous nucleotomy (Kahanovitz 1990; Schreiber 1986), automated percutaneous nucleotomy (Stevenson 1995), and laser disc decompression (Mathews 2002). Newer techniques such as biportal arthroscopic intradiscal discectomy utilise rigid discoscopes and flexible endoscopes to provide additional visualisation of the operative field (Mathews 2002; Sharif‐Alhoseini 2011). Transmuscular tubular discectomy replaces the subperiosteal muscle dissection required in standard MD/OD with a muscle‐splitting transmuscular approach.
See Table 1 for a description of minimally invasive procedures included in this review.
| Reference | Minimal invasive procedure | Description of the procedure |
| Percutaneous nucleotomy | Under fluoroscopy in the posterior‐lateral position, a K‐wire was advanced into the intervertebral space and a dilator and working cannula were introduced into the disc space step by step. Discectomy was performed through the cannula using pituitary forceps | |
| Automated percutaneous discectomy | Through a lateral oblique percutaneous approach, and insertion of 2‐mm disk‐aspiration probe, nucleus pulposus was mechanically removed | |
| Percutaneous endoscopic lumbar discectomy (PELD) | The identified symptomatic disc can be dissected by interlaminar or transforaminal approach using endoscope | |
| Transmuscular tubular microdiscectomy | Tubular discectomy utilises a transmuscular approach rather than a subperiosteal dissection. In this method, a guidewire is inserted percutaneously into the inferior part of the lamina, and its location is confirmed using fluoroscopy. Then, dilators of increasing diameter are inserted sequentially over the guidewire. The tubular retractor is then inserted over the final dilator |
How the intervention might work
MD/OD removes the intervertebral disc portion that has compressed the nerve root or spinal cord, or both. MID procedures are performed using techniques that allow for smaller incisions or less dissection (or both) than microdiscectomy, potentially resulting in lower blood loss, less postoperative pain, shorter hospitalisation and earlier return to work compared with MD/OD (Deen 2003; Mathews 2002). Potential disadvantages of minimally invasive lumbar surgery include a sharp learning curve for the surgeon. In other words, the duration of surgical time of any new technique such as MID will decrease over the course of the learning curve, and evaluation of the efficacy of the MID against MD/OD may be affected by when the comparison occurred on the learning curve (Mathews 2002; Rahimi‐Movaghar 2009; Rahimi‐Movaghar 2010; Rahimi‐Movaghar 2011). In addition, studies have raised the question of whether minimally invasive procedures are as safe and efficient as expected (Arts 2011; Chatterjee 1995; Chung 1999; Fourney 2010; Franke 2009; Hermantin 1999; Krappel 2001; Lew 2001; Mayer 1993; Ruetten 2008).
Why it is important to do this review
Previous studies examining the efficacy and safety of different types of MID (percutaneous nucleotomy, automated percutaneous discectomy, percutaneous endoscopic lumbar discectomy (PELD), transmuscular tubular microdiscectomy) have yielded inconsistent findings. Given the availability of new evidence, the objective of this systematic review was to clarify whether these procedures provide an advantage compared with MD/OD.
Objectives
To compare the benefits and harms of MID versus MD/OD for management of lumbar intervertebral discopathy.
Methods
Criteria for considering studies for this review
Types of studies
For this review, we primarily considered randomised controlled trials (RCTs) and quasi‐randomised controlled trials (QRCTs) comparing MD/OD with a minimally invasive procedure. In RCTs, computer‐generated sequences or randomisation tables are typically used to allocate people to different groups. QRCTs use a method of allocation, such as date of birth or day of the week, which is not truly randomised, resulting in a greater risk of selection bias. We adapted our methodology to follow the recommendations of the Cochrane Back Review Group (Furlan 2009).
Types of participants
We selected studies of adults (aged greater than 12 years and less than 70 years) undergoing surgical treatment for lumbar radiculopathy secondary to herniated discs. Number of levels could be one or multiple. We did not exclude people based on gender or duration of symptoms. We excluded trials of people with lumbar radiculopathy due to causes other than prolapsed disc.
Types of interventions
We included trials of MID compared with MD/OD. We included MID procedures in which the treatment mirrored that of MD/OD in terms of removal of the problematic disc material. These MID procedures include percutaneous endoscopic interlaminar or transforaminal lumbar discectomy (Ditsworth 1998; Mathews 1996), transmuscular tubular microdiscectomy and automated percutaneous lumbar discectomy. We excluded trials of chemical nucleolysis, intradiscal electrothermal annuloplasty (Pauza 2004; Saal 2002), laser discectomy, the Dekompressor and Coblation nucleoplasty (radiofrequency radio waves) in which the mechanism of action involved destruction or disruption of the disc causing mechanical compression using energy or chemicals, rather than removal of disc materials.
Types of outcome measures
We evaluated clinical and functional outcome measures. Where outcome measures were composite, we tried to use item sub‐scores, but we also performed analyses at the composite level. We categorised follow‐up periods as immediately postoperative (first six weeks post operative, which is more a reflection of 'surgical' pain), short term (from six week's post‐operative to one year), medium term (one to five years) or long term (longer than five years).
Primary outcomes
We considered the following variables as primary outcomes:
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pain measure by visual analogue scale (VAS) for each of sciatica and LBP;
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sciatica‐specific outcomes: the Sciatica Bothersomeness Index (SBI) and the Sciatica Frequency Index (SFI) (Grøvle 2008);
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neurological deficit of lower extremity or bowel/urinary incontinence;
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functional outcome including daily activity and return to work, measured by scales such as the Oswestry Disability Index (ODI) or the Roland‐Morris Disability score.
Secondary outcomes
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Complications of surgery including mortality and common adverse events including:
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thromboembolic complications;
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surgical site and other infections;
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procedure‐related complications;
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re‐hospitalisation due to recurrent disc herniation;
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re‐hospitalisation due to other causes;
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surgical re‐intervention;
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dural tear.
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Duration of hospital stay.
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Opioid use.
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Quality of life measured by 36‐item Short Form (SF‐36) or 12‐item Short Form (SF‐12), and overall satisfaction of participants, which is usually reported using a Likert scale.
Search methods for identification of studies
Search strategies for the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE are in Appendix 1. We used specific search terms to identify studies of MID to exclude non‐randomised studies. We applied no language or date restrictions. We did not consider unpublished records in this review.
Electronic searches
We searched the following databases:
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CENTRAL (October 2013) (Ovid SP);
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MEDLINE (1946 to 22 November 2013) (Ovid SP);
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EMBASE (1974 to 22 November 2013) (Ovid SP) (Figure 1).
Study flow diagram.
Searching other resources
We contacted experts in the field and reviewed reference lists of relevant articles.
Data collection and analysis
Selection of studies
One review author (MRR) independently reviewed each title/abstract and list potentially relevant references. A second review author (VRM) checked data abstractions and articles for inclusion. We used a consensus process resolved discrepancies (MRR, VRM, MML, RC, FS).
Data extraction and management
We extracted data into pre‐developed forms. From each study, we collected basic information concerning authors (affiliation, sponsoring), methods (study design, sample size), participants (selection criteria and diagnoses, pain location, age, gender, neurological deficit, quality of life, functional disability), treatments (surgical technique, materials used, levels involved), control treatments (MD/OD) and outcome variables with results. Two review authors extracted data independently. A second review author re‐checked entered data; there were 0.85% minor errors, which were corrected.
Assessment of risk of bias in included studies
We assessed risk of bias using the 12 criteria recommended by the Cochrane Back Review Group (Furlan 2009) (Appendix 3). We scored the items as 'low risk', 'high risk' or 'unclear'. We considered studies to have a 'low risk of bias' overall when they met at least six of the 12 criteria and the study had no serious methodological flaws.
Authors of trials did not assess their own trial. We used the 'Risk of bias' assessment in sensitivity analysis to compare the results after excluding trials with high risk of bias compared with the results including all studies.
We pilot tested our assessment tool to ensure that a similar approach was used across the review team. Two review authors (MRR, VRM) independently assessed the study design and the risk of bias. We calculated the inter‐observer reliability for risk of bias assessment. There were 11 studies with 132 items for risk of bias. Both observers agreed on 84 low risk of bias and agreed on 34 high or unclear risk of bias. Two observers had disagreements in 14 (10+4) items. Therefore, observed agreement was 89%. Expected agreement was 57%. The kappa statistic (or kappa coefficient) was 0.74, which we considered as substantial agreement. Two observers worked together and solved 14 out of 132 items. We contacted authors of trials published since the mid‐2000s to obtain missing information about study methods (randomisation, allocation concealment, blinding).
Measures of treatment effect
We extracted both dichotomous outcomes expressed or calculated as risk ratios (RR) and continuous outcomes reported or calculated as mean difference (MD). For dichotomous outcomes, we reported risk differences in addition to RR estimates. However, for outcomes such as functional status or quality of life, which are measured using different scales, we reported the standardised mean difference (SMD). When calculating an MD, we converted scales to similar measures (e.g. all measures converted to a 100‐ or 10‐point scale). We extracted or calculated a 95% confidence interval (CI) for each outcome. We evaluated clinical relevance with the five questions listed in Appendix 2 (Furlan 2009). We used the guideline suggested by Ostelo 2008 to define clinically important changes.
We summarised effects according to the timing of the outcomes: immediately postoperative (first six weeks' post operative), short term (from six weeks' postoperative to one year), medium term (one to five years) or long term (longer than five years).
Unit of analysis issues
For cluster randomised trials, we conducted the analysis at the same level as the allocation, using a summary measurement from each cluster. If data were available at the individual level, we analysed these data while accounting for the cluster design.
Dealing with missing data
We contacted authors of included trials to request missing information about methodological properties (randomisation, allocation concealment, blinding) and missing data including missing standard deviations (SD) of the trials. We only included trials that were missing less than 20% of clinical data for immediate, short‐ and medium‐term follow‐ups in the analysis. We estimated missing information about parameter variability from ranges if provided, or estimated from comparable trials.
Assessment of heterogeneity
We examined whether the included studies were sufficiently clinically similar by examining the populations, interventions, controls and outcomes (PICO) and other study characteristics (e.g. study design: RCT or QRCT). We did not pool studies with large clinical or statistical differences.
We evaluated statistical heterogeneity by assessing for non‐overlapping CIs, and defined significant statistical heterogeneity as a Q‐test with a P value lower than 0.1 or an I2 statistic greater than 75. If we determined that the results were too heterogeneous to pool, we tried to identify explanations for the heterogeneity through subgroup and sensitivity analyses (see Sensitivity analysis). As background factors such as mean age of the participants and sex ratio may affect treatment outcome, we also tried to adjust these factors using meta‐regression by STATA.
Assessment of reporting biases
We did not formally assess for publication bias because there were too few studies to perform visual or statistical methods for markers of publication bias reliably (e.g. small sample effects).
Data synthesis
Clinical homogeneity is a prerequisite for pooling studies in a meta‐analysis. In the case of statistical heterogeneity, we tried to find an explanation using subgroup and sensitivity analyses. We described individual studies that could not be pooled narratively.
Regardless of whether there were sufficient data available to perform quantitative analyses to summarise the data, we assessed the overall quality of the evidence for each outcome. To accomplish this, we used the GRADE approach, as recommended in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011), and adapted in the updated Cochrane Back Review Group guidelines (Furlan 2009). Factors that may decrease the quality of the evidence are: study design and risk of bias, inconsistency of results, indirectness (not generalisable), imprecision (sparse data) and other factors (e.g. reporting bias). The quality of the evidence for a specific outcome was reduced by one level, according to the performance of the studies against these five factors.
-
High quality evidence: there were consistent findings among at least 75% of RCTs with no limitations of the study design, consistent, direct and precise data and no known or suspected publication biases. Further research is unlikely to change either the estimate or our confidence in the results.
-
Moderate quality evidence: one of the domains was not met. Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
-
Low quality evidence: two of the domains were not met. Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
-
Very low quality evidence: three of the domains were not met. We are very uncertain about the results.
-
No evidence: no RCTs were identified that addressed this outcome.
We used five questions listed in Appendix 2 to evaluate the clinical relevance of the review results. The results of this assessment informed the final results and conclusions.
Subgroup analysis and investigation of heterogeneity
To investigate heterogeneity, we analysed subgroups according to participant characteristics, including neurological deficit, radicular pain and LBP. We also analysed subgroups according to the different surgical procedures in specific minimally invasive techniques and in two subgroups of microdiscectomy and discectomy.
Sensitivity analysis
If we had a sufficient number of studies and comparisons, we used sensitivity analyses to determine the robustness of the review findings. In particular, we performed sensitivity analysis to determine whether the results of the review change when trials are excluded for the following reasons: 1. high risk of bias, 2. unclear methods of randomisation and 3. missing data were estimated. We also included the source of funding in the sensitivity analysis comparing studies that were funded by the industry with studies that were funded by other sources (government, non‐profit organisations and institutions).
Results
Description of studies
We identified 11 studies (sample sizes ranged from 22 to 325 participants; total number of participants across studies was 1172) of MID versus microdiscectomy/discectomy (Arts 2011; Chatterjee 1995; Garg 2011; Hermantin 1999; Huang 2005; Mayer 1993; Righesso 2007; Ruetten 2008; Ryang 2008; Shin 2008; Teli 2010). Eight studies evaluated PELD, one of these eight studies simultaneously evaluated transforaminal and intralaminar endoscopic discectomy, two studies evaluated transmuscular tubular microdiscectomy and one study evaluated automated percutaneous discectomy. We assessed four out of 11 studies as having low overall risk of bias with clear methods of random sequence generations (Arts 2011; Hermantin 1999; Shin 2008; Teli 2010). We assessed the remaining seven studies as having high overall risk of bias or unclear/non‐random sequence generations. With regards to the comparison groups, eight studies evaluated microdiscectomy and three studies evaluated open discectomy. Microdiscectomy was performed by microscope magnification in six studies; headlight loupe in one study and with both microscope magnification and headlight loupe in one study. Duration of follow‐up in the studies ranged from six to 56 months. One study only evaluated participants in the first five days post operation (Shin 2008).
Results of the search
Searches identified 841 references. After exclusion of 370 duplicates, 471 references remained: 74 from CENTRAL, 261 from MEDLINE and 136 from EMBASE. We added three additional references from other resources. Eleven studies met inclusion criteria.
For some of the studies there were missing data or missing information (or both) relevant to the risk of bias assessment. We requested this information from study authors but did not receive any additional information.
Included studies
We included 11 studies (Arts 2011; Chatterjee 1995; Garg 2011; Hermantin 1999; Huang 2005; Mayer 1993; Righesso 2007; Ruetten 2008; Ryang 2008; Shin 2008; Teli 2010).
Excluded studies
We excluded five studies because they compared MD versus OD or discectomy versus sequestrectomy or different types of MID (Henriksen 1996; Lagarrigue 1994; Thomé 2005; Tullberg 1993; Türeyen 2003). We excluded a retrospective observational comparison of MID and discectomy (Harrington 2008). Finally, we excluded three RCTs because they did not meet our inclusion criteria (Franke 2009; Karasek 2000; van den Akker 2011). See Characteristics of excluded studies tables for more details.
Risk of bias in included studies
We assessed seven out of 11 studies as having high overall risk of bias (Chatterjee 1995; Garg 2011; Huang 2005; Mayer 1993; Righesso 2007; Ruetten 2008; Ryang 2008). We described risk of bias for each study in the 'Risk of bias' tables, and the ratings across studies are summarised in Figure 2.
Risk of bias summary: review authors' judgements about each risk of bias item for each included study.
Allocation
We assessed four studies as having low risk for random sequence generation (Arts 2011; Hermantin 1999; Shin 2008; Teli 2010). However, only two studies reported allocation concealment and we assessed these as having low risk for selection bias (Arts 2011; Hermantin 1999). We assessed eight studies as having unclear risk of selection bias (Chatterjee 1995; Garg 2011; Huang 2005; Mayer 1993; Righesso 2007; Ryang 2008; Shin 2008; Teli 2010). We assessed one study as having high risk of selection bias (Ruetten 2008), due to inadequate generation of a randomised sequence and inadequate concealment of allocations prior to assignment.
Blinding
No study was blinded to both participants and outcome assessors. Six studies did not clearly report use of both types of blinding (Chatterjee 1995; Garg 2011; Huang 2005; Mayer 1993; Ryang 2008; Shin 2008), and five were not blinded (Arts 2011; Hermantin 1999; Righesso 2007; Ruetten 2008; Teli 2010).
Incomplete outcome data
We assessed all studies as having low risk of attrition bias except two studies that did not mention it clearly (Ryang 2008; Shin 2008).
Selective reporting
We assessed all studies as having low risk of selective reporting bias except one study that did not mention it clearly (Garg 2011).
Other potential sources of bias
We identified no other potential sources of biases in four studies (Arts 2011; Hermantin 1999; Mayer 1993; Teli 2010). We assessed six studies as having unclear risk of bias related to use of intention‐to‐treat analysis (Garg 2011; Huang 2005; Righesso 2007; Ruetten 2008; Ryang 2008; Shin 2008). We assessed two studies as having high risk of bias related to group differences at baseline (Chatterjee 1995; Righesso 2007). Two other studies did not mention anything about group difference at baseline. Therefore, we rated them as having unclear risk of bias (Ruetten 2008; Shin 2008). Authors did not send us any additional information for missing data, including unclear risk of bias and on SDs).
Effects of interventions
Results for comparisons between MID versus MD/OD are shown in Table 2. We were unable to perform meta‐regression due to the small number of trials.
| S1 | S2 | S3 | S4 | S5 | S6 | S7 | S8 | S9 | S10 | S11 | |
| Q1 | c | b | a | a | a | a | a | a1/a2 | c | a | a |
| Q2 | 1 | 1 | 2 | 2 | 2 | 1 | 1b | 1 | 1 | 1 | 1a/1b |
| PO1 | + | ‐ | ‐ | ‐ | ‐ | ‐ | + | ‐ | ‐ | + | + |
| PO2 | + | ‐ | ‐ | + | + | + | + | + | + | + | + |
| PO2a | + | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ |
| PO2b | + | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ |
| PO3a | ‐ | ‐ | ‐ | + | ‐ | + | + | ‐ | + | ‐ | + |
| PO3b | ‐ | ‐ | ‐ | + | ‐ | + | + | ‐ | + | ‐ | ‐ |
| PO3c | ‐ | ‐ | ‐ | + | ‐ | + | + | ‐ | ‐ | ‐ | ‐ |
| PO3d | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | + | ‐ | ‐ |
| PO3e | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ |
| PO4a1 | ‐ | ‐ | + | ‐ | ‐ | ‐ | + | + | + | ‐ | + |
| PO4a2 | + | ‐ | ‐ | + | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ |
| PO4b | + | ‐ | ‐ | + | ‐ | ‐ | ‐ | + | ‐ | ‐ | ‐ |
| SO1 | ‐ | ‐ | + | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | + |
| SO1a | + | ‐ | + | ‐ | + | ‐ | ‐ | + | + | ‐ | ‐ |
| SO1b | + | ‐ | + | + | + | ‐ | ‐ | + | ‐ | ‐ | + |
| SO1c | + | ‐ | + | ‐ | ‐ | ‐ | ‐ | + | ‐ | ‐ | ‐ |
| SO1d | + | ‐ | + | ‐ | ‐ | + | ‐ | + | + | ‐ | + |
| SO1e | + | ‐ | + | ‐ | ‐ | ‐ | ‐ | + | ‐ | ‐ | ‐ |
| SO1f | + | ‐ | + | ‐ | ‐ | + | ‐ | + | + | ‐ | ‐ |
| SO1g | + | ‐ | + | ‐ | ‐ | ‐ | ‐ | + | + | ‐ | + |
| SO2 | + | + | + | ‐ | + | ‐ | + | ‐ | + | ‐ | ‐ |
| SO3 | ‐ | ‐ | + | + | ‐ | ‐ | ‐ | + | ‐ | ‐ | ‐ |
| SO4a | + | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | + | ‐ | + |
| SO4b | ‐ | ‐ | + | + | + | ‐ | ‐ | + | ‐ | ‐ | ‐ |
| No. | 325 | 71 | 112 | 60 | 22 | 40 | 40 | 200 | 60 | 30 | 212 |
| Severity | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ |
| Age (years) | 18‐70 | NA | 26‐57 | 15‐67 | 39 ± 11 | 12‐55 | < 60 | 20‐68 | 21‐69 | 43 ± 18/ 48 ± 11 | 18‐65 |
| M : F MID | 84 : 82 | NA | 36 : 19 | 22 : 8 | 6 : 4 | 12 : 8 | 10 : 11 | 84 : 116 | 13 : 17 | 7 : 8 | 45 : 25 |
| M : F M/D | 88 : 71 | NA | 44 : 13 | 17 : 13 | 9 : 3 | 14 : 6 | 13 : 6 | 19 : 11 | 5 : 10 | 94 : 48 | |
| F/O | ≥ 24 | ≥ 6 | 12‐18 | 19‐42 | 10‐25 | ≥ 24 | 24‐56 | ≥ 24 | 6‐26 | 5 days | 24‐29 |
Q1. Minimally invasive discectomy
a. percutaneous endoscopic discectomy (1. transforaminal = lateral approach; 2. interlaminar = posterior approach),
b. automated percutaneous discectomy,
c. transmuscular tubular microdiscectomy (guidewire, sequential dilators, tubular retractor with microscopic magnification)
Q2. Microdiscectomy/discectomy
-
Microdiscectomy (a. microscope magnification, b. headlight loupe)
-
Discectomy (without microscope or loupe)
-
Microdiscectomy/discectomy (with or without magnification by microscope or headlight loupe)
++. failure to respond to non‐operative measures ‐ 4‐8 weeks of conservative treatment with rest, analgesia, non‐steroidal anti‐inflammatory drugs and physiotherapy
M : F MID. Male : female ratio in the minimal invasive discectomy group
M : F M/D. Male : female ratio in the micro/discectomy
F/O: duration of follow‐up (range in months; exception is S10 with 5 days' follow‐up)
Primary outcomes (PO)
PO1a. Leg pain assessed by visual analogue scale (VAS)
PO1b. Low back pain assessed by VAS
PO2a. Sciatica Bothersomeness Index (SBI)
PO2b. Sciatica Frequency Index (SFI)
PO3a. Persistent motor deficit
PO3b. Persistent sensory deficit
PO3c. Persistent reflex changes
PO3d. Persistent urinary incontinence
PO3e. Persistent bowel incontinence
PO4a. Functional outcome: daily activity ‐ 1. Oswestry Disability Index; 2. Roland‐Morris Disability score
PO4b. Functional outcome: return to work/duration postoperative disability
Secondary outcomes (SO)
SO1. Complications ‐ mortality
SO1a. Complications ‐ thromboemboli ‐ deep vein thrombosis (DVT)
SO1b. Complications ‐ surgical site and other infections ‐ urinary tract infection (UTI)
SO1c. Complications ‐ procedure related
SO1d. Complications ‐ re‐hospitalisation due to recurrent disc herniation
SO1e. Complications ‐ re‐hospitalisation due to other causes
SO1f. Complications ‐ surgical re‐intervention
SO1g. Complications ‐ dural tear
SO2. Duration of hospital stay
SO3. Postoperative opioid use
SO4a. Quality of life measured by 36‐item Short Form (SF‐36) or 12‐item Short Form (SF‐12)
SO4b. Overall satisfaction of participants
No. = total number of participants in each study
Studies:
S1. Arts 2011
S2. Chatterjee 1995
S3. Garg 2011
S4. Hermantin 1999
S5. Huang 2005
S6. Mayer 1993
S7. Righesso 2007
S8. Ruetten 2008
S9. Ryang 2008
S10. Shin 2008
S11. Teli 2010
Outcome assessment was performed in the study: positive (+)
Outcome assessment was not performed in the study: negative (‐)
Outcome summary
Primary outcomes (PO)
1. Pain measure by VAS for each of:
-
sciatica (PO1a) ‐ Analysis 1.1; Analysis 1.2; Analysis 1.3; Analysis 1.4;
-
LBP (PO1b) ‐ Analysis 2.1; Analysis 2.2.
2. Sciatica‐specific outcomes:
-
SBI (PO2a) ‐ data and analysis: not available;
-
SFI (Grøvle 2008) (PO2b) ‐ data and analysis: not available.
3. Neurological deficit of lower extremity:
-
motor (PO3a) ‐ Analysis 3.1;
-
sensory (PO3b) ‐ Analysis 3.2;
-
reflex change (PO3c) ‐ Analysis 3.3;
-
bowel (PO3d) ‐ Analysis 3.4;
-
urinary incontinence (PO3e).
4. Functional outcome:
-
daily activity ‐ ODI (PO4a1) ‐ Analysis 4.1;
-
Roland‐Morris Disability score (PO4a2);
-
return to work (PO4b1) ‐ Analysis 4.2;
-
postoperative work disability days (PO4b2) ‐ Analysis 4.3.
Secondary outcomes (SO)
1. Complications of surgery (SO1):
-
mortality (SO1);
-
common adverse events:
-
thromboembolic complications (SO1a);
-
surgical site and other infections including urinary tract infections (UTI) (SO1b) ‐ Analysis 5.1;
-
procedure‐related complications (SO1c) ‐ Analysis 5.2;
-
re‐hospitalisation due to recurrent disc herniation (SO1d) ‐ Analysis 5.3;
-
re‐hospitalisation due to other causes (SO1e);
-
surgical re‐intervention (SO1f) ‐ Analysis 5.4;
-
dural tear (SO1g) ‐ Analysis 5.5.
-
2. Duration of hospital stay (SO2)
3. Postoperative opioid use (SO3)
4. Quality of life:
-
measured by SF‐36 or SF‐12 (SO4a) ‐ Analysis 6.1; Analysis 6.2; Analysis 6.3; Analysis 6.4; Analysis 6.5;
-
overall success/satisfaction of participants (SO4b) ‐ Analysis 6.6; Analysis 7.1;
-
Preoperative pain versus postoperative pain at 12 months ‐ Analysis 8.1.
Subgroup analyses
A. MID versus microdiscectomy (not open discectomy)
B. Microendoscopy versus MD/OD for leg pain ‐ Analysis 9.1; LBP ‐ Analysis 9.2; ODI ‐ Analysis 9.3 and re‐operations due to recurrent of discopathy ‐ Analysis 9.4.
Primary outcomes
PO1a. Leg pain assessed by visual analogue scale
Four trials (599 participants) examined leg pain from six months' to two years' follow‐up (Arts 2011; Huang 2005; Mayer 1993; Teli 2010) (Figure 3). Two trials had unclear risk of bias due to non‐adequate randomisation, no allocation concealment and no blinding (Huang 2005; Mayer 1993). Meanwhile, Huang 2005 had no clear intention‐to‐treat analysis and Huang 2005 and Mayer 1993 had unclear co‐interventions. One trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had unclear allocation concealment and high risk of bias for blinding (Teli 2010). We downgraded the level of evidence to low due to the high risk of bias and the small number of participants for minimally invasive techniques. The analysis was consistent with no heterogeneity (I2 = 0%). Based upon four studies, MID was associated with slightly greater leg pain versus MD/OD at 12 months (MD 0.13 on a 0 to 10 scale, 95% CI 0.09 to 0.16) (Figure 3) (summary of findings Table for the main comparison ‐ Leg pain). In both the MID and MD/OD groups, leg pain scores improved significantly from baseline to one year. Following MID, pain decreased a mean of 5.8 points on a 0 to 10 scale (95% CI 5.57 to 6.03), and following MD/OD, pain decreased 6.45 points (95% CI 6.25 to 6.64). One trial found tubular discectomy associated with slightly more leg pain from one to 104 weeks after MID than microdiscectomy (MD 3.3, 95% CI 0.2 to 6.2) (Arts 2011), but three other trials found no difference between endoscopic discectomy and MD/OD (MD 0.08, 95% CI ‐0.04 to 0.20). One trial found no difference in postoperative leg pain between microendoscopic discectomy (MED) and microdiscectomy from one to five days (Shin 2008).
Forest plot of comparison: Outcome 1. Leg pain in two groups of minimally invasive discectomy (MID) and micro/discectomy, medium term (one to five years).
PO1b. Low back pain assessed by visual analogue scale
Three trial (577 participants) examined LBP at 6‐month follow‐up (Arts 2011; Righesso 2007; Teli 2010) (Figure 4). One trial had high risk of bias due to non‐adequate randomisation, no allocation concealment, no blinding, group differences at baseline and no clear intention‐to‐treat analysis (Righesso 2007). One trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had unclear allocation concealment and high risk of bias for blinding (Teli 2010). We downgraded the level of evidence to low due to the high risk of bias and the small number of participants for minimally invasive techniques. The analysis was almost consistent with low heterogeneity (I2 = 35%). Therefore, there was low‐quality evidence that MID (tubular discectomy or endoscopic discectomy) was associated with slightly greater LBP versus MD/OD at six months (MD 0.35 on a 0 to 10 scale, 95% CI 0.19 to 0.51) and at two years (MD 0.54 on a 0 to 10 scale, 95% CI 0.29 to 0.79). There was no significant difference at one year (MD 0.19 on an 0 to 10 scale, 95% CI ‐0.22 to 0.59). Statistical heterogeneity was small to high (I2 = 35% at six months, 90% at one year and 65% at two years) (Figure 4) (summary of findings Table for the main comparison ‐ LBP). Pooled results were similar to results from the largest trial (325 participants), which compared tubular discectomy versus microdiscectomy. In both the MID and MD/OD groups, LBP scores improved significantly from baseline to one year. Following MID, pain decreased a mean of 1.31 points on an 0 to 10 scale (95% CI 1.25 to 1.38), and following micro/discectomy, pain decreased 1.49 points (95% CI 1.39 to 1.58). One study found MED associated with lower LBP intensity at one to five days' follow‐up versus microdiscectomy (Shin 2008).
Forest plot of comparison: Outcome 2. Low back pain in two groups of minimally invasive discectomy (MID) and micro/discectomy at six months, one year and two years.
PO2a. Sciatica Bothersomeness Index
Based on one trial (325 participants), there was low‐quality evidence of no statistically significant difference between tubular discectomy versus microdiscectomy on the SBI from one to 104 weeks (MD 0.5 on a 0 to 24 scale, 95% CI ‐0.3 to 1.3) (Arts 2011). We rated the quality of evidence as low due to availability of only one trial reporting SBI and imprecision/sparse data.
PO2b. Sciatica Frequency Index
Based on one trial (325 participants), there was low‐quality evidence of no statistically significant difference between tubular discectomy versus microdiscectomy on the SFI at 12 months (MD 0.5 on a 0 to 24 scale, 95% CI ‐0.5 to 1.4) (Arts 2011). We rated the quality of evidence as low due to availability of only one trial reporting SFI, and imprecision/sparse data.
PO3a. Persistent motor deficit
Based on four studies (126 participants who had preoperative motor deficit), there was low‐quality evidence of no statistically significant difference between MID and MD/OD for persistent motor deficit at at least six months' follow‐up (RR 0.96, 95% CI 0.56 to 1.63) (Hermantin 1999; Mayer 1993; Righesso 2007; Ryang 2008). Statistical heterogeneity was low (I2 = 15%), despite variability across studies in the proportion of participants with motor deficits that resolved and in the duration of follow‐up (range six to 56 months). We rated the quality of evidence as low due to the high risk of bias and small number of participants with motor deficits in the studies, resulting in imprecise estimates.
PO3b. Persistent sensory deficit
Based on four studies (165 participants who had preoperative sensory deficit), there was low‐quality evidence of no statistically significant difference between MID and MD/OD for persistent sensory deficit at at least six months' follow‐up (RR 0.86, 95% CI 0.65 to 1.15) (Hermantin 1999; Mayer 1993; Righesso 2007; Ryang 2008). Statistical heterogeneity was very low (I2 = 0%), despite variability in the proportion of participants with sensory deficits that resolved and duration of follow‐up. One trial showed most participants improved completely following either endoscopic discectomy or microdiscectomy 24 months after operation (persistent deficit in 1/13 participants following endoscopic discectomy and 5/16 participants following microdiscectomy) (Mayer 1993). In one trial, persistent sensory neurological deficits were reported in 16/26 participants following endoscopic discectomy and 18/28 participants following discectomy after at least 19 months (Hermantin 1999). We rated the quality of evidence as very low due the high risk of bias, small number of participants with baseline sensory deficits and the use of subjective evaluations to assess this outcome.
PO3c. Persistent reflex changes
Based on two studies (47 participants who had preoperative reflex changes), there was low‐quality evidence of statistically significant difference between percutaneous endoscopic discectomy and microdiscectomy or open discectomy for persistent reflex changes at 12 months' follow‐up (RR 0.68, 95% CI 0.49 to 0.96) (Hermantin 1999; Mayer 1993). Statistical heterogeneity was low (I2 = 0%), despite variability in the proportion of participants with reflex changes that resolved and duration of follow‐up. One trial showed most participants improved completely in both groups of endoscopic discectomy (persistent deficit in 2/10 participants) and microdiscectomy (persistent deficit in 2/7 participants) 24 months after operation (Mayer 1993). In the other study, persistent reflex changes were reported with 12/18 participants that underwent endoscopic discectomy and 12/12 participants who underwent standard discectomy (Hermantin 1999). We rated the quality of evidence as low due the high risk of bias and small number of participants with baseline reflex changes. We did not consider this a significant change because of the role of just one study with small number of participants in the analysis (RR 0.68, 95% CI 0.49 to 0.96) (Hermantin 1999).
PO3d. Persistent bowel incontinence
One study reported persistent bowel incontinence, but included no participants with bowel incontinence at baseline (Righesso 2007). Therefore, there was no evidence for the role of MID and MD/OD on postoperative persistent bowel incontinence.
PO3e. Persistent urinary incontinence
Two studies evaluated persistent urinary incontinence, but only included three participants with urinary incontinence at baseline, resulting in unreliable estimates and no evidence for the role of MID and MD/OD on postoperative persistent urinary incontinence (Righesso 2007; Ryang 2008).
PO4a1 and 4a2. Functional outcome: daily activity ‐ Oswestry Disability Index and Roland‐Morris Disability score
Based on five studies (624 participants), there was moderate‐quality evidence due to the high risk of bias of no statistically significant difference between MID and MD/OD on the ODI at more than six months (MD 0.84 on a 0 to 100 scale, 95% CI ‐0.21 to 1.88; I2 = 0%) (summary of findings Table for the main comparison ‐ ODI) (Garg 2011; Righesso 2007; Ruetten 2008; Ryang 2008; Teli 2010). All trials found no significant difference between different types of MID (four studies of MED and one study of minimal access trocar microdiscectomy) versus MD/OD.
Based on one trial (325 participants), there was low‐quality evidence of no statistically significant difference between MID and microdiscectomy on the Roland‐Morris Disability score at most follow‐up time points between four and 104 weeks after surgery (Arts 2011). A statistically significant difference in favour of microdiscectomy over transmuscular tubular microdiscectomy was reported at 52 weeks' follow‐up (MD 1.3, 95% CI 0.03 to 2.6). We rated the quality of evidence as low due to availability of only one trial reporting this outcome, and imprecision/sparse data.
PO4b1. Functional outcome: return to work
Based on one study (60 participants), there was low‐quality evidence of no statistically significant difference between endoscopic discectomy and discectomy for return to work at 19 to 42 months' follow‐up (OR 2.07, 95% CI 0.18 to 24.15) (Hermantin 1999). Twenty‐nine out of 30 participants in endoscopic discectomy and 28/30 participants in discectomy returned to their work. We rated the quality of evidence as low due to only one trial reporting return to work, and imprecision/sparse data.
PO4b2. Functional outcome: postoperative work disability days
Two trials (503 participants) reported inconsistent results for the outcome postoperative work disability days at 24 months' follow‐up (Arts 2011; Ruetten 2008). One study found no clear difference in length of postoperative work disability between transmuscular tubular microdiscectomy (2 weeks, 95% CI 1.6 to 2.4) versus microdiscectomy (2.1 weeks, 95% CI 1.8 to 2.5) (Arts 2011). The other study reported fewer mean postoperative work disability days following percutaneous endoscopic discectomy (24 days) versus microdiscectomy (49 days), but did not report the SD (Ruetten 2008). We rated the quality of evidence as very low due to the high risk of bias, small number of trials and presence of inconsistency.
Secondary outcomes
SO1. Complications ‐ mortality
One study (212 participants) reported mortality but reported no deaths after at least six months of follow‐up (Teli 2010).
SO1a. Complications ‐ thromboemboli ‐ deep vein thrombosis
Based on one study (325 participants), there was low‐quality evidence due to the high risk of bias, one single trial and the small number of participants of no statistically significant difference between MID and MD/OD for thromboemboli and deep vein thrombosis after at least six months' follow‐up (Arts 2011). Statistically heterogeneity was not applicable.
SO1b. Complications ‐ surgical site and other infections including urinary tract infection
Six trials (931 participants) evaluated side effects of postoperative surgical infection (Arts 2011; Garg 2011; Hermantin 1999; Huang 2005; Ruetten 2008; Teli 2010) (Figure 5). One trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had unclear allocation concealment and high risk of bias for blinding (Teli 2010). One trial had high risk of bias due to no clear randomisation, no clear allocation concealment, no clear blinding of participants and personnel, no clear selective reporting and no clear intention‐to‐treat analysis (Garg 2011). One trial had high risk of bias due to no clear randomisation, no clear allocation concealment, no clear blinding and no clear intention‐to‐treat analysis (Huang 2005). One trial had high risk of bias because of non‐randomisation, no allocation, no blinding, no clear group similarity at baseline and no clear intention‐to‐treat analysis (Ruetten 2008). However, no blinding of participants, care provider and outcome assessor and no clear co‐intervention were major problems of the one trial that had no other risk of bias (Hermantin 1999). We downgraded the level of evidence to the moderate level due to the high risk of bias. One participant (1/431) had infection following MID versus 16/500 participants following MD/OD. The analysis was almost consistent with small heterogeneity (I2 = 34%). Therefore, based upon six studies, MID was associated with lower risk of surgical site and other infections including UTI versus MD/OD after at least six months' follow‐up (RR 0.23, 95% CI 0.07 to 0.79).
Forest plot of comparison: Secondary outcome ‐ complication ‐ surgical sites and other infections
SO1c. Complications ‐ procedure related
Based on seven studies (991 participants), there was low‐quality evidence of no statistically significant difference between MID and MD/OD for procedure‐related complications after at least six months' follow‐up (RR 1.01, 95% CI 0.61 to 1.66) (Arts 2011; Garg 2011; Hermantin 1999; Huang 2005; Ruetten 2008; Ryang 2008; Teli 2010). Statistical heterogeneity was low (I2 = 33%). We rated the quality of evidence as low due to high risk of bias and some imprecision in estimates.
SO1d. Complications ‐ re‐hospitalisation due to recurrent disc herniation
Six studies (949 participants) evaluated re‐hospitalisation due to recurrent disc herniation (Arts 2011; Garg 2011; Mayer 1993; Ruetten 2008; Ryang 2008Teli 2010) (Figure 6). One trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had unclear allocation concealment and high risk of bias for blinding (Teli 2010). However, four other trials had high risk of bias because of non‐randomisation, no allocation concealment, and no blinding of participants and personnel (Garg 2011; Mayer 1993; Ruetten 2008; Ryang 2008). We downgraded the evidence to the low level due to high risk of bias and imprecision (high 95% CI). The analysis was consistent with no heterogeneity (I2 = 0%). Based on six studies, there was low‐quality evidence that MID was associated with increased risk of re‐hospitalisation due to recurrent disc herniation versus MD/OD after at least 12 months' follow‐up (RR 1.74, 95% CI 1.03 to 2.94) (Arts 2011; Garg 2011; Mayer 1993; Ruetten 2008; Ryang 2008Teli 2010).
Forest plot of comparison: Secondary outcome 1e ‐ complications ‐ re‐hospitalisation due to recurrent disc herniation six months or greater.
SO1e. Complications ‐ re‐hospitalisation due to other causes
No study evaluated re‐hospitalisation die to other causes.
SO1f. Complications ‐ surgical re‐intervention
Based on three studies (425 participants), there was low‐quality evidence of no statistically significant difference between MID and MD/OD for surgical re‐intervention after at least six months' follow‐up (RR 1.46, 95% CI 0.68 to 3.14) (Arts 2011; Mayer 1993; Ryang 2008). Statistically heterogeneity was low (I2 = 15%). We rated the quality of evidence as low due to the high risk of bias and the small number of events, resulting in imprecise estimates.
SO1g. Complications ‐ dural tear
Based on five studies (887 participants), there was low‐quality evidence of no statistically significant difference between MID and MD/OD for dural tear (RR 1.63, 95% CI 0.82 to 3.22, I2 = 16%) (Arts 2011; Garg 2011; Ruetten 2008; Ryang 2008; Teli 2010). We rated the quality of evidence as low due to high risk of bias and some imprecision in estimates.
SO2. Duration of hospital stay
Five studies (731 participants) examined duration of hospital stay (Arts 2011; Garg 2011; Huang 2005; Ryang 2008; Teli 2010). One study was an outlier with large effect size and unusually high duration of hospital stay for MD/OD (mean 12 days, range 5 to 21) (Garg 2011). Inclusion of this study in the meta‐analysis produced high heterogeneity (I2 = 99%) and significant difference between MID and MD/OD regarding duration of hospital stay (MD ‐2.29, 95% CI ‐4.15 to ‐0.43). In stratified analyses based on the specific minimally invasive technique used, two trials found no difference between tubular microdiscectomy and microdiscectomy (MD ‐0.01, 95% CI ‐0.26 to 0.23, I2 = 0%) (Arts 2011; Ryang 2008). Three trials of endoscopic discectomy reported inconsistent results, with differences versus micro/discectomy ranging from ‐9.0 to +0.21 days (Garg 2011; Huang 2005; Teli 2010). We rated the level of evidence as very low due to the inconsistency, high risk of bias and the small number of participants for specific minimally invasive techniques.
SO3. Postoperative opioid use
Based on only one study (60 participants), there was low‐quality evidence (due to the small number of trials (imprecision)) of no statistically significant difference between endoscopic discectomy and discectomy for postoperative opioid use at 19 to 42 months' follow‐up (OR 0.06, 95% CI 0.00 to 1.15) (Hermantin 1999). Zero out of 30 participants who underwent endoscopic discectomy and 6/30 participants who underwent open discectomy used postoperative opioids.
SO4a. Health‐related quality of life measured by 36‐item Short Form or 12‐item Short Form
Two trials evaluated HRQoL (Arts 2011; Ryang 2008). Ryang 2008 had high overall risk of bias. We downgraded the level of evidence to low due to the high risk of bias and small number of participants. The analysis was consistent with no heterogeneity (I2 = 0%). Based on two studies (385 participants), there was no statistically significant difference between MID and MD/OD in the Physical Health component summary of the SF‐36 at six months' follow‐up (MD 0.96, 95% CI ‐0.12 to 2.03) (Arts 2011; Ryang 2008). However, MID was associated with worse quality on life on three Physical Health component subclasses: Physical Functioning (MD ‐4.70, 95% CI ‐5.05 to ‐4.35), Bodily Pain (MD ‐3.70, 95% CI ‐4.11 to ‐3.28) and General Health (MD ‐2.52, 95% CI ‐2.92 to ‐2.11). There was no significant difference on the Mental Health component summary score at six months' follow‐up (MD ‐4.31, 95% CI ‐9.96 to 1.33).
SO4b. Overall success/satisfaction of participants
Based on five studies (443 participants), there was moderate‐quality evidence due to the high risk of bias of no statistically significant difference between MID and MD/OD for participant‐rated overall satisfaction after at least six months' follow‐up (OR 1.04, 95% CI 0.99 to 1.10) (Chatterjee 1995; Garg 2011; Hermantin 1999; Huang 2005; Ruetten 2008). There was no heterogeneity (I2 = 0%).
Summary for quality of evidence
There was moderate‐quality evidence for lower side effects of surgical site and other infections after at least six months' follow‐up for MID versus MD/OD. However, there was low‐quality evidence for higher leg pain, LBP, side effects of re‐hospitalisation due to recurrent disc herniation after at least six months' follow‐up and lower SF‐36 Physical Functioning subclass after more than six months' follow‐up.
Subgroup analyses
A. Subgroup analysis of minimally invasive discectomy versus microdiscectomy (not open discectomy)
We compared MID with microdiscectomy. Eight of the 11 included studies examined microdiscectomy. Our primary outcome measures showed similar results for the primary analysis. There was low‐quality evidence of a statistically significant difference for medium‐term follow‐up for leg pain (MD 0.13, 95% CI 0.09 to 0.16; I2 = 0%). There was low‐quality evidence of a statistically significant difference at six months' follow‐up for LBP (MD 0.36, 95% CI 0.30 to 0.41; I2 = 3%); among secondary outcome measures, there was no statistically significant difference for surgical site and other infections (RR 0.23, 95% CI 0.05 to 1.02). The control groups for both studies that evaluated HRQoL used microdiscectomy (385 participants) (Arts 2011; Ryang 2008). There was no statistically significant difference between MID and microdiscectomy in the Physical Health component summary of the SF‐36 at six months' follow‐up (MD 0.96, 95% CI ‐0.12 to 2.03). However, MID was associated with worse quality of life on three Physical Health component subclasses: Physical Functioning (MD ‐4.70, 95% CI ‐5.05 to ‐4.35), Bodily Pain (MD ‐3.70, 95% CI ‐4.11 to ‐3.28) and General Health (MD ‐2.52, 95% CI ‐2.92 to ‐2.11). There was no statistically significant difference on the Mental Health component summary score at six months' follow‐up (MD ‐4.31, 95% CI ‐9.96 to 1.33). Therefore, regarding HRQoL, analysis of MID versus microdiscectomy was similar results for the primary analysis.
B. Subgroup analysis of microendoscopy versus microdiscectomy/open discectomy
We compared MED with MD/OD. Eight of the 11 included studies examined MED. There was no statistically significant difference for medium‐term follow‐up for leg pain (MD 0.09, 95% CI ‐0.03 to 0.21) or for LBP at 6 months' follow‐up (MD 0.29, 95% CI ‐0.19 to 0.77) and ODI after at least six months' follow‐up (MD 0.85, 95% CI ‐0.21 to 1.90). Among secondary outcome measures, a comparison of MED versus MD/OD showed that re‐operations due to recurrences of discopathy was statistically significant (RR 2.13, 95% CI 1.01 to 4.49). In particular, there was a statistically significant difference for surgical site and other infections (RR 0.22, 95% CI 0.06 to 0.82), such that participants in the MED group were associated with lower risk of surgical site and other infections including UTI compared with participants in the MD/OD group after at least six months' follow‐up. There was no statistically significant difference for duration of hospital stay (MD ‐3.71, 95% CI ‐10.24 to 2.8). No study evaluated HRQoL between the MED and MD/OD groups.
Sensitivity analysis
Sensitivity analysis of minimally invasive discectomy versus microdiscectomy
We excluded studies with high risk of bias and studies with unclear methods of randomisation. Four studies remained (Arts 2011; Hermantin 1999; Shin 2008; Teli 2010). We performed sensitivity analyses for outcomes that had shown significant results in the primary analyses. We found a statistically significant difference for MID versus microdiscectomy at one year' follow‐up for leg pain (MD 0.13, 95% CI 0.09 to 0.17), but differences were small (less than 0.5 points on a 0 to 10 scale) and did not meet standard thresholds for clinically meaningful differences. There was low‐quality evidence that MID was associated with worse LBP than microdiscectomy at six months' follow‐up (MD 0.36, 95% CI 0.30 to 0.41). For secondary outcomes, MID was not associated with lower risk of surgical site and other infections (RR 0.30, 95% CI 0.05 to 1.70), but there was higher risk of re‐hospitalisation due to recurrent disc herniation (RR 2.13, 95% CI 1.13 to 4.02). In addition, MID was associated with slightly lower quality of life (RR ‐4.70, 95% CI ‐5.05 to ‐4.35) (less than 5 points on a 100‐point scale) on Physical Functioning subclass after at least six months. However, MID was not associated with shorter duration of hospitalisation than microdiscectomy (MD 0.13, 95% CI ‐0.07 to 0.33).
Discussion
Summary of main results
The results of this review showed that leg pain and LBP were worse with MID compared with MD/OD. The differences were small and did not meet standard thresholds for clinically meaningful differences. There were no statistically significant differences on other primary outcomes such as measures of function or persistent neurological deficits, but conclusions were limited by the small number of participants in the trials with neurological deficits at baseline. With secondary outcomes, MID was associated with lower risk of surgical site and other infections and UTI, but higher risk of re‐hospitalisation due to recurrent disc herniation. In addition, MID was associated with slightly lower HRQoL after at least six months' follow‐up (less than 5 points on a 100‐point scale) on some measures, such as some Physical subclasses. Once more, the differences were small and did not meet standard thresholds for clinically meaningful differences.
When we performed subgroup analyses of MID versus microdiscectomy (not open discectomy), which was used in eight of the 11 included studies, there was low‐quality evidence of a statistically significant difference in leg pain at medium‐term follow‐up and LBP at six‐month and two‐year follow‐up, but not at one‐year follow‐up. Meanwhile, MID was associated with increased risk of re‐hospitalisation due to recurrent disc herniation versus microdiscectomy after at least 12 months' follow‐up. Moreover, MID was associated with worse HRQoL after six‐month follow‐up on three Physical Health component subclasses: Physical Functioning, Bodily Pain and General Health. However, there was no statistically significant difference for surgical site and other infections. Finally, subgroup analysis showed primary outcome measures for MID versus microdiscectomy was the same as MID versus MD/OD. In other words, better outcomes for pain improvement are related to using a microscope in the standard MD/OD.
It was difficult to compare specific MID procedures with MD/OD because of the few studies available. Since eight of the 11 MID procedures were percutaneous MED, comparison of MED versus MD/OD showed that there was a low level of evidence of no statistically significant difference for pain and function. In addition, MED was associated with lower risk of surgical site and other infections and UTI, but higher risk of re‐hospitalisation due to recurrent disc herniation.
Overall completeness and applicability of evidence
Although all of the included studies evaluated leg pain following surgery, more than half of the studies reported no other primary outcome, potentially resulting in biased or less precise estimates. Some older studies may have evaluated surgical techniques that would now be considered outdated, potential limiting their applicability (Chatterjee 1995;Hermantin 1999;Mayer 1993). The studied interventions in more recent trials generally appear applicable to current practice. No study was funded by a device company. We were unable to assess for publication bias formally using statistical or graphical methods due to the small number of studies.
Concerning clinical relevance, the positive effects of MD/OD did not exceed the threshold for minimum clinically important differences (MCID), which is 1.5 point (on a 0 to 10 scale) improvement for leg pain and LBP (Ostelo 2008). Moreover, although MID was associated with more re‐operations due to recurrence of discopathy, the difference between the two groups of MID and MD/OD was less than an MCID of 10%. For measures related to quality of life, differences were small (less than 5 points on a 0‐ to 100‐point scale), which is lower than the threshold typically considered to meet MCID (Copay 2008). In contrast, potential advantages of MID were lower risk of surgical site and other infections, and shorter hospital stay. However, similar to the findings described above, these two outcome measures did not meet standard thresholds for clinically meaningful differences.
Quality of the evidence
The low level of evidence across outcomes was due to the high risk of bias and the small number of trials for specific minimally invasive techniques. The analysis was consistent with no/small heterogeneity in these outcome measures: leg pain at one year' follow‐up (I2 = 0%); LBP at six months' follow‐up (I2 = 35%); LBP at two years' follow‐up (I2 = 65%); disability after six months' follow‐up (I2 = 0%); surgical site and other infections after six months' follow‐up (I2 = 34%); re‐ operations due to recurrence of discopathy after six months' follow‐up (I2 = 0%); and HRQoL after six months' follow‐up (I2 = 0%). There was high heterogeneity for LBP at one year' follow‐up (I2 = 90%). We wrote these data just to avoid selective reporting results. In one case, we found medium‐quality evidence for lower side effects of surgical site and other infections after six months' follow‐up for MID versus MD/OD. This was due to high risk of bias in only a few studies.
Potential biases in the review process
We were unable to assess for publication bias formally due to the small number of studies. Although we did not detect signs of potential selective reporting bias, we did not have the original trial protocols to review and several primary outcomes for this review were not reported in included studies. We did not apply language restrictions and utilised methods to reduce potential effects of bias.
Agreements and disagreements with other studies or reviews
Our findings are generally consistent with other systematic reviews. One review found no difference between MED versus MD/OD in the ODI, based on four RCTs of Garg 2011; Huang 2005; Righesso 2007 and Teli 2010 (Smith 2013). One trial in this review reported an increased number of severe complications in the MED group. Another systematic review found no clear differences in benefits or harms between various minimally invasive techniques versus MD/OD, based on six RCTs (Dasenbrock 2012). This review did not include several trials included in our review (Arts 2011; Chatterjee 1995; Garg 2011; Hermantin 1999; Mayer 1993). Another systematic review compared the effectiveness of transforaminal endoscopic surgery and open microdiscectomy in people with symptomatic lumbar disc herniations, but it only included one RCT of Hermantin 1999 (Nellensteijn 2010).
Two systematic reviews evaluated percutaneous lumbar mechanical disc decompression utilising the Dekompressor and laser, but we excluded these interventions from this review (Singh 2009a; Singh 2009b).
Finally, Jacobs et al. performed a systematic review for surgical techniques for sciatica due to herniated disc. However, there were some differences in our inclusion criteria and risk of bias assessment (Jacobs 2012). Moreover, in our review, we focused on outcomes that were highly relevant to participants. Therefore, these differences contributed to differences in overall findings.
Study flow diagram.
Risk of bias summary: review authors' judgements about each risk of bias item for each included study.
Forest plot of comparison: Outcome 1. Leg pain in two groups of minimally invasive discectomy (MID) and micro/discectomy, medium term (one to five years).
Forest plot of comparison: Outcome 2. Low back pain in two groups of minimally invasive discectomy (MID) and micro/discectomy at six months, one year and two years.
Forest plot of comparison: Secondary outcome ‐ complication ‐ surgical sites and other infections
Forest plot of comparison: Secondary outcome 1e ‐ complications ‐ re‐hospitalisation due to recurrent disc herniation six months or greater.
Comparison 1 Leg pain in two groups of minimally invasive discectomy (MID) and micro/discectomy, Outcome 1 Medium term (1‐5 years).
Comparison 1 Leg pain in two groups of minimally invasive discectomy (MID) and micro/discectomy, Outcome 2 Leg pain in 2 groups of MID and micro/discectomy ‐ short term (at 1 day).
Comparison 1 Leg pain in two groups of minimally invasive discectomy (MID) and micro/discectomy, Outcome 3 Leg pain in 2 groups of MID and micro/discectomy ‐ short term (at 3 days).
Comparison 1 Leg pain in two groups of minimally invasive discectomy (MID) and micro/discectomy, Outcome 4 Leg pain in 2 groups of MID and micro/discectomy ‐ short term (at 5 days).
Comparison 2 Low back pain ‐ minimally invasive discectomy (MID) versus micro/discectomy, Outcome 1 Sensitivity analysis for low back pain in 1 year.
Comparison 2 Low back pain ‐ minimally invasive discectomy (MID) versus micro/discectomy, Outcome 2 Endoscopic discectomy vs. micro/discectomy.
Comparison 3 Neurological deficit of lower extremity or bowel/urinary incontinency, Outcome 1 Persistent motor deficits post operative.
Comparison 3 Neurological deficit of lower extremity or bowel/urinary incontinency, Outcome 2 Persistent sensory deficits post operative.
Comparison 3 Neurological deficit of lower extremity or bowel/urinary incontinency, Outcome 3 Persistent reflex deficit postoperative (12 months).
Comparison 3 Neurological deficit of lower extremity or bowel/urinary incontinency, Outcome 4 Persistent bladder dysfunction > 6 months' follow‐up.
Comparison 4 Functional outcomes including daily activity and return to work, Outcome 1 Oswestry Disability Index > 6 months post operative.
Comparison 4 Functional outcomes including daily activity and return to work, Outcome 2 Number of participants returned to work.
Comparison 4 Functional outcomes including daily activity and return to work, Outcome 3 Postoperative work disability days ‐ return to work.
Comparison 5 Secondary outcomes ‐ complications of surgery, Outcome 1 Surgical site and other infections.
Comparison 5 Secondary outcomes ‐ complications of surgery, Outcome 2 Procedure‐related complications.
Comparison 5 Secondary outcomes ‐ complications of surgery, Outcome 3 Re‐hospitalisation due to recurrent disc herniation ‐ ≥6 months.
Comparison 5 Secondary outcomes ‐ complications of surgery, Outcome 4 Surgical re‐intervention.
Comparison 5 Secondary outcomes ‐ complications of surgery, Outcome 5 Dural tear.
Comparison 5 Secondary outcomes ‐ complications of surgery, Outcome 6 Re‐hospitalisation due to recurrent disc herniation ‐ 2 years' follow‐up.
Comparison 5 Secondary outcomes ‐ complications of surgery, Outcome 7 Subgroup analysis for duration of hospital stay.
Comparison 6 Secondary outcomes ‐ quality of life measured by SF‐36 or SF‐12, and overall satisfaction of participants, which is usually reported by a Likert scale, Outcome 1 SF‐36 Physical Functioning subclass > 6 months.
Comparison 6 Secondary outcomes ‐ quality of life measured by SF‐36 or SF‐12, and overall satisfaction of participants, which is usually reported by a Likert scale, Outcome 2 SF‐36 Bodily Pain subclass > 6 months.
Comparison 6 Secondary outcomes ‐ quality of life measured by SF‐36 or SF‐12, and overall satisfaction of participants, which is usually reported by a Likert scale, Outcome 3 SF‐36 General Health subclass > 6 months.
Comparison 6 Secondary outcomes ‐ quality of life measured by SF‐36 or SF‐12, and overall satisfaction of participants, which is usually reported by a Likert scale, Outcome 4 SF‐36 Physical Health component summary (6 months).
Comparison 6 Secondary outcomes ‐ quality of life measured by SF‐36 or SF‐12, and overall satisfaction of participants, which is usually reported by a Likert scale, Outcome 5 SF‐36 Mental Health component summary (6 months).
Comparison 6 Secondary outcomes ‐ quality of life measured by SF‐36 or SF‐12, and overall satisfaction of participants, which is usually reported by a Likert scale, Outcome 6 Overall success (number of participants).
Comparison 7 Automated percutaneous discectomy versus microdiscectomy, Outcome 1 SO4b. Overall satisfaction of participants.
Comparison 8 Preoperative pain versus postoperative pain at 12 months, Outcome 1 Low back pain at 12 months in discectomy/microdiscectomy.
Comparison 9 Microendoscopy versus microdiscectomy/open discectomy (MD/OD), Outcome 1 Leg pain ‐ medium‐term follow‐up.
Comparison 9 Microendoscopy versus microdiscectomy/open discectomy (MD/OD), Outcome 2 Low back pain ‐ 6 months' follow‐up.
Comparison 9 Microendoscopy versus microdiscectomy/open discectomy (MD/OD), Outcome 3 Oswestry Disability Index (ODI) > 6 months' follow‐up.
Comparison 9 Microendoscopy versus microdiscectomy/open discectomy (MD/OD), Outcome 4 Re‐operations due to recurrence of discopathy.
| Minimal invasive discectomy compared with micro/discectomy for lumbar disc herniation | ||||||
| Participant or population: participants with lumbar disc herniation Settings: operated lumbar disc herniation Intervention: minimally invasive discectomy Comparison: micro/discectomy | ||||||
| Outcomes# | Illustrative comparative risks* (95% CI) | Relative effect | No of participants | Quality of the evidence | Comments | |
| Assumed risk | Corresponding risk | |||||
| Micro/discectomy | Minimal invasive discectomy | |||||
| Mean leg pain intensity on a numerical scale, e.g. 0 (no pain) to 10 (maximum pain) ‐ 1‐year post operative | Mean leg pain score ranged across control groups from 0.1 to 1 | Mean leg pain score in the intervention groups was 0.13 higher (0.09 to 0.16) | Not applicable | 599 (4 studies) | ⊕⊕⊝⊝ | There was a difference between the groups that was small in magnitude. However, the difference was not clinically important (< 1.5 out of 10 points) |
| Mean LBP intensity on a numerical scale, e.g. 0 (no pain) to 10 (maximum pain) ‐ 6‐month post operative | Mean LBP score ranged across control groups from 1 to 1.77 | Mean LBP score in the intervention groups was 0.35 higher (0.19 to 0.51) | Not applicable | 577 (3 studies) | ⊕⊕⊝⊝ | There was a difference between the groups that was small in magnitude. However, the difference was not clinically important (<1.5 out of 10 points) |
| Mean LBP intensity on a numerical scale, e.g. 0 (no pain) to 10 (maximum pain) ‐ 1‐year post operative | Mean LBP score ranged across control groups from 0 to 1.75 | Mean LBP score in the intervention groups was 0.19 higher (‐0.22 to 0.59) | Not applicable | 577 (3 studies) | ⊕⊝⊝⊝ | There was no statistically significant difference |
| Mean LBP intensity on a numerical scale, e.g. 0 (no pain) to 10 (maximum pain) ‐ 2‐year post operative | Mean LBP score ranged across control groups from 0 to 1.94 | Mean LBP score in the intervention groups was 0.54 higher (0.29 to 0.79) | Not applicable | 577 (3 studies) | ⊕⊕⊝⊝ | There was a difference between the groups that was small in magnitude. However, the difference was not clinically important (< 1.5 out of 10 points) |
| Persistent motor deficits post operative | Study population 343.7 per 1000 | Study population 338.7 per 1000 | Not applicable | 126 (4 studies) | ⊕⊕⊝⊝ | There was no statistically significant difference |
| Persistent sensory deficits post operative | Study population 550 per 1000 | Study population 459 per 1000 | Not applicable | 165 (4 studies) | ⊕⊕⊝⊝ | There was no statistically significant difference |
| Persistent reflex deficit post operative (12 months) | Study population 737 per 1000 | Study population 500 per 1000 | Not applicable | 47 (2 studies) | ⊕⊕⊝⊝ | There was a difference between the groups. However, the difference was not clinically important |
| Disability (higher ratings mean greater disability). Various instruments were used, e.g. in Oswestry Disability Index > 6 months' post operative 0% (no disability) to 100% (bedridden) | Mean disability score ranged across control groups from 10 to 13 | Mean disability score in the intervention groups was 0.84 higher (‐0.21 to 1.88) | Not applicable | 312 (3 studies) | ⊕⊕⊝⊝ | There was no statistically significant difference |
| Side effects ‐ surgical site and other infections > 6 months' follow‐up | Study population 32 per 1000 | Study population 2.3 per 1000 | RR 0.23 (0.07 to 0.79) | 931 (6 studies) | ⊕⊕⊕⊝ | There was a difference between the groups that was small in magnitude. However, the difference was not clinically important (< 10%) |
| Side effects ‐ re‐hospitalisation due to recurrent disc herniation ≥ 6 months' follow‐up | Study population 43 per 1000 | Study population 75 per 1000 (43 to 103) | RR 1.74 (1.03 to 2.94) | 949 (6 studies) | ⊕⊕⊕⊝ | The magnitude of this difference was small to moderate. However, the difference was not clinically important (< 10%) |
| SF‐36 Physical Functioning subclass > 6 months' follow‐up ‐ on a numerical scale (higher ratings mean higher quality of life), e.g. 0 (the worst) and 100 (the highest) quality | Mean HRQoL score ranged across control groups from 80.4 to 84 | Mean HRQoL score in the intervention group was 4.7 lower (‐5.05 to ‐4.35) | Not applicable | 385 (2 studies) | ⊕⊕⊝⊝ | The magnitude of this difference was in the range of small to moderate. However, this difference was not clinically important (< 10%) |
| The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). GRADE Working Group grades of evidence | ||||||
| # Persistent bladder dysfunction > six months' follow‐up, sciatica‐specific outcomes including the Sciatica Bothersomeness Index (SBI) and the Sciatica Frequency Index (SFI) have been written in the text but did not mention in the 'Summary of finding' table because there was only one study for each and no need for further evaluation and meta‐analysis. 1 Two trials had unclear risk of bias due to non‐adequate randomisation, no allocation concealment and no blinding (Huang 2005; Mayer 1993). Meanwhile, Huang 2005 had no clear intention‐to‐treat analysis and Mayer 1993 had unclear co‐intervention. One other trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had unclear allocation concealment and high risk of bias for blinding (Teli 2010). We downgraded the level of evidence due to the high risk of bias and low precision due to the small number of trials for specific minimally invasive techniques. The analysis was consistent with no heterogeneity (I2 = 0%). 2 One trial had high risk of bias due to non‐adequate randomisation, no allocation concealment, no blinding, group differences at baseline and no clear intention‐to‐treat analysis (Righesso 2007). One other trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had unclear allocation concealment and high risk of bias for blinding (Teli 2010). We downgraded the level of evidence due to the high risk of bias and low precision because of the small number of trials for specific minimally invasive techniques. The analysis was almost consistent with small heterogeneity (I2 = 35%). 3 One trial had high risk of bias due to non‐adequate randomisation, no allocation concealment, no blinding, group differences at baseline and no clear intention‐to‐treat analysis (Righesso 2007). One other trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had unclear allocation concealment and high risk of bias for blinding (Teli 2010). We downgraded the level of evidence due to the high risk of bias, low precision because of the small number of trials for specific minimally invasive techniques and high heterogeneity (I2 = 90%). 4 One trial had high risk of bias due to non‐adequate randomisation, no allocation concealment, no blinding, group differences at baseline and no clear intention‐to‐treat analysis (Righesso 2007). One other trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had unclear allocation concealment and high risk of bias for blinding (Teli 2010). We downgraded the level of evidence due to the high risk of bias and low precision because of the small number of trials for specific minimally invasive techniques. The analysis was almost consistent with small heterogeneity (I2 = 65%). 5 Two trials had high risk of bias due to non‐adequate randomisation, allocation concealment and no blinding (Ryang 2008; Righesso 2007). One trial had unclear risk of bias due to non‐adequate randomisation, no allocation concealment, no blinding and unclear co‐intervention (Mayer 1993). In another trial, there was no blinding of participants, care provider and outcome assessor; and authors did not mention whether there was any co‐intervention or not (Hermantin 1999). The analysis was consistent with small heterogeneity (I2 = 15%). 6 Two trials had high risk of bias due to non‐adequate randomisation, allocation concealment and no blinding (Ryang 2008; Righesso 2007). One trial had unclear risk of bias due to non‐adequate randomisation, no allocation concealment, no blinding and unclear co‐intervention (Mayer 1993). In another trial, there was no blinding of participants, care provider and outcome assessor; and authors did not mention whether there was any co‐intervention or not (Hermantin 1999). The analysis was consistent with no heterogeneity (I2 = 0%). 7 One trial had unclear risk of bias due to non‐adequate randomisation, no allocation concealment, no blinding and unclear co‐intervention (Mayer 1993). In another trial, there was no blinding of participants, care provider and outcome assessor; and authors did not mention whether there was any co‐intervention or not (Hermantin 1999). There was statistically significant difference between minimally invasive discectomy and microdiscectomy/open discectomy. However, we downgraded the evidence because of high risk of bias and low precision due to small sample size. The analysis was consistent with no heterogeneity (I2 = 0%). 8 Only one trial had overall low risk of bias (Teli 2010). Both other trials had high risk of bias due to non‐adequate randomisation, allocation concealment and no blinding (Ryang 2008; Righesso 2007). There was no statistically significant difference between different types of minimally invasive discectomy (microendoscopic discectomy and minimal access trocar microdiscectomy) versus microdiscectomy. However, we downgraded the evidence because of high risk of bias and low precision due to small sample size. The analysis was consistent with no heterogeneity (I2 = 0%). 9 Six trials evaluated side effects of postoperative surgical infection. One trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had unclear allocation concealment and high risk of bias for blinding (Teli 2010). One trial had high risk of bias due to no clear randomisation method, no clear allocation concealment, no clear blinding of participants and personnel, no clear selective reporting and no clear intention‐to‐treat analysis (Garg 2011). One trial had high risk of bias due to no clear randomisation, no clear allocation concealment, no clear blinding and no clear intention‐to‐treat analysis (Huang 2005). One trial had high risk of bias because of non‐randomisation, no allocation, no blinding, no clear group similarity at baseline and no clear intention‐to‐treat analysis (Ruetten 2008). However, there was no blinding of participants, care provider and outcome assessor. Authors did not mention whether there was any co‐intervention or not. Lack of blindness, and unclear co‐intervention were major problems of the one trial that had no other risk of bias (Hermantin 1999). We downgraded the evidence due to the high risk of bias. One participant out of 431 had infection following minimally invasive discectomy versus 16 out of 500 participants in microdiscectomy/open discectomy. The analysis was almost consistent with small heterogeneity (I2 = 34%). 10 One trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had unclear allocation concealment and high risk of bias for blinding (Teli 2010). However, four other trials had high risk of bias because of non‐randomisation, no allocation and no blinding of participants and personnel (Garg 2011; Mayer 1993; Ruetten 2008; Ryang 2008). We downgraded the evidence to the low level due to high risk of bias and imprecision (wide 95% confidence intervals). The analysis was consistent with no heterogeneity (I2 = 0%). 11 One trial had high risk of bias for blinding of participants and personnel (performance bias) and unclear risk of bias for co‐interventions (Arts 2011). Another trial had high overall risk of bias because of non‐randomisation, no allocation concealment, no blinding, unclear group similarity at baseline and no clear intention‐to‐treat analysis (Ryang 2008). We downgraded the level of evidence due to the high risk of bias and low precision because of small number of trials. The analysis was consistent with no heterogeneity (I2 = 0%). | ||||||
| Reference | Minimal invasive procedure | Description of the procedure |
| Percutaneous nucleotomy | Under fluoroscopy in the posterior‐lateral position, a K‐wire was advanced into the intervertebral space and a dilator and working cannula were introduced into the disc space step by step. Discectomy was performed through the cannula using pituitary forceps | |
| Automated percutaneous discectomy | Through a lateral oblique percutaneous approach, and insertion of 2‐mm disk‐aspiration probe, nucleus pulposus was mechanically removed | |
| Percutaneous endoscopic lumbar discectomy (PELD) | The identified symptomatic disc can be dissected by interlaminar or transforaminal approach using endoscope | |
| Transmuscular tubular microdiscectomy | Tubular discectomy utilises a transmuscular approach rather than a subperiosteal dissection. In this method, a guidewire is inserted percutaneously into the inferior part of the lamina, and its location is confirmed using fluoroscopy. Then, dilators of increasing diameter are inserted sequentially over the guidewire. The tubular retractor is then inserted over the final dilator |
| S1 | S2 | S3 | S4 | S5 | S6 | S7 | S8 | S9 | S10 | S11 | |
| Q1 | c | b | a | a | a | a | a | a1/a2 | c | a | a |
| Q2 | 1 | 1 | 2 | 2 | 2 | 1 | 1b | 1 | 1 | 1 | 1a/1b |
| PO1 | + | ‐ | ‐ | ‐ | ‐ | ‐ | + | ‐ | ‐ | + | + |
| PO2 | + | ‐ | ‐ | + | + | + | + | + | + | + | + |
| PO2a | + | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ |
| PO2b | + | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ |
| PO3a | ‐ | ‐ | ‐ | + | ‐ | + | + | ‐ | + | ‐ | + |
| PO3b | ‐ | ‐ | ‐ | + | ‐ | + | + | ‐ | + | ‐ | ‐ |
| PO3c | ‐ | ‐ | ‐ | + | ‐ | + | + | ‐ | ‐ | ‐ | ‐ |
| PO3d | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | + | ‐ | ‐ |
| PO3e | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ |
| PO4a1 | ‐ | ‐ | + | ‐ | ‐ | ‐ | + | + | + | ‐ | + |
| PO4a2 | + | ‐ | ‐ | + | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ |
| PO4b | + | ‐ | ‐ | + | ‐ | ‐ | ‐ | + | ‐ | ‐ | ‐ |
| SO1 | ‐ | ‐ | + | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | + |
| SO1a | + | ‐ | + | ‐ | + | ‐ | ‐ | + | + | ‐ | ‐ |
| SO1b | + | ‐ | + | + | + | ‐ | ‐ | + | ‐ | ‐ | + |
| SO1c | + | ‐ | + | ‐ | ‐ | ‐ | ‐ | + | ‐ | ‐ | ‐ |
| SO1d | + | ‐ | + | ‐ | ‐ | + | ‐ | + | + | ‐ | + |
| SO1e | + | ‐ | + | ‐ | ‐ | ‐ | ‐ | + | ‐ | ‐ | ‐ |
| SO1f | + | ‐ | + | ‐ | ‐ | + | ‐ | + | + | ‐ | ‐ |
| SO1g | + | ‐ | + | ‐ | ‐ | ‐ | ‐ | + | + | ‐ | + |
| SO2 | + | + | + | ‐ | + | ‐ | + | ‐ | + | ‐ | ‐ |
| SO3 | ‐ | ‐ | + | + | ‐ | ‐ | ‐ | + | ‐ | ‐ | ‐ |
| SO4a | + | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | ‐ | + | ‐ | + |
| SO4b | ‐ | ‐ | + | + | + | ‐ | ‐ | + | ‐ | ‐ | ‐ |
| No. | 325 | 71 | 112 | 60 | 22 | 40 | 40 | 200 | 60 | 30 | 212 |
| Severity | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ | ++ |
| Age (years) | 18‐70 | NA | 26‐57 | 15‐67 | 39 ± 11 | 12‐55 | < 60 | 20‐68 | 21‐69 | 43 ± 18/ 48 ± 11 | 18‐65 |
| M : F MID | 84 : 82 | NA | 36 : 19 | 22 : 8 | 6 : 4 | 12 : 8 | 10 : 11 | 84 : 116 | 13 : 17 | 7 : 8 | 45 : 25 |
| M : F M/D | 88 : 71 | NA | 44 : 13 | 17 : 13 | 9 : 3 | 14 : 6 | 13 : 6 | 19 : 11 | 5 : 10 | 94 : 48 | |
| F/O | ≥ 24 | ≥ 6 | 12‐18 | 19‐42 | 10‐25 | ≥ 24 | 24‐56 | ≥ 24 | 6‐26 | 5 days | 24‐29 |
| Q1. Minimally invasive discectomy a. percutaneous endoscopic discectomy (1. transforaminal = lateral approach; 2. interlaminar = posterior approach), b. automated percutaneous discectomy, c. transmuscular tubular microdiscectomy (guidewire, sequential dilators, tubular retractor with microscopic magnification) Q2. Microdiscectomy/discectomy
++. failure to respond to non‐operative measures ‐ 4‐8 weeks of conservative treatment with rest, analgesia, non‐steroidal anti‐inflammatory drugs and physiotherapy M : F MID. Male : female ratio in the minimal invasive discectomy group M : F M/D. Male : female ratio in the micro/discectomy F/O: duration of follow‐up (range in months; exception is S10 with 5 days' follow‐up) Primary outcomes (PO) PO1a. Leg pain assessed by visual analogue scale (VAS) PO1b. Low back pain assessed by VAS PO2a. Sciatica Bothersomeness Index (SBI) PO2b. Sciatica Frequency Index (SFI) PO3a. Persistent motor deficit PO3b. Persistent sensory deficit PO3c. Persistent reflex changes PO3d. Persistent urinary incontinence PO3e. Persistent bowel incontinence PO4a. Functional outcome: daily activity ‐ 1. Oswestry Disability Index; 2. Roland‐Morris Disability score PO4b. Functional outcome: return to work/duration postoperative disability Secondary outcomes (SO) SO1. Complications ‐ mortality SO1a. Complications ‐ thromboemboli ‐ deep vein thrombosis (DVT) SO1b. Complications ‐ surgical site and other infections ‐ urinary tract infection (UTI) SO1c. Complications ‐ procedure related SO1d. Complications ‐ re‐hospitalisation due to recurrent disc herniation SO1e. Complications ‐ re‐hospitalisation due to other causes SO1f. Complications ‐ surgical re‐intervention SO1g. Complications ‐ dural tear SO2. Duration of hospital stay SO3. Postoperative opioid use SO4a. Quality of life measured by 36‐item Short Form (SF‐36) or 12‐item Short Form (SF‐12) SO4b. Overall satisfaction of participants No. = total number of participants in each study Studies: S1. Arts 2011 S2. Chatterjee 1995 S3. Garg 2011 S4. Hermantin 1999 S5. Huang 2005 S6. Mayer 1993 S7. Righesso 2007 S8. Ruetten 2008 S9. Ryang 2008 S10. Shin 2008 S11. Teli 2010 Outcome assessment was performed in the study: positive (+) Outcome assessment was not performed in the study: negative (‐) | |||||||||||
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Medium term (1‐5 years) Show forest plot | 4 | 599 | Mean Difference (IV, Random, 95% CI) | 0.13 [0.09, 0.16] |
| 2 Leg pain in 2 groups of MID and micro/discectomy ‐ short term (at 1 day) Show forest plot | 1 | 30 | Mean Difference (IV, Random, 95% CI) | ‐0.40 [‐2.33, 1.53] |
| 3 Leg pain in 2 groups of MID and micro/discectomy ‐ short term (at 3 days) Show forest plot | 1 | 30 | Mean Difference (IV, Random, 95% CI) | ‐0.5 [‐1.95, 0.95] |
| 4 Leg pain in 2 groups of MID and micro/discectomy ‐ short term (at 5 days) Show forest plot | 1 | 30 | Mean Difference (IV, Random, 95% CI) | 0.10 [‐1.24, 1.44] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Sensitivity analysis for low back pain in 1 year Show forest plot | 3 | Mean Difference (IV, Random, 95% CI) | Subtotals only | |
| 1.1 6 months post operative | 3 | 577 | Mean Difference (IV, Random, 95% CI) | 0.35 [0.19, 0.51] |
| 1.2 1 year post operative | 3 | 577 | Mean Difference (IV, Random, 95% CI) | 0.19 [‐0.22, 0.59] |
| 1.3 2 years post operative | 3 | 577 | Mean Difference (IV, Random, 95% CI) | 0.54 [0.29, 0.79] |
| 2 Endoscopic discectomy vs. micro/discectomy Show forest plot | 1 | Mean Difference (IV, Random, 95% CI) | Subtotals only | |
| 2.1 Early post operative | 1 | 212 | Mean Difference (IV, Random, 95% CI) | ‐0.5 [‐0.79, ‐0.21] |
| 2.2 6 months post operative | 1 | 212 | Mean Difference (IV, Random, 95% CI) | 0.5 [0.21, 0.79] |
| 2.3 1 year post operative | 1 | 212 | Mean Difference (IV, Random, 95% CI) | 0.0 [‐0.29, 0.29] |
| 2.4 2 years post operative | 1 | 212 | Mean Difference (IV, Random, 95% CI) | 0.5 [0.21, 0.79] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Persistent motor deficits post operative Show forest plot | 4 | 126 | Risk Ratio (M‐H, Random, 95% CI) | 0.96 [0.56, 1.63] |
| 2 Persistent sensory deficits post operative Show forest plot | 4 | 165 | Risk Ratio (M‐H, Random, 95% CI) | 0.86 [0.65, 1.15] |
| 3 Persistent reflex deficit postoperative (12 months) Show forest plot | 2 | 47 | Risk Ratio (M‐H, Random, 95% CI) | 0.68 [0.49, 0.96] |
| 4 Persistent bladder dysfunction > 6 months' follow‐up Show forest plot | 1 | 3 | Risk Ratio (M‐H, Random, 95% CI) | 0.0 [0.0, 0.0] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Oswestry Disability Index > 6 months post operative Show forest plot | 3 | 312 | Mean Difference (IV, Random, 95% CI) | 0.84 [‐0.21, 1.88] |
| 2 Number of participants returned to work Show forest plot | 1 | 60 | Odds Ratio (M‐H, Random, 95% CI) | 2.07 [0.18, 24.15] |
| 3 Postoperative work disability days ‐ return to work Show forest plot | 1 | 178 | Mean Difference (IV, Random, 95% CI) | 0.0 [0.0, 0.0] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Surgical site and other infections Show forest plot | 6 | 931 | Risk Ratio (M‐H, Random, 95% CI) | 0.23 [0.07, 0.79] |
| 2 Procedure‐related complications Show forest plot | 7 | 991 | Risk Ratio (M‐H, Random, 95% CI) | 1.01 [0.61, 1.66] |
| 3 Re‐hospitalisation due to recurrent disc herniation ‐ ≥6 months Show forest plot | 6 | 949 | Risk Ratio (M‐H, Random, 95% CI) | 1.74 [1.03, 2.94] |
| 4 Surgical re‐intervention Show forest plot | 4 | 637 | Risk Ratio (M‐H, Random, 95% CI) | 1.46 [0.68, 3.14] |
| 5 Dural tear Show forest plot | 5 | 887 | Risk Ratio (M‐H, Random, 95% CI) | 1.63 [0.82, 3.22] |
| 6 Re‐hospitalisation due to recurrent disc herniation ‐ 2 years' follow‐up Show forest plot | 4 | 777 | Risk Ratio (M‐H, Random, 95% CI) | 1.89 [1.09, 3.27] |
| 7 Subgroup analysis for duration of hospital stay Show forest plot | 2 | Mean Difference (IV, Random, 95% CI) | Subtotals only | |
| 7.1 Sensitivity analysis based on randomisation for duration of hospital stay | 2 | 537 | Mean Difference (IV, Random, 95% CI) | 0.13 [‐0.07, 0.33] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 SF‐36 Physical Functioning subclass > 6 months Show forest plot | 2 | 385 | Mean Difference (IV, Random, 95% CI) | ‐4.70 [‐5.05, ‐4.35] |
| 2 SF‐36 Bodily Pain subclass > 6 months Show forest plot | 2 | 385 | Mean Difference (IV, Random, 95% CI) | ‐3.70 [‐4.11, ‐3.28] |
| 3 SF‐36 General Health subclass > 6 months Show forest plot | 2 | 378 | Mean Difference (IV, Random, 95% CI) | ‐2.52 [‐2.92, ‐2.11] |
| 4 SF‐36 Physical Health component summary (6 months) Show forest plot | 2 | 272 | Mean Difference (IV, Random, 95% CI) | 0.96 [‐0.12, 2.03] |
| 5 SF‐36 Mental Health component summary (6 months) Show forest plot | 2 | 272 | Mean Difference (IV, Random, 95% CI) | ‐4.31 [‐9.96, 1.33] |
| 6 Overall success (number of participants) Show forest plot | 5 | 443 | Risk Ratio (M‐H, Random, 95% CI) | 1.04 [0.99, 1.10] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 SO4b. Overall satisfaction of participants Show forest plot | 1 | 71 | Risk Ratio (M‐H, Random, 95% CI) | 0.89 [0.67, 1.17] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Low back pain at 12 months in discectomy/microdiscectomy Show forest plot | 2 | 602 | Mean Difference (IV, Random, 95% CI) | 2.33 [1.93, 2.73] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Leg pain ‐ medium‐term follow‐up Show forest plot | 3 | 274 | Mean Difference (IV, Random, 95% CI) | 0.09 [‐0.03, 0.21] |
| 2 Low back pain ‐ 6 months' follow‐up Show forest plot | 2 | 252 | Mean Difference (IV, Random, 95% CI) | 0.29 [‐0.19, 0.77] |
| 3 Oswestry Disability Index (ODI) > 6 months' follow‐up Show forest plot | 2 | 252 | Mean Difference (IV, Random, 95% CI) | 0.85 [‐0.21, 1.90] |
| 4 Re‐operations due to recurrence of discopathy Show forest plot | 4 | 564 | Risk Ratio (M‐H, Random, 95% CI) | 2.13 [1.01, 4.49] |
