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Cochrane Database of Systematic Reviews Protocol - Intervention

One‐incision versus two‐incision techniques for arthroscopically‐assisted anterior cruciate ligament reconstruction in adults

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Abstract

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To assess the effects (benefits and harms) of one‐incision versus two‐incision techniques for arthroscopically‐assisted anterior cruciate ligament (ACL) reconstruction in adults.

Background

Description of the condition

The anterior cruciate ligament (ACL) is a tough band of tissue located in the centre of the knee joint that connects the tibia (shin bone) with the femur (thigh bone). It acts mainly to stabilise the knee against forward movement of the tibia relative to the femur. It also helps resist rotatory motion of the knee. The ACL courses from its posterior (back) attachment in the lateral (outer relative to the midline) femoral condyle (one of two rounded prominences of the femur that articulate with the tibia) towards the tibial attachment in its anterior (front) and slightly medial (inner relative to the midline) aspect (Girgis 1975).

Rupture of the ACL is a common injury in young adults involved in physical activities, especially sports such as football, rugby and skiing. As participation in sports and recreational activities increases, the incidence of these injuries tends to increase. ACL injury may be the result of sudden deceleration, hyperextension or a cutting action (Griffin 2000). In particular, the resultant instability of the knee prevents the resumption of a person's former level of activities. Moreover, recurrent episodes of knee instability may cause further injuries, such as meniscal tears, which might lead to early onset of knee osteoarthritis.

Where performed, current surgical treatment of ACL rupture comprises ACL reconstruction under arthroscopic guidance (Jackson 1987). Each year, over 100,000 ACL reconstructions are conducted in the United States alone (Lyman 2009). In ACL reconstruction, the torn ligament is replaced by a piece of tendon (graft), which is either an autograft that is harvested from the patients themselves or an allograft obtained from a cadaver.

Description of the intervention

Typically, arthroscopically‐assisted ACL reconstruction is performed through two standard portals (small stab incisions through which a camera (arthroscope) and instruments are introduced). The general aim is to place the graft as near as possible to that of the native ligament. The structures within the knee joint are visualised through the arthroscope and surgery is performed with small instruments. Bone tunnels are drilled into the tibia and the femur to place the ACL graft in almost the same position as the torn ACL. After introduction and positioning of the graft, the ends are fixed into place at or near the original attachment sites of the torn ACL with the use of various devices. These devices can be grouped according to their underlying mechanisms of fixation: compression (interference screw), expansion (a cross pin system (Rigidfix)) or suspension (button) (Zeng 2013). In the following we illustrate the procedures used in reconstruction with interference screws, which are threaded conical devices made of either metal or bioabsorbable material.

The choice of ACL reconstruction technique is not straightforward. One issue concerns the method of drilling the tunnel into the femur. Traditionally, the femoral tunnel is drilled from outside to inside the knee joint and an incision is made in the outward aspect of the thigh to reach the bone (two‐incision technique) (Bach 1989). In this procedure, the graft is fixed to the femur from outside to inside the joint with an interference screw by direct visualisation of the tunnel through the thigh incision.

The one‐incision arthroscopic technique consists of drilling the femoral tunnel from inside the knee joint under arthroscopic visualisation, thereby sparing the thigh incision and quadriceps (anterior muscles of the thigh) dissection (Hardin 1992; Howell 1999). The graft is fixed to the femur from inside to outside the joint through arthroscopic guidance and then fixed with an interference screw. Thus, the only incision needed is the one for drilling the tunnel into the tibia, which is done (as in the two‐incision technique) through an anterior incision below the knee.

How the intervention might work

ACL reconstruction aims to restore knee stability. An additional goal of strong graft fixation is to facilitate early post‐surgical rehabilitation during the so‐called 'weak link' time when the process of tendon‐bone healing is incomplete.

Because there is no dissection of the tissues on the outward‐facing part of the knee, some have suggested that the one‐incision technique should facilitate rehabilitation more successfully than the two‐incision technique (Hess 2002; Paulos 1994). However, the one‐incision technique is technically more challenging since the fixation of the graft to bone is done from inside the joint under arthroscopic control (Fanelli 1994). As the ultimate success of the ACL reconstruction procedure depends on secure and well placed fixation of the graft to the bone, compromises in graft fixation might be more relevant than avoiding a second incision. Thus, in the choice between the two techniques, there is a balance to be achieved between the potential for speedier recovery in the one‐incision technique and the potential for more reliable graft fixation in the technically less challenging two‐incision technique.

Why it is important to do this review

ACL reconstruction is a common surgical procedure that involves many choices in terms of the type of graft, fixation devices and surgical technique. Some treatment decisions have already been addressed in other Cochrane reviews; these include the type of autograft (Mohtadi 2011), use of computer‐assisted reconstruction (Meuffels 2011) and double versus single bundle reconstruction (Tiamklang 2012). However, research on ACL reconstruction is far from exhausted and many other key treatment decisions have not yet reached consensus, nor have they been systematically reviewed. This includes the use of one‐incision versus two‐incision techniques, the subject of this review.

Objectives

To assess the effects (benefits and harms) of one‐incision versus two‐incision techniques for arthroscopically‐assisted anterior cruciate ligament (ACL) reconstruction in adults.

Methods

Criteria for considering studies for this review

Types of studies

We will include randomised and quasi‐randomised (method of allocating participants to a treatment which is not strictly random, for example, by medical record number or date of birth) controlled clinical trials evaluating one‐incision versus two‐incision techniques for arthroscopically‐assisted ACL reconstruction in adults.

Types of participants

Adults (skeletally mature individuals) with ACL rupture who have undergone primary ACL reconstruction, irrespective of the presence of associated soft tissue knee injuries. We will include trials irrespective of the type of graft used.

We will exclude trials in which patients were treated surgically using open (that is through open arthrotomy reconstruction) rather than arthroscopic methods. We will also exclude trials focusing on the treatment of people with previous ACL reconstruction requiring revision surgery.

Types of interventions

One‐incision versus two‐incision arthroscopically‐assisted reconstruction of ACL injuries.

Types of outcome measures

Primary outcomes

  1. Functional assessments based on subjectively assessed, preferably validated questionnaires of knee function, e.g., the International Knee Documentation Committee (IKDC) subjective part for knee ligament injuries (Irrgang 2001) and the Lysholm score (Lysholm 1982)

  2. Quality of life assessments based on subjective and preferably validated questionnaires, for example, the ACL Quality of Life outcome measure (Mohtadi 1998), the Knee Injury and Osteoarthritis Outcome Score (KOOS) for the knee in general (Roos 1998) and the Medical Outcomes Study 36‐item short‐form health survey (SF‐36) for general measures (Ware 1992)

  3. Adverse events including treatment failure (implant breakage, screw migration, graft loss, residual instability, infection, knee stiffness)

Secondary outcomes

  1. Activity level measured by instruments (for example, Tegner activity level scale (Tegner 1985))

  2. Objective function tests (for example, one leg hop test, vertical jump test)

  3. Static stability measures (for example, Lachman, Pivot‐Shift, Anterior Drawer tests, KT‐arthrometer side to side difference)

  4. Return to previous activity level

  5. Pain measured by scales (such as a visual analogue scale (Revill 1976))

  6. Knee range of motion

  7. Muscle strength (Cybex isokinetic muscle strength testing or equivalent)

  8. Thigh circumference

  9. Lateral and posteroanterior knee radiographs (femoral tunnel position ‐ anatomic or isometric)

Timing of outcome measurement

Where possible, we will present data separately for the short term (less than six months after ACL reconstruction), intermediate term (six months to three years) and long term (three years or longer).

Search methods for identification of studies

Electronic searches

We will search the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (to present), the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (current issue), MEDLINE (1946 to present), EMBASE (1980 to present), and Latin American and Caribbean Health Sciences (LILACS) (1982 to present). We will also search the World Health Organization International Clinical Trials Registry Platform for ongoing and recently completed studies. No restrictions will be applied based on language or publication status.

In MEDLINE, a subject‐specific strategy will be combined with the sensitivity‐maximising version of the Cochrane highly sensitive search strategy for identifying randomised trials (Lefebvre 2011). The search strategies for MEDLINE and CENTRAL are shown in Appendix 1.

Searching other resources

We will check the reference lists from relevant articles. We will search the conference abstracts of the following annual meetings: International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine (ISAKOS), American Orthopaedic Society for Sports Medicine (AOSSM) and American Academy of Orthopaedic Surgeons (AAOS). Authors of trials identified by searching conference proceedings will be contacted for any unpublished trial reports and results.

Data collection and analysis

Selection of studies

Two review authors (FR and VM) will independently search abstracts and titles for potentially eligible studies. Upon obtaining the full‐text reports of these studies, the same two authors will perform independent study selection. Any disagreements will be discussed. Should consensus not be achieved, a third review author (JB) will be consulted.

Data extraction and management

Two review authors (FR and PD) will independently extract the trial characteristics and results data from eligible studies using a pre‐piloted data collection form. We will attempt to contact trial authors in order to obtain missing or unclear data. Disagreements will be resolved by discussion and, where necessary, by approaching a third review author (JB).

Assessment of risk of bias in included studies

Two review authors (FR and CF) will assess the risk of bias of the included studies using the Cochrane Collaboration's 'Risk of bias' tool (Higgins 2011). This consists of seven domains: sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective outcome reporting and other bias (for example, bias from major differences in baseline characteristics, performance bias due to disparity in the experience of the surgeons performing the procedures, and the influence of funding sources as a potential cause of bias). Each domain will be judged as being 'low risk', 'high risk' or ' unclear risk'. We will consider objective and subjective outcomes separately for blinding of participants and personnel, blinding of outcome assessment, and incomplete outcome data. Disagreements will be resolved by discussion and, where necessary, by consultation with a third review author (JB).

Measures of treatment effect

We will calculate risk ratios (RRs) and 95% confidence intervals (95% CIs) for dichotomous outcomes, and mean differences and 95% CIs for continuous outcomes. Standardised mean differences rather than mean differences will be used when pooling data from continuous outcome measures based on different scoring schemes (for example, functional outcomes such as the IKDC, ACL Quality of Life, and Lysholm scores). Results based on change scores will be collected only if final values are not available.

Unit of analysis issues

We anticipate that the clinical trials included in this review will follow the 'standard model' in which participants with unilateral ACL rupture are randomised to either a one‐ or a two‐incision technique. Bilateral ACL ruptures are rare but if these are included in trials the data may be presented for knees rather than for individual patients. Where appropriate corrections have not been made, or cannot be obtained from trial authors, we will still present the data for such trials provided the disparity between the units of analysis and randomisation is small. We will take steps to avoid unit of analysis issues relating to presentation of data at multiple time points; presentation of outcomes, such as overall complications, that could have occurred more than once in individual participants; and pooling of data from 'multi‐arm' studies, where participants of two or more groups are randomised to one incision or two incisions.

Dealing with missing data

We will attempt to contact trial investigators to request missing information and data, such as the number of events or participants, means and standard deviations. Where possible, we will perform intention‐to‐treat analyses. Where possible, we will calculate missing standard deviations (SDs) from other statistics such as standard errors, 95% CIs and exact P values. However, we will not impute missing means or SDs.

Where data continue to be unavailable, we will assess whether or not these are missing at random. When data are thought to be missing at random, or considered to be irrelevant, we will ignore them and work only with the available and relevant data. When data are assumed to be not missing at random, we will conduct sensitivity analyses to explore the potential effects of these missing data on the results.

Assessment of heterogeneity

The heterogeneity of intervention effects of studies will be appraised visually by observing the overlapping of results in the forest plots. We will interpret the lack of overlapping as indicative of possible heterogeneity. Using Review Manager software (RevMan), we will calculate I² values, which we will interpret as follows: insignificant heterogeneity (between 0% to 40%), moderate heterogeneity (30% to 60%), substantial heterogeneity (50% to 90%), and considerable (very substantial) heterogeneity (75% to 100%) (Deeks 2011).

Assessment of reporting biases

If we include more than 10 studies in the meta‐analysis, we will assess reporting bias by generating a funnel plot. This will be assessed through observing the symmetry of the distribution of intervention effects in the plot: the more symmetrical, the higher the chance of absence of reporting bias. In addition, in order to diminish the publication bias effect on asymmetry, pre‐established contour lines containing boundaries of statistical significance will be added (Peters 2008). We will be cautious in our interpretation of the funnel plots and different possible causes for funnel plot asymmetry will be considered before attributing any asymmetry to reporting bias.

Data synthesis

When considered appropriate, results of comparable groups of trials will be pooled using both fixed‐effect and random‐effects models. The choice of the model to report in the review will be guided by careful consideration of the extent of any heterogeneity and whether it can be explained; in addition to other factors such as the number and size of the included studies. Ninety‐five per cent CIs will be used throughout. We will consider not pooling data where there is considerable heterogeneity (I² > 75%) that cannot be explained by the diversity of methodological or clinical features among the trials. Where it is inappropriate to pool data, we will still present trial data in the analyses or tables for illustrative purposes and we will report these in the text.

Subgroup analysis and investigation of heterogeneity

Where data are available, we intend to perform subgroup analyses to assess the effects of the following.

  • Concomitant meniscal injuries: isolated ACL injuries versus ACL injury with associated meniscal tears

  • Delay between ACL injury and reconstruction surgery (acute versus chronic lesions)

  • Different methods of making femoral tunnels: inside‐out versus outside‐in, inside‐out versus transportal, and outside‐in versus transportal

We will investigate whether the results of subgroups are significantly different by inspecting the overlap of CIs and by performing the test for subgroup differences that is available in RevMan (Deeks 2011).

Sensitivity analysis

If sufficient trials are available, we will perform sensitivity analyses to examine various aspects of the trial and review methodology; including the effects of missing data, the selection of a statistical model (fixed‐effect versus random‐effects) for pooling; and the effects of excluding trials at high or unclear risk of bias, such as selection bias arising from lack of allocation concealment, trials with unit of analysis problems related to the inclusion of participants with bilateral ACL injuries, and trials with short‐term follow‐up after ACL reconstruction.

Assessing the quality of the evidence

We will use the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to assess the quality of the body of evidence (Schünemann 2011) for each primary outcome and one of our secondary outcomes, that is, function, quality of life, treatment failure, adverse events and activity level. The quality rating 'high' is reserved for a body of evidence based on randomised controlled trials. We may downgrade the quality rating to 'moderate', 'low' or 'very low' depending on the presence and extent of five factors: study limitations, inconsistency of effect, imprecision, indirectness or publication bias.

'Summary of findings' table

Where data are sufficient, the main results and the quality assessments will be presented in a 'Summary of findings' table (Schünemann 2011).