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Cochrane Database of Systematic Reviews Protocol - Intervention

Hip resurfacing versus traditional total hip arthroplasty for osteoarthritis and other non‐traumatic diseases of the hip

Authors' declarations of interest

Version published: 03 December 2013 Version history

https://doi.org/10.1002/14651858.CD010851
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Abstract

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

To assess the effects of total hip resurfacing versus traditional total hip arthroplasty (THA) for osteoarthritis and other non‐traumatic diseases of the hip.

Background

Description of the condition

Osteoarthritis is a slowly progressive, degenerative joint disease which presents a major public health problem worldwide. Osteoarthritis is characterised by the destruction of the articular (joint) cartilage, subchondral bone alterations and synovitis (inflammation of the synovial membrane of the joints). It affects not only the articular cartilage, but the whole joint. The proliferation of osteoblasts (bone‐forming cells) along the joint margin leads to the formation of osteophytes (bony projections), the proliferation of synovial cells causes hyperplasia (enlargement) of the synovium and subchondral bone formation leads to sclerosis (hardening) of underlying damaged cartilage (Longo 2012). Clinical manifestations of osteoarthritis may include joint pain and dysfunction and, in advanced stages, joint contractures, muscle atrophy and limb deformity (Heijink 2012).

Hip osteoarthritis is a common problem especially after middle age (Garstang 2006; Issa 2006; Jensen 2008). Radiographic evidence of hip osteoarthritis is present in about 5% of the over‐65 population (Lane 2007) and about one in four people can expect to develop symptomatic hip osteoarthritis during their lifetime (Murphy 2010). Since the hip is a weight‐bearing joint, osteoarthritis can cause significant problems, such as hip pain, morning stiffness and limited range of motion. As the condition becomes worse, pain may be present all the time.

Rheumatoid arthritis is a chronic, autoimmune, systemic inflammatory disease in which persistent active inflammation of the synovium leads to joint swelling, tenderness and progressive destruction. These, in turn, lead to pain, disability and emotional, social and economic problems. Rheumatoid arthritis has an overall incidence of 1% in the general population (Gibofsky 2012). Treatment of rheumatoid arthritis in the first instance is focused on the use of steroids and disease‐modifying antirheumatic drugs (Ibrahim 2012). When medical therapy fails to control the disease process, the patient becomes a candidate for surgical treatment (Aulakh 2011). Patients with end‐stage joint deterioration due to osteoarthritis or rheumatoid arthritis constitute the largest group of patients for whom hip arthroplasty surgery is considered (Ethgen 2004).

Description of the intervention

Hip arthroplasty is a surgical procedure in which the diseased cartilage and bone of the hip joint is replaced by a prosthetic implant. It is performed when there is irreversible damage to the joint surfaces, leading to pain, immobility and deformity. It is indicated for patients with intractable pain and substantial functional disabilities who have not had acceptable relief and functional improvement after conservative treatment, and who are not candidates for other, non‐ablative reconstructive procedures such as arthroscopy (Ethgen 2004). Hip arthroplasty is most commonly used to treat joint failure caused by osteoarthritis. Other indications include avascular necrosis, inflammatory arthritis, post‐traumatic arthritis, dysplasia, malignancy and others (Lai 2008; Liu 2009; Singh 2011).

A traditional total hip arthroplasty (THA) consists of replacing the acetabulum (hip bone socket) and resection of the femoral head followed by replacement with a stemmed femoral prosthesis and femoral head prosthesis (AOA 2011; Mirza 2010). In recent years, there has been an increase in the number of THAs performed worldwide. In Sweden, the number of THAs increased by 20% from 8336 in 1987 to 10,015 in 1997; the predicted annual number of THAs by the year 2020 is expected to rise to 12,773 operations, an increase of 28% compared with 1997. In the Netherlands there was an increase of 68% in the number of primary THAs, from 10,359 operations in 1986 to 17,401 in 1997; by the year 2020 the annual number of THAs is likely to increase by 44% to 25,090 operations (Ostendorf 2002). A total of 202,500 primary THA procedures were performed in the United States in 2003. By 2030, the demand for primary total hip arthroplasties is estimated to grow by 174% to 572,000 (Kurtz 2007).

THA is a highly successful and cost‐effective intervention for addressing pain and functional deficits in patients with advanced hip disease. Wear and osteolysis are the foremost concerns in THA (Brown 2009; Garbuz 2010). THA has previously been avoided in young, active patients due to concerns about the durability of prostheses and the projected need for multiple revision procedures with progressive loss of bone stock. The survival of THA components has been reported to be only 56% at a minimum of 22 years follow‐up in the young patient with osteoarthritis (Georgiades 2009). The high failure rates of THA among young, active patients and the desire to preserve bone for future revision operations has led to the development of hip resurfacing arthroplasty (Bozic 2010).

Hip resurfacing arthroplasty is a type of hip replacement that replaces the arthritic surface of the joint. The procedure consists of placing a cap, shaped like a mushroom, over the head of the femur while a matching cup is placed in the acetabulum. It differs from THA in that the femoral head is resurfaced rather than resected, thereby preserving femoral bone stock, which could theoretically decrease morbidity and improve patient outcomes associated with future revision operations (Bozic 2010; Marker 2009).

The first‐generation hip resurfacing system was introduced in the 1970s. It had a large metal head articulated with high‐molecular‐weight polyethylene. However, most surgeons stopped using it because of poor durability (Amstutz 1978; Howie 1990). Despite this initial failure, in recent years there have been great advancements in implant design, bearing surface, instrumentation and surgical technique (Amstutz 2006; McMinn 2006). Modern hip resurfacing implants use a metal‐on‐metal bearing surface. In the UK, the National Institute for Clinical Excellence (NICE) guidelines for hip resurfacing procedures were released in 2002. They state that metal‐on‐metal resurfacing should be carried out in patients who are likely to outlive a conventional hip replacement. The first metal‐on‐metal hip resurfacing system was approved by the Food and Drug Administration (FDA) in the United States in 2006. Since then, total hip resurfacing arthroplasty has grown in popularity as a treatment for symptomatic arthritic hips. In 2008, it was estimated that hip resurfacing accounts for as many as 6% to 9% of all hip arthroplasties in some countries, including Australia (7.9%), France (6%), Germany (9%) and the United Kingdom (7%) (Huo 2008). In 2010, there were 14,298 primary hip resurfacing arthroplasties recorded by the Australian Orthopaedic Association National Joint Replacement Registry (AOA 2011).

How the intervention might work

There are a number of theoretical advantages of hip resurfacing over conventional THA. The preservation of proximal femoral bone is an important aspect of resurfacing because it might allow for straightforward revision to a standard THA if the resurfaced hip fails. The large bearing surface results in improved range of motion and contributes to increased prosthetic joint stability. The metal‐on‐metal articulation has the potential to decrease wear and ultimately to reduce the incidence of implant failure (Garbuz 2010; Smith 2012). Other theoretical advantages of hip resurfacing over conventional THA include normal load transmission, less thigh pain, better biomechanics and retention of proprioception (Girard 2006; McMinn 2006; Nunley 2009).

Although the indications for hip resurfacing arthroplasty are similar to primary THA, including end‐stage arthritis recalcitrant to non‐operative treatments in healthy and willing patients, it favours young, active males with end‐stage osteoarthritis, good bone quality and normal femoral and acetabular anatomy (Nunley 2009). A higher revision rate has been found in women and patients with osteonecrosis, inflammatory arthritis and developmental dysplasia of the hip (de Steiger 2011; Nunley 2009; Prosser 2010; Smith 2012). Hip resurfacing arthroplasty is a technically demanding operation: the surgeon must have extensive training and clinical experience in order to achieve technical proficiency (Sedrakyan 2012).

With the wide use of hip resurfacing arthroplasty, some potential early disadvantages have also been identified, including a risk of femoral neck fracture, avascular necrosis of the femur head, formation of pseudotumour and acetabular bone stock sacrifice (Kim 2008; Loughead 2006; Marker 2007; Zustin 2010). The most commonly reported reasons for failure of hip resurfacing arthroplasty include femoral neck fracture, collapse of the femoral head and component loosening (Sehatzadeh 2012). Hip resurfacing arthroplasty may not suitable for female patients because of a higher risk of osteoporotic fractures of the femoral neck and a greater predisposition to reactions to metal debris (de Steiger 2011; Smith 2012). Metal‐on‐metal articulation produces this metal debris, which may lead to adverse biological reactions, including local soft tissue toxicity, delayed type hypersensitivity reactions, osteolysis and even a risk of carcinogenesis (Keegan 2007). Long‐term follow‐up studies are needed to assess the safety of hip resurfacing arthroplasty.

Why it is important to do this review

For older patients, several THA designs have shown excellent results both in terms of function and value for money. THA continues to be the gold standard for treatment of degenerative hip disorders and most patients will enjoy an excellent quality of life. However, in younger, more active patients, there is a high failure rate of traditional implants at long‐term follow‐up. Hip resurfacing arthroplasty has become more popular due to the improved design and manufacturing of implants, better materials and its theoretical advantages, but there is still controversy in the literature about its effectiveness and safety for osteoarthritis and other non‐traumatic diseases of the hip.

Objectives

To assess the effects of total hip resurfacing versus traditional total hip arthroplasty (THA) for osteoarthritis and other non‐traumatic diseases of the hip.

Methods

Criteria for considering studies for this review

Types of studies

We will include randomised controlled trials (RCTs) or controlled clinical trials which use pseudo‐randomised methods of allocating participants to treatment in this review. Results should be published as a full report and there will be no restrictions on length of follow‐up or language of the paper.

Types of participants

Patients 18 years or older with hip osteoarthritis or other non‐traumatic diseases undergoing implantation of a primary hip prosthesis will be eligible. Patients receiving a hip arthroplasty following trauma, pathological fractures or tumour will be excluded. Patients undergoing revision arthroplasties will be excluded.

Types of interventions

Trials comparing total hip resurfacing arthroplasty with traditional THA (cemented, un‐cemented or hybrid total hip prosthesis) will be included. Different types of prosthesis (cemented, un‐cemented and hybrid hip prosthesis), different types of surface‐bearing materials (metal on polyethylene, ceramic or ceramic‐like materials on polyethylene, metal‐on‐metal and ceramic‐on‐ceramic) and different generations of hip resurfacing systems (first‐generation hip resurfacing system: metal‐on‐polyethylene hip resurfacing device; modern hip resurfacing systems: metal‐on‐metal hip resurfacing device) will be included.

Types of outcome measures

Major outcomes

  1. Survival rate of the implant (e.g. to replace the implant or for another reason indicating failure of the procedure)

  2. Functional hip scores (e.g. Harris Hip Score, Western Ontario and McMaster Universities Arthritis Index (WOMAC) Score, Oxford Hip Score)

  3. Pain

  4. Health‐related quality of life

  5. Global assessment of outcome (participant‐reported)

  6. Total adverse events (e.g. deep vein thrombosis (DVT), pulmonary embolism (PE), deep infection, any event resulting in disability or death, infection, nerve injury, dislocation and other surgical complications)

  7. Re‐operation rate (not involving implant change, short‐ and long‐term)

These outcomes will be reported in the summary of findings tables.

Minor outcomes

  1. Operating time

  2. Intraoperative blood loss

  3. Surgical complications of fixation (e.g., infection, nerve injury, dislocation, fixation cup loosening, stem loosening and fracture around the implant

Minor outcomes will be presented in Additional Tables.

Time points

If available in the included studies, we plan to evaluate the main outcomes for the following endpoints

  • short‐term follow‐up (less than 24 months after operation);

  • intermediate‐term follow‐up (25 to 120 months after operation):

  • long‐term follow‐up (more than 120 months after operation).

Search methods for identification of studies

Electronic searches

We will search the following databases:

  • Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library) using the search strategy outlined in Appendix 1;

  • MEDLINE (Ovid) using the search strategy outlined in Appendix 2;

  • EMBASE (Ovid) using the search strategy outlined in Appendix 3.

Searching other resources

We will search the World Health Organization International Clinical Trials Registry Platform (ICTRP) (http://www.who.int/ictrp/en) and clinicaltrials.gov (http://clinicaltrials.gov) for ongoing and unpublished trials. If we identify any ongoing trials we will contact authors and request full trial reports for inclusion in the review.

We will handsearch the reference lists of retrieved studies and those of narrative and systematic reviews to find additional potentially relevant studies. We will also contact the authors of included studies for additional information, as necessary. W will contact experts in the field and key authors for additional references.

Data collection and analysis

Selection of studies

Two review authors (Xu H and He ML) will screen all the titles, abstracts and keywords of publications identified by the searches to assess their eligibility. We will exclude publications that clearly do not meet the inclusion criteria at this stage. We will retrieve the full text of all potentially relevant papers and two review authors (Xu H and He ML) will independently review complete copies of each study and indicate on a study eligibility form if the study should be included, excluded or they are undecided. We will resolve disagreements regarding study inclusion by discussion between the two review authors and, if necessary, by the involvement of a third independent review author (Xiao ZM). We will contact the corresponding author for clarification if it is unclear whether a trial is eligible for inclusion. All studies marked as 'undecided' by a review author will be discussed further between the two review authors, and then included or excluded.

Data extraction and management

We will extract and record data using data extraction forms, which will be developed and piloted by two authors (Xu H and He ML). We will resolve any differences through discussion with the third author (Xiao ZM). We will attempt to obtain any missing data from the corresponding authors. We will compile the following information from the included studies:

  • General study information (e.g. title, authors, publication year, country).

  • Characteristics of the study: design, study setting, inclusion and exclusion criteria, risk of bias (e.g. randomisation method, allocation procedure, blinding and other issues about bias).

  • Characteristics of the study population and baseline characteristics of the intervention and control groups (age, sex, duration of disease, concurrent treatments) and numbers in each group.

  • Type of prosthesis used.

  • Details of the outcome measures as stated above (for hip function, if there are several measures used, we will extract only WOMAC scores for the meta‐analysis. For pain, if some trials measure overall pain, plus night pain, plus pain on activity, we will extract overall pain for the meta‐analysis).

  • Drop‐outs.

  • Length of follow‐up.

We will use this information to populate the 'Characteristics of Included Studies' table for each included study.

If trials report more than one measure for an outcome:

  • For pain, we will use a hierarchy of six levels:

    • pain overall (global pain);

    • pain on walking;

    • WOMAC osteoarthritis index pain sub‐score;

    • pain on activities other than walking;

    • rest pain;

    • other algofunctional scale.

When more than one is reported, we will take the highest on the list, for example we will choose overall pain over pain on walking.

  • For physical function, we will choose a continuous scale over an ordinal scale and use a hierarchy of eight levels:

    • global disability score;

    • walking disability;

    • WOMAC disability sub‐score;

    • composite disability scores other than WOMAC;

    • disability other than walking;

    • WOMAC global scale;

    • Lequesne osteoarthritis index global score;

    • other algofunctional scale.

When more than one is reported, we will take the highest on the list.

  • For quality of life, we will use a hierarchy of four levels:

    • Short Form‐36 (SF‐36);

    • Short Form‐12 (SF‐12);

    • EuroQoL‐5 Dimensions (EQ‐5D);

    • other scale system.

When more than one is reported, we will take the highest on the list.

  • If both final values and change from baseline values are reported for the same outcome, we will extract the final values.

  • If both unadjusted and adjusted values for the same outcome are reported, we plan to extract the adjusted values.

  • If data are analysed based on an intention‐to‐treat (ITT) sample and another sample (e.g. per‐protocol, as‐treated), we plan to extract ITT sample values for both benefits and harms.

  • If there are multiple time points, we will abstract the data for three timeframes: (a) short‐term: less than 24 months after operation; (b) intermediate‐term: 25 to 120 months after operation; and (c) long‐term: more than 120 months after operation.

Assessment of risk of bias in included studies

Two authors (Xu H and He ML) will independently assess the risk of bias of each trial according to Higgins 2011a (described below), record the information in a table and provide a narrative description in the text. We will resolve disagreements by discussion or by involving a third review author (Xiao ZM) and we will contact the corresponding study authors for clarification if information is unclear.

Sequence generation

Is the allocation sequence adequately generated? (Checking for possible selection bias). For each included study, we will categorise the method used to generate the allocation sequence as:

  • low risk of bias (any truly random process, e.g. random number table; computer random number generator);

  • high risk of bias (any non‐random process, e.g. odd or even dates of birth; hospital or clinic record numbers);

  • unclear risk of bias.

Allocation concealment

Is allocation adequately concealed? (Checking for possible selection bias). For each included study, we will categorise the method used to conceal the allocation sequence as:

  • low risk of bias (e.g. telephone or central randomisation; consecutively numbered sealed opaque envelopes);

  • high risk of bias (open random allocation; unsealed or non‐opaque envelopes; alternation; date of birth);

  • unclear risk of bias.

Blinding of participants and personnel

We will assess whether included studies have reported adequate blinding of participants (to detect the presence of performance bias).

Blinding of outcome assessment

We will consider blinding separately for subjective self‐reported outcomes (such as pain, function, global assessment) and objective outcomes (such as re‐operation rate), as for unblinded outcome assessment, risk of bias for objective outcomes may be very different than for a patient‐reported outcomes.

Incomplete outcome data

Are incomplete outcome data adequately addressed? (Checking for possible attrition bias through withdrawals, drop‐outs and protocol deviations). For each included study and for each outcome, we will describe the completeness of data including attrition and exclusions from the analysis. We will note whether attrition and exclusions are reported, the numbers included in the analysis at each stage (compared with the total number of randomised participants), reasons for attrition or exclusion where reported, and whether missing data are balanced across groups or were related to outcomes. Where sufficient information is reported, or supplied by the trial authors, we will re‐include missing data in the analyses. We will categorise the methods as:

  • low risk of bias (< 20% missing data);

  • high risk of bias (≥ 20% missing data);

  • unclear risk of bias.

Selective reporting bias

Are reports of the study free of suggestion of selective outcome reporting? For each included study, we will describe how we investigated the possibility of selective outcome reporting bias and what we found. We will assess the methods as:

  • low risk of bias (where it is clear that all of the study's pre‐specified outcomes and all expected outcomes of interest to the review have been reported);

  • high risk of bias (where not all the study's pre‐specified outcomes have been reported; one or more reported primary outcomes were not pre‐specified; outcomes of interest were reported incompletely and so cannot be used; study fails to include results of a key outcome that would have been expected to have been reported);

  • unclear risk of bias.

Other sources of bias

Is the study apparently free of other problems that could put it at a high risk of bias? For each included study, we will describe any important concerns we have about other possible sources of bias (for example, whether there was a potential source of bias related to the specific study design or whether the trial was stopped early due to some data‐dependent process). We will assess other sources of bias as:

  • low risk of bias;

  • no risk of bias;

  • unclear risk of bias.

Overall risk of bias

We will make explicit judgements about whether studies are at high risk of bias, according to the criteria given in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011a). With reference to (1) to (6) above, we will assess the likely magnitude and direction of the bias and whether we consider it is likely to impact on the findings. As well, we will consider the impact of missing data by key outcomes.

Measures of treatment effect

We will calculate overall effects from the studies for which data are available. For dichotomous outcomes we will express the results as risk ratio (RR) with 95% confidence intervals (CI). For continuous scales of measurement we will present the mean difference (MD) and 95% CI, or the standardised mean difference (SMD) and 95% CI if different scales are used to measure the same outcome. When different scales are used to measure the same conceptual outcome (e.g. pain), we will back‐translate the SMD to a typical scale (e.g. 0 to 10 for pain) by multiplying the SMD by a typical among‐person standard deviation (e.g. the standard deviation of the control group at baseline from the most representative trial).

Unit of analysis issues

The unit of analysis will be the participant. If studies report resuls for bilateral surgery, but have randomised by person in their analyses, without adjustment for the non‐independence between limbs, there may be potential unit of analysis errors. We will attempt to re‐analyse such studies by calculating sample sizes where possible, as outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011c).

Dealing with missing data

For included studies, we will note levels of attrition. When missing data are discovered during data extraction, we will attempt to contact the study authors to request the required information. Where possible, we will compute missing standard deviations from other statistics such as standard errors, confidence intervals or P values, according to the methods recommended in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011b). If standard deviations cannot be calculated, we will impute them (e.g. from other studies in the meta‐analysis; Higgins 2011c).

Assessment of heterogeneity

We will assess included trials for clinical homogeneity in terms of participants, interventions and comparators. We will examine heterogeneity across studies by inspecting the distribution of point estimates for the effect measure and the overlap in their confidence interval on the forest plot. We will use the I2 statistic to check the statistical consistency, defined as the ratio of between‐study variation compared to the overall variation (Deeks 2011). A value greater than 50% may be considered to be substantial heterogeneity and we will explore the sources of heterogeneity further.

Assessment of reporting biases

In order to determine whether reporting bias is present, we will determine whether the protocol for the trial was published before recruitment of patients to the study was started. For studies published after 1 July 2005, we will screen the International Clinical Trials Registry Platform (ICTRP) of the World Health Organization (DeAngelis 2004). We will evaluate whether selective reporting of outcomes is present (outcome reporting bias).

If there are 10 or more studies in the meta‐analysis, we will analyse reporting bias using the funnel plot method. We will assess funnel plot asymmetry visually and use formal tests for funnel plot asymmetry. If asymmetry is detected in any of these tests or is suggested by a visual assessment, we will use the 'trim and fill' method to investigate it (Sterne 2011).

We will compare the fixed‐effect model against the random‐effects model to assess the possible presence of small sample bias in the published literature (i.e. in which the intervention effect is more beneficial in smaller studies). In the presence of small sample bias, the random‐effects model shows the intervention to be more beneficial than the fixed‐effect model estimate (Sterne 2011).

Data synthesis

We will analyse the results of the studies using Review Manager 5.2 (RevMan 2012). If studies are considered to be sufficiently clinically homogenous, we will pool data in a meta‐analysis using a random‐effects model, irrespective of the I2 values, and perform a sensitivity analysis with the fixed‐effects model.

Summary of findings

We will present the main results of the review in a 'Summary of findings' table: survival rate of the implant (any change of a component); functional measures (e.g. WOMAC, Oxford Hip Score, etc); pain; participant global assessment of success; health‐related quality of life; total adverse event (infection, thrombosis, palsy, death, etc.); and re‐operation rate (not involving implant change). This will provide key information concerning the quality of evidence, the magnitude of effect of the interventions examined and the sum of available data on the main outcomes, as recommended by The Cochrane Collaboration (Schünemann 2011a). This table includes an overall grading of the evidence related to each of the main outcomes using the GRADE approach (Schünemann 2011b).

We will report the absolute risk differences, and relative changes in the 'Summary of findings' table. In addition to the absolute and relative magnitude of effect, we will calculate the number needed to treat (NNT) for benefit (NNTB) or for harm (NNTH) for an additional outcome for each statistically significant estimate of effect. For dichotomous outcomes, the absolute risk difference is calculated by using RevMan to generate the risk difference analysis and then reporting the result as a percentage. The relative per cent change is calculated by finding the risk ratio (RR) from RevMan and then applying the formula RR‐1 equals the relative per cent change. We will calculate the number needed to treat (NNT) from the control group event rate (unless the population event rate is known) and the relative risk using the Visual Rx NNT calculator (Cates 2008). For continuous outcomes, absolute risk difference is derived from the mean difference (MD) generated in RevMan divided by scale of the instrument; relative per cent change is derived from the MD divided by the baseline mean of the control group. We will calculate the NNT using the Wells calculator software available at the Cochrane Musculoskeletal Group (CMSG) editorial office (http://musculoskeletal.cochrane.org/). We will determine the minimal clinically important difference (MCID) for each outcome for input into the calculator.

Subgroup analysis and investigation of heterogeneity

We will use subgroup analysis to explore possible sources of heterogeneity if sufficient data are available. The following subgroup analyses are planned:

  1. patients' ages (18 to 65 years versus ≥ 65 years);

  2. gender (male versus female);

  3. preoperative diagnoses (osteoarthritis versus other non‐traumatic diseases).

We will contact the corresponding author to obtain information as needed.

We will assess differences between subgroups by inspection of the subgroups' confidence intervals; non‐overlapping confidence intervals indicate a statistically significant difference in treatment effect between the subgroups. We will also use the formal test for subgroup interactions in Review Manager (RevMan 2012).

Sensitivity analysis

If sufficient data are available, we plan sensitivity analyses to assess the impact of any bias attributable to inclusion of trials with inadequate or unclear treatment allocation concealment.