Operative and non‐operative treatment options for dislocation of the hip following total hip arthroplasty

Abstract

Background

Dislocation following hip replacement is associated with significant morbidity and functional cost. The cause is usually multifactorial. A variety of treatment options are available which can broadly be classified into operative and non‐operative.

Objectives

To determine the best methods of treatment of recurrent dislocation following total hip replacement.

Search methods

The following databases were searched until August 2006: MEDLINE, EMBASE, CINAHL, the Cochrane Central Register of Controlled Trials (CENTRAL), Health Technology Assessment database (HTA), Database of Abstracts of Reviews of Effectiveness (DARE), International Standard Randomised Controlled Trial Number Register (ISRCTN), and MetaRegister of Controlled Trials (mRCT).

Selection criteria

Randomised and quasi‐randomised trials comparing operative and non‐operative treatments for recurrent dislocation following total hip replacement.

Data collection and analysis

Two independent reviewers applied the inclusion criteria to identified studies.

Main results

Searches identified 269 studies. None fulfilled the inclusion criteria.

Authors' conclusions

The authors invite researchers to perform RCTs comparing different treatment options for recurrent dislocation of the hip. The heterogeneity of the population and variety of underlying causes would favour a multi‐centre study to achieve an adequate sample size.

Plain language summary

Treatments for dislocation of the hip after Total Hip Replacement surgery

This summary of a Cochrane review presents what we know from research about the effects of treatments for dislocation of the hip after total hip replacement surgery. The review shows that:

It is not known what the best treatment for dislocation of the hip after Total Hip Replacement surgery is. This is because no evidence was found that looked at the treatments for dislocation of the hip after surgery.

What are the treatments for dislocation of the hip after Total Hip Replacement surgery? 
 In total hip replacement surgery, the whole hip joint can be replaced by an artificial joint or hip. About 3 out of 100 people who have this surgery will dislocate their hip. Dislocating a hip causes much pain and other problems. There are many ways to fix a dislocated hip. Usually, the first time a dislocation occurs the hip is put into a cast or brace. But repeated dislocations usually need to be fixed with surgery. Unfortunately, the causes for dislocation are many and some are not known making it difficult to know the best way to fix it.

What are the results of this review? 
 No evidence was found that looked at the treatments for dislocation of the hip after surgery.

Background

Dislocation is a devastating complication after total hip arthroplasty, with significant morbidity and functional cost to the patient (Chandler 1982). The prevalence following primary joint replacement is around 3% (Woo 1982), and the cumulative risk increases steadily with time (Berry 2004). Following revision surgery the rate increases to between 5 and 20% (Turner 1994; Woo 1982; Alberton 2002; Williams 1982; Paterno 1997). In addition, the dislocation rate following revision surgery for dislocation is disappointingly high (Daly 1992). It is seen more frequently in patients who have had previous hip surgery (Lewinnek 1978; Fackler 1980), with smaller head sizes (Alberton 2002), patients over the age of 80 years (Ekelund 1992), arthroplasty following hip fracture (Bystrom 2003), in neuromuscular disorders (Cabanela 2000) and in patients with cognitive dysfunction (Woo 1982; Woolson 1999).

Recurrent dislocation is defined as two or more dislocations. Causes of dislocation of total hip arthroplasty have been classified into positional (type I), soft tissue imbalance (type II) and component malposition (type III) (Dorr 1983). First time dislocations (particularly type I) are often treated with closed reduction and immobilisation in a cast or brace, and patient education (Berry 2001; Dorr 1983; Ritter 1976). Recurrent dislocation, (particularly type III) often require revision surgery (Dorr 1983). Causes of dislocation following THA are often multi‐factorial or unknown. The reasons for early versus late dislocations may also be different. In addition to this, it has also been shown that the underlying diagnosis (e.g. osteonecrosis, previous hip fracture, inflammatory arthritis) for the patient undergoing hip arthroplasty may influence the risk of dislocation (Berry 2004).

It is generally accepted that the underlying reason for the instability should be sought and rectified where possible (Ali Khan 1981). However causation is often multifactorial, and each potential cause should not be perceived in isolation (Joshi 1998). Even when a cause, such as impingement is identified and treated, the results can be sub‐optimal suggesting additional methods may be needed to achieve stability (Daly 1992).

Techniques that have been employed to improve the results of revision surgery for dislocation can be broadly classified into those addressing the acetabular liner, femoral head size, and bony or soft tissue reconstruction. Variations of acetabular liner include the use of constrained implants (Shapiro 2003; Bremner 2003; Lombardi 1991; Anderson 1994; Su 2001; Stanton 2002; Shrader 2003; Ranawat 2000), elevated‐rim liners (Cobb 1996) and augmentation wedges (Olerud 1985, Charlwood 2002). Femoral head size may be increased by conversion to a bipolar hemiarthroplasty (Parvizi 2000) and the use of large or jumbo femoral heads (Kelley 1998, Beaule 2002; Bystrom 2003). Reconstructive procedures include trochanteric advancement (Kaplan 1987) and soft tissue reconstruction (Stromsoe 1995; Mahoney 2003; Fujishiro 2003). The variety of the treatment options may reflect the lack of success surgeons have had in tackling this issue.

Objectives

To identify and summarise the evidence from randomised controlled trials assessing the clinical efficacy and safety of different interventions in the treatment of dislocation of the hip following total hip arthroplasty.

The null hypotheses to be tested are: 
 1. There is no difference in outcome between different non‐operative treatment methods 
 2. There is no difference in outcome between non‐operative and operative treatment methods 
 3. There is no difference in outcome between different operative treatment methods

Methods

Criteria for considering studies for this review

Types of studies

All randomised controlled trials comparing treatment options for dislocation of the hip following total hip arthroplasty were considered for inclusion. Quasi‐randomised trials and trials in which the treatment allocation was inadequately concealed were also considered if the remaining methodology was of a satisfactory standard.

Types of participants

All patients who have had a total hip arthroplasty, primary or revision, and sustained a dislocation were considered for inclusion. First time and recurrent dislocations were included.

Types of interventions

The non‐operative interventions are treatment with a hip spica cast or hip abduction brace, and patient education. The operative interventions are treatment with constrained implants, acetabular augmentation or elevated rim, bipolar hemiarthroplasty, large or jumbo femoral heads, trochanteric advancement and soft tissue reconstructions.

Types of outcome measures

Primary measures: 
 Dislocation rate 
 Re‐operation rate 
 Operative measures including: length of surgery, operative blood loss, post‐operative blood transfusion 
 Pain and discomfort 
 Complications related to the implant, periprosthetic fractures, others (as detailed in each individual study)

Secondary measures: 
 Malposition of cup 
 Malposition of stem 
 Length of hospital stay (days) 
 Discharge destination 
 Walking aids at discharge 
 Range of movement of the hip 
 Mobility (use of walking aids) 
 Health related quality of life measures 
 Cup loosening 
 Femoral stem loosening 
 Heterotopic ossification 
 Polyethylene wear 
 Survival rate of the prosthesis 
 Mortality 
 Patient education of techniques to reduce risk of dislocation

Search methods for identification of studies

Relevant RCTs were identified by application of a general search strategy developed by modification of that recommended by Dickersin (1994) and Haynes (1994) in collaboration with the CMSG trials search coordinator. The following databases were searched: MEDLINE (1966‐August 2006), EMBASE (1980‐August 2006), CINAHL (1982‐August 2006), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library Issue 3, 2006), Health Technology Assessment database (HTA), Database of Abstracts of Reviews of Effectiveness (DARE), International Standard Randomised Controlled Trial Number Register (ISRCTN), and MetaRegister of Controlled Trials (mRCT).

In MEDLINE (OVID‐WEB) the following subject specific search was combined with all three levels of the optimal trial search strategy (Higgins 2005):see Appendix 1.

Bibliographies of retrieved studies were investigated and the Science Citation Index used to identify articles that quote the original study (in an effort to find unidentified trials).

Unpublished data was sought from conference proceedings, Internet citations and personal communications. Where possible, authors of published trials were contacted to clarify or provide additional information.

Articles of all languages were considered and translated where necessary.

Data collection and analysis

Two independent reviewers assessed the potential eligibility for inclusion in the review based on the inclusion criteria. Studies that clearly failed to meet the inclusion criteria were not reviewed. The reviewers extracted data separately on to modified pro forma data abstraction forms (template provided by the Musculoskeletal Group) without masking of the study names, authors, institutions or journal of publication. Any differences were resolved by discussion.

In the event of published trials being identified, the data will be analysed in the following manner: quality of included trials will be evaluated independently by the reviewers, using criteria adapted from the Cochrane Handbook (Higgins 2005) and Jadad (Jadad 1996). The main assessment of methodology is the quality of allocation concealment. The following aspects of internal and external validity will be assessed:

Selection biases 
 1. Was there clear concealment of allocation? 
 2. Were the inclusion and exclusion criteria clearly defined? 
 3. Were the treatment and control groups adequately described at entry and if so were the groups well matched or appropriate covariance adjustment made?

Performance biases 
 4. Were the surgeons experienced in both operations prior to the trial? 
 5. Were the care programs other than trial options identical?

Detection biases 
 6. Were the outcome measures clearly defined in the text with a definition of ambiguous terms encountered e.g.. Minimally invasive. 
 7. Were the outcome assessors blind to assignment status? 
 8. Where patients blind to assignment status? 
 9. Was a long‐term follow‐up performed? Minimum of 1 year. 
 10. Was the timing of outcome assessment in both groups comparable and appropriate? 
 11. Was loss to follow‐up reported and if so were less than five per cent of patients lost to follow up?

Statistics 
 12. Was a sample size calculation performed? 
 13. Did the trial include an intention‐to‐treat analysis?

Further information will be obtained from the primary author if the published article provides inadequate information.

The following methods were planned for the review had there been any trials that met the inclusion criteria: 
 For each study, relative risks and 95% confidence limits will be calculated for dichotomous outcomes, and weighted mean differences and 95% confidence limits calculated for continuous outcomes. Results from individually randomised trials will be pooled wherever possible using the fixed effects model. A random effects model will be used where there is statistical or graphical evidence of heterogeneity.

In addition, a further ranking based on the level of evidence will be performed in the manner described by Tugwell (Tugwell 2004) and approved by the CMSG editorial team. A simplified ranking will also be used to grade the strength of scientific evidence for the trial intervention. In decreasing order :

Platinum level 
 The Platinum ranking is given to evidence that meets the following criteria as reported: 
 is a published systematic review that has at least two individual controlled trials each satisfying the following: 
 1. Sample sizes of at least 50 per group. If they do not find a statistically significant difference, they are adequately powered for a 20% relative difference in the relevant outcome. 
 2. Blinding of patients and assessors for outcomes. 
 3. Handling of withdrawals >80% follow up (imputations based on methods such as Last Observation Carried Forward (LOCF) acceptable). 
 4. Concealment of treatment allocation.

Gold level 
 The Gold ranking is given to evidence if at least one randomised clinical trial meets all of the following criteria for the major outcome(s) as reported: 
 1. Sample sizes of at least 50 per group. If they do not find a statistically significant difference, they are adequately powered for a 20% relative difference in the relevant outcome. 
 2. Blinding of patients and assessors for outcomes. 
 3. Handling of withdrawals > 80% follow up (imputations based on methods such as Last Observation Carried Forward (LOCF) acceptable). 
 4. Concealment of treatment allocation.

Silver level 
 The Silver ranking is given to evidence if a systematic review or randomised trial that does not meet the above criteria. Silver ranking would also include evidence from at least one study of non‐randomised cohorts who did and did not receive the therapy or evidence from at least one high quality case‐control study. A randomised trial with a 'head‐to‐head' comparison of agents is considered Silver level ranking unless a reference is provided to a comparison of one of the agents to placebo showing at least a 20% relative difference.

Bronze level 
 The bronze ranking is given to evidence if at least one high quality case series without controls (including simple before/after studies in which the patient acts as their own control) or is derived from expert opinion based on clinical experience without reference to any of the foregoing (for example, argument from physiology, bench research or first principles).

Clinical relevance tables 
 Clinical relevance tables will be compiled under additional tables to improve the readability of the review. For dichotomous outcomes, the number needed to treat will be calculated from the control group event rate and the relative risk using the Visual Rx NNT calculator (Cates 2004). Continuous outcome tables will be presented under additional tables. Absolute benefit will be calculated as the improvement in the intervention group minus the improvement in the control group, in the original units. Relative difference in the change from baseline will be calculated as the absolute benefit divided by the baseline mean of the control group. The NNT for continuous measures will also be calculated.

Results

Description of studies

Searches identified 269 studies. None fulfilled the inclusion criteria.

Risk of bias in included studies

There are as yet no published RCTs included in this review.

Effects of interventions

There are no published results to report from RCTs investigating treatment options for recurrent dislocation of the hip.

Discussion

Given that dislocation following total hip arthroplasty has such a high functional as well as economic cost, there is a need for further research to optimize the treatment of this condition. Dislocation of the hip following total hip arthroplasty is common, and its management can be difficult. There are no studies available to guide non‐operative treatment and rehabilitation. Results from studies on large femoral heads and constrained cups are promising and appear to minimise the risk of re‐dislocation. With constrained cups this may be at the potential cost of early re‐revision due to increased micromotion and early loosening.

Despite the large number of case series of recurrent dislocations in the literature, there remains to be published a comparative study of different techniques.

Authors' conclusions

Implications for practice.

There are various operative and non‐operative techniques described for dealing with the dislocating total hip arthroplasty. The efficacy of these treatment options are yet to be compared by randomised controlled trials.

Implications for research.

The authors invite researchers to conduct randomised controlled trials comparing operative and non‐operative methods for the treatment of the dislocating THA. The heterogeneity of the population and variety of underlying causes is problematic. In order to achieve homogeneous groups for valid comparisons studies would need to be multicentric. Ideally all dislocations would be recorded in national joint registries to give a true indication of the size of the problem. Unanswered questions regarding non operative management include duration of use of abduction braces. And a useful comparison of operative management would be very large metal on metal heads (44 mm+) and constrained cups.

What's new

Date	Event	Description
7 November 2008	Amended	Converted to new review format. CMSG ID: A015‐R

Appendices

Appendix 1. MEDLINE search strategy

1 arthroplasty, replacement, hip/ 
 2 Hip Prosthesis/ 
 3 or/1‐2 
 4 arthroplasty/ or arthroplasty, replacement/ 
 5 Joint Prosthesis/ 
 6 "Prostheses and Implants"/ 
 7 (arthroplasty or replacement or prosthes#s).tw. 
 8 or/4‐7 
 9 hip/ or hip joint/ or hip.tw. 
 10 8 and 9 
 11 3 or 10 
 12 Hip Dislocation/ 
 13 Joint Instability/ 
 14 (displacment$ or dislocat$ or instabilit$ or unstable).tw. 
 15 9 and 14 
 16 or/12‐15 
 17 11 and 16 
 18 clinical trial.pt. 
 19 randomized controlled trial.pt. 
 20 tu.fs. 
 21 dt.fs. 
 22 random$.tw. 
 23 (double adj blind$).tw. 
 24 placebo$.tw. 
 25 or/18‐24 
 26 17 and 25

Characteristics of studies

Characteristics of excluded studies [ordered by study ID]

Study	Reason for exclusion
Atlihan 2002	RCT comparing 4 techniques for hip replacement in 40 patients with congenital dislocation of the hip
Kelley 1998	RCT evaluating the relationship betweem femoral head size / acetabular outer diameter and the prevalence of dislocation, in 30 patients
Peak 2005	RCT evaluating the role of patient restrictions in reducing the prevalence of early dislocation
Toomey 2001	Case series of 13 patients treated with modular component exchange, involving a combination of: use of a longer neck, larger head size, elevated liner rim, reorientaion of the liner or thicker liner

RCT ‐ Randomised controlled trial

Contributions of authors

Riaz Khan initiated and designed the study with the help of Nuki Alakeson and Dan Fick. All authors have contributed to the writing of the protocol. Riaz Khan is the guarantor of the review.

Sources of support

Internal sources

• No sources of support supplied

External sources

• Library services, Royal Australasian College of Surgeons, Australia.

Declarations of interest

None known

Edited (no change to conclusions)