Probable benefit: total hip arthroplasty for trauma

In parallel with the improved medical care models, treatment of the intracapsular neck of femur fracture has been the focus of some significant studies and a recent change in practice; the concept, of course, is that not all patients are the same. NICE recognises and recommends that current standard practice should be to offer replacement arthroplasty for patients with displaced intracapsular neck of femur fractures. A further NICE recommendation has been to offer total hip arthroplasty (THA) to patients within this cohort who are outdoor mobilisers with no more than one stick, have no cognitive impairment and are fit for surgery. This guidance does not, however, make much in the way of distinction for age and frailty – simply a distinction for functional outcomes.

There are a huge number of cohort studies on the topic, variably identifying the advantages of longevity and the potential for better functional results in a total hip arthroplasty, offset against the disadvantages of dislocation rates and increased surgical complexity. Perhaps surprisingly, given the strength of NICE’s recommendations, there are few randomised controlled trials, and those which do exist are not as resoundingly in favour of total hip arthroplasty in active patients as one might expect.

A recent systematic review⁹ identified some RCTs looking at THA versus modular hemiarthroplasty. The outcomes of these studies were somewhat mixed, with four studies showing improved quality of life or function scores with THA, and three showing no functional difference.¹

A further RCT which has been published since this systematic review reports the 12-year outcomes of a single-centre trial.¹⁰ The initial study cohort included 252 patients undergoing cemented hemiarthroplasty versus THA, and did not report any significant difference between modified Harris Hip Score, mortality, complications or revision rates.¹⁰ It is, of course, important to set these results against the obvious attrition bias which occurs in long-term follow-up of patients undergoing hip fracture surgery. At the time of reporting, this study will have been dramatically underpowered.

The generally held fear of acetabular erosion happening in patients treated with a cemented hemiarthroplasty may not stand up to scrutiny in the way that one might think, having read the national guidance. Evidence from Baker et al¹¹ suggests that a fifth of active patients over 60 years of age undergoing hemiarthroplasty result in revision, though acetabular erosion was found in two thirds. This finding is not mirrored in other large series, with the Australian Joint Registry suggesting that the ten-year cumulative rate of revision for bipolar prostheses in neck of femur fractures under 70 years old is 10%. Furthermore, this rate of revision is comparable with that for conventional THAs in the same demographic (12%).¹²

So, if revision is not as much of a problem as one might have been led to believe, is there any evidence to support higher patient satisfaction/function in the active elderly treated with a THA? The evidence is unclear, with some studies showing a mixture of benefits and others no benefits. NICE have therefore suggested that this should be a research priority.