Hip & Pelvis

Hip arthroplasty in femoral neck fracture

The body of evidence on the topic of total hip arthroplasty (THA) as a treatment for neck of femur fracture is growing. There are a number of small randomised controlled trials that are suggestive of better functional outcomes with THA. However, despite this, due in part to the fragility of many patients, this remains a relatively infrequently undertaken procedure. This paper from Edinburgh (United Kingdom) fills in some of the current gaps in knowledge and describes longer-term follow-up than in much of the existing published work in this area.² This study reports the outcomes of 128 consecutive patients undergoing cemented metal-on-polyethylene THA (all undertaken via an anterolateral approach) for femoral neck fracture over a three-year period and these were all identified and prospectively followed-up. As perhaps would be expected, far more patients were female than male. At a mean follow-up of 5.4 years, 16% had died (although again as would be expected in a total hip cohort, none had died before 90 days post-op) and 9% had sufficiently severe dementia to preclude a meaningful response. Of the remainder, 80% responded. The premise of this paper is that it constitutes a five-year follow-up of a group previously reported up to two years, showing no significant differences in Oxford Hip Score, Visual Analogue Score and SF-12 between two-year results and five-year results (the present paper). Overall, patient satisfaction levels remained high and clinical outcomes excellent after this longer period of follow-up. The authors conclude that these encouraging results derive from careful patient selection and that all procedures were undertaken by specialist arthroplasty surgeons (this obviously poses logistical challenges in terms of service planning in the majority of centres). Rather contentiously, the authors also attribute their good results to their use of the modified Hardinge approach in all cases (with the aim of lowering dislocation risk). This, however, is not entirely borne out by their own literature review. The overall conclusion here is that THA gives good mid-term results for femoral neck fracture, provided the correct surgeons undertake it in the correct patients. This is substantiated by their results and certainly adds to the increasing body of evidence in this area to suggest that perhaps more patients should receive THA following this injury. Of course, what this paper doesn’t help us with is the selection criteria which are still very much up for debate.

Dual mobility a favourable option in revision arthroplasty

The use of dual mobility cups has seen a steady increase. Reassured by more modern bearing surfaces with better tribology, the trade-off of increased wear but improved stability seems to be moving in many surgical practices towards a favourable one – particularly in the case of revision surgery where it may not be too difficult to justify the potential for reduced longevity in return for improved stability. There are, however, few reasonable-sized studies on the topic and this study from the Swedish Hip Arthroplasty Register adds a huge amount to what was previously known. The authors from Gothenburg (Sweden) have reviewed the outcomes of 984 hip revision procedures undertaken for dislocation and recorded on the registry between 2005 and 2015.³ Although 523 of these were undertaken using a dual mobility bearing, this study – quite sensibly – only analyses the 436 of these which were undertaken with the most commonly used prosthesis (the ZimmerBiomet Avantage cup). The outcomes from this group are compared against 355 revisions also undertaken using a standard cemented polyethylene cup. A note of caution should of course be injected here – it is highly possible there will be a moderate selection bias, with surgeons in general likely to use the dual mobility cup in the more severe cases of instability. It is therefore all the more heartening that the key take-home message from this study is that both re-revision specifically for dislocation and all-cause re-revision are more likely in the fixed bearing group than the Avantage group (91% ± 3.7% vs 86% ± 4.1%). Although there was a statistical difference in ages between the groups, the cohorts otherwise appeared well matched and the comparison is probably a valid one. The findings of this study support the use of dual mobility acetabulum as a favourable option in revision hip arthroplasty surgery, specifically where instability is the indication for revision. Although registry-based studies are by no means beyond criticism, the large numbers and clear statistical differences with these two bearings from an internationally well respected joint registry certainly merit consideration.