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HipFurther Opinion

Comparison of patient-reported outcomes between hip resurfacing and total hip replacement

EA Lingard, K Muthumayandi, J Holland

J Bone Joint Surg [Br] 2009;91-B:1550-4.

 

Amongst hip replacement surgeons the choice of implant remains an area of great debate. Some of the most contentious issues within this discussion involve hip resurfacing and also whether we should treat younger patients to improve function rather than wait for severe pain and stiffness which may then limit longer-term functional outcomes. This paper provides useful evidence for the debate by comparing the patient-reported outcomes between hip resurfacing and total hip replacement (THR) at one year after surgery.

Resurfacing offers minimal femoral bone resection facilitating future revision surgery and the potential for a virtually anatomical hip after surgery with good biomechanics and proprioception. Girard et al1 have shown more precise restoration of proximal femoral anatomy with hip resurfacing compared with THR. Resurfacings have a low reported rate of dislocation, many patients get back to a high level of activity and enthusiasts remain convinced it is the only sensible option for young active patients with some outstanding published five year results.2,3

A previous long term follow-up of cemented THRs has shown rapidly deteriorating results after five years for young patients with osteoarthritis with  around 82% survivorship at ten years.4 McBryde et alhave shown eight-year survivorship rates of > 97% for resurfacings inserted by either a posterior or an anterolateral approach from a specialist centre but time will provide further data on hip resurfacings at longer term follow-up in larger numbers.

Resurfacings when taken as heterogeneous group rather than split by implant type have been shown by the National Joint Registry6 (NJR) to have a higher risk of early revision than THR. These data fuel the argument for traditional THR for all patients, and some surgeons feel this remains the safest option. It is however important to remember that the failure rates presented by the NJR would not identify a patient with a poor clinical outcome due to recurrent dislocation until it was revised or a patient with a poor outcome from a significant alteration of offset or a large leg length discrepancy. The decision to revise a THR that dislocates is also more arbitrary than the decision to revise a resurfacing with a femoral neck fracture and this could be a source of bias in the short-term.

The Australian Joint Registry7 has more detailed longer term data available about Resurfacings and identifies higher failure rates in patients aged 75 or over and also with smaller component sizes. The Australian Joint Registry also has sufficient numbers to break down rates of revision per 100 observed years by implant type. Excluding implants that have only been implanted in small numbers (less than 100) this shows a wide variation with the best implants achieving rates of revision of  around 0.8% per 100 observed years compared with rates ranging from 1.7 to 3.1 for a variety of other implants. As well as patient and implant factors surgical experience has also been shown to affect rates of revision after hip resurfacing.8

Previously Pollard et al9 compared the outcomes for resurfacing to THR at five to seven years from surgery. They found the resurfacings to have higher UCLA activity scores and better EuroQol quality of life scores. At a longer follow-up than currently reported by the NJR they also found a slightly lower revision or intention to revise rate of 6% for the resurfacing group compared with 8% for the THR. This may be due to the fact that the results are from a specialist orthopaedic centre or alternatively it may be that if resurfacings survive the early post-operative period they have a lower rate of revision due to the low rate of dislocation. It is important, however, not to place too much emphasis on results from one paper from a specialist unit.

Shorter waiting times in the NHS have led to patients presenting earlier for treatment. Changes in lifestyle also mean patients wish and expect to return to a higher level of activity and function than would have been the case in the past. If we are to offer patients surgery at an earlier stage it is important that we can provide them both with satisfactory short term outcomes with a low risk of complication and also long term durable results despite a high level of activity.

As this paper only looks at outcome up to one year no comments can be made on longer term outcome. The authors found a lower rate of complication in the resurfacing group, one deep vein thrombosis out of 132 cases, compared with one death and four dislocations in the THR group of 214 patients. The resurfacing group reported higher satisfaction with functional outcome and a greater improvement in patient reported general health at one year. This fits with Pollard’s9 previous report of higher UCLA activity scores and EuroQol quality of life scores after resurfacing compared with hybrid THR.

One weakness of the study is that the two groups are not exactly comparable. The resurfacing group was smaller and they were younger, more likely to be male and had fewer co-morbid conditions. The low rate of complication seen with the resurfacing group may reflect the fact that it was a single surgeon series with five years previous experience of resurfacing.

The authors have achieved excellent short term outcomes for their Resurfacing patients with a low risk of complications. It is important that we have access to further long term follow-up studies such as this of patient-reported outcomes and rates of complication. We can then use this alongside more generic data from the NJR as it expands with time and our own critically audited data. This should enable us to appropriately inform patients about the various options for hip surgery taking into account their age, physical status and functional expectations. I look forward with great interest to the authors updating their study in the future with longer term results.

References

1. Girard J, Lavigne M, Vendittoli P-A, Roy AG. Biomechanical reconstruction of the hip.  J Bone Joint Surg [Br] 2006;88-B:721-6.
2. Daniel J, Pynsent PB, McMinn DJW. Metal-on-metal resurfacing of the hip in patients under the age of 55 years with osteoarthritis. J Bone Joint Surg [Br] 2004;86-B:177-84.
3. Treacy RBC, McBryde CW, Pynsent PB. Birmingham hip resurfacing arthroplasty. J Bone Joint Surg [Br] 2005;87-B:167-70.
4. Joshi AB, Porter ML, Trail IA, Hunt LP, Murphy JCM, Hardinge K. Long-term results of Charnley low-friction Arthroplasty in young patients. J Bone Joint Surg [Br] 1993;75-B:616-23.
5. McBryde CW, Revell MP, Thomas AM, Treacy RB, Pynsent PB. The influence of surgical approach on outcome in Birmingham hip resurfacing. Clin Orthop 2008;466:920-6.
6. No authors listed. National Joint Registry for England and Wales . Sixth Annual Report. 2009. Available from: http://www.njrcentre.org.uk (date last accessed 22 November 2009).
7. No authors listed. Australian Orthopaedic Association National Joint Replacement Registry. Annual Report 2009. Available from: http://www.dmac.adelaide.edu.au (date last accessed 22 November 2009).
8. Shimmin AJ. The effect of operative volume on the outcome of hip resurfacing. Paper #316. Presented at the American Academy of Orthopaedic Surgeons 76th Annual Meeting. Feb. 25-28, 2009. Las Vegas.
9. Pollard TCB, Baker RP, Eastaugh-Waring, SJ, Bannister GC. Treatment of the young active patient with osteoarthritis of the hip. J Bone Joint Surg [Br] 2006;88-B:592-600.

 

Dunlop DJ

The Royal Orthopaedic Hospital, Birmingham, United Kingdom

E-mail: david.dunlop@roh.nhs.uk