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Total hip arthroplasty versus resurfacing arthroplasty in the treatment of patients with arthritis of the hip joint: single centre, parallel group, assessor blinded, randomised controlled trial

BMJ 2012; 344 doi: (Published 19 April 2012) Cite this as: BMJ 2012;344:e2147

Re: Total hip arthroplasty versus resurfacing arthroplasty in the treatment of patients with arthritis of the hip joint: single centre, parallel group, assessor blinded, randomised controlled trial

Dear Sirs

Costa et al should be commended on undertaking a prospective randomised study. This is a laudable aim and one achieved all too infrequently in orthopaedics. It is a shame, however, that their paper does not have the necessary rigour or provide the detail that is really required to reach useful conclusions.

The authors do not describe the exact approach and technique used by their surgeons. The approach may have a significant impact on outcome, and it is widely known that at least one of the surgeons within that group favours a trans trochanteric approach for hip resurfacing and that this is associated with significant problems post-operatively, including the need for metalwork removal, which would worsen the outcome for that group over the first year1,2.

No radiographic or metal ion data is provided and thus the reader is unable to determine whether these are “good” or “bad” resurfacings or hip replacements 3-5.

No detail regarding the type of re-surfacing implant used has been included. It has become clear that there is a massive difference between the outcome of the Birmingham hip resurfacing implanted in appropriate positions by experienced surgeons and other implants that fare much less well 6-8 .

Very traditional and non-discriminating outcome measures have been used to measure function. These tests have a ceiling effect9,10. Moreover the arbitrary effect sizes mean that there is a high chance of a type 2 error; a 5 point difference in Oxford scores is of considerable magnitude. The reference provided (19) actually states that the minimum clinically significant difference (MCSD) is unknown and whilst 5 might be a good guess a figure of 3 or even 2 may be correct. This undermines the whole power calculation. No rationale or reference is provided for the Harris Hip Score MCSD, a difference of 8% seeming quite large when comparing successful procedures.

We have validated a task based functional assessment tool11 that shows a significant difference between THR and BHR patients with tasks that require balance and proprioception. The authors should consider using modern assessment methods that are designed to show differences in active patients after hip surgery.

Without the corroborative technical, radiographic and functional data, both this dataset and the cost-effectiveness data are invalid.

It is disappointing that this paper has been accepted in its current format.

Yours sincerely

Sam Oussedik
Sujith Konan
Fares Haddad
University College Hospitals, London

1. Cashman JP, Cashman WF. Comparison of complications in transtrochanteric and anterolateral approaches in primary total hip arthroplasty. Orthopedics. 2008 Nov;31(11):1085.
2. Horwitz BR, Rockowitz NL, Goll SR, Booth RE Jr, Balderston RA, Rothman RH, Cohn JC. A prospective randomized comparison of two surgical approaches to total hip arthroplasty. Clin Orthop Relat Res. 1993 Jun;(291):154-63.
3. Hart AJ, Matthies A, Henckel J, Ilo K, Skinner J, Noble PC.Understanding why metal-on-metal hip arthroplasties fail: a comparison between patients with well-functioning and revised birmingham hip resurfacing arthroplasties. AAOS exhibit selection. J Bone Joint Surg Am. 2012 Feb 15;94(4):e22
4. Langton DJ, Sprowson AP, Joyce TJ, Reed M, Carluke I, Partington P, Nargol AV. Blood metal ion concentrations after hip resurfacing arthroplasty: a comparative study of articular surface replacement and Birmingham Hip Resurfacing arthroplasties. J Bone Joint Surg Br. 2009 Oct;91(10):1287-95.
5. Hart AJ, Buddhdev P, Winship P, Faria N, Powell JJ, Skinner JA. Cup inclination angle of greater than 50 degrees increases whole blood concentrations of cobalt and chromium ions after metal-on-metal hip resurfacing. Hip Int. 2008 Jul-Sep;18(3):212-9. 1:
6. Reito A, Puolakka T, Pajamäki J. Birmingham hip resurfacing: five to eight year results. Int Orthop. 2011 Aug;35(8):1119-24.
7. Treacy RB, McBryde CW, Shears E, Pynsent PB. Birmingham hip resurfacing: a minimum follow-up of ten years. J Bone Joint Surg Br. 2011 Jan;93(1):27-33.
8. Baker RP, Pollard TC, Eastaugh-Waring SJ, Bannister GC. A medium-term comparison of hybrid hip replacement and Birmingham hip resurfacing in active young patients. J Bone Joint Surg Br. 2011 Feb;93(2):158-63.
9. Wamper KE, Sierevelt IN, Poolman RW, Bhandari M, Haverkamp D. The Harris hip score: Do ceiling effects limit its usefulness in orthopedics? Acta Orthop. 2010 Dec;81(6):703-7.
10. Marx RG, Jones EC, Atwan NC, Closkey RF, Salvati EA, Sculco TP. Measuring improvement following total hip and knee arthroplasty using patient-based measures of outcome. J Bone Joint Surg Am. 2005 Sep;87(9):1999-2005.
11. Development and validation of a discriminating functional hip score Konan S, Tahmassebi J, Haddad FS. Podium 620, AAOS meeting 2011.

Competing interests: I have received royalties and research support from Smith and Nephew but never in relation to hip resurfacing. Our department research research support from a number of industry partners

04 May 2012
fares haddad
orthopaedic surgeon
Sam Oussedik, Sujith Konan
university college london hospitals
235 Euston Road, London NW1 2BU