Electronic Letters to:

Hip: D. Allen, P. E. Beaulé, O. Ramadan, and S. Doucette Prevalence of associated deformities and hip pain in patients with cam-type femoroacetabular impingement J Bone Joint Surg Br 2009; 91-B: 589-594 [Abstract] [Full text] [PDF]

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Author's reply:

Paul E. Beaule   (7 August 2009)

Acetabular and pincer impingement: do they really mix?

justin p cobb, United Kingdom   (22 July 2009)

Author's reply: 7 August 2009
Paul E. Beaule, Associate Professor University of Ottawa Send letter to journal: Re: Author's reply: pbeaule{at}ottawahospital.on.ca Paul E. Beaule	Sir, We thank Professor Cobb for his comments and words of caution regarding the treatment of associated acetabular retroversion in patients with cam-type femoroacetabular impingement (FAI). More importantly, we entirely share his views. As such, our conclusion could have been worded differently but was more a reflection of current sentiments at various meetings as well as recent literature than a reflection of our own views. Too often the paper of Beck and associates1 has been quoted as stating that the majority of cam impingers have a mixed deformity (>70%), thus requiring one to perform both a chondro-osteoplasty as well as an acetabular rim trimming. This is evident in recent literature where surgeons are performing acetabular rim trimming in association with a chondro-osteoplasty of the head/neck junction in over 70% of their cases.2,3 More importantly, the issue of acetabular rim trimming gets mixed in with the issue of labral refixation/repair versus resection as it relates to functional outcome, further blurring the appropriate indications for performing acetabular rim trimming in the presence of acetabular retroversion. No one would argue that preservation of the acetabular labrum is desirable, however, this does not require trimming of the acetabular rim. As our paper points out, there is currently no clinical evidence supporting the need for correcting acetabular retroversion after the adequate correction of an underlying cam deformity, and further research is required to better understand the dynamic relationship between cam and pincer deformities. P.E. Beaule, Associate Professor, University of Ottawa, Ottawa, Canada. 1. Beck M, Kalhor M, Leunig M, Ganz R. Hip morphology influences the pattern of damage to the acetabular cartilage: femoroacetabular impingement as a cause of early osteoarthritis of the hip. J Bone Joint Surg 2005;87-B:1012-8. 2. Larson CM, Giveans MR. Arthroscopic debridement versus refixation of the acetabular labrum associated with femoroacetabular impingement. Arthroscopy 2009;25:369-76. 3. Philippon MJ, Briggs KK, Yen YM, Kuppersmith DA. Outcomes following hip arthroscopy for femoroacetabular impingement with associated chondrolabral dysfunction: minimum two-year follow-up. J Bone Joint Surg 2009;91-B:16-23.
Acetabular and pincer impingement: do they really mix? 22 July 2009
justin p cobb, professor of orthopaedics imperial college, United Kingdom Send letter to journal: Re: Acetabular and pincer impingement: do they really mix? j.cobb{at}imperial.ac.uk justin p cobb, et al.	Sir, I read this paper with interest. It makes a significant contribution to the literature by documenting the prevalence of asymptomatic cam deformity. However, the secondary conclusion - "Further research is required to determine if the associated pincer deformity needs to be corrected in every case of symptomatic cam deformity." - is concerning, and may be misleading. The separate mechanisms of cam and pincer impingement have been well described.1,2 Using three-dimensional methods such as the senior author’s approach to the quantification of the cam,3 others have already quantified the asymmetric profile of the acetabulum,4 showing that the iliac eminence is normally anterior to the coronal plane of the acetabulum, and thus may be seen on plain radiograph as a ‘cross over’ sign in an acetabulum that is shallow, not deep. It may also produce an inappropriately high lateral centre-edge angle. Therefore, an enthusiastic analyst of plain radiographs may conclude that an acetabulum is either retroverted or too deep, or both, when it is actually normal or even marginally dysplastic. This additional diagnosis may generate additional procedures such as ‘rim trimming’ of the acetabulum. In these patients with cam impingement, who have fundamentally shallow sockets, these additional acetabular reduction procedures have no biomechanical basis, and may lead to iatrogenic acetabular insufficiency, a far more difficult problem to manage. J.P. Cobb, Professor of Orthopaedics, Imperial College, London, UK. 1. Ganz R, Leunig M, Leunig-Ganz K, Harris WH. The etiology of osteoarthritis of the hip: an integrated mechanical concept. Clin Orthop 2008;466:264-72. 2. Ganz R, Parvizi J, Beck M, et al. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop 2003;417:112-20. 3. Beaulé PE, Zaragoza E, Motamedi K, Copelan N, Dorey FJ. Three-dimensional computed tomography of the hip in the assessment of femoroacetabular impingement. J Orthop Res 2005;23: 1286-92. 4. Vandenbussche E, Saffarini M, Taillieu F, Mutschler C. The asymmetric profile of the acetabulum. Clin Orthop 2008;466:417-23.