No Correlation Between Depth of Acetabuloplasty or Postoperative Lateral Center-Edge Angle on Midterm Outcomes of Hip Arthroscopy With Acetabuloplasty and Labral Repair: Letter to the Editor

Abstract

Dear Editor: We read the recent article published in the American Journal of Sports Medicine with lots of enthusiasm. We have a few comments, and any clarification would help the readers understand the concepts better. The lateral center-edge (LCE) angle measurement of the acetabulum has its challenges and controversies in the field of hip preservation. The authors have not described the method they have used to measure the LCE, which is very important for this study. It has been shown that there is a difference when measured to the lateral edge of the acetabulum versus the lateral edge of the sourcil. The sourcil-edge LCE corresponds to 1 to 1.30 area of the clock face, and overresection can cause anterosuperior acetabular deficiency, leading to iatrogenic instability. In this study, no worsening of the instability was reported; however, the method of LCE measurement could affect where the bone was resected, and there was no data on anterior center edge (ACE) angles or computed tomography to evaluate the resection. Rim resection can also lead to a decrease in the weightbearing surface area in the acetabulum, and over resection increases the contact stress across the hip joint, potentially leading to early degeneration. In this study, there were no data on any hip joint space measurement or the Tönnis grade of the radiographic arthritis of the hips in all the patients over the follow-up duration. It would have added more value to the study had the authors included radiographic osteoarthritis (OA) as one of the outcome measures. In this study, we also wanted to point out an error in Table 2. The results displayed that there were only 161 patients out of 192 patients, and it is unclear whether the 31 revisions were included in the analysis. It will be interesting to see whether this would change the outcome of the study once this was corrected considering the fact that this series has a high revision rate (16.1%). Pincer deformity as a cause of OA is questionable, and it may even have some protective effect. Rim resection is generally recommended in hips with overcoverage with specific indications, and acetabular resection is not indicated for hips with borderline or dysplastic range LCE. Moreover, limited rim resection has been shown to be associated with a better outcome even in patients with femoroacetabular impingement because of over coverage. It is also interesting to note that there were no revisions in the group with postoperative LCE angle of .35 compared with the normal/borderline dysplastic range postoperative LCE angle group in the study. Besides, in this study, it is unclear whether the pincer deformity was defined using any preoperative radiographic/imaging studies or using intraoperative dynamic examination alone. Theoretically, any overresection of the rim can lead to underresection of the cam deformity when relying on the dynamic examination alone and would potentially underestimate the LCE angle. Further studies are needed on whether rim resection is indicated in routine cases and the development of osteoarthritis (OA) in various LCE groups following rim resection. It is tempting to make an indirect conclusion from this article that even if you do a bit too much rim resection, it may not affect the results negatively; however, this series is from one of the renowned experienced surgeons (M.J.P.) with an in-depth knowledge of hip preservation procedures, and this study should not encourage less experienced surgeons to do more aggressive rim trimming.