Importance of Retaining Sufficient Acetabular Depth: Successful 2-Year Outcomes of Hip Arthroscopy for Patients With Pincer Morphology as Compared With Matched Controls

Abstract

Background: Patients with pincer-type femoroacetabular impingement are commonly treated with arthroscopic reduction of acetabular depth as measured by the lateral center-edge angle (LCEA). The optimal amount of rim reduction has not been established, although large resections may increase contact pressures through the hip. A recent publication demonstrated inferior surgical outcomes in patients with acetabular overcoverage as compared with normal acetabular coverage. Casual observation of our database suggested equivalent improvements, prompting a similar analysis. Purpose: To analyze patient-reported outcomes after hip arthroscopy for femoroacetabular impingement in patients with acetabular overcoverage who were matched with controls with normal coverage, as well as to analyze associations with reduction in LCEA. Study Design: Cohort study; Level of evidence, 3. Methods: Data were collected prospectively from patients with a minimum 2-year follow-up after receiving hip arthroscopy for femoroacetabular impingement by a single surgeon. Cases were reviewed to identify those with pincer-type morphology (LCEA >40°) and matched according to sex, age, chondral damage, and surgery date in a 1:1 ratio with controls with an LCEA of 25° to 40°. The surgical goal was to reduce the LCEA to the upper end of the normal range with minimal rim resection, usually 35° to 37°. Radiographic measurements of coverage, intraoperative findings, procedures, and patient-reported outcomes were recorded, including the 12-Item International Hip Outcome Tool, Non-arthritic Hip Score, Hip Disability and Osteoarthritis Outcome Score, visual analog scale for pain, rates of revision or reoperation, and conversion to total hip arthroplasty. Results: A total of 114 hips (93 patients) for the pincer group were matched 1:1 from 616 hips (541 patients) for the control group. The pincer group (mean ± SD age, 34.5 ± 12.2 years) did not differ in age, body mass index, or follow-up from controls. LCEA was reduced in both groups pre- to postoperatively: the pincer group from 44.0° ± 2.8° to 34.2° ± 3.5° and the controls from 32.9° ± 3.9° to 31.0° ± 3.0°. No differences in improvement were observed: iHOT-12 improved by 35.7 points in both groups ( P = .9 for analysis of variance interaction) and Nonarthritic Hip Score by 22.3 points ( P = .6). From all eligible surgical procedures, 2-year follow up rates were 2.5% and 2.6% for the pincer and control cohorts, respectively, and 1.2% and 0.3% for conversion to total hip arthroplasty. Conclusion: Arthroscopic management of acetabular overcoverage can achieve excellent results, equivalent to arthroscopy for other causes of symptomatic femoroacetabular impingement. A key finding was smaller rim resections producing a mean postoperative LCEA of 34.2° with a small standard deviation.