Arthroscopic Management of Dysplastic Hip Deformities: Predictors of Success and Failures With Comparison to an Arthroscopic FAI Cohort

Background: Reports regarding arthroscopy for mild hip dysplasia have conflicting results. Hypothesis: Arthroscopy for borderline/mild hip dysplasia would lead to improved outcomes but be inferior to arthroscopy for femoroacetabular impingement (FAI). Study Design: Cohort study; Level of evidence, 3. Methods: A total of 88 hips (77 patients, 71% female; mean age, 33.9 years) with dysplastic radiographic findings were retrospectively reviewed at a mean follow-up of 26.0 months after hip arthroscopy. Specific procedures included labral repair (76%), labral debridement (23%), capsular repair/plication (82%), and femoral osteochondroplasty (72%). Radiographic parameters included lateral center-edge angle, neck-shaft angle, Tonnis angle, extrusion index, femoral head lateralization, and break in the Shenton line. Pre- and postoperative function were evaluated prospectively with the modified Harris Hip Score (mHHS), 12-Item Short Form Health Survey, and visual analog scale for pain. The results of the dysplastic cohort were compared with an age-matched cohort of 231 hips without radiographic dysplasia that underwent arthroscopic FAI correction during the study period (mean follow-up, 22.7 months). Results: The mean lateral center-edge angle was 20.8 degrees (range, 8.7 degrees-24.5 degrees), and the mean Tonnis angle was 11.0 degrees (range, 0 degrees-22.2 degrees). At the time of final follow-up, the dysplastic cohort demonstrated a mean mHHS of 81.3 with a mean 15.6-point improvement in mHHS, compared with 88.4 and 24.4 points, respectively, in the FAI cohort (P = .00044). The dysplastic cohort had 60.9% good/excellent results and 32.2% failures, compared with 81.2% good/excellent results and 10.5% failures for the FAI cohort (P < .01). Failure was defined as an mHHS 70 or eventual pelvic/femoral osteotomy or total hip arthroplasty. Dysplastic hips that underwent capsular plication and labral repair had greater good/excellent results (73%) and mean latest mHHS (85), as well as lower failure rates (18%) compared with the remainder of the dysplastic cohort (P < .05). Grade 4 chondral defects were predictive of lower scores (P = .02). There were no other statistically significant differences for outcomes regarding sex, age, or radiographic parameters (P > .05). There were no iatrogenic subluxations/dislocations. Conclusion: Arthroscopic management of mild to moderate acetabular dysplasia had inferior good/excellent results and higher failure rates when compared with an FAI cohort; therefore, isolated arthroscopic procedures in this population should be cautiously considered. These results were independent of patient sex. Labral repair and capsular plication resulted in better clinical outcomes in this mildly dysplastic cohort.