Hip Dysplasia: Prevalence, Associated Findings, and Procedures From Large Multicenter Arthroscopy Study Group

Purpose: To report observational findings of patients with acetabular dysplasia undergoing hip arthroscopy. Methods: We performed a comparative case series of multicenter registry patients from January 2014 to April 2016 meeting the inclusion criteria of isolated hip arthroscopy, a documented lateral center-edge angle (LCEA), and completion of preoperative patient-reported outcome measures. A retrospective analysis compared range of motion, intra-articular pathology, and procedures of patients with dysplasia (LCEA <= 25 degrees) and patients without dysplasia (LCEA >25 degrees). Results: Of 1,053 patients meeting the inclusion criteria, 133 (13%) had dysplasia with a mean LCEA of 22.8 degrees (standard deviation, 2.4 degrees) versus 34.6 degrees (standard deviation, 6.3 degrees) for non-dysplasia patients. There were no statistically significant differences in preoperative modified Harris Hip Score, International Hip Outcome Tool-12 score, or visual analog scale score (pain). Cam deformity occurred in 80% of dysplasia patients. There was a significant difference in internal rotation between the dysplasia (21 degrees) and non-dysplasia groups (16 degrees, P < .001). Mean internal rotation (33.5 degrees; standard deviation, 15.6 degrees) of the dysplastic subjects without cam morphology was greater than that of the dysplastic patients with cam morphology (18.5 degrees; standard deviation, 11.6 degrees; P < .001). Hypertrophic labra were found more commonly in dysplastic (33%) than non-dysplastic hips (11%, P < .001). Labral tears in patients with dysplasia were treated by repair (76%), reconstruction (13%), and selective debridement (11%); labral treatments were not significantly different between cohorts. The most common nonlabral procedures included femoroplasty (76%) and synovectomy (73%). There was no significant difference between the dysplasia and non-dysplasia groups regarding capsulotomy types and capsular closure rates (96% and 92%, respectively). Conclusions: Dysplasia, typically of borderline to mild severity, comprises a significant incidence of surgical cases (13%) by surgeons performing high-volume hip arthroscopy. Despite having similar preoperative pain and functional profiles to patients without dysplasia, dysplasia patients may have increased flexed-hip internal rotation. Commonly associated cam morphology significantly decreases internal rotation. Arthroscopic labral repair, femoroplasty, and closure of interportal capsulotomy are the most commonly performed procedures.