Treatment of Borderline Acetabular Dysplasia in the Adolescent Patient: Outcomes of Periacetabular Osteotomy

INTRODUCTION: The treatment of borderline acetabular dysplasia [defined as lateral center edge angle (LCEA) 18-25°] is controversial as there is limited evidence regarding the optimal surgical treatment [hip arthroscopy versus periacetabular osteotomy (PAO)]. The decision-making is particularly challenging in the adolescent patient where a durable outcome is particularly important. PURPOSE: To define early clinical outcomes, complications and rates of reoperation in adolescent patients undergoing PAO for the treatment of borderline acetabular dysplasia. METHODS: A prospective single surgeon hip preservation database was retrospectively reviewed for adolescent patients treated with PAO for symptomatic instability in the setting of borderline acetabular dysplasia. A total of 56 hips were identified from 2010 to 2019 and followed for an average of 3.5 ±1.9 years (range, 1-7). Modified Harris hip scores (mHHS) were analyzed relative to minimal clinically important difference (MCID 8) and patient acceptable symptoms state (PASS>74). Complications and reoperations were recorded. RESULTS: The 56 included hips (age 16.3 ±1.4 years; 89% female) had a mean preoperative LCEA of 20.9° ±.2.0° (37%, 18-20°; 63% 20-25°). Concurrent hip arthroscopy for symptomatic labral pathology was performed in 28% of cases. Major improvement in mHHS (27 ±17) from baseline to final follow-up (59 vs. 86, p<0.001) corresponded to a high observed rate of achieving MCID or PASS (91%). Two patients (3.6%) underwent subsequent arthroscopy. There were no other non-hardware removal reoperations. There were no outcome differences between those treated with and without concurrent arthroscopy (p>0.5). CONCLUSION: PAO surgery provides excellent pain relief and improved function in adolescent patients with symptomatic, borderline acetabular dysplasia. The observed reoperation rate (3.6%) is low for this patient population. The PAO remains our preferred treatment for borderline dysplasia with clinical signs and symptoms of hip instability.