Abstract
Background: The optimal treatment of patients with symptomatic borderline acetabular dysplasia is a major controversy in hip preservation, as patients may have primary symptoms of impingement or instability. Intraarticular pathologies driven by these processes may differ and have not been thoroughly investigated. The purpose of this study was to investigate differences in intra-articular disease patterns between borderline hips treated with isolated hip arthroscopy (HS) compared to combined HS with periacetabular osteotomy (HS/PAO). Methods: Patients were prospectively enrolled in a multicenter cohort database. Inclusion criteria were borderline acetabular dysplasia (defined by lateral center edge angle 18-25 degrees), aged 14-40 years who failed standard conservative care. All surgeons had established teams with expertise in HS and PAO with established interobserver reliability for arthroscopic disease assessment. Treatment groups include isolated HS or HS/PAO (performed in combination on same day). Exclusion criteria were isolated PAO without arthroscopy (n=138), revision arthroscopy, and Tonnis osteoarthritis grade 2 or greater. Intraoperative labral and cartilage pathology were compared between the HS group and the HS/PAO group. Results: There were 483 hips (67.8% female) with a mean age of 24.5+7.8 years; 318 (65.8%) underwent HS and 165 (34.2%) underwent HS/PAO. Hips undergoing HS were more likely to have an abnormal labrum than those undergoing HS/PAO (6.3% vs 12.1%, p=0.027), including labral detachment (55.3% vs. 38.8%, p<0.001) and degeneration (28.3% vs. 17.6%, p=0.009). Hips undergoing HS had half the rate of labral hypertrophy than combined HS/PAO (21.1% vs. 44.8%, p<0.001). Acetabular cartilage damage was more likely to be present in isolated HS compared to HS/PAO (77.7%, vs. 64.8%, p=0.003), and higher-grade cleavage (27.7% vs. 11.5%, p<0.001) and chondral defects (7.9% vs. 0.6%, p<0.001) were more likely. Ligamentum teres pathology was similar between groups (14.6% HS vs. 10.5% HS/PAO, p=0.226). Capsular laxity was noted in fewer HS than HS/PAO hips (15.0% vs 33.1%, p<0.001). Conclusion: In this prospective multicenter cohort study of patients undergoing surgical treatment of borderline acetabular dysplasia, hips with impingement-predominant symptoms indicated for isolated HS were more likely to have more advanced labral and cartilage damage compared to hips with instability predominant-symptoms who were indicated for HS/PAO.