TP1.6 Behind the Eight Ball: Prior Operative Treatment of Childhood DDH Is Associated with Poorer Outcomes Following Periacetabular Osteotomy

Abstract Background Outcomes of hip preservation surgery in patients with history of previous developmental dysplasia of the hip (DDH) surgery remain poorly understood. The purpose of this study was to directly compare presentation and outcomes of periacetabular osteotomy (PAO) in patients with residual dysplasia following history of childhood hip surgery (HCS group) against patients with typical adolescent/young adult dysplasia without history of prior childhood surgery (Control group). Methods From a prospective, multicenter database, 2036 PAOs performed between 2008-2015 were identified. We reviewed patients with prior childhood hip surgery to identify those treated for developmental dysplasia of the hip (DDH). We excluded patients with non-DDH diagnoses and those who underwent only femoral-sided surgery. A randomized two-to-one match was performed to select PAOs in hips with no prior childhood hip surgeries. Collected data included demographic and perioperative information, patient reported outcomes (PROs) at baseline, 1-year, 2-years, and pre- and postoperative radiographic data. PROs included modified Harris Hip Score (mHHS), Hip Disability and Osteoarthritis Outcome Score (HOOS), UCLA score, and Short Form-12 (SF-12). Composite failure was defined as failure to reach either minimal clinically important difference or patient acceptable symptom state, or conversion to total hip arthroplasty. Results 192 patients (64 HCS and 128 Control) were included. Preoperatively, the HCS group was younger (18.9±7.1 vs 22.9±8.7 years; p<0.001) with more severe dysplasia via lateral center edge angle (LCEA) (6.4° vs 12.2°; p=0.002), anterior center edge angle (3.7° vs 10.6°; p=0.002), and Tönnis angle (24.6° vs 18.7°; p<0.0001). The HCS cohort demonstrated more preoperative degenerative changes with greater proportion of patients with Tönnis grade II/III changes (19.1% vs 5.6%; p<0.001). There were no differences between groups at presentation in mHHS, HOOS, UCLA, or SF-12 except for higher HOOS QOL in the HCS group (p=0.04). Despite similar rates of achieving correction of LCEA>20° (p>0.05), at 2-year follow-up HCS hips had lower mHHS (76.0±23.8 vs 87.6±13.5, p=0.02) and higher rates of composite failure (37.8% vs 15.6%, p=0.005). Subgroup analysis revealed closed reduced hips were not significantly different from controls radiographically or with respect to PROs (p>0.05). Conclusion Patients with prior open operative treatment for DDH present at younger age with more severe deformity and early degenerative changes compared to those with typical adolescent/young adult dysplasia. Despite similar baseline PROs and radiographic correction, HCS hips have lower PROs at 2-years compared to controls.