O2147: Behind the Eight Ball: Prior Operative Treatment of Childhood DDH Is Associated with Poorer Outcomes Following Periacetabular Osteotomy in a Prospective, Multicenter ANCHOR Study

Background: Residual dysplasia at skeletal maturity is common even after previous childhood surgery for developmental dysplasia of the hip (DDH). However, outcomes of hip preservation surgery in patients with a history of previous 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 a history of childhood hip surgery (HCS group) with patients who have typical adolescent/young adult dysplasia without history of prior childhood surgery (Control group).

Methods: From the Academic Network for Conservational Hip Outcomes Research (ANCHOR) prospective database, 2036 PAO’s were identified between 2008 to 2015. We reviewed all patients with prior childhood hip surgery to identify those treated for DDH. We excluded patients with non-DDH diagnoses and those who underwent femoral-sided surgery only as these wouldn't affect later surgery on the pelvis. A randomized two-to-one match was performed to select PAO’s 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), and Short Form-12 (SF-12).

Results: 189 patients (63 HCS and 126 Control) were included. The HCS group was younger at time of PAO surgery (19.0±7.1 vs 22.9±8.6 years; p=0.002) and had more severe dysplasia preoperatively via lateral center edge angle (LCEA) (6.6° vs 11.3°; p = 0.002), anterior center edge angle (ACEA) (3.9° vs 10.7°; p=0.01), and Tönnis angle (24.7° vs 18.7°; p< 0.0001). Preoperatively, there was no significant difference in qualitative acetabular retroversion (posterior wall sign and crossover sign both p>0.05). The HCS cohort demonstrated more preoperative degenerative changes with a greater proportion of patients with Tönnis grade II and III changes (19.1% vs 5.6%; p = 0.0004), and smaller proportion of hips with excellent joint congruity (12.7 vs 32.0%; p = 0.0085). At surgery, HCS hips achieved similar correction with rates of postoperative LCEA>20° (92.5% vs 94.0%, p=0.72). There were no differences between groups at presentation in mHHS, HOOS, or SF-12 except for higher HOOS QOL in the HCS group (42.1±22.3 vs 35.3±21.8, p=0.04). However, at 2-year follow-up, HCS hips had lower mHHS (76.0±23.8 vs 87.6±13.5, p=0.02) with worse scores in HOOS pain, HOOS ADL, and SF-12 Physical domains (all p< 0.05).

Conclusion: Patients who had prior operative treatment for DDH present at a younger age with more severe deformity and early degenerative changes compared to those with typical adolescent/young adult dysplasia. Although they present with similar functional baselines and achieve similar rates of correction, patients with HCS have lower PROs and poorer early outcomes at 2-year follow-up compared to controls.