SURGICAL PRACTICE VARIATION AND FACTORS INFLUENCING INDICATIONS FOR SPECIFIC INTERVENTIONS FOR HIP DISPLACEMENT IN CHILDREN WITH CEREBRAL PALSY

Hip surveillance regimes for cerebral palsy (CP) recommend referral to orthopaedics when migration percentage (MP) reaches 30%. However, indications for when and how to intervene surgically varies widely. The CP Hip Outcomes Project (CHOP) is a prospective cohort study of 750+ patients (28 sites;10 countries) evaluating different management strategies for hip displacement in non-ambulant children with CP. This study characterizes the practice variation and factors influencing indications for specific hip-intervention strategies among surgeons in CHOP. 28 clinicians (mean:10 yrs experience; >50% CP practice) from 17 sites in North America, Europe, Middle-east, & Australasia evaluated 71 case vignettes of purposefully selected patients from the CHOP database with ages (2–18 yrs), MP (0%-100%), uni/bilateral hip involvement. Radiographs were presented with MP; range of hip motion (R1/R2); parent-report of hip pain &/or contractures interfering with care. A digital-response system captured anonymized surgeon-specific demographics and treatment recommendations for each case - watchful waiting (W); botulinum toxin injection (Btx); adductor releases alone (AdR); AdR & femoral varus derotation osteotomy (VDRO); addition of pelvic osteotomy (PO); salvage surgery (SS); to uni- vs bilateral surgery; open reduction (ORed). Multiple logistic regression was used to evaluate surgeon and patient factors on indications for specific interventions (OR:odds ratios). Patients had a mean age of 6.9 yrs (1.3–17.5yrs); MP of 58% (0–100% each side), with equivalent GMFCS IVs & Vs; boys & girls. 37/71 had hip symptoms. The mean hip abduction R1: 25° (−15 to 80); R2: 37° (−15 to 80). MP, more than age was the major driver of decisions. W was chosen by 40% of surgeons for MPs up to 50%. When MP exceeded 50%, surgery was recommended by 95% of surgeons, independent of other factors. Those who intervened when MP <50%, 15% preferred Btx if R2-R1 difference was >25°; 18% preferred AdR; while 27% performed VDRO. Decision to operate when MP<50% was influenced by presence of hip symptoms. GMFCS level and sex were not related to decisions. AdR alone was seldom offered when MP >60%. VDRO was offered at all ages. PO was offered for children >5 yrs who had acetabular dysplasia. Bilateral surgery was preferred option by >75% of surgeons. ORed was recommended by 40% of surgeons when MP >70%, and by 60% of surgeons when hips were dislocated (MP=100%). Femoral head reduction frog-leg x-rays dropped indications for an ORed from 58% to 18%. SS was preferred for high-dislocations (OR:24), that were irreducible (OR:23), with a deformed femoral head (OR:16) and were symptomatic (OR:8.7), with surgeons varying in their threshold of acceptable femoral head deformity. There is wide variation in the indications for specific interventions among experienced surgeons worldwide who manage hip displacement in CP. MP and presence of hip symptoms are he two drivers of recommendations. Evaluation of comparative effectiveness of these different strategies in the CHOP study will inform future decision-making and narrow practice variation.