PurposeHip dislocation in cerebral palsy (CP) is a serious complication. By radiographic screening and prophylactic surgery of children at risk most dislocations can be prevented. CPUP, the Swedish CP registry and follow-up program, includes annual radiographic examinations of children at Gross Motor Function Classification System (GMFCS) levels III–V. Data from CPUP were analysed to assess the risk of hip displacement in relation to GMFCS levels and age.MethodsAll children at GMFCS levels III–V (N = 353) whose first radiographic screening occurred before 3 years of age were followed between the ages 2–7 years. Migration percentages (MPs) were recorded annually (1,664 pelvic radiographs) and analysed using discrete time survival analysis.ResultsThe risk of hip displacement between 2 years and 7 years of age was significantly (p < 0.05) higher for children at GMFCS level V during the entire study period. The risk was highest at 2–3 years of age and decreased significantly (p < 0.001) with each year of age (OR = 0.71, 95 % CI 0.60–0.83). The cumulative risk at age 7 years for those at GMFCS V for MP ≥ 40 % was 47 % (95 % CI 37–58). The corresponding risk at GMFCS IV was 24 % (16–34) and at GMFCS III 23 % (12–42).ConclusionsChildren at GMFCS V have a significantly higher risk of hip displacement compared with children at GMFCS III–IV. The risk is highest at 2–3 years of age. The results support a surveillance program including radiographic hip examinations as soon as the diagnosis of severe CP is suspected.

Purpose The Salter innominate osteotomy (SIO) in children is traditionally stabilized by Kirschner-wires, which have issues regarding stability, infection and the need to be extracted. To counter these disadvantages, we present a surgical method to stabilize SIO with modern resorbable poly lactic-co-glycolic acid screws. Using a case series of 21 patients treated with SIO for developmental dysplasia of the hip or Legg-Calvé-Perthes disease we evaluate the feasibility of the method. Methods The integrity of the osteotomy was interpreted by radiological measurements of acetabular index, centre-edge angle and Reimer’s index. Perioperative and postoperative complications were evaluated. Results Radiographic evaluation revealed a stable osteotomy and favourable development in all measured parameters with the exception of one patient who fell out of bed the first day postoperatively. No other perioperative surgical complications were observed and there were no local reactions to the resorbable screws. Conclusion Modern resorbable screws carry multiple benefits both for the patient and the surgeon. In our case series the implants provided sufficient stability and the implants caused no local reactions. The use of resorbable implants gave the surgeon a wider range of possible screw placements and avoided the need for implant removal. Level of evidence Level IV – Case series

Background The triple pelvic osteotomy is an established surgical method with multiple modifications regarding surgical technique and choice of implant. The stability of the osteotomy is affected by numerous factors, and among these, the three-dimensional implant configuration is a scientifically less explored aspect. Methods We used a finite element model of a hemi-pelvis with a standardized triple osteotomy to calculate relative flexibility for loads in all translational degrees of freedom for five different implant configurations. Two of the configurations used entry points only feasible when implant removal was not necessary. Results The stability of the osteotomy improved with an increased distance between the implants in the plane of the osteotomy as well as for a more perpendicular angle relative to the osteotomy plane. The implant configurations with more entry points available made this easier to adhere to. Conclusion The use of bioabsorbable implants may provide better opportunities for optimal implant constructs which can, to a certain degree, compensate for the lesser mechanical stiffness of bioabsorbable polymers as compared to metal implants.