Introduction. The standard plane imaging of Graf and the dynamic methods of Harcke are well established methods in assessing hip dysplasia but give limited information in the flexed-abducted treatment position used in the Pavlik harness. The femoral head may sit on the edge of the acetabulum in a flexed position and only reduce when the hips are abducted. This may mean that hips, which reduce when abducted in the Pavlik harness, appear subluxed when scanned in neutral abduction. Harness treatment may thereby be abandoned prematurely due to the failure to confirm reduction. This study identifies ultrasound landmarks on an anterior hip scan which could be used to confirm reduction of the hip in Pavlik Harness. Materials and method. Hips of a newborn piglet were scanned, imaged with magnetic resonance and x-rayed both before and after anatomical dissection. Radiographic markers delineated the position of the tri-radiate cartilage and potential ultrasound landmarks identified to help confirm hip reduction in the flexed-abducted position. Porcine imaging was then compared with that of a human newborn. Results. The porcine model corresponded well to human imaging and we were able to establish a landmark, the ‘Ischial Limb’, which corresponds to the ossification front delineating the posterior ischial edge of the tri-radiate cartilage. This could clearly be seen on anterior hip ultrasound of both the porcine and human hip. This landmark can be used to confirm the hip is reduced by reference to the centre of the femoral head. Discussion and conclusion. We would recommend anterior hip scanning using the ‘Ischial Limb’ as a reference point to confirm hip reduction in Pavlik harness. This simple method is a useful adjunct to conventional ultrasound scanning in the harness treatment of hip instability

Purpose. Following closed or open reduction for developmental dysplasia of the hip (DDH), assessment of reduction is essential. With potentially poor accuracy in confirming reduction, the risk of abnormal hip development and ultimately poor outcome exists if reduction is not achieved. Computed tomography (CT) has been used in recent years to assess reduction. The aim of this study was to compare the accuracy in confirming hip reduction following closed or open reduction in children with DDH, using CT and plain radiographs and to decide whether CT scans improved the assessment of reduction. Methods. We retrospectively reviewed 6 patients treated for DDH at an Academic Hospital. The patients were treated with either closed or open reduction. Post operatively radiographs and CT scans were obtained to assess reduction. Reduction was assessed using Shenton's line, medial joint space, a femoral mid-cervical line through the tri-radiate cartilage and a tri-radiate intersectional line on axial CT. The CT scans were analyzed using Osirix on an Apple Macintosh computer. Results. We were able to obtain measurements in all parameters in only one radiograph, whereas in the CT images all parameters were determined. One patient had radiographs in which no values could be measured. The CT scan however confirmed reduction of that hip. In one patient we assessed a hip as reduced using all the parameters, whereas the tri-radiate intersectional line on axial CT and the Shenton's line on the coronal slice showed that in fact the head was posteriorly subluxed. Conclusion. We conclude that although CT scans did not change our management in this small patient series, CT scans did provide a better means of confirming hip reduction than plain radiographs for patients with DDH following closed or open reduction in a hip spica. NO DISCLOSURES

Purpose. The incidence of hip displacement in children with cerebral palsy is approximately 30% in large population based studies. The purpose of this study was to report the long-term effect of hip surgery on the incidence of hip displacement using a newly validated Cerebral Palsy (CP) hip classification. Method. Retrospectively, a sub-group of 100 children who underwent surgery for hip displacement were identified from a large-population based cohort of children born with CP between January 1990 and December 1992. These children were followed to skeletal maturity and closure of their tri-radiate cartilage. All patients returned at maturity for clinical and radiographic examination, while caregivers completed the disease specific quality of life assessments. Patients were grouped according to motor disorder, topographical distribution and GMFCS. Radiographs were independently graded according to CP hip classification scheme to ensure reliability. Surgical Failures were defined as CP Grade > IV. Results. Ninety-seven children and 194 hips were available for final review. According to GMFCS, greater than half the children were GMFCS IV and V (67/94, 67%), 12 were II and 18 were III. Fifteen hips were dislocated or had salvage surgery for dislocation (15/194, 7.7%) at time of skeletal maturity. The majority of hips were graded Grade II and III (149/194, 76.8%). A total of 39 (39/194, 20%) hips were classified as surgical failure with 95% (37/39) hips occurring in GMFCS IV and V children. Conclusion. Using the CP hip classification scheme, the natural history and outcome of 100 children with CP at skeletal maturity have been described. Despite hip surveillance and surgical intervention GMFCS IV and V children are at the greatest risk for surgical failure at skeletal maturity. In this study, the majority of failures were associated with either no hip surveillance and/or index surgery at a non-specialist centre. In contrast, hip surveillance and index surgery at a specialist tertiary centre was associated with a very high probability of a successful outcome. This is the first population based cohort study of children with cerebral palsy followed from index surgery to skeletal maturity for hip displacement. Surgical success rates for the treatment of hip displacement in children with cerebral palsy have not previously been reported. This information will aid surgeons in the treatment of hip displacement in children with cerebral palsy