Background. Several risk factors for the development of osteonecrosis following treatment of developmental dislocated hip have been reported. The need for further research with a large-enough sample size including statistical adjustment of confounders was demanded. The purpose of the present study was to find reliable predictors of osteonecrosis in patients managed for developmental dislocation of the hip. Methods. A retrospective cohort study of children, who have been hospitalized at our department between January 1998 and February 2007 with a developmental dislocation of the hip, was completed. Sixty-four patients satisfied the criteria for inclusion. Three groups according to age and treatment were identified. Group A and B included patients treated with closed or open reductions aged less than twelve months. Patients of group C were past walking age at the time of reduction and were treated by open reduction combined with concomitant pelvic and femoral osteotomies. The average duration of follow-up for all patients was 6.8 years. Logistic regression analysis was conducted to identify predictors for the development of osteonecrosis. Results. The overall rate of osteonecrosis in group A and B was 27.4% compared to 88.2% in patients of group C. After pooling of all data, no protective effect of the ossific nucleus of the femoral head on the development of osteonecrosis was found (p = 0.14). Additionally, an increase of surgical procedures in children of group C could not be demonstrated (p = 0.17). By using logistic regression analysis the type of reduction and secondary reconstructive procedure due to residual acetabular dysplasia could be identified as predictors for the development of osteonecrosis. Conclusions. Open reduction combined with concomitant osteotomies and secondary reconstructive interventions due to residual acetabular dysplasia increase the risk for osteonecrosis in the treatment of the developmental dislocated hip. Therefore, we advocate early reduction of the dislocated hip in the first year of life to avoid the need for concomitant osteotomies combined with open reduction. Level of Evidence. Prognostic study, level II-1 (retrospective study)

Introduction. Osteoarthritis (OA) of the hip is an important cause of pain and morbidity. The mechanisms and pathogenesis of OA'sdevelopment remain unknown. Minor acetabular dysplasia and subtle variations in proximal femoral morphology are increasingly being recognized as factors that potentially compromise the joint biomechanically and lead to OA. Previous studies have shown that risk of hip OA increased as the femoral head to femoral neck ratio (HNR) decreased. Previous work has described the evolutionary change in inferior femoral neck trabecular density and geometry associated with upright stance, but no study has highlighted the evolutionary change in HNR. The aim of this study was to examine evolutionary evidence that the hominin bipedal stance has lead to alterations in HNR that would predispose humans to hip OA. Methods. A collaboration with The Natural History Museums of London, Oxford and the Department of Zoology, University of Oxford provided specimens from the Devonian, Jurassic, Cretaceous, Miocene, Palaeolithic and Pleistocene periods to modern day. Specimens included amphibious reptiles, dinosaurs, shrews, tupaiae, lemurs, African ground apes, Lucy (A. Afarensis), H. Erectus, H. Neaderthalis and humans. Species were grouped according to gait pattern; HAKF (hip and knee flexed), Arboreal (ability to stand with hip and knee joints extended) and hominin/bi-pedal. Imaging of specimens was performed using a 64 slice CT scanner. Three-dimensional skeletal geometries were segmented using MIMICS software. Anatomical measurements from bony landmarks were performed to describe changes in HNR, in the coronal plane of the different specimens over time using custom software. Measurements of HNR from the specimens were compared with HNR measurements made from AP pelvic radiographs of 119 normal subjects and 210 patients with known hip OA listed for hip arthroplasty. Results. Species from the HAKF group that ambulate via sprawling had the smallest HNR (1.10, SD: 0.09) (p<0.001). Species of the arboreal group (tree dwelling) had the biggest HNR (1.63, SD: 0.15) (p=0.006). The earliest bipedal species (1.41, SD: 0.04) had significantly bigger HNR (p=0.04) in comparison to the normal human subjects (1.33, SD: 0.08). Lower HNR was observed in the OA group (1.3, SD: 0.09). Discussion. The adoption of an upright stance during evolution has created an associated change in the femoral neck bone stock to adapt to the altered loading environment. These data would suggest that the HNR peaked in the Miocene period (10–15 million years ago). The trade-off between mobility and the bony density required to support gait has lead to a decreasing HNR throughout hominid evolution. Evolutionary theory would suggest that modern environmental pressures might pre-dispose future hominid evolution to an increased risk of hip OA

Aims

Debate continues about whether it is better to use a cemented or uncemented hemiarthroplasty to treat a displaced intracapsular fracture of the hip. The aim of this study was to attempt to resolve this issue for contemporary prostheses.