Background Developmental dysplasia encompasses a wide spectrum of hip pathology ranging from a shallow acetabulum to a completely dislocated ‘high-riding' hip.It is a common cause of secondary osteoarthritis in young adults and is the underlying diagnosis in up to 48％ of patients requiring total hip arthroplasty (THA) for coxarthrosis.The aim of this study was to evaluate efficiency and safety of THA using Zweymüller hip implant in the treatment of severe osteoarthritis secondary to developmental dysplasia of the hip (DDH) in adults.Methods From January 2000 to February 2008,35 patients (40 hips) with developmental dysplasia of the hip were included.Five were male and 30 were female,with ages ranging from 26 to 65 years and an average age of 45 years.According to Hartofilakidis classification,there were type Ⅰ in 5 hips,type Ⅱ in 20 hips,type Ⅲ in 15 hips.All the patients were performed the THA using the Zweymüller hip implant.The preoperative average Harris score was 44.The bilateral arthroplasty was performed in 5 patients and the unilateral arthroplasty in 30 patients.The patients mainly suffered from pain and claudication.Clinical and radiological results were analyzed.The Harris score was used for outcome measurement.Results Thirty five patients (40 hips) were followed and the mean follow-up period was 46 months (ranged from 24 months to 96 months).The latest follow-up average Harris score was 88.9 (97.1％ of good rate).All the patients were pain-free and there was no sign of infection,aseptic loosening and subsidence.Conclusions In summary,THA using Zweymüller hip implant is a good treatment method for severe osteoarthritis secondary to DDH in adults.The key techniques for the total hip replacement are as follows:good preoperative plan,firmly placing the acetabular component in the true acetabulum,proper preparation of proximal femur,suitable femoral component choosing and improving the techniques of the bone graft.