Background: The major objectives in total hip replacement for coxarthrosis secondary to DDH are: – Anatomical restoration of the hip rotation center – The restoration of the acetabular contention function – The reconstruction of the acetabular bone stock

Patients and Method: Between 1999 – 2003 there were operated 83 cases of coxarthrosis secondary to hip dysplasia, by total hip arthroplasty both cemented and uncemented. 27 cases were operated with uncemented cups and acetabular reconstruction 20 cases received a HA coated Stryker Secure Fit 40–42 mm cup 7 cases received Zweimuller screwed cup The mean age of the patients was 39 years (21–57 years) The mean weight was 69.5 kg (58–82 kg) Body mass index 28 (25–31) The dysplasia grade was Crowe II 11 cases, Crowe III 16 cases

Results: The mean dimension of the graft (S2), measured on the AP Rx was 43 % of the cup weight bearing surface The S2/S1 fraction exceeded 1 in one case that necessitated revision at 4,5 years due to the resorbtion of the graft All the grafts healed to the host bone in a 6 month interval

Discussions and Conclusions For defects smaller than 20% of the weight bearing surface of the cup, there was an intrinsic stability of the cup and the acetabuloplasty was optional For defects between 20–50% of the cup weight bearing surface it was necessary to perform acetabuloplasty with auto graft from the femoral head fixed with screws in compression For defects larger than 50 % of the weight bearing surface of the cup the fraction S2/S1 is greater than 1 with risk of the resorbtion and collapse of the graft. In such cases we recommend slight ascending of the cup in a position with better bone stock or a protrusion technique method