Hip dysplasia is a common cause of hip pain and functional disability in the 20-40 year old adult. It is characterized by a steep shallow acetabulum resulting in an insufficient coverage of the femoral head. The acetabulum can be retroverted. The proximal femur may be anteverted and the proximal femoral head-neck junction can have formation of exostoses as well. The abnormal biomechanics in the hip joint results in overload of the acetabular rim, which can leads to labral damage with cartilage delamination to follow. The proximal bony abnormality of the femur may result in femoroacetabular impingement aggravating the stress to the rim; worsen the labral stress and the cartilage damage. The natural history of symptomatic hip dysplasia is well described in the literature leading to osteoarthritis without treatment. The periacetabular osteotomy (PAO) is a well established joint preserving surgical treatment. The procedure is known to relieve pain, increase hip joint functionality and to prevent or delay the development of osteoarthritis. Even though PAO is the preferred joint preserving treatment worldwide several issues remains unclear. The overall aim of thesis was to assess intra- and extra articular factors that could influence on the surgical outcome after PAO for treatment of hip dysplasia in adults, and if necessary can a total hip arthroplasty be inserted with a good result in hips with previous PAO?
This PhD thesis composed of three studies. In study I 316 patients (PAO from Dec 1998 to May 2007) were evaluated. Demographic data and pre- and postoperative radiographs were evaluated to identify risk factors predicting failure in term of a THA after PAO. WOMAC were used to evaluate possible pain in the preserved hips. By inquiry to the National Registry of Patients PAO hips converted to THA were identified. The hip joint survival rate was estimated by the Kaplan-Meier analysis, and Cox regression analysis revealed significant predictors of failure. Study III was a descriptive study evaluating the hips in study I converted to a THA and with a minimum of four years followup. Clinical examination and radiographic evaluation were performed at followup. Study II followed 99 patients prospectively scheduled for PAO. Patients underwent routine MRA prior surgery. At 2-year followup a clinical and radiological examination was performed. Logistic regression analysis was used to find odds ratios for significant risk factors that could predict failure in terms of the need for a hip arthroscopy after PAO.
Study I The overall Kaplan-Meier hip survival was 74.8% at 12.4 years. A WOMAC pain score of >10 suggesting clinical failure was seen in 13% of the preserved hips. Age, preoperative Tönnis grade of 2, incongruent hip joint, postoperative joint space 55°) and preoperative borderline dysplasia (CE-angle >20° and