Aim: The purpose of this work is to report the early results from medial protrusio technique for placement of acetabular component without cement in patients who have acetabular dysplasia.

Material and Method: Thirty-two hip replacements were performed in thirty consecutive cases with dysplastic osteoarthritis between 2001 and 2003. In none of the patients an augmentation with bone or cement of the superolateral aspect of the acetabulum was made. Indication for operation was a painful hip joint that could not be alleviated by conservative treatment. According to Crowe’s criteria the dysplasia was evaluated as type I (19); type II (11); type III (3). The size and localization of the true acetabulum were evaluated using Ranawat’s triangle on a weigh-bearing preoperative X-ray. Clinical appraisal of the joint was done preoperatively, at the sixth, twelfth and thirty-six month postoperatively by the scheme of Merle dAubigne and Postel modified by Charnley. In 29 cases the surgery was performed via lateral transgluteal approach of Hardinge-Mulliken and in the rest of the cases through anterolateral approach of Watson-Jones. In all cases the medial wall was perforated with reaming and the medial periosteum was torn to visualize the illiacus muscle.

Results: One to three-year postoperatively clinical results showed significant improvement: in 28 joints 15–18 points (excellent and very good results); in 5 joints 14–16 points (good result). The medialization of the acetabular component is found to be 5.72.8 mm average values. X-ray evidences for medial migration of the acetabular component and early loosening were not found. Nerve palsy and intraoperative fracture of the femur did not occur, but one joint dislocated 24 days after the replacement despite the resection of anterior inferior iliac spine. Excessive medialization and impingement of the femur to the pelvic bone were the reasons for this complication.

Conclusion: When precisely planned the medial protrusion technique without cement fixation of the acetabu-lar component is a good alternative for arthroplasty in dysplastic hip joint. Particular attention must be paid in preserving enough thickness of the anterior and posterior acetabular walls during the reaming process. The perforation of the medial wall must not exceed 25–30% from the surface, because of plain risk of protrusion of the component beyond the teardrop figure of Kohler.