Early results of large head metal-on-metal hip arthroplasties

Total hip arthroplasty significantly improves patient's life quality. However, total joint replacement is associated with possible complications, such as dislocations, infections, fractures and periprosthetic osteolysis. The goal of this study was to evaluate a large head metal-on-metal total hip arthroplasties and analyse short term complications related to them.

Between 9/2005 and 6/2009, a total of 691 hip replacements were performed on 635 patients with the use of Magnum M2 large head cementless metal-on-metal prosthesis in Turku University Hospital. All patients had a scheduled follow-up at two to three months, and at one year. The results were evaluated using X-rays, Harris Hip Score (HHS), and evaluating post-operative complications and reasons for re-operations.

During our follow-up the HHS median raised from its preoperative value of 59.8 to 86.4 two to three months after the operation, and to 93.9 one year after the operation. As a complication we had five infections requiring single open debridement (early infection) or a two stage revision. Seven patients had a periprosthetic femoral fracture that was operated and 11 patients were reoperated because of acetabular component malposition, fracture or early loosening. We did not observe any dislocations, n. ischiadicus damages, squeeking or complications related to high metal ion release (ALVAL-reactions (Aseptic Lymphocyte-dominated Vasculitis-Associated Lesion) or pseudotumours).

The metal-on-metal bearing pair allows large femoral head size, which decreases the risk for dislocation. It may also decrease the risk for osteolysis and aseptic loosening in a long run. Early complication rate related to the bearing surface is minimal. Metal-on-metal prosthesis is a good choice for young and active patients with good bone quality.