Abstract
Introduction. A new interest for Metal-on-Metal (MoM) has risen worldwide. In Finland using of 28mm MoM bearings during the last years has gone up rapidly. MOM bearings in THAs are used more and more in Finland for young patients. We present short-term results of 136 MoM THAs.
Patients and methods. In our Department both 28 mmMetasul- (Sulzer) ja M2a (Biomet) systems have been used. Metasul Pressfit cementless monoblock cup has titanium net on poly cup with cobolt-chrome bearing and the stem used was cementless CLS. M2a system was performed using cementless Biomet Bimetric-stem and cemented Stanmore poly cup with cobolt-chrome bearing. This series consists of 129 consecutive patients and 136 hips operated on in our department during years 2000–2002.
Results. Mean age was 53yrs (20–73), BMI 27,0 (16,4–42,9). Indication was primary athrosis in 87, rheumatoid arthritis in 15, avascular femoral head necrosis in 12, dys-placia with secondary OA in 9, and other in 13. Hardinge approach was used 59 and posterior approach 77 times. Metasul was used 85 and M2a 51 times. Mean follow-up time was 20 months. Pre/postoperative HHS was 54 (23–97)/94(48–100). Leg length discrepancy 1–2,5 cm was noticed in 19 patients. 4 luxations occurred during the follow-up period. No thromboembolic or neurological complications occurred. In 5 operations peroperative fracture of trochanter major was noticed and fixed and in addition to that fissure of the femur was noticed in 5 cases; no signs of loosening was noticed in these. 2 cups had signs of loosening in all 3 zones, 11 cups in 2, and 19 in one zone. One femoral component had signs of loosening in all 7 zones, 2 in 2 zones, and 5 in one zone.
Discussion. Good MoM results from 1970s encouraged us to start again to use MoM THAs in our department. At the same time the trend to use modern MoMs is ascending in Finland. We want to follow these prostheses accurately and get the results quicker than from the national registry. Our series consists of relatively young patients. We can not draw any definite conclusions because of the short follow-up time, but it seems that there are not alerting signs at the moment that we could not continue using 28 mm MoM THAs.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
