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.

Aim: The HA coated Osteonics-Omniþt hip endoprosthesis with the PSL (peripheral self locking) acetabular cup was implanted in our institution between the years 1992 to 1996. This cup is spheric with several holes for screw þxation, and a Òwafße-likeÒ macrostructure along the periphery of the component. This component was connected with the HA coated Osteonics stem. Material and methods: A total of 173 patients (178 hips) mostly < 65 years old (average age, 50.5 years; range, 17–70 years) received a proximally HA-coated femoral prosthesis with a hemispheric metal-backed, HA-coated acetabular cup (PSL), with an average follow-up of 7,5 years (range 5 to 9 years). All operations were performed in the University Hospital by senior surgeons. There were 80 male and 86 female patients. The indications for operation were primary arthrosis in 84, secondary arthrosis (AVN, LPC etc.) in 34, rheumatoid arthritis in 34, posttraumatic in 13, and tumor in one case. This material compiles those cases revised for loosening of the acetabular cup (PSL). Results: Twenty-nine acetabular components have been revised due to the loosening and/or periacetabular osteolysis or access wear of the liner. Add to this there are 6 patients/hips on the waiting list. The total number of loose acetabular cups is therefore 35 (20%). The radiological signs of loosening have usually been evident with clear radiolucent lines (RLL) starting from the Gruen zone 3. At operation the cup have been loose with no signs of bony ingrowth and the HA coating resorbed away in most of the cases. There were no breakage of the screws. Survivorship analysis, based on those cases reported into the Finnish Arthroplasty Register, predicted a survival rate of 88.5% at four years (95%Cl 83.8–93.3, 93 at risk). Conclusions: The loosening rate of more than 20% with only 88.5% survivorship at four years is not acceptable. The bad results are mainly connected with the loosening of the PSL (peripherial self locking) type of acetabular component. The main features of that component are no porous coating, and the HA on the smooth surface. According to the literature and other Nordic implant registers the results with this kind of concept have been alarming. Theoretical disadvantages to HA coatings include the critical parameters required for its application on surfaces, and retrieval studies of implants at the time of revision indicate the potential concern for dissolution and delamination of the coating, especially on smooth metal surfaces. Also the manufacturer have changed the concept towards Ha on porocoating (Securþt). The clinical trials so far have focused on the performance of the femoral component the acetabular components have been of varying designs without any þrm conclusions. The results of this study do not indicate any signiþcant clinical advantage to the use of HA coated acetabular components in primary total hip arthroplasty.