Medium term results of 114 cementfree hip joint endoprostheses type PM implanted until mid - 1986 are presented. The clinical evaluation was based on the methods of Merle d'Aubigné and Harris.

The mean Merle d'Aubigné score increased from 9.15 to 13.95 points and the Harris score from 44.13 to 75.60 points.

After a mean in-situ period of 7.6 years only 35.96% of the operated hips were totally painfree. Twenty-seven prostheses (23.68%) did not need any support when walking (5.62% pre-op). Patients with forty-eight prostheses (42.11%) were able to walk without limitation (18.42% pre-op.). Of the operated hip joints 93.9% were judged subjectively as improved. Eighty-four patients were very satisfied (73.7%), twenty-seven were fairly satisfied (23.6%) and three were not at all satisfied (2.6%).

Radiographically, 61% of the stems showed a change of position, whereas only 8% of the acetabular components shifted. In 71.4% of the cases, a radiolucent line around the stem was seen in zone 14. Approximately two thirds of the cups showed this radiolucency. Atrophy of the cortex was noticed in 37.8% of the cases in zone 6. Periosteal reactions appeared only around the tip of the femoral shaft (26.5%).

Seventy-eight femora showed a bony consolidation around the stem-tip.

Ectopic ossifications were detected at seventy-three joints altogether. In three cases, Brooker-stage IV was reached.

The statistical evaluation showed a low significant correlation between atrophy of cortex in various zones and appearance of pain.

The survival-analysis showed for primary implanted PM prostheses a survival rate of 90.5% (Confidence interval 86.3%-94.6%) after a five year period and of 73.3% (Confidence interval 60.3%-86.4%) after a ten year period in situ.