Heterotopic ossification with total hip endoprostheses in various models of thrombosis prophylaxis.

The influence of thrombosis prophylaxis on the occurrence of heterotopic ossification after implantation of total hip endoprostheses was analyzed in a series of randomized studies. When low-dose heparin or dextran 40 was administered, the rate of ossification was comparatively high (30.1% and 65.1%). When a combination of acetylsalicylic acid and an antirheumatic (oxyphenbutazone) or low-dose heparin with an antirheumatic (indomethacin) was administered, the ossification rate became significantly lower (6.2% and 16.7%). No severe ossification (Arcq degree III) was observed in the groups given an antirheumatic in addition to thrombosis prophylaxis.