The effect of prophylaxis for thrombosis on heterotopic ossification following total hip joint replacement.

The effect of prophylaxis for thrombosis on heterotopic ossification was investigated using 216 total hip joint endoprostheses implanted between 1976 and 1978. During this period a random comparative study of low dose heparin and oxyphenbutazone/acetylsalycilic acid was carried out. The rate of ossification in the 216 hip joints was 17.6%, and was about average for the values specified in literature on this subject. Heterotopic ossification occurred in 30.1% of the 103 hip joints treated with heparin, whilst the rate of ossification in the 113 hip joints treated with oxyphenbutazone/acetylsalycilic acid was only 6.2%. This represents a statistically significant difference in disfavour of prophylaxis with heparin.