HETEROTOPIC OSSIFICATION AFTER TOTAL KNEE ARTHROPLASTY - 54 615 CASESAFTER 1-6 YEARS FOLLOW-UP/

We found heterotopic ossifications in 54 (9%) of 615 cases after total knee arthroplasty. The largest ossifications were located in the ante rior distal femur. in 12 cases smaller ossifications were found in oth er knee regions. The development of heterotopic ossification showed a positive correlation with hypertrophic arthrosis and a negative correl ation with rheumatoid arthritis. We propose a new 3-grade classificati on which refers only to the anterior distal femoral region. Grade III heterotopic ossifications occurred in 4 patients (4 knees) who had cli nical symptoms; 2 were successfully reoperated with removal of the oss ifications, Prophylaxis should be considered in patients with marked h ypertrophic arthrosis or marked periosteal damage to the anterior dist al femur.