Soft tissue reactions of different biodegradable polylactide implants.

Soft tissue reactions resulting from biodegradable polylactide implants to bone have not been adequately examined during their 3-year degradation period. An osteotomy was performed on the medial femoral condyle of 36 sheep and secured by either three poly-L-DL-lactide pins (70/30) (Polypin) or three composite pins [10% beta-tricalcium phosphate (beta-TCP) (90/10)]. A histological examination was performed on the synovial membrane and lymph nodes after 3, 18 and 36 months. After 18 months two non-specific, minor reactions of the synovial membrane were observed in the composite pin group. In both groups different reactions of both inguinal lymph nodes were observed. These had no statistical relevance and could not be clearly attributed to the implants. Due to the slow degradation process of biodegradable polylactide implants, there is no clinically relevant inflammation of either joint or lymph nodes. The addition of 10% beta-TCP did not result in any significant enhancement.