Diaphyseal fractures treated by polylactide and hydroxyapatite pins. Experimental study in rat

In order to develop a biodegradable interlocking nail for fracture fixation , polylactic acid (PLA) pins and hydoxyapatite pins were implanted in the f emoral bone in rats. A distal fracture was performed. The union and the tis sue reaction to PLA and hydroxyapatite versus stainless steel rods were stu died after 15 days, 1, 2 and 6 months implantation. Metal and PLA pins indu ced a union. Hydroxyapatite pins (Ossatite(R)) did not prevent callus forma tion, but did not lead to consolidation in all cases because of weakness of the gelatin matrix binding the apatite particles together. PLA and stainle ss steel pins induced the same union and a similar tissue reaction during t he studied implantation of 6 months. The biocompatility of Ossatite(R) is s atisfactory and the osteo-inductive properties of hydroxyapatite was confir med. With injectable Ossatite(R), we could not obtain rat femoral fracture consolidation. We can confirm good biomaterial tolerance in bone which cont rasts with important soft tissue reactions. Use of such material should be carefully limited to filling intra-osseous cavities. (C) 1999 Kluwer Academ ic Publishers.