APPLICATION OF ORIENTED POLY-L-LACTIDE SCREWS FOR EXPERIMENTAL SALTER-HARRIS TYPE-4 FRACTURE IN DISTAL FEMORAL CONDYLE OF THE DOG

The clinical usefulness of biodegradable oriented poly-L-lactide (PLLA ) screws for experimental Salter-Harris type 4 fracture in the distal femoral condyle of dogs was evaluated. Bony union of the osteotomized fragment of the condyle was almost completed radiographically and hist ologically within 1 to 2 months after surgery, suggesting that PLLA sc rews maintained strength long enough to fix the fragment until bone he aling. At 4 to 6 months after surgery, minute fissures were histologic ally confirmed on the surface of the screw thread, suggesting the earl y stage of biodegradation and absorption of the polymer. During the ob servational period, no significant difference between the treated femu r and the contralateral non-treated femur in either total femoral leng th or maximum condyle width was observed, indicating no growth disturb ance in the treated femur. From these results it was concluded that th e PLLA screw might be an ideal implant for the reduction and fixation of epiphyseal plate fractures such as Salter-Harris type 3 or type 4 f ractures.