Transphyseal bioabsorbable screws cause temporary growth retardation in rabbit femur.

Abstract

A self-reinforced bioabsorbable poly-L-lactide/polyglycolide (SR-PLGA) 80/20 screw 2.0 mm in diameter was implanted transphyseally across the distal growth plate of the right femur in 24 immature rabbits. Radiologic evaluation revealed a mean shortening of 3.1 mm at 3 weeks, 11.1 mm at 6 weeks, 9.3 mm at 24 weeks, 9.0 mm at 48 weeks, and 12.6 mm at 72 weeks compared with the intact contralateral femur. In 13 control rabbits, drilling without screw placement did not cause any statistically significant femoral shortening. Therefore, the transphyseal SR-PLGA 80/20 screw caused growth retardation for 6 weeks postoperatively, after which the normal growth tendency was recovered until the growth plate was closed. The duration of temporary growth retardation correlated with that of strength retention of the SR-PLGA 80/20 copolymer. These findings suggest that SR-PLGA 80/20 screws can be applied in transphyseal bone fixation. The use of bioabsorbable screws for temporary epiphysiodesis seems attractive but requires further study.