The effect of a penetrating biodegradable implant on the growth plate. An experimental study on growing rabbits with special reference to polydioxanone.

: This study examined the fate of a biodegradable polydioxanone (PDS) implant in growing bone in rabbits. In 20 immature rabbits, a PDS rod 2.0 mm in diameter and 25 mm in length was driven into a drill hole of equal bore in the intercondylar portion of the right femur across the central portion of the growth plate. In another 25 immature rabbits, a PDS rod 3.2 mm in diameter and 25 mm in length was driven into a corresponding drill hole using the same technique. The follow-up intervals were three, six, 12, 24, and 36 weeks. The distal femoral growth plates of both femora were analyzed by roentgenographic, microroentgenographic, oxytetracycline-fluorescence, histologic, and histomorphometric studies. Histomorphometric studies showed clear changes at the site of injury and appeared to be an excellent means of providing an exact numerical description of the different cellular areas of the growth plate in experimental studies. A transphyseal PDS implant 2.0 mm in diameter did not cause any permanent growth disturbance of the femur in a growing rabbit. An implant 3.2 mm in diameter caused a growth disturbance similar to a drill hole of equal bore.