EXPERIMENTAL STUDY ON BIOABSORBABLE RIB-CONNECTING PINS PREPARED FROM POLY-L-LACTIDE CONTAINING HYDROXYAPATITE

Abstract

Bioabsorbable rib-connecting pins were prepared from poly-L-lactic acid (P-L-LA) containing hydroxyapatite (HA), which have high modulus and bending strength with drawing to uniaxial direction. The bending strength of the drawn P-L-LA pins containing 5wt% of HA was 16.2kgf/mm². The pin maintained 79.0% of their initial bending strength after 2 months immersion in PBS (p^H 7.4) at 37°C. In seven dogs, the left 8th, 9th and 10th ribs were cut, and pins (P-L-LA+10wt%HA, P-L-LA and stainless steel) were inserted to the medulla of the ribs. The stanless pin was covered with a thick connective tissue. The bone site in direct contact with the stainless pin became thinner and in some cases a clear zone of the bone around the stainless pin was observed on X-ray photograph. In contrast, the P-L-LA pin containing HA showed good biocompatibility and no significant tissue reaction.