POLYCAPROLACTONE GLASS BIOABSORBABLE IMPLANT IN A RABBIT HUMERUS FRACTURE MODEL/

Research in improved materials and methods for internal fixation has c entered on internal fixators made of bioabsorbable materials such as p olylactic acid, polyglycolic acid, and polyparadioxanone. These materi als have two problems: the first is a postoperative complication relat ed to a delayed inflammatory response; and the second is low strength characteristics. An alternative material developed to alleviate these problems is a composite of phosphate glass fibers embedded in the poly mer polycaprolactone, referred to as PCL. Ln this study, intramedullar y pins made of PCT, were compared to stainless steel pins in a rabbit humerus osteotomy model. Specimens were harvested at 0, 6, and 12 week s postoperatively, radiographs and mechanical testing to failure were performed at each time interval, and tissue was examined microscopical ly at 6 and 12 weeks. Histologic results showed PCL pins to be well to lerated with minimal inflammation around the pin. Mechanical testing r evealed the PCL fixation to be weaker initially than the stainless ste el fixation. There was significant stress shielding of stainless-steel -healed rabbit humeri when compared to the PCL/bone humeri. All osteot omies immobilized with PCL healed with abundant periosteal callus prod uction. (C) 1997 John Wiley & Sons, Inc.