Long-term result of a biodegradable osteo-inductive copolymer for the treatment of orbital blowout fracture

PurposeWe have recently reconstructed the orbital wall using a bioabsorbable osteo-inductive copolymer as a support material for the bone defects in patients with orbital blowout fracture. The purpose of this study was to investigate a 2-year follow-up after implantation.Material and methodsIn order to investigate the efficacy and safety of the bioabsorbable osteo-inductive copolymer HA-P(LA/CL), hydroxyapatite-poly(l-lactide-ε-caprolactone), we measured CT density of the implanted copolymers in 7 patients at such time points as 1 week, 6 months and 2 years after surgery along with the long-term outcomes with regard to postoperative complications.ResultsFive patients in whom the intraoperative maximum width of the bone defect was less than 15 mm demonstrated the fracture types of either linear or trap-door. All patients treated with HA-P(LA/CL) copolymer indicated good bone formation with high CT density (>500) at 2 years postoperatively. In contrast, 2 patients in whom the intraoperative maximum width of the bone defect was more than 16 mm demonstrated a punched-out type fracture. Postoperative CT of the HA-P(LA/CL) copolymer showed low density (28.0 and 173.4) at 2 years postoperatively, indicative of limited bone formation. None of the cases demonstrated significant postoperative complications such as diplopia, enophthalmos, infection and extrusion of the implant material.ConclusionThe results of this study demonstrate that surgical treatment of orbital blowout fractures using bioabsorbable osteo-inductive copolymer was useful in linear and trap-door fractures.