Osteopromotion for cranioplasty. An experimental study in rats using a membrane technique.

Various techniques for treatment of large cranial defects have been reported, but the use of alloplastic materials still seems to predominate. The authors have applied and explored a new approach for bone repair which appears promising, even for use in less osteogenic environments such as the adult calvaria. Seventy-two adult Sprague-Dawley rats each received bilateral 8-mm trephine defects in the temporoparietal area; this defect size precludes spontaneous osseous healing during the lifetime of the animal. Five surgical procedures, employing various alternatives of biologically inert expanded polytetrafluoroethylene membrane positioning and intramembranous bone-chip implantation, were performed and compared to control defects. Slight improvement of bone regeneration was demonstrated with subperiosteal ectocranial and endocranial membranes, alone or in combination, and with bone chips alone or in combination with an outer or inner membrane. Virtually complete bone healing was observed in animals receiving both an outer and an inner membrane with interpositioned bone chips. The latter appeared to function primarily as space-holders by keeping the membranes separated throughout the defect. Consequently, this technique seems to significantly promote bone repair by excluding soft-tissue components from the bone-healing site.