Repair of intra-membranous bone fractures and defects in rats. Immunolocalization of bone and cartilage proteins and proteoglycans.

Osseous healing of experimental fractures and defects in membranous bone was studied in an animal model and the appearance and localization of selected bone and cartilage proteins and proteoglycans determined by polyclonal antibodies. The bone lesions were made in the parietal bone of young rats and subsequently studied on days 3, 5, 8, 15, 30, and 100 after surgery. The bone matrix proteins investigated (62 kDa, bone sialoprotein I and II, and osteopontin) appeared early, adjacent to the periosteal surfaces (pericranium and dura mater) and the marginal bone. The staining reactions were maximal at days 8 or 15 after trauma. Similar patterns were discerned for some cartilage macromolecules studied (58 kDa, 59 kDa, and chondrocalcin), although others showed no labelling whatsoever (148 kDa, and 400 kDa proteins). The proteoglycans PG-S1, PG-S2, and PG-LA were not identified. No callus or cartilage formation were associated with the bone healing process, and the differences between the regenerative pattern of the fractures and defects were limited. The findings emphasize the importance of rigid fixation in craniomaxillofacial surgery.