Premature fusion of facial sutures with free periosteal grafts. An experimental study with special reference to bone formation with free periosteal grafts from the tibia, the scapula and the calvarium.

The present study was undertaken to obtain more information on the bone forming mechanisms with free periosteal grafts and to study premature synostosis of facial sutures achieved with free periosteal grafts. The results are based on a material of 196 rabbits operated on at the age of two weeks. It was found that the bone forming mechanism with free periosteal grafts from the tibia, the scapula and the calvarium is essentially the same. When implanted in the tibialis anterior muscle of the leg of the same animal they all produced bone. The mechanism of bone formation is reminiscent of the enchondral bone formation seen in fracture healing. There is no difference in the bone forming mechanism with the periosteum from an enchondrally ossifying bone when compared with the periosteum of an intramembranously ossifying bone. In all the three different periosteal grafts studied, there was a cartilage stage before bone formation. In the muscle, all these three periosteal grafts, in spite of their tubular or membranous bone origin, produced bones tubular in shape. When the transplants were overlying the membranaceous facial bones, membrane shaped bone developed via intramembraneceous type of ossification in the recipient area. It can be concluded from these experiments that the shape and type of bone developed with free periosteal grafts depends mainly on the environmental conditions in the recipient area. Fusion of the premaxillo-maxillary and fronto-nasal sutures was achieved with free periosteal grafts from the tibia. Free periosteal grafts from the scapula and the calvarium failed to develop premature fusion of the sutures. The fusion developed due to increased bone formation in the suture area. The fusion of the premaxillo-maxillary suture stopped the growth in this area and caused a severe growth disturbance of the whole snout. The fusion of the fronto-nasal suture by the bone bridge retarded the growth of the nasal bone on the fused side and led to deviation of the snout to the operated side. Compensatory changes developed in other sites of the cranio-facial skeleton in order to minimize the effects of the growth disturbance. The fused fronto-nasal suture was used as a model to study the treatment of premature synostosis of facial bones. Resection of the fused area led to correction of the developed growth disturbance and to subsequent normal growth of the snout.