Effects of lesion between bone, periosteum and muscle on fracture healing in rats.

We assessed the effects of periosteal detachment from bone and musculature on the healing of diaphyseal fracture. In 30 male Wistar rats we produced a partial osteotomy, which was manually broken in the middiaphysis of the left femur. All fractures were reamed and stabilized with an 1.6 mm steel pin. The animals were randomly assigned to 3 groups. In group 1, a subperiosteal detachment between cortex and periost was created in the middle third of the diaphysis. An extraperiosteal detachment between periost and the surrounding musculature was performed in group 2. In group 3, the periosteum was isolated from the musculature by an extraperiosteal detachment and application of an e-PTFE sheath (Gore-Tex expanded polytetrafluoroethylene) around the shaft between the periost and the surrounding muscles. The rats were killed after 4 weeks and callus formation and mechanical characteristics were measured. All fractures healed by production of external callus. The callus area was significantly less in the group where periost was mechanically isolated from the surrounding muscles compared to the other groups. Bending moment, bending rigidity and fracture energy were less in this group than in groups 1 and 2. No differences were detected between the sub- and extraperiosteal groups, either in callus formation or in mechanical measurements. Our findings underline the importance of the muscle-periosteal connection for periosteal healing of diaphyseal fractures.