Comparison of healing process in open osteotomy model and closed fracture model

Objective: Comparison of the healing process in open osteotomy and closed f racture models that were used to study fracture healing. Design: Randomized, prospective study inexperimental animals, with a recove ry duration of two and four weeks. Setting: Unrestricted cage activity with weight bearing as tolerated. Animals: Thirty-four skeletally mature, female New Zealand White rabbits. I nterventions: Closed fractures and open osteotomies of the tibial diaphysis were reduced and immobilized with four-pin, double-bar external fixators. Main Outcome Measurements: Callus circumference was measured with a tape me asure, bridging callus was assessed on biplane radiographs and evaluated hi stologically, and torsional stiffness and maximum torque were measured. Results: Periosteum damage was more severe and hematoma formation was small er in the osteotomy model, resulting in a delay in biological healing and r estoration of the biomechanical properties. Conclusions: Investigators should consider the difference between the close d fracture and open osteotomy models when selecting an animal model to inve stigate fracture healing.