Comparison of Healing Process in Open Osteotomy Model and Closed Fracture Model

TLDR

The study compares healing in open osteotomy versus closed fracture models to evaluate fracture healing. Thirty-four mature female rabbits underwent randomized closed fractures or open tibial osteotomies, were immobilized with external fixators, and were evaluated at 2 and 4 weeks for callus size, bridging, histology, and biomechanical stiffness. Open osteotomies caused greater periosteal damage, smaller hematoma, and delayed biological and biomechanical healing compared to closed fractures, indicating model choice affects fracture healing outcomes.

Abstract

Objective: Comparison of the healing process in open osteotomy and closed fracture models that were used to study fracture healing. Design: Randomized, prospective study in experimental animals, with a recovery 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. Interventions: 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 measure, bridging callus was assessed on biplane radiographs and evaluated histologically, and torsional stiffness and maximum torque were measured. Results: Periosteum damage was more severe and hematoma formation was smaller in the osteotomy model, resulting in a delay in biological healing and restoration of the biomechanical properties. Conclusions: Investigators should consider the difference between the closed fracture and open osteotomy models when selecting an animal model to investigate fracture healing.