Elastic cartilage grafting in canine radial fracture

Bone has a capability to repair itself when it is fractured. Repair involves the generation of intermediate tissues, such as fibrous connective tissue, cartilage and woven bone, before final bone healing can occur. The process of cartilage-to-bone transition (CBT) is a key for the achievement of rigid bone healing during fracture repair. We tested this potential for elastic cartilage using a long bone defect model in dog. Eight sexually intact female mongrel dogs, 4.57 ± 0.53 years old and weighing 11.48 ± 0.63 kg, were studied. After an ostectomy of the midshaft radius, bone healing was evaluated over an 8-week period in control dogs (n = 4) and dogs in which autologous grafts of auricular cartilage were inserted into the bone defects (n = 4). Quantitative radiographic assessment was conducted every 2 weeks. Eight weeks post-operative, qualitative histopathologic analysis was performed on the operated radii. Furthermore, histological grading was done using the Ulutas et al., scoring system. Experiment dogs had more advanced radiographic healing of ostectomy sites. The defects with elastic cartilage implants were bridged completely with new bony spicules originated from the implants. Transformation of elastic cartilage clusters to mesenchymal connective tissue and bony spicules was obvious in the experiment group. Significant differences were observed for cellular morphology [3 ± 0.82 (experiment) vs. 1.75 ± 0.5 (control)] and cartilage integration [2 (experiment) vs. 1 (control)] at ostectomy sites between the studied groups. This study demonstrated that by using the ostectomy gap model, autologous auricular cartilage enhanced the radiographic and histopathologic aspects of bone healing in dogs.