CORRECTION OF MANDIBULAR NONUNION AND MALOCCLUSION BY PLATE FIXATION AND AUTOGENOUS CORTICAL BONE-GRAFTS IN 2 DOGS

Two dogs were treated for severe malocclusion secondary to segmental d efects in the mandibular bodies as a result of nonhealing mandibular f ractures. The problems of fibrous nonunions with large fracture gaps, the potential for infection, and the severe malocclusion were addresse d in considering definitive surgical correction. The segmental defects in both dogs were spanned by use of autogenous cortical grafts (full- thickness rib segments or full cortical diaphyseal ulnar segments), su pplemented with autogenous cancellous graft, and were stabilized with screw-and-plate fixation. Radiographic evaluation of bone healing and graft incorporation was difficult because of the implants, which obscu red full observation of the bone graft sites. Successful graft revascu larization, determined by (99m)radiophosphate localization, was shown in both dogs; fairly uniform isotope uptake was observed throughout th e graft sites and was continuous with the recipient bone. Mildly incre ased uptake was observed at 6 months and at 1 year after surgery and w as considered consistent with remodeling associated with fracture heal ing. Observation of complete graft revascularization within 1 year pro vided ample evidence that the autografts were incorporated, with suffi cient remodeling to characterize bone union.