Quantitative Analysis of Vascular Response after Mandibular Fracture Repair Using Microcomputed Tomography with Vessel Perfusion

Background: Poor healing after mandibular fracture repair can be a devastating morbidity with significant clinical consequences. Elucidating the vascular response after mandibular fracture may help determine potential areas for therapeutic interventions for nonunions. The authors performed microcomputed tomographic imaging after vessel perfusion to ascertain objective measures of vascular networks. They hypothesized that despite the haversian-based, highly cortical structure of the mandible, the vascular response after fracture healing will return to nearly normal levels soon after bony union, mirroring the results of endochondral, highly trabecular long bones. Methods: Sprague-Dawley rats (n = 12) underwent mandibular osteotomy, and a 2.1-mm fixed gap was set. Animals were euthanized at 40 days after surgery and perfused with Microfil. Specimens underwent microcomputed tomographic analysis for stereologic vascular metrics. Data were compared with nonfractured controls (n = 5). Ninety-five percent confidence intervals and the independent samples t test (p < 0.05) were used to determine statistical differences. Results: Quantitative measures for mandibular fracture versus control revealed similarities in the following vascular metrics: vessel volume fraction (0.028 percent versus 0.032 percent; 95 percent CI, -0.027 to 0.0169 percent), vessel number (0.497 mm(-1) versus 0.472 mm(-1); 95 percent CI, 0.884 to 0.975 mm(-1)), vessel thickness (0.052 mm versus 0.067 mm; 95 percent CI, 0.037 to 0.008 mm), and vessel separation (2.344 mm versus 2.081 mm; 95 percent CI, -0.752 to 1.278 mm). Conclusions: To the authors' knowledge, this is the first study using microcomputed tomography after perfusion to analyze vascular response following mandibular fracture. Their findings establish quantitative similarities and qualitative differences in vascular response to fracture repair of the highly cortical mandible when compared with the highly trabecular long bone. (Past. Reconstr. Stag. 127: 1487, 2011.)