Regenerating Mandibular Bone Using rhBMP--2: Part 2-Treatment of Chronic, Defect Non-Union Fractures

To describe a surgical technique using a regenerative approach and internal fixation for reconstruction of critical size bone defect non-union mandibular fractures.

Case series.

Dogs (n = 6) that had internal fixation of defect non-union mandibular fracture.

In 5 dogs, the repair was staged and extraction of teeth performed during the initial procedure. After 21-98 days (mean, 27 days) pharyngotomy intubation and temporary maxillomandibular fixation were performed. Using an extraoral approach, a locking titanium miniplate was contoured and secured to the mandible. A compression resistant matrix (CRM) infused with rhBMP-2 was implanted in the defect. The implant was then covered with a soft tissue envelope followed by surgical wound closure.

All dogs healed with intact gingival covering over the mandibular fracture site defect and had immediate return to normal function and correct occlusion. Hard-tissue formation was observed clinically within 2 weeks and solid cortical bone formation within 3 months. CT findings in 1 dog at 3 months postoperatively demonstrated that the newly regenerated mandibular bone had 92% of the bone density and porosity compared to the contralateral side. Long-term follow-up revealed excellent outcome.

Mandibular reconstruction using internal fixation and CRM infused with rhBMP-2 is an excellent solution for the treatment of critical size defect non-union fractures in dogs.