Growth of a New Mandible Replacement in a Human Back—First Experiences with In Vivo-Engineered Bone Replacements

Introduction: A major goal of research in bone transplantation is the ability to avoid the creation of secondary bone defects. Experiments in minipigs have shown that it is possible to induce heterotopic bone with the aid of recombinant human bone morphogenetic protein-7 (rhBMP-7). We were able to grow an individually customized bone transplant inside the latissimus dorsi muscle of an adult male patient. This was then transplanted to repair an extended mandibular discontinuity defect.

Material and Methods: Three-dimensional CT scanning and computer-aided design techniques were used to produce an ideal virtual replacement for the mandibular defect. These data were used to create a titanium mesh cage that was then filled with BioOss®-Blocks. These blocks were subsequently infiltrated with 7 mg rhBMP-7 and 20 mL of the patient's own bone marrow. Thus prepared, it was implanted into the latissimus dorsi muscle and 7 weeks later transplanted as a free bone-muscle flap to repair the mandibular defect.

Results: In vivo skeletal scintigraphy revealed bone remodeling and mineralization inside the mandibular transplant both pre- and post-transplantation. Computed tomography provided radiological evidence of new bone formation. Postoperatively, the patient enjoyed an improved degree of mastication and was satisfied with the esthetic outcome of the procedure.

Conclusions: The prefabrication technique as described provides evidence that heterotopic bone induction to form a mandibular replacement inside the latissimus dorsi muscle in a human is possible. This technique allows for a lower operative burden compared to conventional techniques through avoiding the necessity of creating a secondary bone defect. It also provides a better three-dimensional outcome.