Immediate Trans-Oral Tissue Engineered Allogeneic Bone Grafting for Large Continuity Defects. Less Morbidity, More Bone. A Paradigm in Benign Tumor Mandibular Reconstruction?

Reconstruction of hard tissue continuity defects caused by ablative tumor surgery has been traditionally reconstructed with autogenous cancellous marrow grafts or microvascular free flaps. Although results have been predictable from both methods of reconstruction, the morbidity associated with bone harvest is quite significant for the patient. With the advances made in tissue engineering, successful and predictable results has been obtained with using a combination of 100% cadaver bone, Bone Marrow Aspirate Concentrate (BMAC) and rhBMP-2 for immediate reconstruction for benign tumor extirpations via extra-oral approach. In light of these successful outcomes the same combination was evaluated with an intraoral approach. This case study aims to evaluate the success of immediate mandibular reconstruction via intra-oral approach without any autogenous bone harvesting.

Patients Methods:The aim of this retrospective study is to share our experience with the use of 100% allogeneic bone in combination with BMP and BMAC via trans-oral approach for immediate reconstruction of continuity defects resulted from benign tumor surgery. The present study reviewed patients treated at the UTHealth Oral and Maxillofacial Surgery in the dates between July 2014 to January 2016. We identified 5 patients, 3 men and 2 women. All patients presented to our service with biopsy proven benign tumors,. All patients were ASA I/II with no history of chemotherapy or radiation. Patients were given the option of a vascularized free fibula vs. avascular autogenous bone graft vs. composite allogeneic tissue engineering. All 5 patients chose composite allogeneic tissue engineering reconstruction citing less morbidity and hospital stay. Those with extensive soft tissue involvement were treated with a free flap or planned for delayed avascular/tissue engineering bone graft. All lesions were resected transorally and a titanium reconstruction plate was fashioned and placed. All patients were evaluated and determined to have adequate soft tissue for primary closure following strict oncological principles. All defects range from 4cm to 12cm. Our criteria for success with these cases are as follows:1) Unity of bony defect, 2)>3cm bone height and >1cm width, 3) Arch coordination, 4) Implantable bone, 5) Maintenance of osseous content for>18 months, and 6) Restoration of acceptable facial form. The freeze-dried cortical-cancellous bone in combination with rhBMP-2/ACS and 120cc of BMAC obtained from the anterior hip. We used the traditional 10 cc of crushed cortical-cancellous bone for each 1 cm of defect. Out of the 5 patients, 4 had maxillomandibular fixation for 3 weeks.

Results:We report a 100% success rate related to reconstruction with our rigid criteria as previously stated. All patients demonstrated excellent bone quality both clinically as well as radiographically for endosseous dental implant placement. With the trans-oral approach the average operating time was 3.4 hours and hospital stay was 1.2 days. Patients were able to return to work within 1 week but most defer to return after 3 weeks due to the edema from rhBMP-2. No patients complained of any pain from the BMAC harvest sites.

Conclusions: With the advancement in tissue engineering, using only allogeneic bone and growth factors via trans-oral approach seems to have become reality. The combination of 100% allogeneic bone, BMAC and rh-BMP2 is an effective and predictable technique for immediate reconstruction of continuity defects from ablative benign tumor surgery. Patient selection is critical in using this method; it is absolutely essential that enough soft tissue is available for primary closure without tension. Overall we had no donor site morbidity, less intraoperative time, fewer admission days and overall reduction in total costs compared to traditional methods. However, due to our limited number of subjects more comparative studies and randomized controlled clinical trials will help to determine the true efficacy of this technique.