(51) Extended Temporomandibular Joint Replacement as an Alternative Treatment Option for Mandibular Reconstruction

Abstract: Mandibular reconstruction of large defects involving the mandibular ramus and body secondary to tumors or traumatic injuries has been a significant challenge for the oral and maxillofacial surgeon. There are currently limited treatment options available to manage these patients. The purpose of this presentation is to describe the extended temporomandibular joint (TMJ) customized total joint replacement (eTMJR) as an alternative treatment option for complicated traumatic injuries to the mandible and large aggressive benign neoplasms.A 33-year-old male presented to the emergency room with a gunshot wound to the left side of his face. Physical exam and CT review demonstrated a comminuted left mandibular body and ramus fracture. He underwent early debridement and open reduction and internal fixation (ORIF) of the left mandibular fracture with a reconstruction plate. Postoperatively, the patient did well but he was left with a large defect that was stabilized only with a gap-bridging plate. His maximal incisal opening (MIO) was around 10 mm with associated joint pain. All treatment options were discussed with the patient, which included a vascularized bone graft, non-vascularized bone graft, or an eTMJR. He elected to proceed with the joint replacement with an eTMJR. No bone graft was indicated due to presence of first molar occlusion. The patient progressed well postoperatively with improvement in his MIO to 26 mm without pain. His lower facial third was well-proportioned with appropriate contours and the facial nerve function was intact.A 27-year-old female presented with a history of left lower jaw soreness for several years. She had a large, well-defined multilocular radiolucency surrounding Tooth #17 on imaging. An incisional biopsy was performed, which confirmed the diagnosis of ameloblastoma. She was planned for a segmental resection with appropriate 1.5 cm margins, extraction of Teeth #17-20, and placement of a reconstruction plate with an intraoral approach. The patient did not have any postoperative complications and her facial nerve function was uncompromised. Two years after this initial surgery, she returned to the clinic after hearing a pop in her jaw with immediate malocclusion. Imaging revealed failure of the hardware with fracture of the reconstruction plate. She no longer had enough bone stock to proceed with a reconstruction plate and ASIC bone graft, so she was planned for an eTMJR and ASIC bone graft. The condylar and fossa components of the eTMJR prosthesis were then placed and fixated. A 5x3 cm monocortical ASIC block was obtained along with cancellous bone, was divided and contoured to approximate the buccolingual dimension of the native mandible, and was fixated to the eTMJR. An amalgam of cancellous bone and BMP was then used to pack around the block graft and wrapped in a thin bioguide membrane. Immediate postoperative evaluation of the patient found improvement in facial contour and function. Once the bone graft healed, she was rehabilitated with implants to sites #19 and 20 to restore first molar occlusion (Fig. 1). The eTMJR is a modification of the standard alloplastic condyle and fossa components to further extend the implant to accommodate the specific mandibular defect. The eTMJR can re-establish form, function, and continuity including placement of implants and teeth. However, long-term success and patient satisfaction must be studied in comparison to other options.References 1. Pogrel MA, Podlesh S, Anthony JP, Alexander J. A comparison of vascularized and nonvascularized bone grafts for reconstruction of mandibular continuity defects. J Oral Maxillofac Surg. 1997 Nov;55(11):1200-6. doi: 10.1016/s0278-2391(97)90165-8. PMID: 9371107.2. Khattak YR, Arif H, Gull H, Ahmad I. Extended total temporomandibular joint reconstruction prosthesis: A comprehensive analysis. J Stomatol Oral Maxillofac Surg. 2023 Sep;124(4):101404. doi: 10.1016/j.jormas.2023.101404. Epub 2023 Jan 30. PMID: 36720364.

Figure 1