GP4d - Reconstruction of Large Mandibular Defects With Femur Bone Using the Synthes Reamer Irrigator Aspirator (RIA-2) System

Abstract: PurposeMandibular reconstruction represents a core challenge in the field of oral and maxillofacial surgery, and the decision between vascularized and nonvascularized grafts has long been subject to debate and dogma. An oft-cited rule dictates that defects greater than 6 cm should be reconstructed with a vascularized bone graft (VBG). [Allsopp et al, 2016] The disadvantages of free flap reconstruction include prolonged hospitalization, increased surgical time and cost, increased donor site morbidity, and need for microvascular trained surgeons. Common nonvascularized bone graft sources, including iliac crest, have shortcomings including limited quantity of bone and common relative contraindications such as obesity and arthritis. In contrast, the femur is an abundant but scarcely discussed source of autogenous bone in the craniomaxillofacial literature. In this technique, the synthes reamer irrigator aspirator (RIA-2) is used to harvest corticocancellous bone from the femoral shaft, typically under fluoroscopy. This minimally invasive procedure performed by an orthopedic surgeon, without need for subspecialty training, can yield up to 90 cc of bone per femur. [Kanakaris et al, 2011] The purpose of this report is to demonstrate that reconstruction of mandibular defects greater than 6 cm can be safely and predictably accomplished with the use of femur reamer autogenous bone grafting.MethodsThis is a retrospective case series of patients who underwent ablation of benign mandibular pathology and reconstruction with autogenous femur obtained via RIA-2, recombinant human bone morphogenetic protein-2 (BMP), and allogenic bone grafting. Inclusion criteria included benign pathology requiring segmental mandibulectomy, defects greater than 6 cm without condylar involvement, and a minimum of 6-month follow-up. Exclusion criteria included those with a history of radiation therapy, malignant pathology, tobacco use, or poorly controlled systemic disease. Success criteria were defined as graft consolidation and bony continuity, return to presurgery functional status, and adequate bone for dental rehabilitation.

Results: Five patients met the inclusion criteria with reconstructive surgery occurring between June 2023 and March 2024. Mean patient age was 51.9 years with a range of 38 to 63. Pathology included ameloblastoma (3), glandular odontogenic cyst (1), and osteomyelitis (1). Three patients underwent immediate reconstruction, 2 patients underwent staged ablation and reconstruction. The average size of the defect was 8.5 cm in length and 3.2 cm in height as measured on panorex. Average amount of uncompressed bone harvested from the femur was 34 cc. Mean amount of 13.8 cc allogeneic bone graft was used to supplement the autogenous with BMP. The median follow-up was 6 months. None of the patients reported persistent gait disturbances and all were walking on postoperative day one. For patients undergoing delayed reconstruction, the average time between ablation and reconstruction was 5 months. Average time in maxillomandibular fixation was four weeks. Despite one postoperative complication of intraoral dehiscence, all patients demonstrated successful consolidation of the graft with bony continuity and adequate bone stock for implant therapy.

Conclusions: Corticocancellous femur bone is an underutilized source of autogenous, nonvascularized bone for reconstruction of mandibular defects. We recommend surgeons consider this option for patients who meet appropriate criteria, namely those with segmental mandibular defects secondary to benign pathology greater than 6 cm without history of head and neck radiation. Future studies are needed with larger sample sizes and longer follow-up to evaluate long-term restoration of function.ReferencesAllsopp, B. J., Hunter-Smith, D. J., & Rozen, W. M. (2016). Vascularized versus nonvascularized bone grafts: What is the evidence? Clinical Orthopaedics & Related Research, 474(5), 1319–1327. https://doi.org/10.1007/s11999-016-4769-4 Kanakaris, N. K., Morell, D., Gudipati, S., Britten, S., & Giannoudis, P. V. (2011). Reaming Irrigator Aspirator System: Early experience of its multipurpose use. Injury, 42. https://doi.org/10.1016/s0020-1383(11)70009-2

Figure 1: Preoperative computed tomography volume render showing mandibular ameloblastoma.
Figure 2: Intraoperative view of mandible via transcutaneous approach following ablation of lesion with nonvascularized bone graft and custom reconstruction plate in situ.
Figure 3: Six month postoperative panorex showing consolidation of nonvascularized graft with bony continuity of mandible.