Hybrid Mandibular Reconstruction Technique: Preliminary Case Series of Prosthetically-driven Vascularized Fibula Free Flap Combined with Tissue Engineering and Virtual Surgical Planning
Free fibula flap (FFF) reconstruction of mandibular segmental defects is a technique which has been widely used since its introduction by Hidalgo in 1989 (1). However, the height mismatch between the native mandible and the fibula vascularized bone may affect the long-term prosthestic outcome due to excessive crown-to-implant ratio. Moreover, the altered ridge relationship between the maxilla and the vascularized neo-mandible leads to skewed axis of occlusal loading (2). To compensate for mandible-fibular height discrepancy and altered inter-arch ridge relationship, three strategies have been published: (i) double-barrel fibula (3,4), (ii) distraction osteogensis (DO) of free vascularized fibula (5,6), (iii) inferior border fibula with superior grafting (7). This paper aims to introduce a novel technique that involves superior border fibula placement with inferior grafting. In addition, we will discuss incorporation of virtual surgical planning and tissue engineering using stem cells and bone morphogenic protein for a prosthetically-driven vascular reconstruction.
Material and methods:
For this study, we included patients with segmental defects greater than 6cm. Preoperatively all the patients underwent CT-scanning according to the medical modeling protocol of both the maxillofacial region and lower extremities. Virtual surgical planning was performed to prefabricate mandibular and fibular cutting guides and pre-bent plates based on superior positioning of the fibula. The shape and position of the fibula was rendered specific to the prosthetic plan. All fibulas were designed such that vascular pedicles were posterolingual to the fibula projecting anteriorly. Intraoperatively, two separate teams performed mandibular resection and fibula free flap harvest simultaneously utilizing the prefabricated surgical guides. The remaining portion of the fibula was double-milled, washed and mixed with stem cells obtained from the anterior iliac crest using the BMAC© system, (rhBMP-2) Medtronic infuse©, allograft and platelet rich plasma (PRP). This mixture was placed in the inferior defect.
This preliminary series contains the one year follow up data of four patients undergoing the protocol. The data variables assessed included (1) graft assessment: flap survival, height of reconstruction and vestibular depth; (2) cosmetic data: cephalometric tracing of hard and soft tissues, patient subjective satisfaction; (3) functional metrics: maximal incisal opening, excursive movements and speech-swallow function.
Results:
The protocol achieved favorable bony and soft tissue healing, as well as excellent facial contour and functional outcome. Specifically, all patients’ FFF were successful, with excellent bony height and ridge relationships. Two patients received immediate dental implants for hybrid-type prostheses, while one patient received secondary implant placement for fixed teeth-only restorations. Excellent subjective and objective facial cosmetic outcomes were achieved. Mandible had excellent range of motion in function, patient maintained good swallow-speech capacity.
Conclusion:
In this study, we introduce our preliminary case series using the prothetically-driven hybrid mandibular reconstruction technique. The technique may be utilized for favorable prosthetic and cosmetic outcome for a large segmental mandibular defect (>9cm) and allows a single stage surgery with immediate implant placement for precise prosthetic rehabilitation with hybrid-type prostheses, fixed teeth-only prostheses, or removable overdentures. Moreover, a tissue engineering technique with stem cells, bone morphogenic protein, PRP, and bone graft can be safely used with a vascularized free flap and has a positive effect on soft tissue and bony healing. Outcomes have been promising and definitive results are to be determined by long-term follow-up.