Accuracy of computer-assisted mandibular reconstructions with free fibula flap: Results of a single-center series

Abstract

We evaluated the accuracy of computer-assisted mandibular reconstructions. Patients and methods: We retrospectively reviewed data for 26 patients who had mandibular reconstruction with a microvascular free fibula flap, January 2015 to June 2018. Postoperative mandible models were obtained from computed tomography scans. After registering the models to the corresponding preoperative plan, we performed comparative measurements. Patients were grouped by condylar involvement and subdivided based on number of fibular segments used for reconstruction. For each segment, we measured length and osteotomy angles. For the final postoperative outcome, we compared intercoronoid, intergonial, and anteroposterior distances and intersegmental plane shift. Results: Means (SD) for deviation of each osteotomy angle and fibular segment length were 1.98°(2.98) and 1.78 mm (2.69), respectively, remaining constant across subgroups. Other mean values were as follows: intercoronoid distance deviation, 3.86 mm (range, 0.20-11.21 mm); intergonial distance deviation, 3.14 mm (range, 0.05-8.28 mm); anteroposterior distance deviation, 2.92 mm (range, 0.03-8.49 mm); and intersegmental plane shift, 11.00°(range, 2.76-24.15°). Where the condyle was preserved, the intercoronoid and intergonial deviation means differed significantly (respectively 5.02 mm and 4.88 mm, both P < 0.05) for one-segmented and threesegmented fibular reconstructions. Furthermore, reconstructions involving the condylar region compared with condyle preservation showed significantly different intersegmental plane shifts (7.18°; P < 0.05). Conclusion: Computer-assisted surgery provides cutting guides for obtaining accurate fibular segments, but current fixation methods lead to inaccuracies and reproducibility errors. In multisegmental transfer with condylar involvement, computer-assisted fixation is recommended to ensure accuracy of the preoperative plan.

Spatial deviations of the temporomandibular joint after oncological mandibular reconstruction

“…The mandible provides attachment to muscles and ligaments that contract during masticatory function and maintain the mandible in equilibrium. Generally, mandibular defects in different regions cause varying deviations of the TMJ 2,3,10 . In the present study, patients with anterior defects were excluded in order to reduce this possible bias 2 .…”

“…For instance, anterior mandibular defects cause less interference to the TMJ, whilst lateral defects show more severe impacts. If the condyle is removed, transplanted bone grafts are passively placed in the glenoid fossa without an anatomical anchor 3,9 , thereby increasing mobility of the neomandible and inducing severe TMJ deviations 1,9,10 . In the case that the condyle is preserved, the intact joint capsule and the encapsulated fossa-disc-condyle help to stabilize the free end of the transplanted bone graft and contribute to initial stability of the fossa-condyle 3,9 .…”

“…The algorithm deposits reconstruction discrepancy on the operated side for assessing spatial accuracy; therefore, this was termed 'absolute deviation'. However, under physiological conditions, the mandible is distracted by muscles and adapts to occlusal contacts 6,10 . In order to investigate spatial deviations of the TMJ physiologically, the postoperative and preoperative models were superimposed based on the maxilla so that the mandibles could be compared in the physiological state.…”

Clinical evaluation of an automated virtual surgical planning platform for mandibular reconstruction

“…[3][4][5][6][7][8][9][10][11][12] Although the specifics of VSP vary, they all follow the general workflow of segmenting radiological data to create a 3D model, planning on the model, and using surgical guides to carry out the reconstruction plan. Generally, VSP can be divided into three modes: external planning through a commercial planning service in which the surgeon has a virtual meeting with the third party, 7,9,11 in-house planning using commercial dedicated planning software, 4,5,10 and, less commonly, in-house planning using a custom software workflow. 3,8,12 VSP has been shown to reduce operating and ischemia time, [4][5][6]13 and in some cases shown to improve the accuracy of reconstructions compared to the standard freehand approach.…”

“…The quality of the reconstruction directly impacts mastication, deglutition, and facial aesthetics. A wave of virtual surgical planning (VSP) has recently emerged as an improvement on the traditional freehand approach 3‐12 . Although the specifics of VSP vary, they all follow the general workflow of segmenting radiological data to create a 3D model, planning on the model, and using surgical guides to carry out the reconstruction plan.…”