Improved Temporomandibular Joint Position After 3-Dimensional Planned Mandibular Reconstruction

Abstract

Virtual surgical planning (VSP) using computer-aided design and manufacturing (CAD-CAM) has been reported to aid in craniofacial reconstruction. The reported improvements have been related mainly to operative performance, with limited evaluations of the position and function of the temporomandibular joint (TMJ). This study analyzed the radiographic detail of postoperative outcomes related to the TMJ. Patients who underwent mandibular reconstruction with and without VSP were analyzed. All patients underwent preoperative computed tomography (CT) of their mandible. In the VSP group, CAD-CAM planning was performed preoperatively using CT Digital Imaging and Communications in Medicine (DICOM) data. Postoperative CT images from the 2 groups were quantitatively compared to evaluate the TMJ. CT images were digitized for 2- and 3-dimensional analysis using surgical planning software (Materialise, Leuven, Belgium). Anatomic landmarks and cephalometric relations were analyzed. Sixteen patients who underwent traditional planning or VSP for mandibular reconstruction were compared. Two groups (n= 8 each) were compared for positioning of the mandibular condyle in the glenoid fossa. Measurements of superior, anterior, and lateral movements were comparable in the pre- and postoperative groups for the traditional and VSP groups (P < .001 by analysis of variance). Subgroup analysis evaluating ipsilateral changes in the mandibular condyle position for traditional planning versus VSP noted decreased percentages of change in superior (22 vs 10%; P < .05), anterior (32 vs 15%; P < .05), and lateral (7 vs 1%, P < .01) shifts of the condyle for left mandibular reconstructions (n=8). Ipsilateral right mandibular reconstructions (n= 6) showed changes in superior (62 vs 15%; P< .05) and anterior (5 vs 9%; not significant) shifts. These data showed comparable pre- and postoperative positions of the TMJ for traditional and VSP mandibular reconstructions. Evaluation of condyle movements showed differences in the ipsilateral position in the pre- and postoperative groups. VSP resulted in decreased superior and lateral shifts of the ipsilateral condyle and decreased changes in the condylar and condylar neck angles. This work shows that VSP can lead to increased precision in reconstruction leading to preserved normative anatomic relations.