Spatial Deviations of Temporomandibular Joint After Oncological Mandibular Reconstruction

Abstract

Statement of the problem: Spatial deviations of the temporomandibular joint (TMJ) after oncological mandibular reconstruction are rarely studied. The objectives are to clarify whether and how the 3D-printed patient-specific surgical plates and the preservation of condyle or ramus affect the spatial deviations of the condyle and the fossa-condyle relationship under different conditions.

Materials and methods used in the investigation of the problem: Patients who have undergone oncological mandibular reconstruction via computer-assisted surgery (CAS) were included. Two superimposition algorithms were developed to study the absolute deviations and physiological deviations of the TMJ respectively.

Method of data analysis: A total of 33 patients were included. Various outcome parameters were established to evaluate the spatial deviations.

Results of investigation and outcomes data: In algorithm 1 of absolute deviations evaluation, patients in the 3D-printed plate group showed smaller absolute deviations of TMJ compared to the conventional plate group in terms of the angulation shift of the condyle (mean difference: 9.4 ± 3.1°; P = .004), intercondylar distance deviation (mean difference: 2.0 ± 1.0mm; P = .041), and absolute distance deviation of condyle (mean difference: 4.4 ± 1.6mm; P = .009). There was no statistically significant difference in absolute deviations of TMJ regardless of whether the condyle or ramus was preserved. In algorithm 2 of physiological deviations evaluation, the non-operated contralateral TMJ was affected. The impact on the contralateral condyle was smaller in the study group of 3D-printed plates (mean difference: 0.4 ± 0.2mm; P = .015). Significant higher deviations of the condyle and joint space were identified in patients with both the condyle and ramus removed.

Conclusions relevant to the problem: The 3D-printed patient-specific surgical plates can improve the spatial accuracy of TMJ. Under physiological conditions, the deviations of TMJ in the operated side can be transmitted to the contralateral TMJ. The removal of both condyle and ramus can cause more severe spatial interference to TMJ and should be further confirmed.