Anatomic Considerations For The First Temporomandibular joint vascularized composite allotransplantation
Nima Khavanin, MD, Diana Lee, BS, Amir H. Dorafshar, MD, Edward H. Davidson, MA (Cantab.) MBBS.
Johns Hopkins Hospital, Baltimore, MD, USA.
Background: Given the specialized function of the TMJ and its unique anatomical components, concomitant TMJ transplant is an obvious adjunct in the reconstructive armamentarium for face transplantation in scenarios involving TMJ pathology. The objective of this study is to investigate the fidelity of anatomic morphology to identify key parameters to guide patient section and mitigate donor-recipient anatomic mismatch.
Methods: Geometric analysis was performed on 100 skeletally mature maxillofacial CT scans. Exclusion criteria included mandibular trauma and dentoalveolar disease. Parameters measured were posterior height, ramus tilt, anterior height, intercondylar widths, condyle height, coronoid height, interglenoid distances, symphyseal and gonial angles, condyle and glenoid volumes, and condyle shapes. Parameters were compared by gender and ethnicity using chi-squared, independent sample t-tests, and one-way ANOVA. Correlation with age was assessed using Pearson correlation coefficients. Bilateral measurements were compared using paired-sample t-tests.
Results: Mean intercondylar width was 102.5 mm (SD 7.0 mm), anterior height 21.5 mm (5.5), and posterior height 65.3 mm (7.7), Males demonstrate larger geometric parameters e.g. intercondylar width (4 mm mean difference, p=0.005), anterior height (2.3 mm, p=0.032), posterior height (5 mm, p=0.001). Asians demonstrated statistically larger intercondylar width (8 mm difference to Caucasians, p<0.001). Increased age was associated with greater anterior height, gonial angle, and symphyseal angle; decreased glenoid height; and change in condyle shape. Despite significant disparity of laterality measurements within individuals, posterior height, glenoid and condyle volumes are equivalent.
Conclusions: Mandibular morphology is highly variable. Patient selection for TMJ transplant must consider age, ethnicity and gender as well as individualized geometric parameter profiles to ensure anatomic compatibility.
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