Kinematic assessment of the temporomandibular joint before and after partial metal fossa eminence replacement surgery: A prospective study

Purpose: This study compared the functional kinematic outcome of the temporomandibular joint (TMJ) in patients with end-stage TMJ osteoarthritis before and after TMJ hemijoint replacement surgery. Materials and Methods: Fourteen patients (15 joints), with a mean age of 46.1 years, undergoing metal fossa eminence hemijoint replacement surgery, participated in this study. Each patient's jaw motion was recorded using an electromagnetic tracking device and patient-specific computed tomography images. A visual analog scale patient response questionnaire was used before and after the operation to assess the subjective outcome of the surgery. Results: The mean linear distance (LD) traveled by the incisors increased significantly due to the surgical intervention, from 30.4 +/- 6.9 mm preoperatively to 35.5 +/- 5.3 mm postoperatively (P = .02). The LD of the operated condyle decreased from 14.1 +/- 5.7 mm to 11.4 +/- 6.2 mm, but this was not significant. The mean LD for the unoperated condyle remained similar (preoperative, 13.2 +/- 5.9 mm; postoperative, 13.3 +/- 6.5 mm). The total mandibular rotation increased significantly, from 19.3 +/- 4.9 degrees preoperatively to 24.8 +/- 3.9 postoperatively (P < .01). Conclusions: Kinematic data support the functional efficiency of hemijoint replacement surgery, with benefits of increased maximal mouth opening, preservation of operated and unoperated condyle translation motion, and increased mandibular rotation. (C) 2008 American Association of Oral and Maxillofacial Surgeons.