Four-Dimensional Computed Tomography Evaluation of Condylar Movement in a Patient With Temporomandibular Joint Osteoarthritis

Temporomandibular joint (TMJ) osteoarthritis (OA) is a disease of the bone, cartilage, and supporting tissues of the joint. Patients with advanced TMJ-OA often have symptoms such as pain, swelling, and joint dysfunction, and they sometimes require surgical intervention when conservative treatment is not effective. The etiology of TMJ-OA remains elusive. The usefulness of 4-dimensional (4D) computed tomography (CT) in motion analysis of various joints has recently been reported. This article introduces a novel imaging technique of 4D CT that aims to identify kinematic features that may be associated with the etiology of TMJ-OA. In a 69-year-old female patient with severe TMJ-OA, 4D CT evaluation of condylar movement was performed. During the scan, she was instructed to masticate a cookie normally and her natural condylar movement during mastication was evaluated. The coronal 4D CT motion images showed that the synovial cavity was narrower on the affected side than on the unaffected side. Repeated friction between the articular surface of the condyle and the caudal surface of the articular eminence was observed during natural mastication. Although friction between the condyle and articular eminence has been considered a factor in the initiation and progression of TMJ-OA in previous experimental studies using animals, this is the first study to directly visualize the friction between the atrophic and flattened condylar surface and the articular eminence. Four-dimensional CT is a novel imaging technique with the potential to assess kinematic features that cannot be visualized with other imaging modalities in patients with TMJ disease.