Investigation of a possible relationship between kinematic points and condylar attachments of the lateral ligaments

Kinematic points are proposed as reference for assessment of condyle motion. They are defined by coincidence between open-closing and protrusive trajectories. According to anatomical findings, this feature should also apply to the condylar attachment of the lateral ligament that should guide the condyle on an arc around its tubercular fixation. Our aim was to examine if evidence for a correspondence between the kinematic point and the condylar attachment of the ligament could be derived from condylar dynamics. In 60 asymptomatic volunteers, open-closing and protrusive jaw movements were recorded with 6 d.f. Kinematic points were found 2. 5+/-2.9 mm anterior and 4.3+/-2.9 mm inferior from the terminal-hinge point. Their coinciding traces could be fitted by arcs with radii of 11.7+/-2.2 mm. The centres of the arcs were found 10.4+/-1.6 mm anterior and 4.9+/-2.4 mm superior from the kinematic points. When compared to anatomy, the local distributions of kinematic points and arc centres corresponded well to the condylar and tubercular fixation areas of the ligament. The findings provide circumstantial evidence for a correspondence between kinematic points and the attachment of the lateral ligament. Kinematic points could provide a better means to assess condyle motion than other posterior landmarks, when in addition, movements of adjacent points and rotational properties are considered.