A biomechanical basis for primary arthroplasty of the temporomandibular joint.

Biomechanical principles of temporomandibular joint (TMJ) loading are unique, particularly in an orthopedic system that exhibits curvilinear general plane motion. Certain type-specific derangements can be surgically challenging and may primarily require open arthrotomy techniques rather than arthroscopy. This article discusses the basic biomechanical principles in normal and pathologic function. Three-dimensional preoperative imaging of TMJs is necessary for appropriate assessment of all patients and when open techniques are necessary as the initial surgical procedure.

Prospective multicenter comparison of 4 temporomandibular joint operations.

PURPOSE: This study was designed to compare the outcomes of 4 operations used for the treatment of painful temporomandibular joints with an internal derangement. PATIENTS AND METHODS: A prospective, controlled study of arthroscopy, condylotomy, discectomy, and disc repositioning was conducted at 3 sites. All sites used the same inclusion and exclusion criteria. Trained, independent examiners assessed pain, diet, and range of motion before operation and 1 month and 1 year after operation. RESULTS: There were statistically significant reductions in the amount of pain ( P < .001) and daily time in pain ( P < .001) that were similar for all 4 operations 1 month and 1 year after the procedures. The degrees of change after each of the 4 procedures were not statistically different from each other (amount: P = .453 and time: P = .416). Ability to chew, as measured by diet visual analog scale, was substantially improved 1 year after operation ( P < .001). The degrees of change for diet at 1 year also were not different from each other ( P = .314). There were, however, statistically significant differences ( P < .05) in range of motion that varied with procedure. CONCLUSIONS: All 4 operations were followed by marked improvements in pain and diet. The amounts of improvement varied slightly by operation, but these differences were not statistically significant. There were small but statistically significant differences between procedures for range of motion. If these findings are confirmed, they have an important implication for procedure selection.