ABSTRACT
BACKGROUND: The rationale for the Latarjet procedure was described as the "triple blocking" effect. Satisfactory surgical outcomes have been reported after surgery. However, it has been reported that the "triple blocking" effect increases joint stability, but it does not fully restore it. Moreover, the procedure is nonanatomic and concerns remain regarding the effects. The study of scapulohumeral rhythm, which is a clinical parameter used for the functional evaluation of shoulder kinematics, can offer new perspectives on the rationale for the procedure. This study aimed to compare the shoulder kinematics of patients after the Latarjet procedure to the shoulders of a healthy population using magnetic and inertial measurement units with a motion analysis system. METHODS: A retrospective study with prospective data collection was conducted on 28 patients who underwent the open Latarjet procedure for recurrent shoulder instability. At a minimum 12-month follow-up, each patient was evaluated by assessing the range of motion, the Rowe score, and the Constant-Murley score. Patients were examined using the ShowMotion 3D kinematic tracking system (NCS Lab, Modena, Italy), which uses wireless wearable noninvasive magnetic and inertial measurement units sensors to assess the three-dimensional kinematics of the shoulder. For each plane of elevation (ie, flexion and abduction), the scapulohumeral rhythm was described by three scapulothoracic rotations (ie, protraction-retraction, mediolateral rotation and posterior-anterior tilting) as a function of humeral anteflexion or humeral abduction. RESULTS: The mean time from first shoulder dislocation to surgery was 6.6 ± 3 years (range, 1-12 years). No intraoperative complications occurred, and computed tomography (CT) performed 3 months after surgery showed graft union in all patients. After a mean follow-up time of 32.4 ± 20 months (range, 12-96), the mean Constant-Murley score and Rowe scores were 94.5 ± 4.8 (range, 84-100) and 96.7 ± 3.5 (range, 90-100), respectively. All patients showed no signs of glenohumeral arthritis on X-ray examination. Scapular posterior tilt and scapular internal rotation were significantly greater in the patient group than in the healthy population for the flexion-extension and abduction-adduction movements along the whole shoulder range of motion (all P < .05); no differences were found in upward/downward scapular rotation. CONCLUSION: A greater scapular posterior tilt and scapular internal rotation were observed after the Latarjet procedure. The modified position of the scapula was maintained during the entire range of motion, suggesting a shoulder-stabilizing kinematic effect in addition to the bony, sling and bumper effects.
