Kinematics of the shoulder joint in tennis players

Abstract Objectives Shoulder pain and injury are common in tennis players. The precise causes for such pain remain unclear. Impingement at critical tennis positions and glenohumeral instability have never been dynamically evaluated in vivo. The purpose of this study was to evaluate the different types of impingement and stability during tennis movements. Design Laboratory study. Methods Type and frequency of impingement as well as percentage of subluxation were evaluated in 10 tennis players through a novel dedicated patient-specific measurement technique based on optical motion capture and Magnetic Resonance Imaging (MRI). Results All volunteers, nine male and one female, had a clinically functional rotator cuff. MRI revealed 11 rotator cuff lesions in six subjects and six labral lesions in five subjects. Lateral subacromial, anterior subacromial, internal anterosuperior, and internal posterosuperior impingements were observed in four, three, two and seven subjects, respectively. No instability could be demonstrated in this population. Conclusions Tennis players presented frequent radiographic signs of structural lesions that could mainly be related to posterosuperior impingements due to repetitive abnormal motion contacts. This is the first study demonstrating that a dynamic and precise motion analysis of the entire kinematic chain of the shoulder is possible through a non-invasive method of investigation. This premier kinematic observation offers novel insights into the analysis of shoulder impingement and instability that could, with future studies, be generalized to other shoulder pathologies and sports. This original method may open new horizons leading to improvement in impingement comprehension.