The biomechanics of the sternoclavicular joint: an experimental and computational study.

BACKGROUND: This study aims to thoroughly investigate the biomechanics of the sternoclavicular joint (SCJ), a key component of the shoulder complex. METHODS: Inertial sensors were used on live human subjects to measure joint movements during abduction-adduction, flexion-extension, and shrugging. These motion data were then applied to a musculoskeletal model (OpenSim) to analyze the SCJ's range of motion and joint forces. The model was validated using previously published data involving transcortical pins for motion tracking and results from instrumented shoulder prostheses for kinetic comparison. RESULTS: Findings highlighted the range of motion of SCJ: at least 25° of elevation, 35° of retraction, with peak reaching 75% of body weight. The model has been validated against experimental results and on the whole it was found able to provide reliable biomechanical information concerning clavicle elevation and SCJ forces; the estimation of clavicle retraction has resulted to be more critical: here the use of inertial measurement units (IMUs) may produce an underestimation of angular displacements due toto skin motion relative to the underlying bones, making more invasive approaches are required. CONCLUSION: Overall, the study provides biomechanical insights on SCJ biomechanics, and suggests a validated methodology for further analyses.