Mechanical Properties of the Shoulder Ligaments under Dynamic Loading.

Bone-ligament-bone specimens of coracoclavicular joint, acromioclavicular joint, and sternoclavicular joint were obtained from 33 fresh human cadaver shoulders that were harvested. A high-speed Instron machine and a test fixture and clamps designed specifically for this study were utilized. Two high rates and one quasi-static rate were utilized in this study. Ligament failure was the most common failure mode in the acromioclavicular joint tests. Bone fractures occurred at the caracoid and the majority of specimens failed at the ligament in the coracoclavicular joint tests. The specimen failed in most cases at the bone in the sternoclavicular joint tests. Quasi-static tests and high rate 2 tests had more bone fracture cases than high rate 1 tests in the coracoclavicular and acromioclavicular joint tests. Deflection at failure, strain at failure, cross sectional area, load at failure, Young's modulus and stress at failure were found of the three shoulder joints. There are no significant relationships between age and cross-sectional area, weight or height, nor between the mechanical properties of the shoulder joint and weight, height, or age.