A Dynamic Elbow Testing Apparatus for Simulating Elbow Joint Motion in Varying Shoulder Positions.

PURPOSE

To develop and evaluate the capabilities of a dynamic elbow testing apparatus that simulates unconstrained elbow motion throughout the range of humerothoracic (HTA) abduction.

METHODS

Elbow flexion was generated by six computer-controlled electromechanical actuators that simulated muscle action, while six degree-of-freedom joint motion was measured using an optical tracking device. Repeatability of joint kinematics was assessed at four HTA angles (0°, 45°, 90°, 135°) and with two muscle force combinations (A1-biceps brachialis, brachioradialis and A2-biceps, brachioradialis). Repeatability was determined by comparing kinematics at every 10° of flexion over five flexion-extension cycles (0° to 100°).

RESULTS

Multiple muscle force combinations can be used at each HTA angle to generate elbow flexion. Trials showed that the testing apparatus produced highly repeatable joint motion at each HTA angle and with varying muscle force combinations. The intraclass correlation coefficient was greater than 0.95 for all conditions.

CONCLUSIONS

Repeatable smooth cadaveric elbow motion was created that mimicked the in vivo situation.

CLINICAL RELEVANCE

These results suggest that the dynamic elbow testing apparatus can be used to characterize elbow biomechanics in cadaver upper extremities.