Lateral collateral ligament (LCL) injuries are often treated non-operatively or with surgical repair. If instability persists, hinged elbow orthoses (HEOs) are often recommended. However, these orthoses are designed as a straight hinge, which does not account for the native carrying angle of the elbow. A custom HEO was designed to adjust the orthosis valgus angulation to measure in vitro elbow kinematics and biomechanics. An in vitro study investigated the effect of HEO valgus angulation during simulated active and passive flexion, in the vertical dependent and varus positions, with the forearm pronated and supinated. In the vertical dependent position, the orthosis did not produce instability and in the varus position, greater HEO angles trended towards improving elbow stability. Passive flexion was not found to worsen instability. In a subsequent study, a novel LCL tensioning mechanism is introduced to examine the effects of orthosis valgus angulation on LCL loads. No significant differences were found, as the tension did not change much throughout the range of motion. Future work is proposed to further improve the understanding of elbow kinematics and biomechanics to optimize rehabilitation techniques, surgical protocols and orthosis designs.