Utility of an image-based technique to detect changes in joint congruency following simulated joint injury and repair: An in vitro study of the elbow

BACKGROUND: Investigating joint mechanics is important when determining the etiology of osteoarthritis, as degenerative changes are thought to occur due to altered joint mechanics. The objective of this study was to demonstrate the utility of an x-ray computed tomography-based approach to evaluate joint congruency in the setting of subtle kinematic alterations, employing an in vitro model of collateral ligament repair of the elbow. METHODS: Active and passive elbow flexion was performed in 4 and 5 fresh-frozen cadaveric upper extremities respectively using an elbow motion simulator in the valgus gravity dependent positions. The collateral ligaments were sectioned and repaired. A registration and inter-bone distance algorithm were then used to examine ulnohumeral joint congruency (quantified as surface area) throughout elbow flexion. Valgus angulation was also measured. FINDINGS: Following ligament sectioning and repair, there was a 1.2±1.0° increase in valgus angulation in active flexion and a 21.2±26.2% decrease in surface area. In passive flexion, valgus angulation increased 3.3±2.2° and surface area decreased 57.9±39.9%. INTERPRETATION: The technique described to quantify joint congruency proved to be sensitive enough to detect large changes in joint surface interactions inspite of only small changes in traditionally measured kinematics. These changes in joint congruency may, in part, explain the high incidence of arthritis that has been reported following ligament injuries of the elbow, even in the absence of clinically detectable instability. This technique, when adapted for in vivo use, will be a useful tool to evaluate joint function and the effectiveness of treatments non-invasively.