Computational model of the human elbow and forearm: application to complex varus instability.

Computational modeling is an effective way to predict the response of complex systems to perturbations that are difficult or impossible to measure experimentally. A computational model of the human elbow was developed wherein joint function was dictated by three-dimensional osteoarticular interactions, soft tissue constraints, muscle action, and external loading. The model was validated against two cadaveric experiments that examined the significance of coronoid process (CP) fractures, lateral ulnar collateral ligament (LUCL) ruptures, and radial head (RH) resection in varus stability. The model was able to accurately reproduce the trend of decreasing resistance to varus displacement with increased CP resection, with a significant drop in stability observed at >50% resection. In addition, the model showed that isolated repair of either the LUCL or RH conferred significant varus stability to the joint in the presence of a deficient coronoid, with the ligament responsible for the greatest increase in stability. Predicted magnitudes of joint contact force support claims that the ulnohumeral articulation is the most significant osseous stabilizer of the joint in varus, with the radiohumeral articulation having an increased role with increasing coronoid resection at low flexion angles. With confidence in the predictive ability of this computational model, future simulations could further investigate joint function under other loading scenarios and injury states.