Development and validation of a computational musculoskeletal model of the elbow and forearm

Computational modeling is a powerful tool to study normal, injured, and repaired joint function. Existing musculoskeletal models of the elbow have all limited their applicability by assuming fixed joint axes of rotation or prescribing specific kinematics. The purpose of this study was to develop and validate a model of the elbow and forearm whereby joint behavior was dictated by articular contact, ligamentous constraints, muscle loading, and external perturbations. A three-dimensional computer representation of the humerus, ulna, and radius was produced from computed tomography scans, ligaments were modeled as linear springs, select muscles were represented as constant-magnitude force vectors, and reaction forces were automatically applied at points of bone-to-bone contact. A commercial rigid body dynamics program was used to simulate joint function, and validation was accomplished through a comparison of model predictions to results obtained in published studies which explored elbow range of motion and the effects of coronoid process removal on joint stability. The computational model accurately predicted flexion-extension motion limits, and relationships between coronoid process removal, flexion angle, and varus constraining forces. The model was also able to compute parameters that the experimental investigations could not, such as forces within ligaments and contact forces between bones. The potential medical applications for this model and modeling approach are significant, and are anticipated to ultimately have value as a predictive clinical tool.