Computer Graphics-Based Analysis of Anterior Cruciate Ligament in a Partially Replaced Knee

Artificial human knee with partial prosthetic replacement was modelled in the sagittal plane in order to analyze the role of anterior cruciate ligament in an unconstrained artificial knee. The cruciate and collateral ligaments were modelled as non-linear elastic fibers that stretched and resisted relative movements of the bone. Role of fibers in the anterior and posterior fibers of the anterior cruciate ligament was analyzed during simulated tests similar to those used in clinical practice. Anterior half of the ligament was found to resist forces for all simulated flexion positions of the joint. The posterior half resisted forces in low and in high flexion positions and remained unstitched during for nearly 30–90° flexion. The model calculations agreed with experimental observations on cadaver knees reported in the literature. A graphical interface facilitated visual analysis of the joint while the ligament fibers stretched sequentially developing forces and unstretched becoming slack as the joint flexed or the femoral and tibial bones with prosthetic parts moved relative to each other. The cruciate ligaments controlled the joint kinematics after replacement. The model analysis helps in visual analysis and in gaining insight into the joint behavior with clinical relevance.