The anterior cruciate ligament plays a major role in maintaining the stability of the knee joint, is susceptible to injury under strenuous activity. ACL injuries can lead to joint instability and complications such as osteoarthritis. Despite this, there is a lack of material models capable of predicting damage at a localized fiber level, hindering our ability to understand how damage develops in real-time. The present work develops a continuum-damage material model of the ACL and applies the model to a finite element simulation of the knee undergoing high quadriceps tendon loading. Using quadriceps tendon loadings of 1000, 1500, and 2000 N, the development of microstructural damage within the ACL tissue was examined, and the effects of localized damage on the joint kinematics were investigated. Damage tended to develop in the mid-substance of the ACL in the present model in the anterior medial bundle region and could induce significant changes in the joint kinematics. Using this model, new insights into the development of ACL injury mechanisms can be investigated.