The main objective of this work is to develop a static and spatial model of the human knee, based on mechanism theory, to provide orthopedic surgeons information that relates forces at the anterior cruciate ligament graft (ACL) with its fixing position. This fixing position must be defined at the preoperative planning phase of the ligament replacement surgery. The best position for the graft insertion is taken as the one where the force developed at the graft is similar to the forces seen in an intact ligament during the knee flexion movement. The methodology for the static model is based on reimplementing a pure kinematic knee model available in the literature. In particular, this kinematic model is redefined using Davies’ method to obtain a static model that yields the forces at ligaments and condyles. The current kinematic model is able to satisfactorily reproduce the passive movement of the knee. We believe that any theoretical improvement in modeling and simulation of the forces at ligaments and grafts is an important contribution to the preoperative planning and improve the medical decision making capacity.