Tears of the A.C.L. When excessive force is placed upon the A.C.L., it will tear. The A.C.L. can tear at its insertion into the femur or tibia, or it may tear mid substance. A torn A.C.L. will result in an unstable knee which may give the sensation of "giving way". The A.C.L. gets its blood supply and nourishment from the tibia and the femur. When the A.C.L. is torn, this blood supply is permanently disrupted, and it will not heal. A surgical procedure known as an Arthroscopic A.C.L. reconstruction, is the only effective method available to achieve complete knee stability.