While surgical anterior cruciate ligament reconstruction (ACLR) of the knee restores passive stability, studies are showing consistently poor long-term outcomes. Unusually high risks of early-onset osteoarthritis and re-injury, and low rate of return to sport following ACLR all seem to be related to a chronic tendency to land stiff-legged from a jump or hop, which itself may be due to fear of re-injury. Decreased knee bending for force absorption simultaneously decreases performance level and increases risk for injury and arthritic changes.