The anterior cruciate ligament (ACL) is one of four strong ligaments connecting the bones of the knee joint. If overstretched, the ACL can tear. Reconstruction of a torn ACL is now a common surgical procedure. The amount of tension applied to the ACL during reconstruction may indirectly affect the possible onset of arthritis over time. The purpose of this study is to determine the effect of initial graft tension set during ACL reconstruction surgery on the progression of knee arthritis over at least a 12-year period.