Natural history of ACL tears: From rupture to osteoarthritis

The anterior cruciate ligament (ACL) was originally identifi ed and described as far back as the time of Galen (1). However, a description of an ACL injury did not occur for over a millennium, as the fi rst report of this injury can be traced to the 1850s when Stark described two patients with this condition (2). While attempts to surgically repair this ligament date back to the early 20th century (3, 4), the routine treatment of ACL tears did not become mainstream until the genesis of sports medicine as a medical discipline in the 1970s. Many of the early surgeons treating ACL injuries recognized the relevance of this ligament to knee stability - primarily for activities that involve cutting, twisting, or pivoting. Correspondingly, it has been well documented that chronic knee instability is associated with meniscal damage and chondral injury (5-13).