Paradoxes in the history of the anterior cruciate ligament

A historic review of anterior cruciate ligament (ACL) investigation reveals two important paradoxes. (1) Ideas and concepts recently proposed were first put forth much earlier. (2) Controversy regarding this ligament continues despite the increased amount of information available. Much of the recent ACL literature, although regarded as newly discovered, has its roots in far older, and apparently forgotten or overlooked, work. Examples include: (1) ACL intactness is best tested at full extension; (2) hemarthrosis and ACL rupture are closely associated; and (3) ACL rupture sometimes masquerades as a minor injury. Additionally, early investigators achieved notable advances in surgical techniques. These contributions disappeared from the literature for two major reasons. First, early investigators observed few patients, with typical practitioners rarely seeing ACL injuries, and consequently, little data existed to support their observations. Second, observations could not be confirmed until the advent of widespread, successful surgery. Undoubtedly, orthopedists now know much more about the ACL, yet many issues remain controversial. Does the ACL perform a vital function? What is the efficacy of operative versus nonoperative treatment? What are the relative merits of direct repair, intraarticular substitutes, and extraarticular nonanatomic procedures? The origins and continued existence of controversy stem from several sources, including the less than rigorous study design and the scarcity of natural history, long-term follow-up studies, and basic science studies. The perception of the ACL as a simple structural unit has also perpetuated this controversy.(ABSTRACT TRUNCATED AT 250 WORDS)