MRI and arthroscopic findings in acute and chronic ACL injuries. A pictorial essay

Knee injuries involving the Anterior cruciate ligament (ACL) are common sports injuries with over two million cases occurring every year. The number of ACL injuries has increased over the years due to increasing participation of young adults in sporting activities. ACL is commonly injured in athletic activities involving rapid deceleration, change of direction, pivoting and jumping. Most ACL tears (approximately 80%) are complete, occurring around the middle one-third of the ACL (90%) or less frequently close to the femoral (7%) or tibial (3%) attachments. Less frequently, (approximately 20%), ACL tears are incomplete with partial disruption of the ACL fibers. The majority of ACL injuries can be diagnosed on the basis of history of injury and clinical examination. However, the accuracy of clinical examination is not adequately high thus it has to be complemented with MR imaging (MRI) evaluation. Currently, MRI and arthroscopy are the reference standards for diagnosing an ACL injury. The purpose of this study is to present a wide spectrum of MRI appearances with arthroscopic correlation in a series of patients with an acute or chronic ACL injury. Materials and Methods