Traumatic isolated rupture of the knee medial collateral ligament : diagnosis and long term effects

• Isolated partial rupture of the knee medial collateral ligament (MCL) is the most common traumatic knee ligament injury. Owing to the good short- and medium-term functional results after conservative treatment, this injury has been regarded as harmless. The outcome after combination injuries, with simultaneous rupture of the anterior cruciate ligament (ACL), is more uncertain.The main purpose of this investigation was to improve the diagnosis of MCL injury and of concomitant injuries in acute knee trauma, in order to differentiate between the long-term effects of isolated and combined MCL injuries on knee function, sports participation, knee biomechanics and the development of secondary changes in articular cartilage and subchondral bone.Magnetic resonance imaging (MRI) was used with the aim to replace arthroscopy in the diagnosis of acute knee injuries with hemarthrosis. In patients, knee function and stability were assessed 4 years following conservative treatment of isolated partial MCL injury, thus evaluating any residual biomechanical abnormalities that could influence the long-term prognosis. Further, the 10-year outcome after isolated partial MCL injury and combined MCL/ACL injuries was evaluated with special reference to knee performance, knee stability and the development of radiographic arthrosis. Secondary changes to articular cartilage and bone were further evaluated with MRI and analysis of proteoglycan fragment concentrations in joint fluid. Finally, the effects of removal of the MCL during postnatal growth on rat knee joint development were studied with special reference to bone apposition and cartilage changes.Because of the low diagnostic accuracy for significant meniscal tears, MRI was not as reliable as arthroscopy for the diagnosis and screening of acute knee injuries. However, MRI was found to be superior to weight-bearing radiography and chemical analysis of joint fluid in the detection, staging, localisation and sizing of early articular cartilage changes in the knee joint.In a 10-year perspective, partial MCL injury lead to a small, permanent increase in valgus rotation and decrease in initial valgus stiffness of the knee joint, but knee function and sporting performance were excellent. In 13% of the cases subtle radiographic changes (Fairbank signs) were present. Combined MCL/ACL injuries had a similarly good long-term functional outcome, in spite of a higher number of reinjuries, increased sagittal knee translation, and a higher incidence of subtle radiographic arthrosis (50%) than after an isolated injury. The animal experiment further suggested that a loss of the MCL during growth alters the bony development of the knee joint.

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MEDICIN

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