South African Journal of Sports Medicine

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Anterior cruciate ligament injuries of the knee: Patterns of association between the mechanism of injury and pathology visualised on magnetic resonance imaging

G L Strauss, D C Janse van Rensburg, C C Grant, A Jansen van Rensburg, M D Velleman, L Fletcher


Background: Anterior cruciate ligament (ACL) injuries are common among athletes and the general public. These injuries may lead to significant absence from all activities with associated financial and social burdens for the patient. No definitive association has been described between the mechanism of injury and the pathology to enable the implementation of preventative measures to limit these injuries.
Aim: To determine whether there is an association between the mechanism of injury and the pathology seen on a magnetic resonance imaging (MRI) scan in ACL injuries.
Methods: This was a cross-sectional analytical study. Eighty-seven male patients with an ACL injury and who had an MRI scan of the knee within the last two years participated in this study. Participants were contacted to give their informed consent to participate in this study. The mechanism of injury and the pathology seen on the MRI scan was noted and categorised into different groups of injuries and associated pathologies. Statistical analyses included summaries of the data and a test for the association between the mechanism of injury and the pathology. Since there were multiple pathology responses to each mechanism, a modified version of the chi-square test for independence was used. A five percent level of significance was specified.
Results: MRI scans of ACL injuries indicated that the mechanism of a solid foot plant with rotation of the knee has a greater tendency to be associated with medial meniscal injuries (77%). There was also a 54% possibility for it to be associated with lateral meniscal injuries. A solid foot plant with a valgus stress on the knee showed a higher incidence of associated medial collateral ligament (MCL) injuries (41%) and femoral bone bruising (62%). These two mechanisms of injury are the most common in ACL injuries and contribute to the clinical significance found in this study. The p-value was, however, not statistically significant (p=0.44, chi-square value=20.27, df=45) for any association between the pathology and the mechanism of injury.
Conclusion: Some injury mechanisms causing an ACL injury were more common than others and had more associated pathologies. The most common mechanism of injury noted in this study was a solid foot plant with either rotation of the knee or valgus stress on the knee. Strengthening the tissue structures involved in those movement patterns causing these mechanisms can possibly limit future ACL injuries in athletes and the general public.

Keywords: knee injury, mechanism, association, pathology, MRI scan, prevention
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