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Meniscal Tears Are Common in Asymptomatic Knees

MRI-identified meniscal tears aren't always symptomatic.

Magnetic resonance imaging is used commonly to diagnose meniscal tears in patients with knee complaints. However, meniscal tears sometimes are noted in asymptomatic knees. To determine the prevalence of asymptomatic meniscal tears, Swiss researchers performed bilateral knee MRI in 100 patients with unilateral symptoms that were consistent with meniscal tear; none of the patients had a history of problems in the contralateral knee.

Meniscal tears were noted in the symptomatic knee in 57 patients, 36 of whom also had meniscal tears in the contralateral asymptomatic knee. Among the 43 patients without meniscal tears in the symptomatic knee, none had meniscal tears in the asymptomatic knee. The prevalence of horizontal or oblique partial-thickness tears was similar on symptomatic and asymptomatic sides; in contrast, the prevalence of full-thickness, radial, and displaced tears was significantly greater on symptomatic sides than on asymptomatic sides. On the symptomatic sides, MRI frequently revealed abnormalities of collateral ligaments and pericapsular soft tissue, as well as edema-like bone marrow abnormalities; such findings were noted only rarely on asymptomatic sides.

Comment: These findings suggest that patients with suspected meniscal tears are predisposed to bilateral MRI abnormalities but that symptoms are associated with only certain kinds of tears. Moreover, MRI frequently reveals nonmeniscal abnormalities in the symptomatic (but not contralateral) knee. For primary care physicians, one message is that meniscal tears that are visualized on MRI aren't always symptomatic.

— Allan S. Brett, MD

Published in Journal Watch General Medicine September 19, 2003

Citation(s):

Zanetti M et al. Patients with suspected meniscal tears: Prevalence of abnormalities seen on MRI of 100 symptomatic and 100 contralateral asymptomatic knees. AJR Am J Roentgenol 2003 Sep; 181:635-41.

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