MR imaging of Baker cysts: association with internal derangement, effusion, and degenerative arthropathy.

PURPOSE: To determine the prevalence of Baker cyst in a general orthopedic population and its association with effusion, internal derangement, and degenerative arthropathy.

MATERIALS AND METHODS: Reports of 400 knee magnetic resonance imaging examinations were reviewed. Presence of Baker cyst, effusion, internal derangement (meniscal and/or anterior cruciate ligament tears), medial collateral ligament injury, and degenerative arthropathy was recorded. Uni- and multivariate logistic regressions were used to evaluate associations between Baker cyst and these conditions. Probabilities of having a Baker cyst given these conditions were also calculated.

RESULTS: No association was found between Baker cyst and anterior cruciate ligament tear or medial collateral ligament injury. There were significant associations (P < .001) with effusion, meniscal tear, and degenerative arthropathy. There were also significant associations (P < .01) for effusion, meniscal tear, and degenerative arthropathy, independent of one another. Probability of having Baker cyst given the presence of any one variable was .08-.10; any two variables, .19-.21; and all three variables, .38.

CONCLUSION: The association between Baker cyst and joint effusion was confirmed. A relationship with meniscal tear and degenerative joint disease independent of effusion was also demonstrated. The probability of having a Baker cyst increases as the number of these associated conditions increases.