Abstract
Objective:To determine MRI findings that can differentiate anterior cruciate ligament (ACL) tears from mucoid degeneration.Material and Methods:Thirty-seven patients with complete ACL tears and 43 with ACL mucoid degeneration were included in this study. Discontinuity, the abnormal signal intensity of the ACL on fat-saturated-PD weighted images, contusions, a deep lateral femoral notch, anterior tibial translation, uncovered posterior horn of the lateral meniscus, a celery stalk appearance, thickening, ganglion cysts, intraosseous cysts, the ACL, Blumensaat, and posterior cruciate ligament (PCL) angles were evaluated. Optimum threshold values, sensitivity, specificity, and 95% CIs for the angles were calculated to predict the tear.Results:The prevalence of the significant findings in a tear versus mucoid degeneration, respectively, was as follows: discontinuity (97% vs. 0%, p < 0.001), contusions (65% vs. 2%, p < 0.001), the deep lateral femoral notch (22% vs. 0%, p = 0.001), anterior tibial translation (70% vs. 14%, p < 0.001), uncovered the lateral meniscus (46% vs. 7%, p < 0.001), a celery stalk appearance (0% vs. 66%, p < 0.001), thickening (19% vs. 100%, p < 0.001), ganglion cysts (14% vs. 70%, p < 0.001), and intraosseous cysts (8% vs. 63%, p < 0.001). Threshold values of ACL, Blumensaat, and PCL angles to predict the tear were ≤36° (78% sensitivity, 91% specificity), >11° (84%, 81%), and ≤96° (65%, 91%), respectively.Conclusion:A celery stalk appearance in the mucoid degeneration and discontinuity in an ACL tear are important in the differential diagnosis. ACL, Blumensaat, and PCL angles can be helpful in settings of diagnostic uncertainty.
Highlights
Anterior cruciate ligament (ACL) tears are one of the common injuries of the knee and can lead to substantial disability [1]
The bone contusions were significantly more frequently observed with an ACL tear, but rare with mucoid degeneration (65% vs. 2%, respectively; P < 0.001)
An anterior tibial translation greater than 5 mm was more common in the ACL tear group than the mucoid degeneration group (70% vs.14%, respectively; P < 0.001)
Summary
Anterior cruciate ligament (ACL) tears are one of the common injuries of the knee and can lead to substantial disability [1]. Used secondary MRI signs include bone contusions in the lateral femoral condyle and posterolateral tibial plateau, anterior translation of the tibia, uncovered posterior horn of the lateral meniscus, decreased posterior cruciate ligament (PCL) angle, and Segond fracture [1, 2, 6,7,8,9,10,11,12,13,14,15,16,17]. There is no cutoff age for surgery, the treatment of ACL tears in patients younger than 40–50 years of age with high-grade injury is usually reconstruction [18, 19]
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