Central Hole Tear of the Discoid Meniscus of the Knee in Magnetic Resonance Imaging: Mimicking the Bucket-Handle Tear

Objective: To analyze the prevalence and describe the magnetic resonance imaging (MRI) features of central hole tear (CHT) of the discoid meniscus. Methods: Thirty-six patients with arthroscopically proven CHT who underwent knee MRI were included. We retrospectively reviewed the clinical history and evaluated the MRI findings which have been known as the findings of bucket-handle tear (BHT) and osteoarthritis. Results: A CHT accounts for 15% of discoid meniscus tears. In all patients, CHT involved the lateral meniscus. Of 36 patients, 28 (78%) had not any history of trauma to the knee. Intercondylar notch sign, coronal truncation sign, absent bow tic sign, and flipped meniscus sign were seen in 36 (100%), 35 (97%), 34 (94%), and 10 patients (28%), respectively. In addition, 26 (72%), 21 (58%), and 17 (47%) of 36 patients showed osteophytes formation, chondral lesion, and subchondral bone change, respectively. Of these 36 patients 23 (64%) an (61%) demonstrated increased signal intensity in the meniscus on proton density-weighted image and irregularities of the margin of the residual menisci, respectively. Conclusions: Although a CHT had many of the MRI features of BHT, it was usually accompanied by changes of osteoarthritis. Presence of degenerative change, absence of trauma, and presence in the lateral meniscus are features that favor a CHT over a BHT of the meniscus.