Radiology Teaching Files > Case 22887619

Contributed by: bala chandiran, Radiologist, govt.general hospital,pondicherry, India.
Patient: 24 year old male
History: A twenty four old male was referred for evaluation of internal derangement of right knee.

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Findings: MR 1)sagittal in FLASH,MEDIC and P.D. T2W sequences and 2)Coronal TIRM T1W sequences showed complex signal intensity with class II tears in the anterior and posterior horns of medial and lateral menisci.There was also ACL tear and lateral collateral ligament tear.Joint effusion and fluid collection in lateral compartment were also seen.
Discussion: Meniscal injuries are the most common of all knee injuries, the medial meniscus being injured 10 times more frequently than the lateral due to the more firm attachment of the medial meniscus to the tibial plateau and capsule. Meniscal injuries commonly occur when the normal rotation of the tibia is forcibly prevented during flexion or extension; therefore the history usually involves a twisting injury, often medially with the knee in the full weight-bearing position or with a valgus stress while the knee is flexed. The patient's history of an effusion occurring several days after the initial injury is consistent with an isolated injury of the meniscus because meniscal injuries that occur with ligamentous injuries classically cause a large effusion (often hemorrhagic) acutely within minutes of the initial injury. . A meniscal tear is diagnosed when a signal abnormality unequivocally reached the articular surface of the meniscus in at least two adjacent images. Meniscal tears were classified into four groups adapted from previously published classification systems : horizontal or oblique partial-thickness tears, radial tears, vertical or complex full-thickness tears, and tears with displaced meniscal fragments. The injury is classified as a Class 3 meniscal injury if it communicates with at least one articular surface on MRI. Class 3 injuries are usually symptomatic (pain, locking) and are evident on MRI, or upon visual inspection at either surgery or autopsy. Class 1 injuries are those that appear as globular (non-linear) signal abnormalities and do not communicate with an articular surface on MRI; these are frequently asymptomatic and due to meniscal degeneration. Class 2 injuries are linear signal abnormalities and do not communicate with articular surfaces on MRI; these are also frequently asymptomatic. MR imaging studies determine the presence or absence of meniscal lesions, including contour irregularity, peripheral separation, and tear. Contour irregularity is defined as an altered meniscus shape with truncation, blunting, flattening, or rounding of the inner borders on coronal T1- or T2*-weighted or sagittal intermediate- or T2-weighted MR images. Peripheral meniscus separation is defined by the presence of high signal intensity on T2-weighted images between the meniscus and the capsule. Meniscal tear is defined as an abnormal intrameniscal signal that extended to the articulating surface of the meniscus on more than one coronal T2*-weighted or sagittal intermediate- or T2-weighted MR image. MR imaging criteria for unstable meniscal lesions are based on the presence of a displaced meniscal fragment and on determination of meniscal lesion extent, shape, and signal intensity .They have a high specificity and a high positive predictive value for the recognition of instability among all meniscal lesions
References: 1.C Ruff, JP Weingardt, PD Russ and RF Kilcoyne, MR imaging patterns of displaced meniscus injuries of the knee. AJR 170 ,1998, pp. 63–67 2. B. C. Vande Berg, P. Poilvache, F. Duchateau,, Lesions of the Menisci of the Knee ; Value of MR Imaging Criteria for Recognition of Unstable Lesions, AJR 2001; 176:771-776
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Additional Details:

Case Number: 22887619Last Updated: 01-20-2009
Anatomy: Skeletal System   Pathology: Trauma
Access Level: Readable by all users
Keywords: mri in internal derangement of knee

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