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Collateral Ligament Injury MRI

Practice Essentials

Magnetic resonance imaging (MRI) has a primary role in the diagnosis of musculoskeletal soft tissue injuries of the knee. MRI is an accurate and cost-effective means of evaluating a wide spectrum of knee injuries, ranging from cruciate-collateral ligament injuries to cartilage deficiencies. MRI enables the most comprehensive imaging assessment of the knee and, when performed early after injury, can aid in predicting which patients require further treatment. Detection of associated internal derangements of the knee makes MRI superior to ultrasonographic imaging.
 

Radiographs may demonstrate an acute fracture but commonly are either negative or may demonstrate indirect signs of an acute soft-tissue injury. Computed tomography (CT) is usually reserved for diagnosis of suspected fractures or assessment of complex fractures, although associated ligamentous injuries may be evident on CT scans obtained for evaluation of osseous injuries.
 

Medial collateral ligament (MCL) injury is the most common knee injury in high school, collegiate, and professional football athletes and typically occurs when a valgus force is applied to the knee. The annual incidence of MCL injuries in high school football players is 24.2 per 100,000 athletes.

MCL tears are rarely isolated. More commonly, they are associated with other soft tissue injuries of the knee, such as anterior cruciate ligament (ACL) tears and medial meniscal tears (O’Donoghue’s unhappy triad). In one study, nearly 78% of patients who sustained a grade III MCL injury had an injury to another associated structure. Of those additional injuries, 95% involved the ACL.

The differential diagnosis includes damage to other medial structures of the knee: the pes anserinus or semitendinosus, vastus medialis, femoral quadriceps, or medial gastrocnemius tendons. Tears to the lateral collateral ligament (LCL) are less common and never occur in isolation. Typically, these injuries are associated with damage to the popliteal tendon arcuate ligament (the posterolateral reinforcement of the joint capsule), the ACL, and the posterior cruciate ligament (PCL).
  

(A coronal, proton-density (PD) MRI scan of the MCL is shown below.)

Proton density coronal image shows the anterior ve

Proton density coronal image shows the anterior vertical portion of the medial collateral ligament as a thin, taut, well-defined, low-signal structure extending from the medial femoral epicondyle to the medial tibial metaphysis (straight arrows). Distal insertion of the anterior cruciate ligament is visualized (curved arrow).

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Grading system

The grading system for MCL and LCL tears, which is the same as that used for other ligaments evaluated by MRI, is as follows:

Grade 1 – Microscopic tears

Grade 2 – Partial tears

Grade 3 – Complete tears

Examples of these injuries are seen in the images below.

Grade I medial collateral ligament tear with surro

Grade I medial collateral ligament tear with surrounding intermediate signal consistent with edema (straight arrows) on a coronal proton density sequence. Note the normal thickness and signal of the medial collateral ligament and continued close apposition to the femoral and tibial cortices.

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Corresponding fast spin-echo inversion recovery im

Corresponding fast spin-echo inversion recovery image demonstrates surrounding edema (white arrows).

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Grade II medial collateral ligament tear seen on a

Grade II medial collateral ligament tear seen on a coronal proton density image shows slight thickening of the medial collateral ligament and separation from the underlying cortices (arrows).

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Corresponding coronal fast spin-echo inversion rec

Corresponding coronal fast spin-echo inversion recovery image shows surrounding edema (small arrows). Note bone bruise of the lateral tibial plateau (large arrow), another sequela of the valgus stress.

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Grade III medial collateral ligament tear on a cor

Grade III medial collateral ligament tear on a coronal fast spin-echo T2-weighted image demonstrates a disrupted ligament that is thickened and retracted, with surrounding edema (black arrow).

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Acute grade III tear with a folded ligament (arrow

Acute grade III tear with a folded ligament (arrow) and surrounding edema on a coronal proton density image.

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Corresponding coronal fast spin-echo inversion rec

Corresponding coronal fast spin-echo inversion recovery image.

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There have been studies on the superficial MCL (sMCL) tibial side avulsion classification. The sMCL tibial side avulsion revealed the characteristic waving of the sMCL midsubstance portion on MRI images, which Taketomi et al called the “wave sign.” The sMCL tibial avulsions were classified into 3 types, depending on the location of the ruptured end with respect to the pes anserinus tendons
:

Type 1: The sMCL was detached from the original tibial insertion, and the ruptured end was identified beneath the pes anserinus tendons.

Type 2: The sMCL was located over or above the pes anserinus tendons (the Stener-like lesion).

Type 3: The sMCL was entrapped in the medial knee joint space.

For excellent patient education resources, visit eMedicineHealth’s First Aid and Injuries Center. Also, see eMedicineHealth’s patient education articles Knee Injury and Magnetic Resonance Imaging (MRI).

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