Medial Collateral Knee Ligament Injury Workup

Updated: Oct 27, 2022
  • Author: Thomas M DeBerardino, MD, FAAOS, FAOA; Chief Editor: Craig C Young, MD  more...
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Imaging Studies


Radiography should be performed to rule out fractures of the tibial plateau, patella, or distal femur. Osteochondral effects can also be observed. Anterior-posterior, lateral, and patellofemoral views are usually sufficient. In skeletally immature patients, stress views may be helpful in identifying an associated physeal injury. [6]

The Pellegrini-Stieda lesion is indicative of an old injury and appears as a calcification at the femoral insertion of the MCL. [6]

The lateral capsular sign, or Segond fracture, suggests an associated ACL tear. This is a chip of bone still attached to the capsule after the capsule is avulsed from the lateral tibia. [6]

Stress radiography is a useful adjunct for confirming the grade of MCL injury. Valgus stress radiographs have been shown to accurately and reliably measure medial compartment opening. Differentiation between either meniscofemoral- and meniscotibial-based injuries was noted to be difficult. When comparing with the normal opposite knee at 20° of flexion, a grade III MCL injury is suspected if greater than 3.2 mm of medial compartment opening is noted. Valgus stress radiographs provide objective and reproducible measurements of medial compartment opening. [7]

Magnetic resonance imaging (MRI)

MRI is indicated when associated injuries are suspected. Associated ACL, PCL, and meniscal tears can be identified. Osteochondral fractures and bone bruises may also be identified. Injury of the MCL can be localized to the femoral, midsubstance, or tibial regions. [2]

A systematic review by Meyer et al showed that the correlation of MRI findings with physical examination findings was moderate to strong (65-92%) in patients with MCL injuries. In addition, MRI was more sensitive than physical examination in identifying MCL lesions. [8]

Diagnostic ultrasonography

Studies have suggested that diagnostic ultrasonography can be useful in evaluating MCL injuries.



Joint aspiration

If a significant joint effusion is present, evaluation may be difficult. Using aseptic technique, the knee may be aspirated to allow for a more complete evaluation. A local anesthetic can be injected if the knee is too painful for evaluation.