Collateral Ligament Injury

Key Features

Essentials of Diagnosis

• Caused by a valgus or varus blow or stress to the knee

• Pain and instability in the affected area

• Limited range of motion

General Considerations

• The medial collateral ligament (MCL)

  • Most commonly injured ligament in the knee

  • Usually injured with a valgus stress to the partially flexed knee

  • Can also occur with a blow to the lateral leg

  • Commonly injured with acute anterior cruciate ligament (ACL) injuries

• The lateral collateral ligament (LCL)

  • Less commonly injured

  • Can occur with a medial blow to the knee

• Since both collateral ligaments are extra-articular, injuries to these ligaments may not lead to any intra-articular effusion

• Affected patients may have difficulty walking initially, but this can improve when the swelling decreases

Clinical Findings

Symptoms and Signs

• Pain along the course of the ligaments

• Limited range of motion due to pain, especially during the first 2 weeks following the injury

Diagnosis

Imaging

• Radiographs

  • Usually nondiagnostic except for avulsion injuries

  • Should be used to rule out fractures that can occur with collateral ligament injuries

• MRI

  • Usually not needed for isolated MCL injuries

  • Should be used to evaluate possible associated cruciate ligament injuries

  • Should be done for LCL or posterolateral corner injuries to exclude associated injuries and to determine their significance

Diagnostic Procedures

• Varus and valgus stress tests are best methods to assess the collateral ligaments (Table 41–6)