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Lateral collateral ligament injury
Other Resources UpToDate PubMed

Lateral collateral ligament injury

Contributors: Connor Sholtis BA, Sandeep Mannava MD, PhD
Other Resources UpToDate PubMed

Synopsis

Causes / typical injury mechanism: The lateral collateral ligament (LCL) is a very strong, cord-like structure in the posterolateral compartment (PLC) of the knee that serves as the primary varus stabilizer. It is one of the least commonly injured structures of the knee, and it typically requires extreme varus pressure or external tibial rotation to induce injury. Injury rarely occurs in isolation and often involves other structures of the knee, particularly in the PLC (ie, LCL, popliteus complex, popliteofibular ligament, lateral capsule, iliotibial band, biceps femoris, lateral head of gastrocnemius).

Classic history and presentation: Because isolated injury to the LCL is rare, LCL lesions most commonly present in conjunction with feelings of instability and dull pain in the affected knee. The knee may or may not be swollen, depending on the chronicity and mechanism of the injury. LCL tears are also often associated with peroneal nerve damage (foot drop and/or numbness on the dorsum of foot) because it courses superficially in the lateral knee. Injury may present acutely (< 3 weeks) or chronically (> 3 weeks), with chronic cases having a greater risk of degenerative changes in the knee secondary to instability.

Prevalence: Because of frequent concurrent injury, it has been speculated that PLC pathologies are underreported and undertreated. A large 10-year study of more than 17 000 European athletes with sports-related injuries showed that approximately 37% experienced injury to the knee. Only 1.1% of knee injuries involved lesions of the LCL.
  • Age – Nearly 70% of patients with knee injuries were male.
  • Sex / gender – Nearly 65% were between 20 and 39 years, with the 20-29 year age group comprising nearly 45% of patients. 
Risk factors: The most commonly implicated sports for knee injuries include soccer and skiing, but LCL injury has been specifically associated with tennis and gymnastics. Furthermore, automobile accidents can produce the extreme forces needed for lateral knee injury.

Grade / classification system: The grade of an LCL injury is determined by the amount of lateral joint line opening with varus stress:
  • Grade 1 – less than 5 mm
  • Grade 2 – 5-9 mm
  • Grade 3 – 10 mm or more

Codes

ICD10CM:
M23.649 – Other spontaneous disruption of lateral collateral ligament of unspecified knee

SNOMEDCT:
444468005 –  Injury of lateral collateral ligament of knee

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Last Reviewed:11/17/2020
Last Updated:11/17/2020
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Lateral collateral ligament injury
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