Collateral Ligament Pathology Clinical Presentation

Updated: Apr 10, 2021
  • Author: Michael P Nogalski, MD; Chief Editor: Thomas M DeBerardino, MD  more...
  • Print


Collateral ligament inuries may be either contact or noncontact injuries. Generally, pain is experienced at the time of injury and increases over the following few days. Patients with isolated injuries often are able to bear weight on the leg. Patients with complete or combined ligament injuries often report feeling a "pop" at the time of injury. The patient usually is unable to continue playing when the injury occurs during a game. Swelling over the medial side of the knee may occur gradually.


Physical Examination

Often, the patient holds the knee in slight flexion. A mild or large effusion may be present. If the effusion is large and occurred shortly after the injury, especially if it is identified as a hemarthrosis, other injuries, such as an ACL tear, are likely and should carefully be ruled in or out. [23] Palpation of the knee reveals tenderness over the medial side of the knee, and it may be in the specific part of the medial collateral ligament (MCL) that is injured. In severe injuries, ecchymosis may be observed 1-2 days following the injury.

Medial collateral ligament injuries of the knee

Isolated testing of the ligament should be performed with the knee in 20 degrees of flexion. Pain with valgus stress and no medial joint space other than a normal (equal to the other injured side) opening of 0-5 mm indicates a grade 1 sprain. Pain and opening of the joint space up to 10 mm with an endpoint indicates a grade 2 injury to the MCL. Complete joint space opening of more than 10 mm indicates a grade 3 injury. Marked medial laxity suggests possible concomitant knee ligament injuries or reduced knee dislocation.

Careful evaluation of the medial joint line and tests for meniscal injury should also be performed to confirm that the pain is due to stress of the ligament and not to mechanical pain from a torn medial meniscus. The Apley grind/distraction test can be helpful but not entirely diagnostic or specific for this. With the patient prone, the knee is flexed to 90 degrees and the foot and ankle are grasped. The tibia is then rotated on the femur with distraction and compression of the tibia on the femur. If pain is generated in the unloaded situation, in which the ligament is stretched, then the medial pain is likely due to ligamentous or capsular injury. If the pain is worsened by compression, then a meniscal or chondral origin of the pain is more likely.

The patellofemoral joint and the medial retinacular structures should be evaluated and palpated for signs of retinacular tears and signs of instability as well. A torn or strained medial retinaculum can be very painful and can generate similar pain and have a similar history of injury. Vastus medialis disruptions are observed in up to 21% of knee ligament injuries. [24]

Lateral collateral ligament injuries

Specific examination maneuvers can be performed to identify injury to the lateral or posterolateral structures and to distinguish between pure rotational instability due to a torn posterolateral complex and additional laxity due to posterior cruciate ligament (PCL) insufficiency. In any case, a routine examination should be performed to carefully evaluate all ligaments around the knee if a lateral or posterolateral injury is suspected.

Valgus testing at 30 degrees should demonstrate laxity of the lateral collateral ligament (LCL). The quality of the endpoint should be noted, and if this test finding is indeed positive, a search for other injuries with the other tests outlined below should be initiated. With the knee in a figure-of-4 position, the LCL can be palpated as a taut structure when intact. If a soft spot is present in this region, the LCL, at minimum, has been injured. In any suspected lateral injury, careful evaluation of the peroneal nerve for possible injury is prudent. See Other Tests for diagnostic tests for LCL injuries.

LCL injuries can be grouped into classes similar to those in MCL injuries. Grade 1 injuries show normal or up to 5 mm of joint space opening with a solid endpoint. A similar solid endpoint is observed with grade 2 injuries, but opening up to 10 mm is possible. Grade 3 injuries demonstrate greater than 10 mm of joint space opening and often are associated with other ligament injuries.