The varus stress test assesses the integrity of the lateral collateral ligament (LCL) in the knee joint. The LCL is one of the four major ligaments that stabilise the knee. The LCL in particular, protects against excess outside movement or varus stress. In other words, it protects against forces which push the knee outwards from the inside.
Knee ligaments
How to Perform the Varus Stress Test:
The patient usually lies on their back on the examination table with the knee slightly flexed, typically around 20-30 degrees.
Hold the patient’s thigh with one hand to keep the femur from moving.
With your other hand, grasp just above the patient’s ankle. Apply a varus force by pushing the lower leg toward the body’s midline, keeping the knee slightly flexed.
Assess the amount of lateral opening (varus laxity) at the knee joint and compare it to the opposite side. Also, note the quality of the end feel.
- Positive: If there is excessive lateral opening of the knee joint compared to the contralateral side or if there’s a soft or mushy end feel instead of a firm end feel, it may indicate a tear or laxity of the LCL. This finding suggests instability in the knee joint and is indicative of an LCL injury.
- Negative: If there is minimal lateral opening and a firm end feel, it suggests that the LCL is intact and providing appropriate stability to the knee joint.
Purpose of the Varus Stress Test:
- Assessing LCL Integrity: The varus stress test is primarily used to evaluate injuries or laxity of the LCL. LCL injuries can occur due to direct trauma, such as a blow to the inside of the knee, or from non-contact injuries, such as sudden changes in direction during sports activities.
- Clinical Assessment: The test helps clinicians diagnose LCL injuries and determine the appropriate management, whether it’s conservative treatment, such as physical therapy, or surgical intervention, depending on the severity of the injury and associated symptoms.
The varus stress test, along with other tests and MRI scans, helps clinicians decide how to treat and rehabilitate knee injuries, especially those on the knee’s outer side.
