The varus stress test checks for joint laxity on the outside of the knee, which usually represents an injury to the lateral collateral ligament (LCL).
Maneuver: With the patient lying on their back, position one hand at the joint line on the outer part of the knee. Fix the other hand on the ankle of the affected side. Flex the knee between 20° and 30° and apply a lateral or varus force to the knee. This can be done either by reaching over the top of the knee, or by approaching the patient from the inside aspect of the knee with the leg off to the side. Approximately, 15 to 20 lbs of force should be applied during the test. The test can also be repeated at 0° with the knee in full extension.
Tip: Fixing the ankle and pushing laterally with the hand at the knee allows force to be easily applied to the knee due to the leverage of the long bone of the shin. If the leg opens on a varus stress testing, be extra careful when testing the ACL, PCL and posterolateral corner. The LCL is not commonly torn in isolation.
Positive Findings: A positive test demonstrates increased lateral joint laxity compared to the unaffected side. A Grading system from 1 to 3 can be used which is based on the amount of joint space opening (Grade 1 = 5 mm, Grade 2 = 5 to 10 mm, Grade 3 > 10 mm).
In this video Andreas demonstrates how to perform the varus stress test at the knee joint to assess the lateral collateral ligament.
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