Glossary
Varus and valgus stress tests
Quick answer
Varus and valgus stress tests check the side ligaments of the knee. The surgeon gently bends the knee inwards (valgus) to test the medial collateral ligament and outwards (varus) to test the lateral collateral ligament, feeling for opening of the joint, explains Doha knee surgeon Dr. Pablo Gelber at Aman Hospital.
How the tests are done
You lie on your back and relax the leg. The surgeon holds the thigh with one hand and the ankle with the other, then applies a gentle sideways force at the knee, first with the knee straight and then bent about 30 degrees.
A valgus stress pushes the knee inwards, stretching the inner side. A varus stress pushes it outwards, stretching the outer side. If a ligament is injured you may feel tenderness along that side, and sometimes a gapping sensation.
What they tell the surgeon
Testing at 30 degrees isolates the collateral ligament. If the joint also opens with the knee fully straight, the cruciate ligaments or the posterolateral corner are probably injured too, which points to a more serious injury.
The opening is graded. Grade 1 means tenderness without opening, grade 2 means some opening with a firm end point, and grade 3 means clear opening without a firm stop. Most MCL injuries heal well with a brace and physiotherapy; higher-grade LCL and posterolateral corner injuries more often need surgery.
Imaging
An MRI shows where the ligament is torn and whether other structures are involved. Stress X-rays can measure the gap when the grade is uncertain.
Frequently asked questions
What is the difference between varus and valgus?
Valgus means the lower leg is pushed outwards so the knee moves inwards, stressing the MCL. Varus is the opposite, stressing the LCL on the outside.
Will the test make my injury worse?
No. The force used is gentle and controlled. It may be tender if the ligament is freshly injured, and the surgeon stops if it hurts too much.
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