Valgus Stress Test
The valgus stress test, also known as the medial stress test, is used to assess the integrity of the medial collateral ligament (MCL) of the knee. MCL injuries are common in the athletic population and can occur as either isolated injuries, or combined with other structural injuries .
- Begin with the patient in a supine position. Their leg should be relaxed as this test is performed.
Performing the Test
- The examiner places one hand at the outside of the knee, acting as a pivot point, while the other hand is placed at the foot. The medial joint line is palpated while the examiner simultaneously applies an abducting force at the the foot, and a valgus force through the knee joint.
- This test is typically performed at both 30 and 0 degrees of knee flexion. When performed at 30 degrees, the MCL is more isolated from other medial joint structures, with a sensitivity of .86-.96 for MCL tears. This can be followed by performing the second version of the test, at 0 degrees of knee flexion, which allows for assessment of other medial joint structures.
- The two versions are summarized below:
- Knee valgus @ 0° - Along with the MCL, the Medial Joint Capsule of The Knee, anterior cruciate ligament (ACL), and the posterior cruciate ligament (PCL) are stressed.
- Knee valgus @ 30° - The MCL is the prime stabilizer in this position and is therefore the primary structure assessed. The medial joint capsule is also stressed in this position.
- Positive findings may include excessive gapping at the medial joint and/or pain, indicating MCL damage. This may also indicate capsular or cruciate ligament laxity, depending on what degree of knee flexion the test is performed at.
- It should be noted that some joint gapping is considered normal at 30 degrees. No gapping should be present at 0 degrees.
Significance of Test
Overall, the MCL plays a crucial role in the stability of the knee and acts as the primary valgus restraint in a flexed knee. If knee hypermobility is present due to a sprained MCL, the ACL is placed under higher stress loads with valgus forces (particularly at 45 degrees of knee flexion). Therefore, special precautions should be taken with individuals who present with a lax MCL to decrease any risk of further injury, particularly of the ACL .
- Aronson PA, Gieck JH, Hertel J, Rijke AM, Ingersoll CD. Tibiofemoral joint positioning for the valgus stress test. Journal of Athletic Training. 2010 Jul;45(4):357-63.
- Garvin GJ, Munk PL, Vellet AD. Tears of the medial collateral ligament: magnetic resonance imaging findings and associated injuries. Canadian Association of Radiologists journal= Journal l'Association canadienne des radiologistes. 1993 Jun 1;44(3):199-204.
- Manske RC. Postsurgical orthopedic sports rehabilitation: knee & shoulder. Elsevier Health Sciences; 2006.
- Ellenbecker TS. Knee ligament rehabilitation. Churchill livingstone; 2000