Knee Ligament Tests to Determine Causes of Knee Pain

If you have knee pain, your physical therapist or healthcare provider may perform knee special tests to determine if a ligament sprain may be causing your problem. Knee special tests stress various ligaments in your knee, assessing their integrity to help guide your knee pain diagnosis and, ultimately, your treatment.

The knee joint is stabilized by four important ligaments. These are the anterior cruciate ligament, posterior cruciate ligament, medial collateral ligament, and lateral collateral ligament.

Each separate ligament prevents excessive motion of the knee. The anterior cruciate ligament prevents excessive anterior glide of your shin under your thigh bone. The posterior cruciate ligament prevents excessive posterior motion of your shin below your femur. Your medial collateral ligament prevents excessive abduction of the tibia and guards an excessive force coming from the outside area of your knee. Your lateral collateral ligament prevents excessive adduction of the tibia and guards against an excessive force coming from the inside aspect of your knee.

When damaged, your knee becomes unstable in the direction that the injured ligament stabilized. If you suspect that you have damaged a knee ligament, you must check in with your healthcare provider to get an accurate picture of your condition and to start on the correct treatment.

You may benefit from a visit with a physical therapist to assess your knee. He or she may perform knee special tests to check the integrity of your knee ligaments. 

There are four special tests each to evaluate the four ligaments of your knee. Learn the names of these tests, the ligaments they evaluate, and how to perform them. Remember, if you have a knee condition, check in with your healthcare provider before performing these knee special tests.

Anterior Drawer Test

The Anterior Test

Brett Sears, PT

The anterior drawer test is used to assess the integrity of your anterior cruciate ligament (ACL). This ligament prevents forward slippage of your shin bone underneath your thigh bone.

The test is performed by lying down on your back with your knee bent. Another person grasps your tibia just behind your knee and gently pulls forward. Excessive motion of your tibia underneath your femur indicates a positive test and an ACL tear may be suspected.

Posterior Drawer Test

The posterior drawer test evaluates the posterior cruciate ligament (PCL). This ligament prevents your shin bone from slipping backward underneath your thigh bone.

To perform this test, place the knee in ninety degrees of flexion with the patient lying supine and the foot stabilized on the table. Grasp the anterior aspect of the tibia over the tibial tuberosity and push forward (displacing the tibia posteriorly) with a steady force. If the tibia moves posteriorly more than normal (compare with the uninjured leg) the test is positive. This is indicative of a possible posterior cruciate ligament tear or injury.

Valgus Stress Test

The valgus or abduction stress test evaluates the medial collateral ligament (MCL). To perform this test, place the knee in thirty degrees of flexion. While stabilizing the knee, press firmly against the outside portion of the knee while holding the ankle stable. If the knee gaps on the inner portion of the joint greater than normal (compare with the uninjured leg), the test is positive. This is indicative of a medial collateral ligament tear.

Often a "clunk" will be felt when performing the valgus stress test if the medial collateral ligament is injured.

Varus Stress Test

The varus or adduction stress test evaluates the lateral collateral ligament (LCL). To perform this test, place the knee in thirty degrees of flexion. While stabilizing the knee, adduct the ankle. If the knee joint adducts greater than normal (compare with the uninjured leg), the test is positive. You should notice gapping on the outer side of the knee joint. Many times a "clunk" will be felt if the lateral collateral ligament is injured or torn. This is indicative of a lateral collateral ligament tear.

If your PT finds that any of these tests are positive for a possible ligament tear, you can still begin treatment, but your therapist may recommend that you have an MRI to confirm a sprain. 

Severe knee ligament sprains may require surgery to fix, but research also suggests that pre-operative physical therapy can offer positive benefits.

If you have injured your knee, you may benefit from physical therapy to help you regain normal mobility in the joint. Your PT may perform knee special tests to assess the ligaments around your knee. If your PT suspects a significant ligament tear around your knee, he or she may recommend you check in with an orthopedic surgeon to fully assess your condition.

Edited by Brett Sears, PT.

4 Sources
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  2. Badri A, Gonzalez-lomas G, Jazrawi L. Clinical and radiologic evaluation of the posterior cruciate ligament-injured knee. Curr Rev Musculoskelet Med. 2018;11(3):515-520. doi:10.1007/s12178-018-9505-0

  3. Rossi R, Dettoni F, Bruzzone M, Cottino U, D'elicio DG, Bonasia DE. Clinical examination of the knee: know your tools for diagnosis of knee injuries. Sports Med Arthrosc Rehabil Ther Technol. 2011;3:25. doi:10.1186/1758-2555-3-25

  4. Grawe B, Schroeder AJ, Kakazu R, Messer MS. Lateral Collateral Ligament Injury About the Knee: Anatomy, Evaluation, and Management. J Am Acad Orthop Surg. 2018;26(6):e120-e127. doi:10.5435/JAAOS-D-16-00028

Additional Reading
  • Failla, MJ, et al. Does Extended Preoperative Rehabilitation Influence Outcomes 2 Years After ACL Reconstruction? A Comparative Effectiveness Study Between the MOON and Delaware-Oslo ACL Cohorts. Am J Sports Med. 2016 Oct; 44(10): 2608-2614.
  • Shaarani, SR, etal. Effect of prehabilitation on the outcome of anterior cruciate ligament reconstruction. AM J Sports Med. 2013 Sep; 41(9):2117-27.

By Laura Inverarity, DO
 Laura Inverarity, PT, DO, is a current board-certified anesthesiologist and former physical therapist.