The Valgus Stress Test is a knee special test used to assess medial knee response when a valgus force is applied to the tibiofemoral joint. It is most commonly used to support assessment reasoning around medial collateral ligament involvement after a valgus or rotational knee injury.
A positive finding may include familiar medial knee pain, increased medial joint opening, or a softer end-feel compared with the other side. However, the test does not confirm an MCL injury on its own and should be interpreted alongside history, mechanism of injury, swelling, range of motion, strength, functional testing and other ligament tests.
The Valgus Stress Test is one of the most common orthopaedic tests used in knee assessment. It applies a valgus force to the knee to observe pain, laxity and end-feel on the medial side of the joint.
The test is often associated with the medial collateral ligament, commonly called the MCL. The MCL helps resist valgus stress at the knee. Testing at approximately 30 degrees of knee flexion is commonly used because it places greater emphasis on the MCL by reducing the contribution of some other stabilising structures. Testing in full extension may provide additional information about broader medial, capsular or multi-ligament involvement.
The Valgus Stress Test can be useful after a direct blow to the outside of the knee, a twisting injury, a sport collision, or a movement where the knee was forced inward. However, pain, guarding, swelling and acute irritability can affect the result.
This test should not be used as a stand-alone diagnostic tool. A positive test may increase suspicion of medial knee ligament involvement when it matches the history and other findings, but it does not prove the condition. A negative test may reduce suspicion in some situations, but it does not fully exclude medial knee injury.
Test name: Valgus Stress Test
Region: Knee
Primary structure assessed: Medial collateral ligament and medial knee structures
Common use: Medial knee pain or suspected MCL involvement after traumatic or valgus mechanism
Positive finding: Medial knee pain, increased medial joint opening, or softer end-feel compared with the other side
Negative finding: No relevant pain, no meaningful side-to-side laxity and firm end-feel
Common angles: Approximately 30 degrees knee flexion and full extension
Main limitation: Diagnostic accuracy is limited when used alone.
The Valgus Stress Test is a manual knee assessment where the professional applies a valgus force to the knee. In practical terms, the lower leg is moved outward relative to the thigh, creating stress through the medial side of the knee.
The test is usually performed in two positions:
At approximately 30 degrees of knee flexion
This position is commonly used to assess the MCL more specifically.
In full knee extension
This position may suggest broader medial, capsular, cruciate or multi-ligament involvement if increased opening is present.
The professional observes and records pain, gapping, end-feel, side-to-side difference and symptom reproduction.
The Valgus Stress Test may be used to support assessment reasoning around:
Medial knee pain after trauma
Suspected MCL involvement
Valgus or rotational knee injury mechanism
Medial joint line tenderness or symptoms
Knee instability sensation
Sport collision injuries
Skiing, football, netball, basketball or change-of-direction mechanisms
Side-to-side knee laxity comparison
Whether further assessment or referral may be appropriate
The test is useful because it is quick, easy to perform and clinically familiar. It is most meaningful when combined with history and other assessment findings.
The Valgus Stress Test assesses the knee’s response to valgus loading.
It may provide information about:
Medial knee pain response
Medial joint opening
End-feel quality
Side-to-side laxity difference
MCL-related assessment reasoning
Possible broader medial knee involvement
Irritability under valgus load
It does not directly assess:
Ligament fibre integrity with certainty
MRI findings
Meniscus status
ACL or PCL integrity
Strength
Running capacity
Readiness for sport or work
Tissue healing
Functional performance
The test may be useful for clients with:
Medial knee pain after trauma
A valgus or rotational injury mechanism
A direct blow to the outside of the knee
A feeling of medial knee instability
Sport-related knee injury
Difficulty with cutting, landing or pivoting
Medial knee symptoms during load-bearing tasks
A need for baseline or retest documentation in Measurz
It may also be useful for professionals learning how to structure knee ligament assessment.
Consider the Valgus Stress Test when:
The injury mechanism suggests valgus stress
The client reports medial knee pain after trauma
MCL involvement is part of the assessment reasoning
You want to compare medial laxity side to side
You need to document pain and end-feel under valgus load
You are building a broader knee ligament assessment profile
It should usually be combined with observation, palpation, range of motion, swelling assessment, functional testing and other knee special tests.
Use caution or avoid the test when:
There is suspected fracture
The knee is highly irritable or acutely swollen
The client cannot relax the limb
The client cannot tolerate manual stress
There is severe pain before testing
There are neurological symptoms
There is a major deformity or inability to bear weight after trauma
The professional is not confident the test can be performed safely
Stop the test if pain increases sharply, the client becomes distressed, the knee feels unstable in a concerning way, or the client asks to stop.
The Valgus Stress Test usually requires no equipment.
Optional equipment includes:
Measurz app
Pain rating scale
Treatment table or plinth
Towel roll or bolster
Video recording for education or comparison
Notes field for angle, pain, laxity and end-feel
Instrumented laxity device if available in specialist settings
Ask the client to lie supine on a plinth or firm surface.
Expose the knee enough to observe alignment, swelling and movement. Make sure the client is comfortable and relaxed.
Test the unaffected or less symptomatic side first where appropriate to understand the client’s normal end-feel.
The client lies supine with the tested knee relaxed.
For the 30-degree test:
Hip relaxed
Knee flexed to approximately 30 degrees
Lower leg supported
Foot and ankle relaxed
For the extension test:
Knee close to full extension
Limb relaxed
Avoid hyperextension or forced locking
The professional stands on the side of the tested leg.
One hand stabilises the lateral side of the distal femur or knee region. The other hand controls the ankle or distal tibia.
For a right knee example:
Place one hand on the lateral aspect of the knee or distal femur to stabilise.
Place the other hand around the distal tibia or ankle.
Keep the client’s limb relaxed.
Stabilise the thigh so the force is applied through the knee rather than rotating the whole limb.
The pelvis and hip should remain relaxed and neutral.
Apply a valgus force to the knee.
This means the distal tibia is gently moved laterally while the knee is stabilised, stressing the medial side of the knee.
Apply the force gradually and compare with the opposite side.
Tell the client:
“Stay relaxed and let me move your leg. I am going to apply a gentle stress to the knee. Tell me if this reproduces your familiar symptoms and where you feel it.”
A positive finding may include:
Familiar medial knee pain
Increased medial joint opening compared with the other side
Softer or less distinct end-feel
Apprehension or symptom reproduction
Greater laxity at 30 degrees
Greater laxity in full extension suggesting broader involvement
Record whether the positive finding was based on pain, laxity, end-feel or a combination.
A negative finding may include:
No relevant medial knee pain
No meaningful side-to-side laxity difference
Firm end-feel
No familiar symptom reproduction
Similar response to the opposite side
A negative finding does not fully exclude medial knee injury.
Stop the test if:
Pain increases sharply
The client asks to stop
The client cannot relax
The knee feels grossly unstable
The professional cannot control the movement
The client experiences neurological symptoms
The test is not safe or meaningful
Use a gradual and controlled force. Do not bounce, jerk or force the knee. Acute knee injuries may be painful and guarded, so interpretation may be limited in early assessment.
A positive Valgus Stress Test may increase suspicion of MCL involvement when it matches the client’s history, mechanism of injury and medial knee symptoms. Pain without laxity may suggest a lower-grade or pain-dominant medial knee response, while clear gapping or a softer end-feel may increase suspicion of structural laxity.
Increased opening at approximately 30 degrees may be more suggestive of MCL involvement. Increased opening in full extension may raise concern for broader injury involving other stabilising structures, but this should be interpreted carefully and within professional scope.
A positive test does not confirm an MCL injury. Pain can arise from other medial knee structures, and guarding may affect the result.
A negative Valgus Stress Test may reduce suspicion of clinically meaningful medial laxity, especially when history, palpation, swelling and functional assessment are also reassuring. However, a negative result does not fully exclude MCL involvement or other medial knee conditions.
The finding is more meaningful when combined with:
Mechanism of injury
Location of pain
Swelling
Palpation findings
Range of motion
Functional tolerance
Other ligament tests
Gait and movement assessment
Imaging where relevant
Kastelein et al. studied adults aged 18 to 65 with traumatic knee injury in general practice and used MRI as the reference standard for MCL lesions. Their findings support cautious interpretation rather than stand-alone diagnosis.
Reported diagnostic values from this evidence include:
Condition or presentation: Traumatic knee injury with suspected MCL lesion
Population: Adults aged 18–65 presenting to general practice within 5 weeks of trauma
Test variation: Valgus stress at 30 degrees, pain and laxity findings
Reference standard: MRI
Sensitivity/specificity: Reported values vary depending on whether pain or laxity is used as the outcome
Positive likelihood ratio: Pain with valgus stress at 30 degrees had a positive likelihood ratio of approximately 2.3
Combined finding: Adding pain and laxity with valgus stress at 30 degrees to history-taking improved the positive likelihood ratio to 6.4
Key limitation: This was a general practice traumatic knee injury population, and the findings should not be applied automatically to all sport, chronic, paediatric or post-operative presentations.
Plain-language interpretation:
A positive test finding may increase suspicion when it fits the history.
The test is stronger when combined with mechanism of injury and other findings.
A single positive valgus stress test does not confirm an MCL lesion.
A negative test does not fully exclude medial knee involvement.
Likelihood ratios are more useful when interpreted with the pre-test picture.
The Valgus Stress Test has clinical value because it directly applies valgus load to the knee and allows comparison of pain, gapping and end-feel side to side.
Reliability may be affected by:
Examiner experience
Client guarding
Acute pain and swelling
Knee flexion angle
Force magnitude
Hand placement
Interpretation of end-feel
Whether pain or laxity is used as the main positive finding
Validity is better when the test is interpreted with history and other findings. It is less valid as a stand-alone diagnostic test because pain and laxity can be influenced by multiple factors.
Instrumented or stress-imaging methods may quantify joint gapping more objectively in specialist settings, but manual clinical testing remains common and should be documented carefully.
Common errors include:
Testing only one angle
Applying force too aggressively
Not comparing with the opposite side
Not recording whether pain or laxity was positive
Ignoring end-feel quality
Testing when the client is guarding strongly
Assuming pain means ligament damage
Assuming no pain means no injury
Not checking other ligament tests
Calling the test diagnostic
Limitations include:
Manual force is difficult to standardise
Pain can limit interpretation
Swelling and guarding can hide laxity
A positive test does not confirm an MCL injury
A negative test does not exclude all medial knee conditions
Acute testing may be less reliable than delayed reassessment
Combined injuries may change interpretation
The Valgus Stress Test may be useful for:
Medial knee assessment
MCL-related assessment reasoning
Side-to-side laxity comparison
Baseline documentation
Retesting over time
Deciding whether further assessment may be needed
Communicating findings to clients
Supporting Measurz knee assessment reports
It is best used as part of a cluster that includes history, swelling, range of motion, palpation, gait, functional tasks and other ligament tests.
Record:
Test name: Valgus Stress Test
Side tested
Knee angle: 30 degrees or full extension
Result: positive, negative, unclear or unable to test
Pain score
Symptom location
Pain quality
Laxity: none, mild, moderate or marked
End-feel: firm, soft or absent
Comparison side
Mechanism of injury
Irritability
Guarding or compensations
Reason for stopping if relevant
Related findings
Confidence in result
Further assessment or referral notes if appropriate
Retest date if relevant
Recording these details improves repeatability, communication, client education, assessment reasoning, monitoring over time, team consistency and reporting quality.
Varus Stress Test
Lachman Test
Anterior Drawer Test
Posterior Drawer Test
McMurray Test
Thessaly Test
Knee Girth
Knee Range of Motion
Single-leg squat
Hop testing
Balance testing
It assesses the knee’s response to valgus load and is commonly used to support reasoning around MCL involvement.
A positive finding may include medial knee pain, increased medial joint opening or a softer end-feel compared with the other side.
Both may be useful. Around 30 degrees is commonly used for MCL emphasis. Full extension may provide information about broader stabilising structures.
No. It may increase suspicion, but it does not confirm injury on its own.
No. A negative test may reduce suspicion, but it does not fully exclude medial knee involvement.
Yes. Pain and laxity provide different information and should be recorded separately in Measurz.
It can be useful, but acute pain, swelling and guarding may limit interpretation.
History, mechanism, palpation, swelling, range of motion, other ligament tests, gait and functional assessment.
The Valgus Stress Test is commonly used to assess medial knee response to valgus load.
Testing at 30 degrees and full extension provides different information.
Positive findings may include pain, gapping or altered end-feel.
The test does not confirm or exclude MCL injury on its own.
Diagnostic value improves when combined with history and other findings.
Measurz recording should include angle, pain, laxity, end-feel and side-to-side comparison.
Kastelein, M., Wagemakers, H. P. A., Luijsterburg, P. A. J., Verhaar, J. A. N., Koes, B. W., & Bierma-Zeinstra, S. M. A. (2008). Assessing medial collateral ligament knee lesions in general practice. The American Journal of Medicine, 121(11), 982–988.e2. doi:10.1016/j.amjmed.2008.05.041
Logerstedt, D. S., Scalzitti, D. A., Risberg, M. A., Engebretsen, L., Webster, K. E., Feller, J., Snyder-Mackler, L., & Axe, M. J. (2017). Knee stability and movement coordination impairments: Knee ligament sprain revision 2017. Journal of Orthopaedic & Sports Physical Therapy, 47(11), A1–A47. doi:10.2519/jospt.2017.0303
NICE. (2024). Knee pain — assessment: Examination. National Institute for Health and Care Excellence Clinical Knowledge Summaries.
Phisitkul, P., James, S. L., Wolf, B. R., & Amendola, A. (2006). MCL injuries of the knee: Current concepts review. Iowa Orthopaedic Journal, 26, 77–90.
Smith, T. O., Davies, L., & Hing, C. B. (2016). A systematic review to determine the reliability of knee joint clinical assessment tests. The Knee, 23(2), 219–228. doi:10.1016/j.knee.2015.06.010
