Varus Test: What a Positive Result Means for Your Knee

What is a positive Varus test?

A positive Varus test, primarily conducted on the knee joint, indicates excessive laxity or pain on the lateral (outer) side of the knee when a varus stress is applied, most commonly signifying an injury to the Lateral Collateral Ligament (LCL) and/or other posterolateral corner structures.

Understanding the Varus Stress Test

The Varus stress test is a specific orthopedic assessment used by healthcare professionals to evaluate the integrity of the knee's lateral stabilizing structures, particularly the Lateral Collateral Ligament (LCL). This ligament is crucial for preventing excessive inward bowing of the knee (varus angulation) and maintaining stability. The test is a key component of a comprehensive knee examination when a lateral knee injury is suspected, often following direct trauma to the medial side of the knee or a hyperextension injury.

The Concept of Varus Stress

To understand the test, it's essential to grasp the concept of "varus." In anatomical terms, a varus deformity refers to an angulation of a distal segment away from the midline of the body. For the knee, this means the lower leg (tibia) is angled inwards relative to the thigh (femur), creating a "bow-legged" appearance. Varus stress is the application of a force that attempts to create or exaggerate this angulation. During the test, this force is applied to the medial (inner) side of the knee while the lateral side is simultaneously pulled apart, stressing the structures designed to resist this motion.

How the Varus Stress Test is Performed

The Varus stress test is typically performed with the patient lying supine (on their back). The examiner stabilizes the thigh (femur) with one hand and applies an inward-directed force to the medial aspect of the knee with the other hand, simultaneously applying an outward traction force to the ankle. This maneuver attempts to open the lateral joint line. The test is usually performed in two positions:

• At 0 degrees (full extension): This position assesses the integrity of the LCL, the posterior cruciate ligament (PCL), and the posterior capsule.
• At 20-30 degrees of flexion: Flexing the knee isolates the LCL, as the posterior capsule and cruciates become less taut, allowing for a more specific evaluation of the LCL's stability.

Interpreting a Positive Varus Test

A Varus test is considered "positive" if there is:

• Excessive Gapping: Noticeable opening or separation of the lateral joint line compared to the uninjured knee. This indicates laxity or rupture of the lateral stabilizing structures.
• Pain: Significant pain reported by the patient along the lateral knee joint line, even without excessive gapping, can also indicate a strain or partial tear.

The degree of laxity can be graded to assess the severity of the injury:

• Grade I (Mild): Pain with varus stress, but no discernible gapping. This suggests a stretch or microscopic tear of the LCL.
• Grade II (Moderate): Pain with varus stress and some gapping, but with a firm endpoint. This indicates a partial tear of the LCL.
• Grade III (Severe): Significant gapping with varus stress and no discernible endpoint. This suggests a complete rupture of the LCL and potentially concomitant injuries to other posterolateral corner structures.

Structures Implicated: While a positive Varus test primarily points to an LCL injury, especially when performed in 20-30 degrees of flexion, excessive gapping at 0 degrees of extension may also suggest damage to:

• Posterior Cruciate Ligament (PCL): Contributes to stability in full extension.
• Posterolateral Corner (PLC) Structures: A complex group of ligaments and tendons (e.g., popliteus tendon, popliteofibular ligament, lateral gastrocnemius head) that provide significant rotatory and varus stability to the knee. Combined LCL and PLC injuries are common and more complex.

Clinical Significance and Next Steps

A positive Varus test is a critical finding that guides further diagnostic and treatment decisions. It indicates a need for:

• Further Imaging: An MRI (Magnetic Resonance Imaging) is typically ordered to confirm the diagnosis, assess the extent of the LCL injury, and identify any other associated injuries (e.g., meniscal tears, bone bruises, or other ligamentous damage).
• Rehabilitation Planning: For Grade I and II LCL injuries, conservative management with physical therapy, rest, and bracing is often effective. The focus is on pain management, restoring range of motion, strengthening surrounding musculature, and proprioceptive training.
• Surgical Consultation: Grade III LCL tears, especially those combined with other ligamentous injuries (e.g., ACL, PCL, or significant PLC damage), may require surgical repair or reconstruction to restore knee stability and prevent chronic instability or osteoarthritis.

Limitations and Considerations

It is important to remember that the Varus stress test is just one component of a thorough clinical examination. Its findings must be correlated with the patient's medical history, mechanism of injury, other physical examination findings (e.g., palpation, range of motion, other ligamentous tests), and imaging results. A false negative can occur if muscle guarding is present, or if the test is not performed correctly. Conversely, a false positive might occur if the patient has underlying joint hypermobility.

Conclusion

A positive Varus test is a significant clinical indicator of instability in the lateral knee compartment, most commonly due to injury to the Lateral Collateral Ligament. Understanding its implications is crucial for fitness professionals and individuals alike, as it necessitates professional medical evaluation to determine the extent of the injury and guide appropriate rehabilitation or intervention, ensuring optimal recovery and return to activity.