Thumb Ligament Instability Tests: How to Check for Gamekeeper's Thumb

These tests (Valgus and Varus stress) are used to assess the collateral ligaments of the thumb's Metacarpophalangeal (MCP) joint. The valgus test is the primary test for "Gamekeeper's Thumb" or "Skier's Thumb."

1. Purpose

The primary purpose is to test the integrity of the collateral ligaments of the thumb's Metacarpophalangeal (MCP) joint.

• The Valgus Stress Test checks the medial or Ulnar Collateral Ligament (UCL), which is commonly injured in "Gamekeeper's Thumb" or "Skier's Thumb."
• The Varus Stress Test checks the lateral or Radial Collateral Ligament (RCL).

2. How to Perform

The patient is positioned in sitting. The examiner stabilizes the patient's 1st metacarpal (hand) and holds their proximal phalanx (thumb).

Valgus Stress Test (for Medial Stability / UCL)

1. Stabilize the 1st metacarpal.
2. Gently apply a valgus (abducting, or outward) force to the MCP joint.
3. This is done with the thumb in both full extension and slight flexion.

Varus Stress Test (for Lateral Stability / RCL)

1. Stabilize the 1st metacarpal.
2. Gently apply a varus (adducting, or inward) force to the MCP joint.
3. This is also done in both full extension and slight flexion.

3. Positive & Negative Sign

Positive Sign (Test is POSITIVE):
A positive test (indicating a ligament tear) is:

• Valgus Test: Excessive gapping (laxity) on the medial side of the joint, often more than 30-35 degrees, or 15 degrees more than the uninjured side. This indicates a UCL tear ("Gamekeeper's Thumb").
• Varus Test: Excessive gapping (laxity) on the lateral side of the joint compared to the uninjured side. This indicates an RCL tear.

Negative Sign (Test is NEGATIVE):
A negative test is a "firm" end-feel with no pain or increased gapping on either test.