What physical examination tests should be performed for a patient with pain at the base of the thumb?

Physical Examination Tests for Thumb Base Pain

The pressure-shear test should be your primary provocative maneuver for evaluating suspected thumb carpometacarpal (CMC) arthritis, as it demonstrates superior diagnostic accuracy (98%) and sensitivity (99%) compared to the traditional grind test 1.

Essential Physical Examination Components

Inspection and Palpation

• Direct palpation of the CMC joint for point tenderness (sensitivity 94%, specificity 81%) 2
• Assess for visible swelling, subluxation, or deformity at the thumb base 3
• Evaluate for joint laxity or stiffness 3

Provocative Maneuvers (in order of diagnostic utility)

1. Pressure-Shear Test (First-line)

• Diagnostic accuracy: 98%
• Sensitivity: 99%, Specificity: 95% 1
• This test significantly outperforms all other maneuvers and should be your go-to examination technique

2. Thumb Adduction Test

• Sensitivity: 94%, Specificity: 93%
• Excellent interrater reliability (κ = 0.79) 2

3. Thumb Extension Test

• Sensitivity: 94%, Specificity: 95%
• Excellent interrater reliability (κ = 0.84) 2

4. Seesaw Test (Alternative)

• Involves flexion and extension of the thumb metacarpal on the trapezium with continuous axial pressure
• Sensitivity: 42-71%, Specificity: 82-86%
• Superior to grind test with better interrater agreement (κ = 0.59 vs 0.08) 4

5. Lever Test

• Grasp the first metacarpal just distal to the basal joint and "shuck" back and forth in radial and ulnar directions
• Best reproduces the patient's presenting pain 5

Tests to Avoid or Use Cautiously

Grind Test (Traditional but inferior)

• Sensitivity: only 13-64% across studies
• Specificity: 91-100%
• Poor interrater reliability (κ = 0.08-0.31) 4, 5, 2
• Highest false-negative rate among all tests 5
• While historically popular, this test is of limited diagnostic value and should not be relied upon as your primary examination maneuver

Metacarpal Flexion and Extension Tests

• Poor diagnostic accuracy (47% and 55% respectively)
• Low sensitivity (36% and 46%) 1

Clinical Algorithm

1. Start with inspection for deformity, swelling, subluxation
2. Palpate the CMC joint for point tenderness
3. Perform the pressure-shear test as your primary provocative maneuver
4. Add thumb adduction and extension tests for confirmation
5. Consider the lever test if you want to best reproduce the patient's typical pain pattern

Important Caveats

• A positive test is defined as pain greater than 0 on provocation 5
• Ask patients to rate whether the test fully, partially, or does not reproduce their typical thumb pain 5
• The grind test's poor sensitivity means a negative result does NOT rule out CMC arthritis
• Always obtain plain radiographs (posteroanterior, lateral, and oblique views) as initial imaging, which may be the only study needed 6