Abnormal finger morphology Thumb sign 2025-07-30T14:15:06Z The distal phalanx of the adducted thumb extends beyond the ulnar border of the palm (The thumb protrudes from the clenched fist). The Steinberg or the thumb sign is elicited by asking the patient to fold his thumb into the closed fist. If the thumb tip extends from the palm of the hand, the test is positive. Steinberg sign