
Hitchhiker’s thumb means you can move your thumb joint backward beyond the normal range of motion, as far as 90 degrees.
Hitchhiker’s Thumb (Distal Hyperextensibility): Symptoms, Causes & Outlook. Cleveland Clinic. Published May 31, 2022. Accessed April 28, 2025. https://my.clevelandclinic.org/health/diseases/23118-hitchhikers-thumb