I often receive emails from patients with TFCC tears who report wrist splinting (normal wrist extension/cock up) makes their wrist hurt more than without the splinting. The Piano Key Sign is a common test performed by physicians as a part of the clinical assessment of the wrist. Simply described, imagine the ulna head as a piano key. The examiner would press on the ulna head and if painful, would indicate a positive Piano Key Sign. A stable wrist would cause the ulna head to spring back like a piano key without pain. You can read all about the test all over medical text books as an indicator of a TFCC tear or DRUJ (distal radial ulna joint) instability.