The short thumb spica can immobilize the CMC joint and the MP joint of the thumb. True or false?

• A. True
• B. False
• C. Not used for this purpose
• D. Depends on the orthosis design

Answer: (A)

Immobilizing the base of the thumb requires restricting motion at both the carpometacarpal (CMC) joint and the metacarpophalangeal (MCP) joint. A short thumb spica is designed to do exactly that by securing the wrist and wrapping around the thumb so movement at the CMC and MCP joints is limited. This stabilization helps protect ligaments, reduce pain, and promote healing after injuries or after surgery. While designs can vary and some may allow limited IP movement or extend to immobilize more joints, the standard purpose of a short thumb spica is to immobilize the CMC and MCP joints of the thumb.