A 25-year-old woman presents with pain and inability to move her left thumb after falling onto an outstretched hand during a skiing accident. The thumb appears deformed and is swollen. What is the likely diagnosis and what are the next steps?
The presentation suggests a thumb dislocation, likely at the metacarpophalangeal (MCP) joint. This injury is often caused by forceful hyperextension of the thumb. An X-ray should be obtained to confirm the diagnosis and identify any associated fractures. The joint should be reduced as soon as possible, often under local anesthesia due to the pain, and then immobilized with a thumb spica splint.