Sprain of metacarpophalangeal joint of unsp thumb, init

This code signifies a ligamentous injury to the joint connecting the metacarpal bone and the phalanx of the thumb, without specifying which thumb is affected. It indicates a stretching or tearing of the soft tissues supporting this joint, resulting in pain, swelling, and limited motion.

Apply this code for a patient presenting with a newly diagnosed sprain of the thumb's metacarpophalangeal (MCP) joint, where the specific side (left or right) is not documented. This is appropriate for the initial evaluation and treatment of the injury.

• Only use this code when the laterality of the thumb sprain is not specified in the medical record.
• Ensure the encounter is truly the "initial encounter" for this specific injury, meaning the patient is receiving active treatment for the first time.
• If the laterality is known, use a more specific code (e.g., S63.641A for right thumb, S63.642A for left thumb).