Hallux rigidus, unspecified foot

This code signifies a degenerative arthritic condition affecting the metatarsophalangeal (MTP) joint of the great toe, characterized by stiffness and pain. It indicates an unspecified laterality, meaning the documentation does not specify whether the condition affects the left or right foot. The hallmark of hallux rigidus is progressive loss of motion in the great toe joint.

Use this code when documentation confirms a diagnosis of hallux rigidus but does not specify the affected foot (e.g., "hallux rigidus" without "left" or "right"). This code is appropriate for initial evaluations, follow-up visits, and surgical planning when laterality is not yet determined or explicitly documented. Supporting documentation should include clinical findings consistent with MTP joint arthritis, such as pain, stiffness, and limited range of motion.

• Avoid using this code if laterality (left or right foot) is clearly documented; instead, use the more specific M20.21 (right) or M20.22 (left).
• Ensure the medical record explicitly states "hallux rigidus" or a similar clinical term for the great toe MTP joint arthritis.
• Consider sequencing this code as a primary diagnosis if it is the main reason for the encounter, or as a secondary diagnosis if it is a co-morbidity.