M20.20 Hallux rigidus, unspecified foot

Billable ICD-10-CM code, FY2026.

Applies from M20 Acquired deformities of fingers and toes

Excludes1 (never code together)

• acquired absence of fingers and toes (Z89.-)
• congenital absence of fingers and toes (Q71.3-, Q72.3-)
• congenital deformities and malformations of fingers and toes (Q66.-, Q68-Q70, Q74.-)

MS-DRG index

Defines the logic of DRG(s) 564-566 in MDC 08.

Approximate ICD-9-CM (GEMs)

• 735.2 Hallux rigidus (approximate)

Code annotations containing back-references to M20.20

Back-references to M20.2

• Type 2 Excludes: M19 Other and unspecified osteoarthritis ("hallux rigidus (M20.2)")
• Type 2 Excludes: M21.6 Other acquired deformities of foot ("deformities of toe (acquired) (M20.1-M20.6-)")

Back-references to M20

• Type 2 Excludes: M21 Other acquired deformities of limbs ("acquired deformities of fingers or toes (M20.-)")
• Type 2 Excludes: M24.5 Contracture of joint ("acquired deformities of limbs (M20-M21)")
• Type 2 Excludes: M25 Other joint disorder, not elsewhere classified ("acquired deformities of limb (M20-M21)")
• Type 2 Excludes: M95 Other acquired deformities of musculoskeletal system and connective tissue ("acquired deformities of limbs (M20-M21)")
• Type 1 Excludes: Z89 Acquired absence of limb ("acquired deformities of limbs (M20-M21)")

Nearby codes

• M20.1 Hallux valgus (acquired)
• M20.10 Hallux valgus (acquired), unspecified foot
• M20.11 Hallux valgus (acquired), right foot
• M20.12 Hallux valgus (acquired), left foot
• M20.2 Hallux rigidus
• M20.20 Hallux rigidus, unspecified foot (this code)
• M20.21 Hallux rigidus, right foot
• M20.22 Hallux rigidus, left foot
• M20.3 Hallux varus (acquired)
• M20.30 Hallux varus (acquired), unspecified foot
• M20.31 Hallux varus (acquired), right foot