M21.90 Unspecified acquired deformity of unspecified limb

Billable ICD-10-CM code, FY2026.

Applies from M21 Other acquired deformities of limbs

Excludes1 (never code together)

• acquired absence of limb (Z89.-)
• congenital absence of limbs (Q71-Q73)
• congenital deformities and malformations of limbs (Q65-Q66, Q68-Q74)

Excludes2 (not included here)

• acquired deformities of fingers or toes (M20.-)
• coxa plana (M91.2)

MS-DRG index

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

Approximate ICD-9-CM (GEMs)

• 736.9 Acquired deformity of limb, site unspecified (approximate)

Code annotations containing back-references to M21.90

Back-references to M21

• Type 1 Excludes: M23 Internal derangement of knee ("deformity of knee (M21.-)")
• 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)")

Diagnosis Index entries for M21.90

• Deformity › joint (acquired) NEC
• Deformity › limb (acquired)

Nearby codes

• M21.86 Other specified acquired deformities of lower leg
• M21.861 Other specified acquired deformities of right lower leg
• M21.862 Other specified acquired deformities of left lower leg
• M21.869 Other specified acquired deformities of unspecified lower leg
• M21.9 Unspecified acquired deformity of limb and hand
• M21.90 Unspecified acquired deformity of unspecified limb (this code)
• M21.92 Unspecified acquired deformity of upper arm
• M21.921 Unspecified acquired deformity of right upper arm
• M21.922 Unspecified acquired deformity of left upper arm
• M21.929 Unspecified acquired deformity of unspecified upper arm
• M21.93 Unspecified acquired deformity of forearm