M90.559 Osteonecrosis in diseases classified elsewhere, unspecified thigh

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Applies from M90 Osteopathies in diseases classified elsewhere

Excludes1 (never code together)

• osteochondritis, osteomyelitis, and osteopathy (in):
• cryptococcosis (B45.3)
• diabetes mellitus (E08-E13 with .69-)
• gonococcal (A54.43)
• neurogenic syphilis (A52.11)
• renal osteodystrophy (N25.0)
• salmonellosis (A02.24)
• secondary syphilis (A51.46)
• syphilis (late) (A52.77)

Applies from M90.5 Osteonecrosis in diseases classified elsewhere

Code first

• underlying disease, such as:
• caisson disease (T70.3)
• hemoglobinopathy (D50-D64)

Risk adjustment (HCC)

• CMS-HCC V28: HCC 92 — Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis
• CMS-HCC V22: HCC 39 — Bone/Joint/Muscle Infections/Necrosis
• RxHCC V08: HCC 80 — Aseptic Necrosis of Bone
• ESRD V24: HCC 39

MS-DRG index

Defines the logic of DRG(s) 553-554 in MDC 08.

Approximate ICD-9-CM (GEMs)

• 731.8 Other bone involvement in diseases classified elsewhere (approximate)
• 733.42 Aseptic necrosis of head and neck of femur (approximate)

Medicare Code Edits (MCE v43.1 (April 2026))

• Manifestation codes as principal diagnosis: Manifestation codes describe the manifestation of an underlying disease, not the disease itself, and are not allowed as principal diagnosis.
• Unspecified code (laterality): Unspecified codes for which a more specific code identifying laterality (right, left, bilateral) exists within the same code family.

Code annotations containing back-references to M90.559

Back-references to M90

• Type 1 Excludes: M87 Osteonecrosis ("osteochondropathies (M90-M93)")

Nearby codes

• M90.542 Osteonecrosis in diseases classified elsewhere, left hand
• M90.549 Osteonecrosis in diseases classified elsewhere, unspecified hand
• M90.55 Osteonecrosis in diseases classified elsewhere, thigh
• M90.551 Osteonecrosis in diseases classified elsewhere, right thigh
• M90.552 Osteonecrosis in diseases classified elsewhere, left thigh
• M90.559 Osteonecrosis in diseases classified elsewhere, unspecified thigh (this code)
• M90.56 Osteonecrosis in diseases classified elsewhere, lower leg
• M90.561 Osteonecrosis in diseases classified elsewhere, right lower leg
• M90.562 Osteonecrosis in diseases classified elsewhere, left lower leg
• M90.569 Osteonecrosis in diseases classified elsewhere, unspecified lower leg
• M90.57 Osteonecrosis in diseases classified elsewhere, ankle and foot