2026 ICD-10-CM Diagnosis Code M87.859Other osteonecrosis, unspecified femur

ICD-10-CM Codes›M00–M99›M86-M90›M87

ICD-10-CM M87.859
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

M87.859 is a billable ICD-10-CM diagnosis code for other osteonecrosis, unspecified femur. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 553 through 554. The code is flagged as an unspecified code, since codes identifying laterality exist in the same family. Coders also document this condition as familial avascular necrosis of femoral head. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Aseptic necrosis and osteonecrosis.

Code Identity

ICD-10-CM Code
M87.859
Billable Status
Yes — Valid for Submission
Code Describes
Other osteonecrosis, unspecified femur
Short Description
Other osteonecrosis, unspecified femur
Same as the full description in the CMS dataset.
Parent Code
M87.85
Other osteonecrosis, pelvis and femur

Code Classification

ChapterM00–M99Diseases of the musculoskeletal system and connective tissue
SectionM86-M90Other osteopathies
CategoryM87Osteonecrosis
This CodeM87.859Other osteonecrosis, unspecified femur

Code EditsBilling

Medicare Code Editor checks that affect claim validity for M87.859.

Unspecified codes
Unspecified codes exist in the ICD-10-CM classification for circumstances when documentation in the medical record does not provide the level of detail needed to support reporting a more specific code. However, in the inpatient setting, there should generally be very limited and rare circumstances for which the laterality (right, left, bilateral) of a condition is unable to be documented and reported. The following pages contain the list of unspecified ICD-10-CM diagnosis codes for which there is a more specific code to identify laterality (right, left, bilateral) within that code family.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Familial avascular necrosis of femoral head
  • Osteonecrosis of capital femoral epiphysis
  • Osteonecrosis of femoral condyle
  • Osteonecrosis of head of femur
  • Osteonecrosis of hip
  • Osteonecrosis of lateral femoral condyle
  • Osteonecrosis of medial femoral condyle
  • Osteonecrosis of neck of femur

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MUS030
Aseptic necrosis and osteonecrosis
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Osteonecrosis

Osteonecrosis is a disease caused by reduced blood flow to bones in the joints. In people with healthy bones, new bone is always replacing old bone. In osteonecrosis, the lack of blood causes the bone to break down faster than the body can make enough new bone. The bone starts to die and may break down.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert M87.859 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
733.42 Aseptic necrosis femur
Approximate The match is approximate rather than exact.
ICD-9-CM
733.43 Asept necro femur condyl
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About M87.859Overview

Is M87.859 (Other osteonecrosis, pelvis and femur) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report other osteonecrosis, unspecified femur on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does M87.859 group to?

When other osteonecrosis, unspecified femur is the principal diagnosis on an inpatient stay, it groups to MS-DRG 553, 554, with relative weights from 0.8301 to 1.2963 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of M87.859?

Under the General Equivalence Mappings, other osteonecrosis, unspecified femur converts to ICD-9-CM 733.42 (aseptic necrosis femur) and 733.43 (asept necro femur condyl). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.