M87.80Other osteonecrosis, unspecified bone

M87.80 is the ICD-10-CM diagnosis code for other osteonecrosis, unspecified bone. It belongs to category M87 (osteonecrosis), block M86-M90 (other osteopathies) and chapter 13 (diseases of the musculoskeletal system and connective tissue). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within M87.8, choose M87.80 (unspecified bone) only when documentation doesn't support a more specific option: shoulder (M87.81), humerus (M87.82), of radius, ulna and carpus (M87.83), hand and fingers (M87.84), pelvis and femur (M87.85), tibia and fibula (M87.86), ankle, foot and toes (M87.87), other site (M87.88) and 1 more.

Use an additional code to identify major osseous defect, if applicable (M89.7-).

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 553 (Bone Diseases and Arthropathies with MCC, relative weight 1.2494) and DRG 554 (Bone Diseases and Arthropathies without MCC, relative weight 0.8331), in MDC 08 (Diseases and Disorders of the Musculoskeletal System and Connective Tissue), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It is an unspecified code for which a more specific option (often laterality) exists, and the Medicare Code Editor flags it for review on inpatient claims.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 733.40 (aseptic necrosis of bone, site unspecified).