Is ICD-10-CM code M99 billable?

No, M99 (Biomechanical lesions, not elsewhere classified) is a non-billable ICD-10-CM code. It must be coded to a more specific subcategory before it can be used for reimbursement.

What chapter does ICD-10-CM code M99 belong to?

M99 belongs to Chapter 13 of the ICD-10-CM tabular list: M00–M99 (Diseases of the Musculoskeletal System and Connective Tissue).

M99Not billable, use a more specific code below

Biomechanical lesions, not elsewhere classified

chapter 13: Diseases of the Musculoskeletal System and Connective Tissue

91 billable codes under M99: 3 are a CC; none map to an HCC.A CC or MCC (major CC) is a secondary diagnosis that raises the MS-DRG payment.

Official coding guidelines

From the ICD-10-CM Official Guidelines for Coding and Reporting, FY 2027 (CMS and NCHS). Links open the PDF at the right page.

Covers site and laterality, acute injury versus chronic musculoskeletal conditions, 7th characters for pathologic fractures, osteoporosis with or without current fracture, and multisystem inflammatory syndrome.

Site and laterality (page 60)
Acute traumatic versus chronic or recurrent musculoskeletal conditions (page 61)
Coding of Pathologic Fractures (page 61)
Osteoporosis (page 61)
Multisystem Inflammatory Syndrome (page 62)

Read Section I.C.13 (page 60)

All codes under M99

M99 can't be used on a claim. Pick a billable code below; grey headings group them.

M99 MS-DRGs

As the principal diagnosis, the billable codes under M99 group to these 15 MS-DRGs (v44.0). Which one applies depends on procedures performed, secondary diagnoses (CC/MCC), and the patient's age and discharge status.

DRG 551 Medical Back Problems with MCC (72 of 91 codes)
DRG 552 Medical Back Problems without MCC (72 of 91 codes)
DRG 963 Other Multiple Significant Trauma with MCC (10 of 91 codes)
DRG 964 Other Multiple Significant Trauma with CC (10 of 91 codes)
DRG 965 Other Multiple Significant Trauma without CC/MCC (10 of 91 codes)
DRG 564 Other Musculoskeletal System and Connective Tissue Diagnoses with MCC (9 of 91 codes)
DRG 565 Other Musculoskeletal System and Connective Tissue Diagnoses with CC (9 of 91 codes)
DRG 566 Other Musculoskeletal System and Connective Tissue Diagnoses without CC/MCC (9 of 91 codes)
DRG 555 Signs and Symptoms of Musculoskeletal System and Connective Tissue with MCC (6 of 91 codes)
DRG 556 Signs and Symptoms of Musculoskeletal System and Connective Tissue without MCC (6 of 91 codes)
DRG 562 Fracture, Sprain, Strain and Dislocation Except Femur, Hip, Pelvis and Thigh with MCC (3 of 91 codes)
DRG 563 Fracture, Sprain, Strain and Dislocation Except Femur, Hip, Pelvis and Thigh without MCC (3 of 91 codes)
DRG 183 Major Chest Trauma with MCC (1 of 91 codes)
DRG 184 Major Chest Trauma with CC (1 of 91 codes)
DRG 185 Major Chest Trauma without CC/MCC (1 of 91 codes)

Other codes that refer to M99

Notes on these codes point to M99.

M43.5 Excludes1: biomechanical lesions NEC (M99.-)
Z82.6 Includes: Conditions classifiable to M00-M99
Z87.3 Includes: Conditions classifiable to M00-M99

Code history

Valid since FY2016, when ICD-10-CM took effect on October 1, 2015. No changes since.