Diseases of the musculoskeletal system and connective tissue (M00–M99) ICD-10-CM
Chapter 13 of the ICD-10-CM classification spans codes M00–M99 and contains 8,303 diagnosis codes for diseases of the musculoskeletal system and connective tissue, of which 6,445 are billable. The chapter is organized into 20 sections listed below, each linking to its code ranges and individual codes.
Chapter Coding Notes
Note: Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition
Excludes2: arthropathic psoriasis (L40.5-), certain conditions originating in the perinatal period (P04-P96), certain infectious and parasitic diseases (A00-B99), compartment syndrome (traumatic) (T79.A-), complications of pregnancy, childbirth and the puerperium (O00-O9A), congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99), endocrine, nutritional and metabolic diseases (E00-E88), injury, poisoning and certain other consequences of external causes (S00-T88), neoplasms (C00-D49), symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Sections in This Chapter 20 ranges · 8,303 codes
The info icon previews the code ranges inside each row and its instructional notations from the official Tabular List.
About Chapter 13
These conditions affect joints, muscles, tendons, bones, cartilage, connective tissue, and the back. The chapter also includes jaw disorders and certain problems that arise during or after musculoskeletal procedures.
The joint groups separate infectious joint disease, autoinflammatory syndromes, inflammatory conditions involving multiple joints, osteoarthritis, and other joint disorders. Separate groups address jaw and tooth-alignment conditions and connective tissue disorders affecting the body more broadly. Back conditions divide into deforming, spinal, and other back disorders.
Other groups distinguish muscle disorders, disorders of the joint lining and tendons, other soft tissue conditions, bone density and structure disorders, other bone disorders, and cartilage disorders. Further groups cover procedural complications, fractures around an internal prosthetic joint, and problems involving body mechanics.
An additional character can distinguish an initial encounter, a subsequent encounter, or a lasting effect. For pathological fractures, it also distinguishes routine or delayed healing, failure to unite, and healing in an abnormal position. Spinal fractures distinguish routine from delayed healing; chronic gout distinguishes whether tophi are present.
FY 2027 changes: The FY 2027 ICD-10-CM update, effective October 1, 2026, added 31 codes and deleted 9 codes in this chapter.
Questions About This Page
How many codes are in the M00-M99 range?
The M00-M99 range contains 8,303 ICD-10-CM diagnosis codes in FY 2027. 6,445 of them are billable, and the rest are category headers that organize the chapter.
What conditions does M00-M99 cover?
The range covers diseases of the musculoskeletal system and connective tissue. The sections listed above break it into groups of related conditions, and each one links to its own page with the full code list.
Related References
Source: CMS FY 2027 ICD-10-CM Tabular List and order file, effective October 1, 2026 through September 30, 2027.
