Chapter 13

M00–M99: Diseases of the Musculoskeletal System and Connective Tissue

Diseases of the Musculoskeletal System and Connective Tissue diagnostic classification updated for 2026.

Chapter Instructions

Excludes2(Not included here. Code separately if applicable.)
  • 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)
Internal Codes
  • M76.812

    Anterior tibial syndrome, left leg

  • M76.819

    Anterior tibial syndrome, unspecified leg

  • M76.82

    Posterior tibial tendinitis

  • M76.821

    Posterior tibial tendinitis, right leg

  • M76.822

    Posterior tibial tendinitis, left leg

  • M76.829

    Posterior tibial tendinitis, unspecified leg

  • M76.89

    Other specified enthesopathies of lower limb, excluding foot

  • M76.891

    Other specified enthesopathies of right lower limb, excluding foot

  • M76.892

    Other specified enthesopathies of left lower limb, excluding foot

  • M76.899

    Other specified enthesopathies of unspecified lower limb, excluding foot

  • M76.9

    Unspecified enthesopathy, lower limb, excluding foot

  • M77

    Other enthesopathies

  • M77.0

    Medial epicondylitis

  • M77.00

    Medial epicondylitis, unspecified elbow

  • M77.01

    Medial epicondylitis, right elbow

  • M77.02

    Medial epicondylitis, left elbow

  • M77.1

    Lateral epicondylitis

  • M77.10

    Lateral epicondylitis, unspecified elbow

  • M77.11

    Lateral epicondylitis, right elbow

  • M77.12

    Lateral epicondylitis, left elbow

  • M77.2

    Periarthritis of wrist

  • M77.20

    Periarthritis, unspecified wrist

  • M77.21

    Periarthritis, right wrist

  • M77.22

    Periarthritis, left wrist

  • M77.3

    Calcaneal spur

  • M77.30

    Calcaneal spur, unspecified foot

  • M77.31

    Calcaneal spur, right foot

  • M77.32

    Calcaneal spur, left foot

  • M77.4

    Metatarsalgia

  • M77.40

    Metatarsalgia, unspecified foot

  • M77.41

    Metatarsalgia, right foot

  • M77.42

    Metatarsalgia, left foot

  • M77.5

    Other enthesopathy of foot and ankle

  • M77.50

    Other enthesopathy of unspecified foot and ankle

  • M77.51

    Other enthesopathy of right foot and ankle

  • M77.52

    Other enthesopathy of left foot and ankle

  • M77.8

    Other enthesopathies, not elsewhere classified

  • M77.9

    Enthesopathy, unspecified

  • M79

    Other and unspecified soft tissue disorders, not elsewhere classified

  • M79.0

    Rheumatism, unspecified

  • M79.1

    Myalgia

  • M79.10

    Myalgia, unspecified site

  • M79.11

    Myalgia of mastication muscle

  • M79.12

    Myalgia of auxiliary muscles, head and neck

  • M79.18

    Myalgia, other site

  • M79.2

    Neuralgia and neuritis, unspecified

  • M79.3

    Panniculitis, unspecified

  • M79.4

    Hypertrophy of (infrapatellar) fat pad

  • M79.5

    Residual foreign body in soft tissue

  • M79.6

    Pain in limb, hand, foot, fingers and toes

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