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
  • M22.01

    Recurrent dislocation of patella, right knee

  • M22.02

    Recurrent dislocation of patella, left knee

  • M22.1

    Recurrent subluxation of patella

  • M22.10

    Recurrent subluxation of patella, unspecified knee

  • M22.11

    Recurrent subluxation of patella, right knee

  • M22.12

    Recurrent subluxation of patella, left knee

  • M22.2

    Patellofemoral disorders

  • M22.2X

    Patellofemoral disorders

  • M22.2X1

    Patellofemoral disorders, right knee

  • M22.2X2

    Patellofemoral disorders, left knee

  • M22.2X9

    Patellofemoral disorders, unspecified knee

  • M22.3

    Other derangements of patella

  • M22.3X

    Other derangements of patella

  • M22.3X1

    Other derangements of patella, right knee

  • M22.3X2

    Other derangements of patella, left knee

  • M22.3X9

    Other derangements of patella, unspecified knee

  • M22.4

    Chondromalacia patellae

  • M22.40

    Chondromalacia patellae, unspecified knee

  • M22.41

    Chondromalacia patellae, right knee

  • M22.42

    Chondromalacia patellae, left knee

  • M22.8

    Other disorders of patella

  • M22.8X

    Other disorders of patella

  • M22.8X1

    Other disorders of patella, right knee

  • M22.8X2

    Other disorders of patella, left knee

  • M22.8X9

    Other disorders of patella, unspecified knee

  • M22.9

    Unspecified disorder of patella

  • M22.90

    Unspecified disorder of patella, unspecified knee

  • M22.91

    Unspecified disorder of patella, right knee

  • M22.92

    Unspecified disorder of patella, left knee

  • M23

    Internal derangement of knee

  • M23.0

    Cystic meniscus

  • M23.00

    Cystic meniscus, unspecified meniscus

  • M23.000

    Cystic meniscus, unspecified lateral meniscus, right knee

  • M23.001

    Cystic meniscus, unspecified lateral meniscus, left knee

  • M23.002

    Cystic meniscus, unspecified lateral meniscus, unspecified knee

  • M23.003

    Cystic meniscus, unspecified medial meniscus, right knee

  • M23.004

    Cystic meniscus, unspecified medial meniscus, left knee

  • M23.005

    Cystic meniscus, unspecified medial meniscus, unspecified knee

  • M23.006

    Cystic meniscus, unspecified meniscus, right knee

  • M23.007

    Cystic meniscus, unspecified meniscus, left knee

  • M23.009

    Cystic meniscus, unspecified meniscus, unspecified knee

  • M23.01

    Cystic meniscus, anterior horn of medial meniscus

  • M23.011

    Cystic meniscus, anterior horn of medial meniscus, right knee

  • M23.012

    Cystic meniscus, anterior horn of medial meniscus, left knee

  • M23.019

    Cystic meniscus, anterior horn of medial meniscus, unspecified knee

  • M23.02

    Cystic meniscus, posterior horn of medial meniscus

  • M23.021

    Cystic meniscus, posterior horn of medial meniscus, right knee

  • M23.022

    Cystic meniscus, posterior horn of medial meniscus, left knee

  • M23.029

    Cystic meniscus, posterior horn of medial meniscus, unspecified knee

  • M23.03

    Cystic meniscus, other medial meniscus

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