2020 ICD-10-CM Diagnosis Code M23

Internal derangement of knee

    2016 2017 2018 2019 2020 Non-Billable/Non-Specific Code
  • M23 should not be used for reimbursement purposes as there are multiple codes below it that contain a greater level of detail.
  • The 2020 edition of ICD-10-CM M23 became effective on October 1, 2019.
  • This is the American ICD-10-CM version of M23 - other international versions of ICD-10 M23 may differ.
Type 1 Excludes
Type 1 Excludes Help
A type 1 excludes note is a pure excludes. It means "not coded here". A type 1 excludes note indicates that the code excluded should never be used at the same time as M23. A type 1 excludes note is for used for when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
  • ankylosis (
    ICD-10-CM Diagnosis Code M24.66

    Ankylosis, knee

      2016 2017 2018 2019 2020 Non-Billable/Non-Specific Code
    M24.66
    )
  • current injury - see injury of knee and lower leg (S80-S89
    ICD-10-CM Range S80-S89

    Injuries to the knee and lower leg

    Type 2 Excludes
    • burns and corrosions (T20-T32)
    • frostbite (T33-T34)
    • injuries of ankle and foot, except fracture of ankle and malleolus (S90-S99)
    • insect bite or sting, venomous (T63.4)
    • S80 Superficial injury of knee and lower leg
    • S81 Open wound of knee and lower leg
    • S82 Fracture of lower leg, including ankle
    • S83 Dislocation and sprain of joints and lig...
    • S84 Injury of nerves at lower leg level
    • S85 Injury of blood vessels at lower leg lev...
    • S86 Injury of muscle, fascia and tendon at l...
    • S87 Crushing injury of lower leg
    • S88 Traumatic amputation of lower leg
    • S89 Other and unspecified injuries of lower ...
    )
  • deformity of knee (
    ICD-10-CM Diagnosis Code M21
    • M21 Other acquired deformities of limbs
      • M21.0 Valgus deformity, not elsewhere classified
        • M21.00 Valgus deformity, not elsewhere classified, u...
        • M21.02 Valgus deformity, not elsewhere classified, e...
          • M21.021 Valgus deformity, not elsewhere classified, r...
          • M21.022 Valgus deformity, not elsewhere classified, l...
          • M21.029 Valgus deformity, not elsewhere classified, u...
        • M21.05 Valgus deformity, not elsewhere classified, h...
          • M21.051 Valgus deformity, not elsewhere classified, r...
          • M21.052 Valgus deformity, not elsewhere classified, l...
          • M21.059 Valgus deformity, not elsewhere classified, u...
        • M21.06 Valgus deformity, not elsewhere classified, k...
          • M21.061 Valgus deformity, not elsewhere classified, r...
          • M21.062 Valgus deformity, not elsewhere classified, l...
          • M21.069 Valgus deformity, not elsewhere classified, u...
        • M21.07 Valgus deformity, not elsewhere classified, a...
          • M21.071 Valgus deformity, not elsewhere classified, r...
          • M21.072 Valgus deformity, not elsewhere classified, l...
          • M21.079 Valgus deformity, not elsewhere classified, u...
      • M21.1 Varus deformity, not elsewhere classified
        • M21.10 Varus deformity, not elsewhere classified, un...
        • M21.12 Varus deformity, not elsewhere classified, el...
          • M21.121 Varus deformity, not elsewhere classified, ri...
          • M21.122 Varus deformity, not elsewhere classified, le...
          • M21.129 Varus deformity, not elsewhere classified, un...
        • M21.15 Varus deformity, not elsewhere classified, hi...
          • M21.151 Varus deformity, not elsewhere classified, ri...
          • M21.152 Varus deformity, not elsewhere classified, le...
          • M21.159 Varus deformity, not elsewhere classified, un...
        • M21.16 Varus deformity, not elsewhere classified, kn...
          • M21.161 Varus deformity, not elsewhere classified, ri...
          • M21.162 Varus deformity, not elsewhere classified, le...
          • M21.169 Varus deformity, not elsewhere classified, un...
        • M21.17 Varus deformity, not elsewhere classified, an...
          • M21.171 Varus deformity, not elsewhere classified, ri...
          • M21.172 Varus deformity, not elsewhere classified, le...
          • M21.179 Varus deformity, not elsewhere classified, un...
      • M21.2 Flexion deformity
        • M21.20 …… unspecified site
        • M21.21 Flexion deformity, shoulder
          • M21.211 Flexion deformity, right shoulder
          • M21.212 Flexion deformity, left shoulder
          • M21.219 Flexion deformity, unspecified shoulder
        • M21.22 Flexion deformity, elbow
          • M21.221 Flexion deformity, right elbow
          • M21.222 Flexion deformity, left elbow
          • M21.229 Flexion deformity, unspecified elbow
        • M21.23 Flexion deformity, wrist
          • M21.231 Flexion deformity, right wrist
          • M21.232 Flexion deformity, left wrist
          • M21.239 Flexion deformity, unspecified wrist
        • M21.24 Flexion deformity, finger joints
          • M21.241 Flexion deformity, right finger joints
          • M21.242 Flexion deformity, left finger joints
          • M21.249 Flexion deformity, unspecified finger joints
        • M21.25 Flexion deformity, hip
          • M21.251 Flexion deformity, right hip
          • M21.252 Flexion deformity, left hip
          • M21.259 Flexion deformity, unspecified hip
        • M21.26 Flexion deformity, knee
          • M21.261 Flexion deformity, right knee
          • M21.262 Flexion deformity, left knee
          • M21.269 Flexion deformity, unspecified knee
        • M21.27 Flexion deformity, ankle and toes
          • M21.271 Flexion deformity, right ankle and toes
          • M21.272 Flexion deformity, left ankle and toes
          • M21.279 Flexion deformity, unspecified ankle and toes...
      • M21.3 Wrist or foot drop (acquired)
      • M21.4 Flat foot [pes planus] (acquired)
        • M21.40 Flat foot [pes planus] (acquired), unspecifie...
        • M21.41 Flat foot [pes planus] (acquired), right foot...
        • M21.42 …… left foot
      • M21.5 Acquired clawhand, clubhand, clawfoot and clu...
      • M21.6 Other acquired deformities of foot
        • M21.61 Bunion
        • M21.62 Bunionette
        • M21.6X Other acquired deformities of foot
          • M21.6X1 Other acquired deformities of right foot
          • M21.6X2 Other acquired deformities of left foot
          • M21.6X9 Other acquired deformities of unspecified foo...
      • M21.7 Unequal limb length (acquired)
        • M21.70 Unequal limb length (acquired), unspecified s...
        • M21.72 Unequal limb length (acquired), humerus
          • M21.721 Unequal limb length (acquired), right humerus...
          • M21.722 Unequal limb length (acquired), left humerus
          • M21.729 Unequal limb length (acquired), unspecified h...
        • M21.73 Unequal limb length (acquired), ulna and radi...
          • M21.731 Unequal limb length (acquired), right ulna
          • M21.732 Unequal limb length (acquired), left ulna
          • M21.733 Unequal limb length (acquired), right radius
          • M21.734 Unequal limb length (acquired), left radius
          • M21.739 Unequal limb length (acquired), unspecified u...
        • M21.75 Unequal limb length (acquired), femur
          • M21.751 Unequal limb length (acquired), right femur
          • M21.752 Unequal limb length (acquired), left femur
          • M21.759 Unequal limb length (acquired), unspecified f...
        • M21.76 Unequal limb length (acquired), tibia and fib...
          • M21.761 Unequal limb length (acquired), right tibia
          • M21.762 Unequal limb length (acquired), left tibia
          • M21.763 Unequal limb length (acquired), right fibula
          • M21.764 Unequal limb length (acquired), left fibula
          • M21.769 Unequal limb length (acquired), unspecified t...
      • M21.8 Other specified acquired deformities of limbs...
        • M21.80 Other specified acquired deformities of unspe...
        • M21.82 Other specified acquired deformities of upper...
          • M21.821 Other specified acquired deformities of right...
          • M21.822 Other specified acquired deformities of left ...
          • M21.829 Other specified acquired deformities of unspe...
        • M21.83 Other specified acquired deformities of forea...
          • M21.831 Other specified acquired deformities of right...
          • M21.832 Other specified acquired deformities of left ...
          • M21.839 Other specified acquired deformities of unspe...
        • M21.85 Other specified acquired deformities of thigh...
          • M21.851 Other specified acquired deformities of right...
          • M21.852 Other specified acquired deformities of left ...
          • M21.859 Other specified acquired deformities of unspe...
        • M21.86 Other specified acquired deformities of lower...
          • M21.861 Other specified acquired deformities of right...
          • M21.862 Other specified acquired deformities of left ...
          • M21.869 Other specified acquired deformities of unspe...
      • M21.9 Unspecified acquired deformity of limb and ha...
        • M21.90 Unspecified acquired deformity of unspecified...
        • M21.92 Unspecified acquired deformity of upper arm
          • M21.921 Unspecified acquired deformity of right upper...
          • M21.922 Unspecified acquired deformity of left upper ...
          • M21.929 Unspecified acquired deformity of unspecified...
        • M21.93 Unspecified acquired deformity of forearm
          • M21.931 Unspecified acquired deformity of right forea...
          • M21.932 Unspecified acquired deformity of left forear...
          • M21.939 Unspecified acquired deformity of unspecified...
        • M21.94 Unspecified acquired deformity of hand
          • M21.941 Unspecified acquired deformity of hand, right...
          • M21.942 Unspecified acquired deformity of hand, left ...
          • M21.949 Unspecified acquired deformity of hand, unspe...
        • M21.95 Unspecified acquired deformity of thigh
          • M21.951 Unspecified acquired deformity of right thigh...
          • M21.952 Unspecified acquired deformity of left thigh
          • M21.959 Unspecified acquired deformity of unspecified...
        • M21.96 Unspecified acquired deformity of lower leg
          • M21.961 Unspecified acquired deformity of right lower...
          • M21.962 Unspecified acquired deformity of left lower ...
          • M21.969 Unspecified acquired deformity of unspecified...
    M21.-
    )
  • osteochondritis dissecans (
    ICD-10-CM Diagnosis Code M93.2

    Osteochondritis dissecans

      2016 2017 2018 2019 2020 Non-Billable/Non-Specific Code
    M93.2
    )
  • recurrent dislocation or subluxation of joints (
    ICD-10-CM Diagnosis Code M24.4

    Recurrent dislocation of joint

      2016 2017 2018 2019 2020 Non-Billable/Non-Specific Code
    Applicable To
    • Recurrent subluxation of joint
    Type 2 Excludes
    M24.4
    )
  • recurrent dislocation or subluxation of patella (
    ICD-10-CM Diagnosis Code M22.0

    Recurrent dislocation of patella

      2016 2017 2018 2019 2020 Non-Billable/Non-Specific Code
    M22.0-
    ICD-10-CM Diagnosis Code M22.1

    Recurrent subluxation of patella

      2016 2017 2018 2019 2020 Non-Billable/Non-Specific Code
    Applicable To
    • Incomplete dislocation of patella
    M22.1
    )
The following code(s) above M23 contain annotation back-references
Annotation Back-References
In this context, annotation back-references refer to codes that contain:
  • Applicable To annotations, or
  • Code Also annotations, or
  • Code First annotations, or
  • Excludes1 annotations, or
  • Excludes2 annotations, or
  • Includes annotations, or
  • Note annotations, or
  • Use Additional annotations
that may be applicable to M23:
  • M00-M99
    2020 ICD-10-CM Range M00-M99

    Diseases of the musculoskeletal system and connective tissue

    Note
    • Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition
    Type 2 Excludes
    • 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)
    Diseases of the musculoskeletal system and connective tissue
  • M20-M25
    2020 ICD-10-CM Range M20-M25

    Other joint disorders

    Type 2 Excludes
    Other joint disorders
Code History
  • 2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
  • 2017 (effective 10/1/2016): No change
  • 2018 (effective 10/1/2017): No change
  • 2019 (effective 10/1/2018): No change
  • 2020 (effective 10/1/2019): No change
Code annotations containing back-references to M23:
  • Type 1 Excludes: S83
    ICD-10-CM Diagnosis Code S83

    Dislocation and sprain of joints and ligaments of knee

      2016 2017 2018 2019 2020 Non-Billable/Non-Specific Code
    Code Also
    • any associated open wound
    Includes
    • avulsion of joint or ligament of knee
    • laceration of cartilage, joint or ligament of knee
    • sprain of cartilage, joint or ligament of knee
    • traumatic hemarthrosis of joint or ligament of knee
    • traumatic rupture of joint or ligament of knee
    • traumatic subluxation of joint or ligament of knee
    • traumatic tear of joint or ligament of knee
    Type 1 Excludes
    • derangement of patella (M22.0-M22.3)
    • injury of patellar ligament (tendon) (S76.1-)
    • internal derangement of knee (M23.-)
    • old dislocation of knee (M24.36)
    • pathological dislocation of knee (M24.36)
    • recurrent dislocation of knee (M22.0)
    Type 2 Excludes
    • strain of muscle, fascia and tendon of lower leg (S86.-)
  • Type 2 Excludes: M24.1
    ICD-10-CM Diagnosis Code M24.1

    Other articular cartilage disorders

      2016 2017 2018 2019 2020 Non-Billable/Non-Specific Code
    Type 2 Excludes
ICD-10-CM Codes Adjacent To M23
M22.42 …… left knee
M22.8 Other disorders of patella
M22.8X Other disorders of patella
M22.8X1 …… right knee
M22.8X2 …… left knee
M22.8X9 …… unspecified knee
M22.9 Unspecified disorder of patella
M22.90 …… unspecified knee
M22.91 …… right knee
M22.92 …… 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 …… right knee
M23.007 …… left knee

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.