Spontaneous rupture of synovium and tendon (M66) ICD-10-CM
The M66 code range covers spontaneous rupture of synovium and tendon with 135 ICD-10-CM diagnosis codes. 103 of them are billable and valid for claim submission in fiscal year 2026, and the category headers group them but cannot themselves be billed.
Includes
This note appears immediately under a three character code title to further define, or give examples of, the content of the category.
- rupture that occurs when a normal force is applied to tissues that are inferred to have less than normal strength
Type 2 Excludes
A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.
- rotator cuff syndrome M75.1
- rupture where an abnormal force is applied to normal tissue - see injury of tendon by body region
Codes in the M66 Range 135 codes · 103 billable
- M66 Spontaneous rupture of synovium and tendonNon-billable
- M66.0 Rupture of popliteal cyst
- M66.1 Rupture of synoviumNon-billable
- M66.10 Rupture of synovium, unspecified joint
- M66.11 Rupture of synovium, shoulderNon-billable
- M66.111 Rupture of synovium, right shoulder
- M66.112 Rupture of synovium, left shoulder
- M66.119 Rupture of synovium, unspecified shoulder
- M66.12 Rupture of synovium, elbowNon-billable
- M66.121 Rupture of synovium, right elbow
- M66.122 Rupture of synovium, left elbow
- M66.129 Rupture of synovium, unspecified elbow
- M66.13 Rupture of synovium, wristNon-billable
- M66.131 Rupture of synovium, right wrist
- M66.132 Rupture of synovium, left wrist
- M66.139 Rupture of synovium, unspecified wrist
- M66.14 Rupture of synovium, hand and fingersNon-billable
- M66.141 Rupture of synovium, right hand
- M66.142 Rupture of synovium, left hand
- M66.143 Rupture of synovium, unspecified hand
- M66.144 Rupture of synovium, right finger(s)
- M66.145 Rupture of synovium, left finger(s)
- M66.146 Rupture of synovium, unspecified finger(s)
- M66.15 Rupture of synovium, hipNon-billable
- M66.151 Rupture of synovium, right hip
- M66.152 Rupture of synovium, left hip
- M66.159 Rupture of synovium, unspecified hip
- M66.17 Rupture of synovium, ankle, foot and toesNon-billable
- M66.171 Rupture of synovium, right ankle
- M66.172 Rupture of synovium, left ankle
- M66.173 Rupture of synovium, unspecified ankle
- M66.174 Rupture of synovium, right foot
- M66.175 Rupture of synovium, left foot
- M66.176 Rupture of synovium, unspecified foot
- M66.177 Rupture of synovium, right toe(s)
- M66.178 Rupture of synovium, left toe(s)
- M66.179 Rupture of synovium, unspecified toe(s)
- M66.18 Rupture of synovium, other site
- M66.2 Spontaneous rupture of extensor tendonsNon-billable
- M66.20 Spontaneous rupture of extensor tendons, unspecified site
- M66.21 Spontaneous rupture of extensor tendons, shoulderNon-billable
- M66.211 Spontaneous rupture of extensor tendons, right shoulder
- M66.212 Spontaneous rupture of extensor tendons, left shoulder
- M66.219 Spontaneous rupture of extensor tendons, unspecified shoulder
- M66.22 Spontaneous rupture of extensor tendons, upper armNon-billable
- M66.221 Spontaneous rupture of extensor tendons, right upper arm
- M66.222 Spontaneous rupture of extensor tendons, left upper arm
- M66.229 Spontaneous rupture of extensor tendons, unspecified upper arm
- M66.23 Spontaneous rupture of extensor tendons, forearmNon-billable
- M66.231 Spontaneous rupture of extensor tendons, right forearm
- M66.232 Spontaneous rupture of extensor tendons, left forearm
- M66.239 Spontaneous rupture of extensor tendons, unspecified forearm
- M66.24 Spontaneous rupture of extensor tendons, handNon-billable
- M66.241 Spontaneous rupture of extensor tendons, right hand
- M66.242 Spontaneous rupture of extensor tendons, left hand
- M66.249 Spontaneous rupture of extensor tendons, unspecified hand
- M66.25 Spontaneous rupture of extensor tendons, thighNon-billable
- M66.251 Spontaneous rupture of extensor tendons, right thigh
- M66.252 Spontaneous rupture of extensor tendons, left thigh
- M66.259 Spontaneous rupture of extensor tendons, unspecified thigh
- M66.26 Spontaneous rupture of extensor tendons, lower legNon-billable
- M66.261 Spontaneous rupture of extensor tendons, right lower leg
- M66.262 Spontaneous rupture of extensor tendons, left lower leg
- M66.269 Spontaneous rupture of extensor tendons, unspecified lower leg
- M66.27 Spontaneous rupture of extensor tendons, ankle and footNon-billable
- M66.271 Spontaneous rupture of extensor tendons, right ankle and foot
- M66.272 Spontaneous rupture of extensor tendons, left ankle and foot
- M66.279 Spontaneous rupture of extensor tendons, unspecified ankle and foot
- M66.28 Spontaneous rupture of extensor tendons, other site
- M66.29 Spontaneous rupture of extensor tendons, multiple sites
- M66.3 Spontaneous rupture of flexor tendonsNon-billable
- M66.30 Spontaneous rupture of flexor tendons, unspecified site
- M66.31 Spontaneous rupture of flexor tendons, shoulderNon-billable
- M66.311 Spontaneous rupture of flexor tendons, right shoulder
- M66.312 Spontaneous rupture of flexor tendons, left shoulder
- M66.319 Spontaneous rupture of flexor tendons, unspecified shoulder
- M66.32 Spontaneous rupture of flexor tendons, upper armNon-billable
- M66.321 Spontaneous rupture of flexor tendons, right upper arm
- M66.322 Spontaneous rupture of flexor tendons, left upper arm
- M66.329 Spontaneous rupture of flexor tendons, unspecified upper arm
- M66.33 Spontaneous rupture of flexor tendons, forearmNon-billable
- M66.331 Spontaneous rupture of flexor tendons, right forearm
- M66.332 Spontaneous rupture of flexor tendons, left forearm
- M66.339 Spontaneous rupture of flexor tendons, unspecified forearm
- M66.34 Spontaneous rupture of flexor tendons, handNon-billable
- M66.341 Spontaneous rupture of flexor tendons, right hand
- M66.342 Spontaneous rupture of flexor tendons, left hand
- M66.349 Spontaneous rupture of flexor tendons, unspecified hand
- M66.35 Spontaneous rupture of flexor tendons, thighNon-billable
- M66.351 Spontaneous rupture of flexor tendons, right thigh
- M66.352 Spontaneous rupture of flexor tendons, left thigh
- M66.359 Spontaneous rupture of flexor tendons, unspecified thigh
- M66.36 Spontaneous rupture of flexor tendons, lower legNon-billable
- M66.361 Spontaneous rupture of flexor tendons, right lower leg
- M66.362 Spontaneous rupture of flexor tendons, left lower leg
- M66.369 Spontaneous rupture of flexor tendons, unspecified lower leg
- M66.37 Spontaneous rupture of flexor tendons, ankle and footNon-billable
- M66.371 Spontaneous rupture of flexor tendons, right ankle and foot
- M66.372 Spontaneous rupture of flexor tendons, left ankle and foot
- M66.379 Spontaneous rupture of flexor tendons, unspecified ankle and foot
- M66.38 Spontaneous rupture of flexor tendons, other site
- M66.39 Spontaneous rupture of flexor tendons, multiple sites
- M66.8 Spontaneous rupture of other tendonsNon-billable
- M66.80 Spontaneous rupture of other tendons, unspecified site
- M66.81 Spontaneous rupture of other tendons, shoulderNon-billable
- M66.811 Spontaneous rupture of other tendons, right shoulder
- M66.812 Spontaneous rupture of other tendons, left shoulder
- M66.819 Spontaneous rupture of other tendons, unspecified shoulder
- M66.82 Spontaneous rupture of other tendons, upper armNon-billable
- M66.821 Spontaneous rupture of other tendons, right upper arm
- M66.822 Spontaneous rupture of other tendons, left upper arm
- M66.829 Spontaneous rupture of other tendons, unspecified upper arm
- M66.83 Spontaneous rupture of other tendons, forearmNon-billable
- M66.831 Spontaneous rupture of other tendons, right forearm
- M66.832 Spontaneous rupture of other tendons, left forearm
- M66.839 Spontaneous rupture of other tendons, unspecified forearm
- M66.84 Spontaneous rupture of other tendons, handNon-billable
- M66.841 Spontaneous rupture of other tendons, right hand
- M66.842 Spontaneous rupture of other tendons, left hand
- M66.849 Spontaneous rupture of other tendons, unspecified hand
- M66.85 Spontaneous rupture of other tendons, thighNon-billable
- M66.851 Spontaneous rupture of other tendons, right thigh
- M66.852 Spontaneous rupture of other tendons, left thigh
- M66.859 Spontaneous rupture of other tendons, unspecified thigh
- M66.86 Spontaneous rupture of other tendons, lower legNon-billable
- M66.861 Spontaneous rupture of other tendons, right lower leg
- M66.862 Spontaneous rupture of other tendons, left lower leg
- M66.869 Spontaneous rupture of other tendons, unspecified lower leg
- M66.87 Spontaneous rupture of other tendons, ankle and footNon-billable
- M66.871 Spontaneous rupture of other tendons, right ankle and foot
- M66.872 Spontaneous rupture of other tendons, left ankle and foot
- M66.879 Spontaneous rupture of other tendons, unspecified ankle and foot
- M66.88 Spontaneous rupture of other tendons, other sites
- M66.89 Spontaneous rupture of other tendons, multiple sites
- M66.9 Spontaneous rupture of unspecified tendon
About the M66 Code Range
The ICD-10 code range M66 covers disorders involving the spontaneous rupture of synovium and tendons, including specific ruptures such as the rupture of popliteal cysts and various tendon ruptures across multiple joints and limbs. These codes are used to document non-traumatic, spontaneous tears or ruptures without external injury.
This section includes codes for precise locations, including the shoulder, elbow, wrist, hands and fingers, hip, ankle, foot, toes, and other specific sites. For example, the ICD-10 code M66.0 is designated for the rupture of a popliteal cyst, also known as a synovial popliteal cyst or rupture of synovial cyst of the knee, helping coders associate common terms with this diagnosis. Codes like M66.2 and M66.3 specify spontaneous ruptures of extensor and flexor tendons respectively, and subcodes detail right or left-sided occurrences and unspecified sites. The category also accommodates ruptures of other tendons, including important ones such as the Achilles and plantar fascia (M66.8 series). Utilizing these codes allows accurate capture of spontaneous tendon and synovium ruptures, aiding in clear communication for clinical documentation and treatment.
Questions About This Page
How many billable codes are in the M66 range?
Of the 135 codes in this range, 103 are billable and valid for claim submission from October 1, 2025 through September 30, 2026. Category header codes group them but cannot be reported on claims.
What does the M66 range classify?
The range classifies spontaneous rupture of synovium and tendon. Each code links to its own reference page with billing status, MS-DRG grouping, coding notes, and clinical information.
Related References
Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.
