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  3. M00–M99
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  5. Synovitis and tenosynovitis (M65)

Synovitis and tenosynovitis (M65)

ICD-10 code M65 covers a range of conditions involving inflammation of tendon sheaths and synovial membranes, including synovitis and tenosynovitis. These codes are used to specify and locate inflammation or infection of tendon sheaths, such as abscesses, infective tenosynovitis, calcific tendinitis, trigger finger/thumb, and other forms of synovitis at various body sites.

This section includes detailed codes like M65.0 for abscesses of tendon sheaths, which can involve different sites such as shoulders, arms, forearms, hands, thighs, legs, ankles, and feet. For example, terms like “abscess of tendon sheath” or “abscess of tendon of upper limb” relate directly to these codes. The codes also cover M65.1 for other infective tenosynovitis, which includes infections like pyogenic or mycobacterial tenosynovitis, and Lyme arthritis. M65.2 details calcific tendinitis, also known as osteodesmosis, affecting upper or lower limbs. Trigger finger and thumb conditions are captured under M65.3, with synonyms such as “acquired trigger finger” or “snapping thumb syndrome” aiding correct coding. Specific codes like M65.4 address radial styloid tenosynovitis (de Quervain). Other synovitis or tenosynovitis not otherwise specified are classified from M65.8 through M65.9, covering various sites and unspecified cases. This granularity helps medical coders assign the appropriate ICD-10 code for accurate documentation and billing of tendon and synovial inflammatory disorders.

  • Diseases of the musculoskeletal system and connective tissue (M00–M99)

    • Disorders of synovium and tendon (M65-M67)

        • Synovitis and tenosynovitis (M65)

        • M65 Synovitis and tenosynovitis
        • M65.0 Abscess of tendon sheath
        • M65.00 Abscess of tendon sheath, unspecified site
        • M65.01 Abscess of tendon sheath, shoulder
        • M65.011 Abscess of tendon sheath, right shoulder
        • M65.012 Abscess of tendon sheath, left shoulder
        • M65.019 Abscess of tendon sheath, unspecified shoulder
        • M65.02 Abscess of tendon sheath, upper arm
        • M65.021 Abscess of tendon sheath, right upper arm
        • M65.022 Abscess of tendon sheath, left upper arm
        • M65.029 Abscess of tendon sheath, unspecified upper arm
        • M65.03 Abscess of tendon sheath, forearm
        • M65.031 Abscess of tendon sheath, right forearm
        • M65.032 Abscess of tendon sheath, left forearm
        • M65.039 Abscess of tendon sheath, unspecified forearm
        • M65.04 Abscess of tendon sheath, hand
        • M65.041 Abscess of tendon sheath, right hand
        • M65.042 Abscess of tendon sheath, left hand
        • M65.049 Abscess of tendon sheath, unspecified hand
        • M65.05 Abscess of tendon sheath, thigh
        • M65.051 Abscess of tendon sheath, right thigh
        • M65.052 Abscess of tendon sheath, left thigh
        • M65.059 Abscess of tendon sheath, unspecified thigh
        • M65.06 Abscess of tendon sheath, lower leg
        • M65.061 Abscess of tendon sheath, right lower leg
        • M65.062 Abscess of tendon sheath, left lower leg
        • M65.069 Abscess of tendon sheath, unspecified lower leg
        • M65.07 Abscess of tendon sheath, ankle and foot
        • M65.071 Abscess of tendon sheath, right ankle and foot
        • M65.072 Abscess of tendon sheath, left ankle and foot
        • M65.079 Abscess of tendon sheath, unspecified ankle and foot
        • M65.08 Abscess of tendon sheath, other site
        • M65.1 Other infective (teno)synovitis
        • M65.10 Other infective (teno)synovitis, unspecified site
        • M65.11 Other infective (teno)synovitis, shoulder
        • M65.111 Other infective (teno)synovitis, right shoulder
        • M65.112 Other infective (teno)synovitis, left shoulder
        • M65.119 Other infective (teno)synovitis, unspecified shoulder
        • M65.12 Other infective (teno)synovitis, elbow
        • M65.121 Other infective (teno)synovitis, right elbow
        • M65.122 Other infective (teno)synovitis, left elbow
        • M65.129 Other infective (teno)synovitis, unspecified elbow
        • M65.13 Other infective (teno)synovitis, wrist
        • M65.131 Other infective (teno)synovitis, right wrist
        • M65.132 Other infective (teno)synovitis, left wrist
        • M65.139 Other infective (teno)synovitis, unspecified wrist
        • M65.14 Other infective (teno)synovitis, hand
        • M65.141 Other infective (teno)synovitis, right hand
        • M65.142 Other infective (teno)synovitis, left hand
        • M65.149 Other infective (teno)synovitis, unspecified hand
        • M65.15 Other infective (teno)synovitis, hip
        • M65.151 Other infective (teno)synovitis, right hip
        • M65.152 Other infective (teno)synovitis, left hip
        • M65.159 Other infective (teno)synovitis, unspecified hip
        • M65.16 Other infective (teno)synovitis, knee
        • M65.161 Other infective (teno)synovitis, right knee
        • M65.162 Other infective (teno)synovitis, left knee
        • M65.169 Other infective (teno)synovitis, unspecified knee
        • M65.17 Other infective (teno)synovitis, ankle and foot
        • M65.171 Other infective (teno)synovitis, right ankle and foot
        • M65.172 Other infective (teno)synovitis, left ankle and foot
        • M65.179 Other infective (teno)synovitis, unspecified ankle and foot
        • M65.18 Other infective (teno)synovitis, other site
        • M65.19 Other infective (teno)synovitis, multiple sites
        • M65.2 Calcific tendinitis
        • M65.20 Calcific tendinitis, unspecified site
        • M65.22 Calcific tendinitis, upper arm
        • M65.221 Calcific tendinitis, right upper arm
        • M65.222 Calcific tendinitis, left upper arm
        • M65.229 Calcific tendinitis, unspecified upper arm
        • M65.23 Calcific tendinitis, forearm
        • M65.231 Calcific tendinitis, right forearm
        • M65.232 Calcific tendinitis, left forearm
        • M65.239 Calcific tendinitis, unspecified forearm
        • M65.24 Calcific tendinitis, hand
        • M65.241 Calcific tendinitis, right hand
        • M65.242 Calcific tendinitis, left hand
        • M65.249 Calcific tendinitis, unspecified hand
        • M65.25 Calcific tendinitis, thigh
        • M65.251 Calcific tendinitis, right thigh
        • M65.252 Calcific tendinitis, left thigh
        • M65.259 Calcific tendinitis, unspecified thigh
        • M65.26 Calcific tendinitis, lower leg
        • M65.261 Calcific tendinitis, right lower leg
        • M65.262 Calcific tendinitis, left lower leg
        • M65.269 Calcific tendinitis, unspecified lower leg
        • M65.27 Calcific tendinitis, ankle and foot
        • M65.271 Calcific tendinitis, right ankle and foot
        • M65.272 Calcific tendinitis, left ankle and foot
        • M65.279 Calcific tendinitis, unspecified ankle and foot
        • M65.28 Calcific tendinitis, other site
        • M65.29 Calcific tendinitis, multiple sites
        • M65.3 Trigger finger
        • M65.30 Trigger finger, unspecified finger
        • M65.31 Trigger thumb
        • M65.311 Trigger thumb, right thumb
        • M65.312 Trigger thumb, left thumb
        • M65.319 Trigger thumb, unspecified thumb
        • M65.32 Trigger finger, index finger
        • M65.321 Trigger finger, right index finger
        • M65.322 Trigger finger, left index finger
        • M65.329 Trigger finger, unspecified index finger
        • M65.33 Trigger finger, middle finger
        • M65.331 Trigger finger, right middle finger
        • M65.332 Trigger finger, left middle finger
        • M65.339 Trigger finger, unspecified middle finger
        • M65.34 Trigger finger, ring finger
        • M65.341 Trigger finger, right ring finger
        • M65.342 Trigger finger, left ring finger
        • M65.349 Trigger finger, unspecified ring finger
        • M65.35 Trigger finger, little finger
        • M65.351 Trigger finger, right little finger
        • M65.352 Trigger finger, left little finger
        • M65.359 Trigger finger, unspecified little finger
        • M65.4 Radial styloid tenosynovitis [de Quervain]
        • M65.8 Other synovitis and tenosynovitis
        • M65.80 Other synovitis and tenosynovitis, unspecified site
        • M65.81 Other synovitis and tenosynovitis, shoulder
        • M65.811 Other synovitis and tenosynovitis, right shoulder
        • M65.812 Other synovitis and tenosynovitis, left shoulder
        • M65.819 Other synovitis and tenosynovitis, unspecified shoulder
        • M65.82 Other synovitis and tenosynovitis, upper arm
        • M65.821 Other synovitis and tenosynovitis, right upper arm
        • M65.822 Other synovitis and tenosynovitis, left upper arm
        • M65.829 Other synovitis and tenosynovitis, unspecified upper arm
        • M65.83 Other synovitis and tenosynovitis, forearm
        • M65.831 Other synovitis and tenosynovitis, right forearm
        • M65.832 Other synovitis and tenosynovitis, left forearm
        • M65.839 Other synovitis and tenosynovitis, unspecified forearm
        • M65.84 Other synovitis and tenosynovitis, hand
        • M65.841 Other synovitis and tenosynovitis, right hand
        • M65.842 Other synovitis and tenosynovitis, left hand
        • M65.849 Other synovitis and tenosynovitis, unspecified hand
        • M65.85 Other synovitis and tenosynovitis, thigh
        • M65.851 Other synovitis and tenosynovitis, right thigh
        • M65.852 Other synovitis and tenosynovitis, left thigh
        • M65.859 Other synovitis and tenosynovitis, unspecified thigh
        • M65.86 Other synovitis and tenosynovitis, lower leg
        • M65.861 Other synovitis and tenosynovitis, right lower leg
        • M65.862 Other synovitis and tenosynovitis, left lower leg
        • M65.869 Other synovitis and tenosynovitis, unspecified lower leg
        • M65.87 Other synovitis and tenosynovitis, ankle and foot
        • M65.871 Other synovitis and tenosynovitis, right ankle and foot
        • M65.872 Other synovitis and tenosynovitis, left ankle and foot
        • M65.879 Other synovitis and tenosynovitis, unspecified ankle and foot
        • M65.88 Other synovitis and tenosynovitis, other site
        • M65.89 Other synovitis and tenosynovitis, multiple sites
        • M65.9 Synovitis and tenosynovitis, unspecified DELETED CODE
        • M65.90 Unspecified synovitis and tenosynovitis, unspecified site NEW CODE
        • M65.91 Unspecified synovitis and tenosynovitis, shoulder
        • M65.911 Unspecified synovitis and tenosynovitis, right shoulder NEW CODE
        • M65.912 Unspecified synovitis and tenosynovitis, left shoulder NEW CODE
        • M65.919 Unspecified synovitis and tenosynovitis, unspecified shoulder NEW CODE
        • M65.92 Unspecified synovitis and tenosynovitis, upper arm
        • M65.921 Unspecified synovitis and tenosynovitis, right upper arm NEW CODE
        • M65.922 Unspecified synovitis and tenosynovitis, left upper arm NEW CODE
        • M65.929 Unspecified synovitis and tenosynovitis, unspecified upper arm NEW CODE
        • M65.93 Unspecified synovitis and tenosynovitis, forearm
        • M65.931 Unspecified synovitis and tenosynovitis, right forearm NEW CODE
        • M65.932 Unspecified synovitis and tenosynovitis, left forearm NEW CODE
        • M65.939 Unspecified synovitis and tenosynovitis, unspecified forearm NEW CODE
        • M65.94 Unspecified synovitis and tenosynovitis, hand
        • M65.941 Unspecified synovitis and tenosynovitis, right hand NEW CODE
        • M65.942 Unspecified synovitis and tenosynovitis, left hand NEW CODE
        • M65.949 Unspecified synovitis and tenosynovitis, unspecified hand NEW CODE
        • M65.95 Unspecified synovitis and tenosynovitis, thigh
        • M65.951 Unspecified synovitis and tenosynovitis, right thigh NEW CODE
        • M65.952 Unspecified synovitis and tenosynovitis, left thigh NEW CODE
        • M65.959 Unspecified synovitis and tenosynovitis, unspecified thigh NEW CODE
        • M65.96 Unspecified synovitis and tenosynovitis, lower leg
        • M65.961 Unspecified synovitis and tenosynovitis, right lower leg NEW CODE
        • M65.962 Unspecified synovitis and tenosynovitis, left lower leg NEW CODE
        • M65.969 Unspecified synovitis and tenosynovitis, unspecified lower leg NEW CODE
        • M65.97 Unspecified synovitis and tenosynovitis, ankle and foot
        • M65.971 Unspecified synovitis and tenosynovitis, right ankle and foot NEW CODE
        • M65.972 Unspecified synovitis and tenosynovitis, left ankle and foot NEW CODE
        • M65.979 Unspecified synovitis and tenosynovitis, unspecified ankle and foot NEW CODE
        • M65.98 Unspecified synovitis and tenosynovitis, other site NEW CODE
        • M65.99 Unspecified synovitis and tenosynovitis, multiple sites NEW CODE

Instructional Notations

Type 1 Excludes

A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.

  • chronic crepitant synovitis of hand and wrist M70.0
  • current injury - see injury of ligament or tendon by body region
  • soft tissue disorders related to use, overuse and pressure M70

Clinical Terms

The following clinical terms provide additional context, helping users better understand the clinical background and common associations for each diagnosis listed in this section. Including related terms alongside ICD-10-CM codes supports coders, billers, and healthcare professionals in improving accuracy, enhancing documentation, and facilitating research or patient education.

Acquired Hyperostosis Syndrome

Syndrome consisting of SYNOVITIS; ACNE CONGLOBATA; PALMOPLANTAR PUSTULOSIS; HYPEROSTOSIS; and OSTEITIS. The most common site of the disease is the upper anterior chest wall, characterized by predominantly osteosclerotic lesions, hyperostosis, and arthritis of the adjacent joints. The association of sterile inflammatory bone lesions and neutrophilic skin eruptions is indicative of this syndrome.

Giant Cell Tumor of Tendon Sheath

A tumor arising in the SYNOVIAL MEMBRANE; SYNOVIAL BURSA; or TENDON sheath. It is characterized by OSTEOCLAST-like GIANT CELLS; FOAM CELLS; pigmented HEMOSIDERIN-laden MACROPHAGES and inflammatory infiltrate. It is classified either as diffuse or localized tenosynovitis.

Synovial Membrane

The inner membrane of a joint capsule surrounding a freely movable joint. It is loosely attached to the external fibrous capsule and secretes SYNOVIAL FLUID.

Synovitis

Inflammation of the SYNOVIAL MEMBRANE.

Synovitis, Pigmented Villonodular

Diffuse outgrowth arising from the SYNOVIAL MEMBRANE; SYNOVIAL BURSA; or TENDON sheath around the joint cavity, with extension to surrounding soft tissue. It is characterized by pigmented HEMOSIDERIN-containing MACROPHAGES; FOAM CELLS; and multinucleated GIANT CELLS. It usually occurs in the hands and feet, and around large joints, such as in the ankle and knee joints.

Tendon Entrapment

Narrowing or stenosis of a tendon's retinacular sheath. It occurs most often in the hand or wrist but can also be found in the foot or ankle. The most common types are DE QUERVAIN DISEASE and TRIGGER FINGER DISORDER.

Tenosynovitis

Inflammation of the synovial lining of a tendon sheath. Causes include trauma, tendon stress, bacterial disease (gonorrhea, tuberculosis), rheumatic disease, and gout. Common sites are the hand, wrist, shoulder capsule, hip capsule, hamstring muscles, and Achilles tendon. The tendon sheaths become inflamed and painful, and accumulate fluid. Joint mobility is usually reduced.