ICD-10-CM Code M66.33

Spontaneous rupture of flexor tendons, forearm

Version 2020 Non-Billable Code

Not Valid for Submission

M66.33 is a "header" nonspecific and non-billable code code, consider using a code with a higher level of specificity for a diagnosis of spontaneous rupture of flexor tendons, forearm. The code is NOT valid for the year 2020 for the submission of HIPAA-covered transactions.

ICD-10:M66.33
Short Description:Spontaneous rupture of flexor tendons, forearm
Long Description:Spontaneous rupture of flexor tendons, forearm

Consider the following ICD-10 codes with a higher level of specificity:

  • 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

Index to Diseases and Injuries

The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10 code(s). The following references for the code M66.33 are found in the index:


Code Classification

  • Diseases of the musculoskeletal system and connective tissue (M00–M99)
    • Disorders of synovium and tendon (M65-M67)
      • Spontaneous rupture of synovium and tendon (M66)

Code History

  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016
    (First year ICD-10-CM implemented into the HIPAA code set)
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020

Information for Patients


Arm Injuries and Disorders

Of the 206 bones in your body, three of them are in your arm: the humerus, radius, and ulna. Your arms are also made up of muscles, joints, tendons, and other connective tissue. Injuries to any of these parts of the arm can occur during sports, a fall, or an accident.

Types of arm injuries include

  • Tendinitis and bursitis
  • Sprains
  • Dislocations
  • Broken bones
  • Nerve problems
  • Osteoarthritis

You may also have problems or injure specific parts of your arm, such as your hand, wrist, elbow, or shoulder.


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Sprains and Strains

A sprain is a stretched or torn ligament. Ligaments are tissues that connect bones at a joint. Falling, twisting, or getting hit can all cause a sprain. Ankle and wrist sprains are common. Symptoms include pain, swelling, bruising, and being unable to move your joint. You might feel a pop or tear when the injury happens.

A strain is a stretched or torn muscle or tendon. Tendons are tissues that connect muscle to bone. Twisting or pulling these tissues can cause a strain. Strains can happen suddenly or develop over time. Back and hamstring muscle strains are common. Many people get strains playing sports. Symptoms include pain, muscle spasms, swelling, and trouble moving the muscle.

At first, treatment of both sprains and strains usually involves resting the injured area, icing it, wearing a bandage or device that compresses the area, and medicines. Later treatment might include exercise and physical therapy.

NIH: National Institute of Arthritis and Musculoskeletal and Skin Diseases


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