2021 ICD-10-CM Code M66.173

Rupture of synovium, unspecified ankle

Version 2021
Billable Code
Unspecified Code
MS-DRG Mapping

Valid for Submission

M66.173 is a billable diagnosis code used to specify a medical diagnosis of rupture of synovium, unspecified ankle. The code M66.173 is valid during the fiscal year 2021 from October 01, 2020 through September 30, 2021 for the submission of HIPAA-covered transactions.

The ICD-10-CM code M66.173 might also be used to specify conditions or terms like rupture of synovium - ankle/foot.

Unspecified diagnosis codes like M66.173 are acceptable when clinical information is unknown or not available about a particular condition. Although a more specific code is preferable, unspecified codes should be used when such codes most accurately reflect what is known about a patient's condition. Specific diagnosis codes should not be used if not supported by the patient's medical record.

ICD-10:M66.173
Short Description:Rupture of synovium, unspecified ankle
Long Description:Rupture of synovium, unspecified ankle

Code Classification

Approximate Synonyms

The following clinical terms are approximate synonyms or lay terms that might be used to identify the correct diagnosis code:

Convert M66.173 to ICD-9 Code

The General Equivalency Mapping (GEM) crosswalk indicates an approximate mapping between the ICD-10 code M66.173 its ICD-9 equivalent. The approximate mapping means there is not an exact match between the ICD-10 code and the ICD-9 code and the mapped code is not a precise representation of the original code.

Information for Patients


Ankle Injuries and Disorders

Your ankle bone and the ends of your two lower leg bones make up the ankle joint. Your ligaments, which connect bones to one another, stabilize and support it. Your muscles and tendons move it.

The most common ankle problems are sprains and fractures. A sprain is an injury to the ligaments. It may take a few weeks to many months to heal completely. A fracture is a break in a bone. You can also injure other parts of the ankle such as tendons, which join muscles to bone, and cartilage, which cushions your joints. Ankle sprains and fractures are common sports injuries.


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Code History

  • FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016 (First year ICD-10-CM implemented into the HIPAA code set)