2026 ICD-10-CM Diagnosis Code M21.862Other specified acquired deformities of left lower leg
ICD-10-CM Codes›M00–M99›M20-M25›M21
- Billable — Valid for Submission
- Not Chronic
M21.862 is a billable ICD-10-CM diagnosis code for other specified acquired deformities of left lower leg. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 564 through 566. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Acquired deformities (excluding foot).
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Acquired bilateral genu recurvatum
- Acquired deformity of left knee
- Acquired deformity of left lower leg
- Acquired deformity of right knee
- Acquired deformity of right lower leg
- Acquired genu recurvatum
- Acquired genu recurvatum of left knee
- Acquired genu recurvatum of right knee
- Acquired internal tibial torsion
- Acquired internal torsion of tibia of bilateral lower limbs
- Acquired internal torsion of tibia of left lower limb
- Acquired internal torsion of tibia of right lower limb
- Bilateral acquired deformity of knee regions
- Bilateral acquired deformity of lower legs
- Internal tibial torsion
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Leg Injuries and Disorders
Your legs are made up of bones, blood vessels, muscles, and other connective tissue. They are important for motion and standing. Playing sports, running, falling, or having an accident can damage your legs. Common leg injuries include sprains and strains, joint dislocations, and fractures (broken bones).
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert M21.862 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About M21.862Overview
Is M21.862 (Other specified acquired deformities of lower leg) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report other specified acquired deformities of left lower leg on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does M21.862 group to?
When other specified acquired deformities of left lower leg is the principal diagnosis on an inpatient stay, it groups to MS-DRG 564, 565, 566, with relative weights from 0.7493 to 1.5436 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of M21.862?
Under the General Equivalence Mappings, other specified acquired deformities of left lower leg converts to ICD-9-CM 736.6 (acq knee deformity NEC). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
