ICD10BillableValid for clinical use

ICD-10 Code M21.20: Flexion deformity, unspecified site

M21.20 is a billable ICD-10 diagnosis code used to classify Flexion deformity, unspecified site in medical records and claims. You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records. ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Diseases of the musculoskeletal system and connective tissue (M00-M99).

Reviewed by HealthAssure Clinical TeamUpdated 21 May 2026

What is this code?

ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Diseases of the musculoskeletal system and connective tissue (M00-M99).

When is it used?

  • May be used when a clinician documents flexion deformity, unspecified site in a patient's medical record.
  • May appear in hospital records, claims, referrals, and clinical documentation.
  • This code can be used as a clinically usable diagnosis entry in standardized coding workflows.

What it does not mean

  • A code alone does not explain severity, treatment plan, or outcome.
  • A medical code should not be treated as a substitute for a doctor's diagnosis or advice.

Code hierarchy

chapter
13Diseases of the musculoskeletal system and connective tissue (M00-M99)
block
M00-M25Arthropathies
block
M20-M25Other joint disorders
category
M21Other acquired deformities of limbs
category
M21.2Flexion deformity
currentM21.2

Where you may see this code

You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records.

Related specialists

Orthopedic SpecialistRheumatologist

Coding guidelines

Compatibility

Legacy and official ICD code match exactly.
Legacy codes
M21.20

Common synonyms

Flexion deformity, unspecified siteFlexion deformity

Frequently asked questions

Code details

CodeM21.20
SystemICD10
Display nameFlexion deformity, unspecified site
ChapterDiseases of the musculoskeletal system and connective tissue (M00-M99)
BlockOther joint disorders

Flags

BillableYes
Valid clinical useYes

Source

SourceICD-10
Version2026-annual
Releaseannual
Year2026

Index terms

Matched terms
DeformityDeformityFlexion
See also
Deformity, limb, flexion

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.

ICD-10 Code M21.20 for Flexion deformity, unspecified site | HealthAssure