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v1.0.0
ICD-10 Guide
ICD-10 CodesM21.26

M21.26

Billable

Flexion deformity, knee

BILLABLE STATUSYes
IMPLEMENTATION DATEOctober 1, 2015
LAST UPDATED09/17/2025

Code Description

ICD-10 M21.26 is a billable code used to indicate a diagnosis of flexion deformity, knee.

Key Diagnostic Point:

Flexion deformity of the knee is characterized by an abnormal bending of the knee joint, resulting in a reduced ability to extend the leg fully. This condition can be acquired due to various factors, including trauma, degenerative diseases such as osteoarthritis, or neurological conditions that affect muscle control. Patients may present with difficulty walking, pain, and instability in the knee joint. The deformity can lead to compensatory changes in gait and posture, potentially causing secondary issues in the hips and lower back. Treatment options often include physical therapy, bracing, and in severe cases, surgical interventions such as osteotomy or arthroplasty to correct the deformity and restore function. Accurate diagnosis and documentation are crucial for effective management and coding, as the severity and underlying cause of the flexion deformity can significantly influence treatment decisions.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Variety of underlying causes (trauma, degenerative diseases, neurological conditions)
  • Need for detailed documentation of the degree of flexion and functional limitations
  • Potential for co-existing conditions that may complicate coding
  • Variability in treatment approaches based on severity and patient history

Audit Risk Factors

  • Inadequate documentation of the degree of flexion deformity
  • Failure to specify the underlying cause of the deformity
  • Incorrect coding of associated conditions or complications
  • Lack of evidence for conservative treatment attempts before surgical intervention

Specialty Focus

Medical Specialties

Orthopedics

Documentation Requirements

Detailed clinical notes on the range of motion, pain levels, and functional limitations.

Common Clinical Scenarios

Patients with post-traumatic knee flexion deformities or those with degenerative joint disease.

Billing Considerations

Documentation should include imaging results and any prior treatments attempted.

Physical Medicine and Rehabilitation

Documentation Requirements

Comprehensive assessments of functional capabilities and rehabilitation goals.

Common Clinical Scenarios

Patients undergoing rehabilitation post-surgery or those with chronic knee issues.

Billing Considerations

Focus on the impact of the deformity on daily activities and quality of life.

Coding Guidelines

Inclusion Criteria

Use M21.26 When
  • Follow the official ICD
  • CM coding guidelines, ensuring that the code is used in conjunction with appropriate documentation of the condition's severity and any related diagnoses
  • Include any relevant modifiers to indicate the complexity of the case

Exclusion Criteria

Do NOT use M21.26 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

27447CPT Code

Knee arthroplasty, total

Clinical Scenario

Used for patients with severe flexion deformity requiring surgical correction.

Documentation Requirements

Pre-operative assessments, imaging studies, and surgical notes.

Specialty Considerations

Orthopedic surgeons must document the rationale for surgery and expected outcomes.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of knee deformities, improving the accuracy of data collection and reimbursement processes. M21.26 provides a clear distinction between types of knee deformities, facilitating better patient management and research.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of knee deformities, improving the accuracy of data collection and reimbursement processes. M21.26 provides a clear distinction between types of knee deformities, facilitating better patient management and research.

Reimbursement & Billing Impact

reimbursement processes. M21.26 provides a clear distinction between types of knee deformities, facilitating better patient management and research.

Resources

Clinical References

  • •
    ICD-10-CM Official Guidelines for Coding and Reporting

Coding & Billing References

  • •
    ICD-10-CM Official Guidelines for Coding and Reporting

Frequently Asked Questions

What is the primary cause of flexion deformity in the knee?

Flexion deformity can result from various factors, including trauma, degenerative joint diseases, or neurological conditions that affect muscle control and joint stability.