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ICD-10 Guide
ICD-10 CodesM21.161

M21.161

Billable

Varus deformity, not elsewhere classified, right knee

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

Code Description

ICD-10 M21.161 is a billable code used to indicate a diagnosis of varus deformity, not elsewhere classified, right knee.

Key Diagnostic Point:

Varus deformity of the knee, commonly referred to as 'bowleggedness', is characterized by an inward angulation of the knee joint, resulting in a misalignment of the lower limb. This condition can be acquired due to various factors, including obesity, osteoarthritis, or previous injuries that affect the knee's structural integrity. Patients with varus deformity may experience pain, instability, and difficulty in ambulation, which can significantly impact their quality of life. The right knee specifically indicates that the deformity is unilateral, which may require targeted interventions. Treatment options often include physical therapy, bracing, or surgical procedures such as osteotomy to realign the knee joint. Accurate coding is essential for proper reimbursement and to ensure that the patient's medical history reflects the specific nature of their condition. Documentation should detail the onset, duration, and any associated symptoms to support the diagnosis and treatment plan.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Differentiating between acquired and congenital deformities
  • Understanding the specific anatomical location (right knee)
  • Identifying associated conditions or complications
  • Documenting the severity and impact on function

Audit Risk Factors

  • Insufficient documentation of the deformity's acquired nature
  • Lack of detailed clinical notes regarding treatment plans
  • Inconsistent coding of associated conditions
  • Failure to document the impact on daily activities

Specialty Focus

Medical Specialties

Orthopedics

Documentation Requirements

Detailed clinical notes including physical examination findings, imaging results, and treatment plans.

Common Clinical Scenarios

Patients presenting with knee pain, instability, or difficulty walking due to varus deformity.

Billing Considerations

Ensure that the documentation clearly states the acquired nature of the deformity and any previous treatments.

Physical Therapy

Documentation Requirements

Progress notes detailing the patient's functional status, treatment interventions, and response to therapy.

Common Clinical Scenarios

Patients undergoing rehabilitation post-surgery or those receiving conservative management for varus deformity.

Billing Considerations

Document specific functional limitations and goals to support the need for therapy.

Coding Guidelines

Inclusion Criteria

Use M21.161 When
  • Follow the official ICD
  • CM coding guidelines, ensuring that the code is used only when the varus deformity is not classified elsewhere
  • Document the specific location and acquired nature of the deformity

Exclusion Criteria

Do NOT use M21.161 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

27447CPT Code

Osteotomy, knee, medial or lateral

Clinical Scenario

Used for surgical correction of varus deformity.

Documentation Requirements

Pre-operative assessment, surgical notes, and post-operative follow-up documentation.

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 conditions like varus deformity, improving the accuracy of patient records and reimbursement processes.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of conditions like varus deformity, improving the accuracy of patient records and reimbursement processes.

Reimbursement & Billing Impact

reimbursement processes.

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 difference between varus and valgus deformity?

Varus deformity refers to inward angulation of the knee, while valgus deformity refers to outward angulation. Both can affect knee function and require different treatment approaches.