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ICD-10 Guide
ICD-10 CodesM21.16

M21.16

Billable

Varus deformity, not elsewhere classified, knee

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

Code Description

ICD-10 M21.16 is a billable code used to indicate a diagnosis of varus deformity, not elsewhere classified, knee.

Key Diagnostic Point:

Varus deformity of the knee, also known as bowleggedness, is characterized by an inward angulation of the knee joint, resulting in a lateral deviation of the tibia. This condition can be acquired due to various factors including obesity, osteoarthritis, or previous injuries that affect the knee's alignment. Patients with varus deformity may experience pain, instability, and difficulty with ambulation. The deformity can lead to increased stress on the medial compartment of the knee, potentially resulting in degenerative changes over time. Treatment options may include physical therapy, bracing, or surgical interventions such as osteotomy to correct the alignment. Accurate diagnosis and coding are essential for appropriate management and reimbursement, as varus deformity can significantly impact a patient's quality of life and functional capabilities.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Differentiating between acquired and congenital deformities
  • Understanding the specific anatomical implications of varus deformity
  • Identifying associated conditions such as osteoarthritis
  • Documenting the severity and impact on function

Audit Risk Factors

  • Inadequate documentation of the deformity's acquired nature
  • Failure to document associated conditions or comorbidities
  • Lack of clarity in the treatment plan
  • Inconsistent coding of related procedures

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 and deformity, post-operative follow-ups for corrective procedures.

Billing Considerations

Ensure that the documentation clearly states the acquired nature of the deformity and any associated conditions.

Physical Therapy

Documentation Requirements

Progress notes detailing functional assessments, treatment interventions, and patient responses.

Common Clinical Scenarios

Rehabilitation following surgical correction of varus deformity.

Billing Considerations

Document the impact of the deformity on mobility and function to support the need for therapy.

Coding Guidelines

Inclusion Criteria

Use M21.16 When
  • According to ICD
  • 10 guidelines, M21
  • 16 should be used when the varus deformity is not classified elsewhere
  • Coders must ensure that the documentation supports the diagnosis and that any associated conditions are also coded appropriately

Exclusion Criteria

Do NOT use M21.16 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

27447CPT Code

Osteotomy, knee

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 surgical intervention.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of varus deformity, improving the accuracy of diagnoses and treatment plans. This specificity aids in better tracking of outcomes and resource allocation.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of varus deformity, improving the accuracy of diagnoses and treatment plans. This specificity aids in better tracking of outcomes and resource allocation.

Reimbursement & Billing Impact

impact of the deformity on the patient's function are essential for justifying the medical necessity of procedures.

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 varus deformity?

Varus deformity can be caused by a variety of factors including obesity, osteoarthritis, and previous knee injuries that alter the alignment of the knee joint.