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ICD-10 Guide
ICD-10 CodesM21.96

M21.96

Billable

Unspecified acquired deformity of lower leg

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

Code Description

ICD-10 M21.96 is a billable code used to indicate a diagnosis of unspecified acquired deformity of lower leg.

Key Diagnostic Point:

M21.96 refers to an unspecified acquired deformity of the lower leg, which encompasses a range of conditions that result in structural abnormalities due to non-congenital factors. These deformities can arise from various causes, including trauma, infections, inflammatory diseases, or degenerative conditions. Common examples include malalignment due to previous fractures, post-surgical changes, or conditions like osteoarthritis that lead to joint deformities. The lower leg consists of the tibia and fibula, and deformities can manifest as angular deformities, shortening, or rotational abnormalities. The lack of specificity in this code means that it is crucial for healthcare providers to document the underlying cause and nature of the deformity to ensure accurate coding and appropriate treatment planning. Treatment may involve physical therapy, orthotic devices, or surgical interventions aimed at correcting the deformity and restoring function.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Variability in documentation of the underlying cause of the deformity
  • Need for precise clinical details to differentiate from other deformities
  • Potential overlap with other codes for acquired deformities
  • Variations in treatment approaches that may affect coding

Audit Risk Factors

  • Insufficient documentation of the deformity's cause
  • Inconsistent coding practices among providers
  • Failure to link the deformity to a specific clinical scenario
  • Lack of follow-up documentation to support ongoing treatment

Specialty Focus

Medical Specialties

Orthopedics

Documentation Requirements

Detailed descriptions of the deformity, including measurements and functional impact.

Common Clinical Scenarios

Patients presenting with post-traumatic deformities or degenerative changes in the lower leg.

Billing Considerations

Orthopedic surgeons must document the specific nature of the deformity and any prior interventions.

Physical Medicine and Rehabilitation

Documentation Requirements

Functional assessments and treatment plans that address the deformity's impact on mobility.

Common Clinical Scenarios

Rehabilitation following corrective surgery or management of chronic deformities.

Billing Considerations

Focus on the functional implications of the deformity and the patient's rehabilitation goals.

Coding Guidelines

Inclusion Criteria

Use M21.96 When
  • According to ICD
  • 10 coding guidelines, M21
  • 96 should be used when the specific cause of the acquired deformity is not documented
  • Coders should ensure that the medical record supports the use of this code and consider additional codes that may provide more specificity

Exclusion Criteria

Do NOT use M21.96 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

27500CPT Code

Osteotomy, tibia

Clinical Scenario

Used in cases where surgical correction of a lower leg deformity is necessary.

Documentation Requirements

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

Specialty Considerations

Orthopedic surgeons must provide detailed operative reports to support the procedure.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more detailed coding of acquired deformities, improving the specificity of patient records and facilitating better treatment planning. M21.96 serves as a catch-all for unspecified cases, but it is essential for providers to strive for more specific coding when possible.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more detailed coding of acquired deformities, improving the specificity of patient records and facilitating better treatment planning. M21.96 serves as a catch-all for unspecified cases, but it is essential for providers to strive for more specific coding when possible.

Reimbursement & Billing Impact

The transition to ICD-10 has allowed for more detailed coding of acquired deformities, improving the specificity of patient records and facilitating better treatment planning. M21.96 serves as a catch-all for unspecified cases, but it is essential for providers to strive for more specific coding when possible.

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 documentation is needed to support the use of M21.96?

Documentation should include a detailed clinical description of the deformity, the underlying cause, and any relevant imaging studies or assessments that support the diagnosis.