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v1.0.0
ICD-10 Guide
ICD-10 CodesM21.76

M21.76

Billable

Unequal limb length (acquired), tibia and fibula

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

Code Description

ICD-10 M21.76 is a billable code used to indicate a diagnosis of unequal limb length (acquired), tibia and fibula.

Key Diagnostic Point:

Unequal limb length, specifically affecting the tibia and fibula, is a condition characterized by a discrepancy in the lengths of the lower limbs due to acquired factors. This condition can arise from various causes, including trauma, surgical interventions, infections, or diseases that affect bone growth and development. For instance, a fracture that heals improperly may result in one limb being shorter than the other. Additionally, conditions such as osteomyelitis or tumors can lead to limb length discrepancies. Patients may experience functional limitations, gait abnormalities, and increased risk of joint problems due to the uneven distribution of weight and altered biomechanics. Treatment often involves corrective procedures such as limb lengthening surgeries or orthopedic interventions to address the underlying cause and restore balance. Accurate coding is essential for proper reimbursement and to ensure that the patient's condition is adequately documented for future care.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Variability in documentation of acquired causes
  • Differentiation from congenital limb length discrepancies
  • Need for precise measurement and assessment of limb lengths
  • Potential for multiple underlying conditions contributing to the discrepancy

Audit Risk Factors

  • Inadequate documentation of the acquired cause
  • Failure to specify the affected limb
  • Lack of supporting clinical evidence for the diagnosis
  • Inconsistent coding of related procedures

Specialty Focus

Medical Specialties

Orthopedics

Documentation Requirements

Detailed history of the injury or condition, imaging results, and treatment plans.

Common Clinical Scenarios

Post-fracture limb length discrepancies, post-surgical complications leading to unequal limb lengths.

Billing Considerations

Ensure that all relevant surgical notes and follow-up assessments are included in the documentation.

Physical Medicine and Rehabilitation

Documentation Requirements

Functional assessments, therapy notes, and progress reports.

Common Clinical Scenarios

Rehabilitation following corrective surgery for limb length discrepancies.

Billing Considerations

Document the impact of the discrepancy on the patient's mobility and quality of life.

Coding Guidelines

Inclusion Criteria

Use M21.76 When
  • According to the ICD
  • CM guidelines, M21
  • 76 should be used when the unequal limb length is acquired and specifically affects the tibia and fibula
  • Coders must ensure that the documentation supports the diagnosis and that any associated conditions are also coded appropriately

Exclusion Criteria

Do NOT use M21.76 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

27599CPT Code

Unlisted procedure, femur or tibia

Clinical Scenario

Used when performing a limb lengthening procedure.

Documentation Requirements

Detailed operative report and pre-operative assessments.

Specialty Considerations

Orthopedic specialists should ensure that all relevant clinical data is included.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of acquired conditions like unequal limb length, 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 acquired conditions like unequal limb length, 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 documentation is needed to support the use of M21.76?

Documentation should include a detailed history of the acquired condition, clinical findings, imaging results, and any treatment plans or surgical notes that relate to the limb length discrepancy.