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ICD-10 Guide
ICD-10 CodesM21.739

M21.739

Billable

Unequal limb length (acquired), unspecified ulna and radius

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

Code Description

ICD-10 M21.739 is a billable code used to indicate a diagnosis of unequal limb length (acquired), unspecified ulna and radius.

Key Diagnostic Point:

Unequal limb length, or limb length discrepancy, refers to a condition where one limb is shorter or longer than the other due to acquired factors. This can occur due to various reasons such as trauma, surgical interventions, or diseases affecting bone growth and development. In the case of M21.739, the specific focus is on the ulna and radius, which are the two long bones in the forearm. Acquired deformities can arise from conditions such as fractures that heal improperly, infections that affect bone integrity, or conditions like osteomyelitis. Patients may present with functional limitations, gait abnormalities, or cosmetic concerns. Treatment options often include corrective procedures such as limb lengthening, osteotomy, or the use of orthotic devices to improve function and appearance. Accurate coding is essential for proper reimbursement and to reflect the complexity of the patient's condition and treatment plan.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Variability in documentation of limb length discrepancies
  • Need for precise measurement and assessment of limb lengths
  • Differentiation between congenital and acquired conditions
  • Potential for multiple underlying causes requiring thorough investigation

Audit Risk Factors

  • Inadequate documentation of the cause of limb length discrepancy
  • Failure to specify the affected bones
  • Lack of detailed treatment plans or follow-up documentation
  • Inconsistent measurements reported in clinical notes

Specialty Focus

Medical Specialties

Orthopedics

Documentation Requirements

Detailed clinical notes including measurements of limb lengths, imaging studies, and treatment plans.

Common Clinical Scenarios

Patients presenting with post-fracture limb length discrepancies or those requiring corrective surgery.

Billing Considerations

Ensure that all relevant imaging and surgical notes are included to support the diagnosis and treatment.

Physical Medicine and Rehabilitation

Documentation Requirements

Comprehensive assessments of functional limitations and rehabilitation goals.

Common Clinical Scenarios

Patients undergoing rehabilitation post-surgery for limb lengthening or correction.

Billing Considerations

Document functional assessments and progress notes to justify the need for ongoing therapy.

Coding Guidelines

Inclusion Criteria

Use M21.739 When
  • According to ICD
  • 10 guidelines, M21
  • 739 should be used when the specific cause of the unequal limb length is acquired and not congenital
  • Documentation must clearly indicate the nature of the acquired condition and the specific bones involved

Exclusion Criteria

Do NOT use M21.739 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

27599CPT Code

Unlisted procedure, femur or tibia

Clinical Scenario

Used when performing corrective surgery for limb length discrepancy.

Documentation Requirements

Detailed operative notes and pre-operative assessments.

Specialty Considerations

Orthopedic specialists should ensure all relevant imaging and measurements are documented.

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 is the difference between congenital and acquired unequal limb length?

Congenital unequal limb length is present at birth due to genetic or developmental factors, while acquired unequal limb length develops later in life due to trauma, disease, or surgical interventions.