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ICD-10 Guide
ICD-10 CodesM21.75

M21.75

Billable

Unequal limb length (acquired), femur

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

Code Description

ICD-10 M21.75 is a billable code used to indicate a diagnosis of unequal limb length (acquired), femur.

Key Diagnostic Point:

Unequal limb length (acquired), specifically involving the femur, refers to a condition where one leg is shorter or longer than the other due to factors that are not congenital but rather acquired over time. This can occur due to various reasons such as trauma, surgical interventions, infections, or diseases that affect bone growth and development. Common causes include fractures that heal improperly, osteomyelitis, or conditions like arthritis that may lead to joint deformities. The acquired nature of this condition often necessitates a thorough evaluation to determine the underlying cause and appropriate treatment options. Patients may experience functional limitations, gait abnormalities, and discomfort, which can significantly impact their quality of life. Treatment may involve physical therapy, orthotic devices, or surgical interventions aimed at correcting the limb length discrepancy. Accurate coding is essential for proper management and reimbursement, as it reflects the complexity of the patient's condition and the interventions required.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Variety of potential underlying causes (trauma, surgery, disease)
  • Need for detailed documentation of the acquired nature
  • Differentiation from congenital limb length discrepancies
  • Potential for associated conditions requiring co-coding

Audit Risk Factors

  • Inadequate documentation of the acquired nature of the condition
  • Failure to specify the underlying cause of the limb length discrepancy
  • Incorrect coding of associated conditions
  • Lack of clarity in treatment plans and outcomes

Specialty Focus

Medical Specialties

Orthopedics

Documentation Requirements

Detailed history of the limb length discrepancy, including onset, cause, and treatment history.

Common Clinical Scenarios

Post-fracture evaluations, pre-surgical assessments for limb lengthening procedures, and management of osteomyelitis.

Billing Considerations

Ensure that all surgical interventions and their outcomes are documented to support coding.

Physical Therapy

Documentation Requirements

Assessment of functional limitations, treatment goals, and progress notes.

Common Clinical Scenarios

Rehabilitation following corrective surgery or management of gait abnormalities.

Billing Considerations

Documenting the impact of limb length discrepancy on mobility and function is crucial.

Coding Guidelines

Inclusion Criteria

Use M21.75 When
  • According to ICD
  • 10 guidelines, M21
  • 75 should be used when the limb length discrepancy is acquired and specifically involves the femur
  • Coders must ensure that the documentation supports the acquired nature and any associated conditions are coded appropriately

Exclusion Criteria

Do NOT use M21.75 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

27400CPT Code

Osteotomy, femur

Clinical Scenario

Used for surgical correction of limb length discrepancies.

Documentation Requirements

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

Specialty Considerations

Orthopedic documentation must clearly outline the need for surgery due to acquired limb length discrepancy.

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 M21.75, improving the accuracy of patient records and facilitating better treatment planning and reimbursement processes.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of acquired conditions like M21.75, improving the accuracy of patient records and facilitating better treatment planning 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 limb length discrepancies?

Congenital discrepancies are present at birth and result from developmental issues, while acquired discrepancies develop later due to trauma, surgery, or disease.