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ICD-10 Guide
ICD-10 CodesM21.37

M21.37

Billable

Foot drop (acquired)

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

Code Description

ICD-10 M21.37 is a billable code used to indicate a diagnosis of foot drop (acquired).

Key Diagnostic Point:

Foot drop, also known as drop foot, is a condition characterized by difficulty in lifting the front part of the foot, leading to dragging of the foot while walking. This acquired deformity can result from various underlying causes, including neurological disorders, muscular diseases, or injuries affecting the peroneal nerve. Common causes include stroke, multiple sclerosis, or trauma to the knee or lower leg. Patients may present with a steppage gait, where they lift their knee higher than normal to avoid dragging the foot. The condition can significantly impact mobility and quality of life, necessitating interventions such as physical therapy, orthotic devices, or surgical procedures to correct the underlying issue or improve function. Corrective procedures may include tendon transfers or nerve decompression, depending on the etiology. Accurate diagnosis and coding are crucial for appropriate management and reimbursement.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Variety of underlying causes leading to foot drop
  • Potential for co-existing conditions affecting coding
  • Need for precise documentation of the cause
  • Variability in treatment approaches

Audit Risk Factors

  • Inadequate documentation of the underlying cause
  • Failure to specify if the condition is unilateral or bilateral
  • Misclassification of foot drop as congenital
  • Lack of supporting clinical evidence for the diagnosis

Specialty Focus

Medical Specialties

Neurology

Documentation Requirements

Detailed neurological examination findings, imaging results, and history of neurological disorders.

Common Clinical Scenarios

Patients with stroke, multiple sclerosis, or peripheral neuropathy presenting with foot drop.

Billing Considerations

Ensure documentation reflects the neurological basis for foot drop to support coding.

Orthopedics

Documentation Requirements

Surgical notes, imaging studies, and details of any orthopedic interventions.

Common Clinical Scenarios

Patients with traumatic injuries to the knee or lower leg resulting in foot drop.

Billing Considerations

Document any corrective procedures performed and their outcomes.

Coding Guidelines

Inclusion Criteria

Use M21.37 When
  • Follow official ICD
  • CM coding guidelines, ensuring accurate documentation of the underlying cause of foot drop
  • Include details on laterality and any associated conditions

Exclusion Criteria

Do NOT use M21.37 When
  • Exclude congenital causes unless specified

Related ICD-10 Codes

Related CPT Codes

64718CPT Code

Neuroplasty, peripheral nerve

Clinical Scenario

Performed for decompression of the peroneal nerve in cases of foot drop.

Documentation Requirements

Surgical notes detailing the procedure and indications.

Specialty Considerations

Orthopedic or neurosurgical documentation must support the need for surgery.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of foot drop, enabling better tracking of the condition's prevalence and associated costs. It has improved the granularity of data for research and quality improvement initiatives.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of foot drop, enabling better tracking of the condition's prevalence and associated costs. It has improved the granularity of data for research and quality improvement initiatives.

Reimbursement & Billing Impact

The transition to ICD-10 has allowed for more specific coding of foot drop, enabling better tracking of the condition's prevalence and associated costs. It has improved the granularity of data for research and quality improvement initiatives.

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 are the common causes of acquired foot drop?

Common causes include neurological conditions such as stroke or multiple sclerosis, traumatic injuries to the knee or lower leg, and conditions affecting the peroneal nerve.