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ICD-10 Guide
ICD-10 CodesM66.379

M66.379

Billable

Spontaneous rupture of flexor tendons, unspecified ankle and foot

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

Code Description

ICD-10 M66.379 is a billable code used to indicate a diagnosis of spontaneous rupture of flexor tendons, unspecified ankle and foot.

Key Diagnostic Point:

Spontaneous rupture of flexor tendons in the ankle and foot is a condition characterized by the unexpected tearing of the tendons that flex the toes and foot. This condition can occur without any apparent trauma or injury, often linked to underlying conditions such as rheumatoid arthritis, diabetes, or chronic inflammatory diseases. Patients may present with sudden pain, swelling, and loss of function in the affected area. The flexor tendons are crucial for toe movement and stability, and their rupture can lead to significant functional impairment. Diagnosis typically involves a thorough clinical examination, imaging studies such as MRI or ultrasound, and sometimes surgical exploration. Treatment may include conservative management with immobilization and physical therapy, or surgical repair if the rupture is severe. The prognosis varies based on the extent of the injury and the timeliness of intervention.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Variability in clinical presentation and severity of tendon rupture
  • Need for precise documentation of the spontaneous nature of the rupture
  • Differentiation from traumatic tendon injuries
  • Potential for co-existing conditions affecting tendon health

Audit Risk Factors

  • Inadequate documentation of the spontaneous nature of the rupture
  • Failure to specify the affected tendon(s)
  • Lack of imaging studies to support the diagnosis
  • Inconsistent coding of related conditions

Specialty Focus

Medical Specialties

Orthopedics

Documentation Requirements

Detailed notes on the mechanism of injury, imaging results, and treatment plan.

Common Clinical Scenarios

Patients presenting with sudden onset pain in the ankle or foot, often after minimal or no trauma.

Billing Considerations

Ensure clear documentation of the spontaneous nature of the rupture and any associated conditions.

Rheumatology

Documentation Requirements

Comprehensive history of underlying conditions such as rheumatoid arthritis or diabetes.

Common Clinical Scenarios

Patients with chronic inflammatory conditions presenting with tendon issues.

Billing Considerations

Document the relationship between systemic conditions and tendon health.

Coding Guidelines

Inclusion Criteria

Use M66.379 When
  • Follow official ICD
  • 10 coding guidelines, ensuring accurate documentation of the spontaneous nature of the rupture
  • Include any relevant co
  • morbidities that may affect treatment

Exclusion Criteria

Do NOT use M66.379 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

27301CPT Code

Repair of flexor tendon

Clinical Scenario

Used when surgical repair is performed following a spontaneous rupture.

Documentation Requirements

Operative report detailing the procedure and findings.

Specialty Considerations

Orthopedic documentation must clearly link the procedure to the diagnosis.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of tendon injuries, improving the accuracy of diagnoses and treatment plans. M66.379 provides a clear classification for spontaneous ruptures, which aids in better patient management and resource allocation.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of tendon injuries, improving the accuracy of diagnoses and treatment plans. M66.379 provides a clear classification for spontaneous ruptures, which aids in better patient management and resource allocation.

Reimbursement & Billing Impact

The transition to ICD-10 has allowed for more specific coding of tendon injuries, improving the accuracy of diagnoses and treatment plans. M66.379 provides a clear classification for spontaneous ruptures, which aids in better patient management and resource allocation.

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 spontaneous and traumatic tendon rupture?

Spontaneous tendon rupture occurs without any significant trauma, often due to underlying conditions, while traumatic rupture results from a specific injury or event.