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ICD-10 Guide
ICD-10 CodesM66.321

M66.321

Billable

Spontaneous rupture of flexor tendons, right upper arm

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

Code Description

ICD-10 M66.321 is a billable code used to indicate a diagnosis of spontaneous rupture of flexor tendons, right upper arm.

Key Diagnostic Point:

Spontaneous rupture of flexor tendons in the right upper arm is a condition characterized by the unexpected tearing of the flexor tendons, which are responsible for bending the fingers and wrist. This injury can occur without any apparent trauma or overuse, often linked to underlying conditions such as rheumatoid arthritis or tenosynovitis. The flexor tendons are encased in a synovial sheath that can become inflamed, leading to increased friction and eventual rupture. Symptoms typically include sudden pain, swelling, and loss of function in the affected area. Diagnosis is primarily clinical, supported by imaging studies such as ultrasound or MRI to confirm the rupture and assess the extent of damage. Treatment often involves surgical intervention to repair the torn tendon, followed by rehabilitation to restore function. Accurate coding is essential for proper management and reimbursement, as it reflects the complexity of the injury and the required treatment.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Differentiating between spontaneous and traumatic ruptures
  • Identifying the specific tendon involved
  • Documenting associated conditions like tenosynovitis
  • Understanding the implications of surgical repair versus conservative management

Audit Risk Factors

  • Inadequate documentation of the spontaneous nature of the rupture
  • Failure to specify the anatomical location accurately
  • Misclassification of the type of tendon involved
  • Lack of supporting imaging documentation

Specialty Focus

Medical Specialties

Orthopedic Surgery

Documentation Requirements

Detailed operative notes, imaging studies, and pre-operative assessments.

Common Clinical Scenarios

Surgical repair of ruptured flexor tendons following spontaneous rupture.

Billing Considerations

Ensure documentation reflects the surgical approach and any complications.

Rheumatology

Documentation Requirements

Comprehensive history of underlying conditions, treatment plans, and response to therapy.

Common Clinical Scenarios

Management of spontaneous tendon ruptures in patients with rheumatoid arthritis.

Billing Considerations

Document the relationship between inflammatory conditions and tendon integrity.

Coding Guidelines

Inclusion Criteria

Use M66.321 When
  • Follow official ICD
  • CM coding guidelines, ensuring accurate documentation of the spontaneous nature of the rupture and the specific tendon involved
  • Include any relevant comorbidities that may affect treatment

Exclusion Criteria

Do NOT use M66.321 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

26340CPT 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 surgeons should document the specific tendon repaired.

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. M66.321 provides a clear distinction between spontaneous and traumatic ruptures, facilitating better patient management.

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. M66.321 provides a clear distinction between spontaneous and traumatic ruptures, facilitating better patient management.

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. M66.321 provides a clear distinction between spontaneous and traumatic ruptures, facilitating better patient management.

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 or injury, often due to underlying conditions, while traumatic rupture results from a specific injury or excessive force applied to the tendon.