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ICD-10 Guide
ICD-10 CodesM66.37

M66.37

Billable

Spontaneous rupture of flexor tendons, ankle and foot

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

Code Description

ICD-10 M66.37 is a billable code used to indicate a diagnosis of spontaneous rupture of flexor tendons, 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 flexor tendons, which are responsible for the movement of the toes and foot. This condition can occur without any preceding trauma or injury, often associated with underlying conditions such as tenosynovitis, which is inflammation of the tendon sheath. Patients may present with sudden pain, swelling, and loss of function in the affected area. The diagnosis is typically confirmed through clinical examination and imaging studies, such as ultrasound or MRI, which can visualize the extent of the tendon rupture. Treatment may involve conservative management, including rest and immobilization, or surgical intervention to repair the ruptured tendon, depending on the severity of the injury and the patient's overall health. Accurate coding is essential for proper reimbursement and to reflect the complexity of the condition in medical records.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Differentiating between spontaneous and traumatic ruptures
  • Identifying associated conditions like tenosynovitis
  • Variability in surgical repair techniques
  • Need for precise documentation of symptoms and imaging findings

Audit Risk Factors

  • Inadequate documentation of the spontaneous nature of the rupture
  • Failure to document associated conditions like tenosynovitis
  • Incorrect coding of the surgical procedure performed
  • Lack of imaging reports to support the diagnosis

Specialty Focus

Medical Specialties

Orthopedic Surgery

Documentation Requirements

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

Common Clinical Scenarios

Patients presenting with acute pain and swelling in the ankle or foot, often after a sudden movement.

Billing Considerations

Ensure that the documentation clearly states the mechanism of injury and any associated conditions.

Physical Medicine and Rehabilitation

Documentation Requirements

Functional assessments, treatment plans, and progress notes.

Common Clinical Scenarios

Patients undergoing rehabilitation post-surgery for tendon repair.

Billing Considerations

Document the patient's functional limitations and response to therapy.

Coding Guidelines

Inclusion Criteria

Use M66.37 When
  • Follow the official ICD
  • CM coding guidelines, ensuring accurate documentation of the spontaneous nature of the rupture and any associated conditions
  • Include relevant imaging findings and treatment plans

Exclusion Criteria

Do NOT use M66.37 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

26300CPT Code

Repair of flexor tendon

Clinical Scenario

Used when surgical repair is performed for a spontaneous tendon rupture.

Documentation Requirements

Operative report detailing the procedure and findings.

Specialty Considerations

Orthopedic surgeons should document the extent of the repair and any complications.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of tendon ruptures, 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 tendon ruptures, 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 primary cause of spontaneous rupture of flexor tendons?

The primary cause is often related to underlying conditions such as tenosynovitis or degenerative changes in the tendon, which weaken the tendon structure and lead to rupture.