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ICD-10 Guide
ICD-10 CodesM66.36

M66.36

Billable

Spontaneous rupture of flexor tendons, lower leg

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

Code Description

ICD-10 M66.36 is a billable code used to indicate a diagnosis of spontaneous rupture of flexor tendons, lower leg.

Key Diagnostic Point:

Spontaneous rupture of flexor tendons in the lower leg is a condition characterized by the unexpected tearing of the flexor tendons, which are responsible for bending the toes and foot. This condition can occur due to various factors, including underlying degenerative changes, inflammatory conditions such as tenosynovitis, or acute trauma. 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 options may include conservative management with rest and immobilization or surgical intervention to repair the ruptured tendon, depending on the severity of the injury and the patient's functional needs. Surgical repair often involves tendon suturing or grafting, followed by rehabilitation to restore strength and mobility. Accurate coding is essential for proper reimbursement and tracking of treatment outcomes.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Differentiating between spontaneous and traumatic ruptures
  • Identifying the specific tendon involved
  • Understanding associated conditions like tenosynovitis
  • Documenting surgical interventions accurately

Audit Risk Factors

  • Inadequate documentation of the mechanism of injury
  • Failure to specify the tendon involved
  • Lack of imaging studies to support diagnosis
  • Improper coding of associated conditions

Specialty Focus

Medical Specialties

Orthopedic Surgery

Documentation Requirements

Detailed operative notes, imaging results, and pre-operative assessments are necessary.

Common Clinical Scenarios

Patients presenting with acute pain and swelling in the lower leg after a fall or sports injury.

Billing Considerations

Ensure that the surgical approach and any graft materials used are clearly documented.

Physical Medicine and Rehabilitation

Documentation Requirements

Comprehensive evaluations of functional limitations and rehabilitation plans.

Common Clinical Scenarios

Patients recovering from tendon repair surgery requiring physical therapy.

Billing Considerations

Document progress notes that reflect improvements in range of motion and strength.

Coding Guidelines

Inclusion Criteria

Use M66.36 When
  • Follow the official ICD
  • CM coding guidelines, ensuring that the code is used only when the rupture is spontaneous and not due to trauma
  • Document any associated conditions such as tenosynovitis or other inflammatory disorders that may contribute to the tendon rupture

Exclusion Criteria

Do NOT use M66.36 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

26300CPT Code

Repair of tendon, flexor, lower leg

Clinical Scenario

Used when surgical repair is performed for a spontaneous rupture.

Documentation Requirements

Operative report detailing the procedure and any graft materials used.

Specialty Considerations

Orthopedic surgeons should ensure accurate coding of the procedure based on 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 granularity of data for treatment outcomes and reimbursement. M66.36 provides a clear distinction between spontaneous and traumatic ruptures, aiding in accurate clinical documentation and billing.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of tendon injuries, improving the granularity of data for treatment outcomes and reimbursement. M66.36 provides a clear distinction between spontaneous and traumatic ruptures, aiding in accurate clinical documentation and billing.

Reimbursement & Billing Impact

reimbursement. M66.36 provides a clear distinction between spontaneous and traumatic ruptures, aiding in accurate clinical documentation and billing.

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 spontaneous rupture of flexor tendons?

Common causes include chronic degenerative changes, inflammatory conditions such as tenosynovitis, and sometimes systemic diseases that weaken tendon integrity.