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ICD-10 Guide
ICD-10 CodesM66.21

M66.21

Billable

Spontaneous rupture of extensor tendons, shoulder

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

Code Description

ICD-10 M66.21 is a billable code used to indicate a diagnosis of spontaneous rupture of extensor tendons, shoulder.

Key Diagnostic Point:

Spontaneous rupture of extensor tendons in the shoulder is a condition characterized by the unexpected tearing of the extensor tendons, which are responsible for extending the arm and fingers. This condition can occur without any significant trauma or injury, often associated with underlying degenerative changes or inflammatory processes. Patients may present with sudden pain, swelling, and loss of function in the shoulder area. The rupture can lead to significant impairment in daily activities, particularly those requiring arm extension. Diagnosis typically involves a thorough clinical examination, imaging studies such as MRI or ultrasound, and sometimes arthroscopy to confirm the extent of the injury. Treatment options may include conservative management with physical therapy and anti-inflammatory medications, or surgical intervention to repair the ruptured tendon, depending on the severity of the rupture and the patient's functional needs. Accurate coding is essential for proper reimbursement and to reflect the complexity of the condition.

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 mechanism of injury
  • Differentiation from other shoulder injuries and conditions
  • Potential for co-existing conditions affecting treatment and coding

Audit Risk Factors

  • Inadequate documentation of the mechanism of injury
  • Failure to specify the exact tendon involved
  • Lack of imaging studies to support diagnosis
  • Inconsistent coding of related surgical procedures

Specialty Focus

Medical Specialties

Orthopedic Surgery

Documentation Requirements

Detailed operative reports, imaging results, and post-operative care notes.

Common Clinical Scenarios

Patients presenting with acute shoulder pain and loss of function, often after minor trauma or spontaneously.

Billing Considerations

Ensure documentation reflects the specific tendon involved and the surgical technique used for repair.

Physical Medicine and Rehabilitation

Documentation Requirements

Comprehensive assessment of functional limitations and rehabilitation progress notes.

Common Clinical Scenarios

Patients undergoing rehabilitation post-surgery for tendon repair or those managed conservatively.

Billing Considerations

Document functional outcomes and any co-morbid conditions affecting recovery.

Coding Guidelines

Inclusion Criteria

Use M66.21 When
  • Follow official ICD
  • CM coding guidelines, ensuring accurate documentation of the diagnosis, treatment plan, and any associated conditions
  • Include details on the specific tendon involved and the nature of the rupture

Exclusion Criteria

Do NOT use M66.21 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

23470CPT Code

Repair of ruptured tendon, shoulder

Clinical Scenario

Used when surgical repair of the extensor tendon is performed.

Documentation Requirements

Operative report detailing the procedure and findings.

Specialty Considerations

Orthopedic surgeons must document the specific tendon repaired and the surgical technique used.

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. M66.21 provides a clear distinction for spontaneous ruptures, which aids in clinical management and reimbursement.

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. M66.21 provides a clear distinction for spontaneous ruptures, which aids in clinical management and reimbursement.

Reimbursement & Billing Impact

reimbursement.

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 extensor tendons?

Common causes include degenerative changes due to aging, chronic inflammatory conditions, and overuse injuries. Patients may also have underlying systemic diseases that weaken tendon integrity.