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ICD-10 Guide
ICD-10 CodesM61.173

M61.173

Billable

Myositis ossificans progressiva, unspecified ankle

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

Code Description

ICD-10 M61.173 is a billable code used to indicate a diagnosis of myositis ossificans progressiva, unspecified ankle.

Key Diagnostic Point:

Myositis ossificans progressiva (MOP) is a rare genetic disorder characterized by the abnormal formation of bone in muscles and connective tissues. This condition typically manifests after trauma or injury, leading to progressive ossification of soft tissues, particularly in the limbs. The unspecified ankle designation indicates that the condition affects the ankle region but does not specify the exact location or severity of the ossification. Patients may experience muscle weakness, stiffness, and restricted mobility due to the formation of heterotopic bone. The condition is often misdiagnosed as other muscle disorders or injuries, complicating treatment. Diagnosis is primarily clinical, supported by imaging studies such as X-rays or MRIs that reveal abnormal bone formation. Management focuses on symptomatic relief, physical therapy, and avoiding invasive procedures that may exacerbate the condition. Understanding the nuances of MOP is crucial for accurate coding and effective patient management.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Rarity of the condition leading to limited familiarity among coders.
  • Potential for misdiagnosis with other muscle disorders.
  • Need for precise documentation of symptoms and imaging results.
  • Variability in clinical presentation and progression.

Audit Risk Factors

  • Inadequate documentation of clinical findings.
  • Failure to specify the location of ossification.
  • Misinterpretation of imaging results.
  • Inconsistent coding practices across providers.

Specialty Focus

Medical Specialties

Rheumatology

Documentation Requirements

Detailed clinical notes on symptoms, physical examination findings, and imaging results.

Common Clinical Scenarios

Patients presenting with unexplained muscle stiffness and swelling after trauma.

Billing Considerations

Ensure thorough documentation of the patient's history and any previous treatments to support the diagnosis.

Orthopedics

Documentation Requirements

Surgical notes if any procedures are performed, along with pre- and post-operative assessments.

Common Clinical Scenarios

Patients requiring surgical intervention for severe mobility restrictions due to ossification.

Billing Considerations

Document the rationale for surgical decisions and any complications encountered.

Coding Guidelines

Inclusion Criteria

Use M61.173 When
  • Follow the official ICD
  • CM coding guidelines, ensuring accurate documentation of the condition's specifics
  • Include details on the patient's history, clinical findings, and any imaging studies that support the diagnosis

Exclusion Criteria

Do NOT use M61.173 When
  • Exclude conditions that may mimic MOP unless clearly documented

Related ICD-10 Codes

Related CPT Codes

20610CPT Code

Arthrocentesis, aspiration and/or injection into a major joint or bursa

Clinical Scenario

Used when joint aspiration is performed to relieve symptoms.

Documentation Requirements

Document the reason for aspiration and any findings during the procedure.

Specialty Considerations

Orthopedic specialists should ensure clear documentation of joint status pre- and post-procedure.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of myositis ossificans progressiva, improving the accuracy of data collection and reimbursement processes. It has also highlighted the need for detailed documentation to support the diagnosis.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of myositis ossificans progressiva, improving the accuracy of data collection and reimbursement processes. It has also highlighted the need for detailed documentation to support the diagnosis.

Reimbursement & Billing Impact

reimbursement processes. It has also highlighted the need for detailed documentation to support the diagnosis.

Resources

Clinical References

  • •
    Myositis ossificans progressiva overview

Coding & Billing References

  • •
    Myositis ossificans progressiva overview

Frequently Asked Questions

What is myositis ossificans progressiva?

Myositis ossificans progressiva is a rare genetic disorder characterized by the abnormal formation of bone in muscles and connective tissues, often following trauma.