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ICD-10 Guide
ICD-10 CodesM22.42

M22.42

Billable

Chondromalacia patellae, left knee

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

Code Description

ICD-10 M22.42 is a billable code used to indicate a diagnosis of chondromalacia patellae, left knee.

Key Diagnostic Point:

Chondromalacia patellae refers to the softening and breakdown of the cartilage on the underside of the kneecap (patella). This condition is often associated with knee pain, particularly in the anterior region, and can result from overuse, injury, or misalignment of the knee joint. In the left knee, symptoms may include pain during activities such as climbing stairs, squatting, or sitting with bent knees. The condition can be diagnosed through physical examination, imaging studies like MRI, and sometimes arthroscopy. Chondromalacia is often linked to other internal derangements of the knee, including meniscal tears and ligament injuries, which can complicate the clinical picture. Treatment options may include physical therapy, anti-inflammatory medications, and in some cases, arthroscopic procedures to repair or remove damaged cartilage. Accurate coding for chondromalacia patellae is essential for proper treatment planning and reimbursement.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Differentiating between chondromalacia and other knee conditions.
  • Need for precise documentation of symptoms and imaging findings.
  • Potential co-occurrence with meniscal tears or ligament injuries.
  • Variability in treatment approaches and their documentation.

Audit Risk Factors

  • Inadequate documentation of the patient's symptoms.
  • Failure to document imaging results supporting the diagnosis.
  • Misclassification of chondromalacia severity.
  • Lack of clarity on associated conditions like meniscal tears.

Specialty Focus

Medical Specialties

Orthopedics

Documentation Requirements

Detailed notes on physical examination findings, imaging results, and treatment plans.

Common Clinical Scenarios

Patients presenting with knee pain, swelling, and functional limitations.

Billing Considerations

Documentation should clearly differentiate between chondromalacia and other knee pathologies.

Physical Therapy

Documentation Requirements

Progress notes detailing treatment interventions and patient responses.

Common Clinical Scenarios

Rehabilitation following arthroscopic procedures or conservative management of knee pain.

Billing Considerations

Focus on functional outcomes and improvements in range of motion.

Coding Guidelines

Inclusion Criteria

Use M22.42 When
  • Follow official ICD
  • 10 coding guidelines, ensuring that the diagnosis is supported by clinical documentation
  • Include any relevant imaging studies and treatment plans
  • 42 should be used when the left knee is specifically affected

Exclusion Criteria

Do NOT use M22.42 When
No specific exclusions found.

Related ICD-10 Codes

Related CPT Codes

29881CPT Code

Arthroscopy, knee, diagnostic, with or without synovial biopsy

Clinical Scenario

Used when performing arthroscopy to assess chondromalacia.

Documentation Requirements

Document indications for surgery and findings during the procedure.

Specialty Considerations

Orthopedic surgeons should ensure detailed operative reports.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for more specific coding of conditions like chondromalacia, improving the accuracy of diagnoses and treatment plans.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for more specific coding of conditions like chondromalacia, improving the accuracy of diagnoses and treatment plans.

Reimbursement & Billing Impact

The transition to ICD-10 has allowed for more specific coding of conditions like chondromalacia, improving the accuracy of diagnoses and treatment plans.

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 chondromalacia patellae?

Chondromalacia patellae is primarily caused by overuse, misalignment of the knee joint, or previous injuries that lead to cartilage degeneration.