Knee Arthroscopy CPT Codes for 2025 

Orthopedic coding for knee procedures requires more than just knowing the procedural terminology, it demands a comprehensive understanding of knee anatomy, pathology, and surgical intent. Accurate coding not only impacts reimbursement but also supports clinical integrity, audit defense, and practice benchmarking.

The knee joint, being the largest and most complex in the body, is a modified hinge joint comprising three compartments within a single synovial cavity:

• Lateral Tibiofemoral Joint (Lateral Compartment): Between the lateral condyle of the femur, lateral meniscus, and lateral condyle of the tibia; a weight-bearing surface.
• Medial Tibiofemoral Joint (Medial Compartment): Between the medial condyle of the femur, medial meniscus, and medial condyle of the tibia.
• Patellofemoral Joint (Patellofemoral Compartment): Between the patella and the patellar surface of the femur.

Articular cartilage covers the ends of bones within the joint, while the synovium (synovial membrane) produces fluid that lubricates the joint. Understanding these structures is crucial for proper code selection during knee arthroscopic debridement and synovectomy procedures.

Difference Between Articular Cartilage and Synovium.

When coding arthroscopic knee procedures, it’s critical to distinguish between the articular cartilage and the synovium, as each has different functions, pathologies, and corresponding CPT codes. Misunderstanding their roles or confusing one for the other can lead to coding inaccuracies and claim denials.

• Synovium: Lining inside the joint capsule; inflamed in synovitis. Code: 29875 or 29876 (based on compartment count).
• Articular Cartilage: Covers bone surfaces within the joint. Code: 29877 for chondroplasty (cartilage debridement).

CPT 29875 vs CPT 29876: Limited vs Major Synovectomy

Accurate coding of knee arthroscopic synovectomy hinges on the number of compartments treated and the presence of other concurrent procedures. The CPT guidelines clearly distinguish between a limited synovectomy, involving a single compartment, and a major synovectomy, which spans two or more compartments. Misclassifying these codes can lead to claim denials or bundling issues.

• CPT 29875: Arthroscopy, knee, surgical; synovectomy, limited (e.g., plica or shelf resection) (separate procedure)
  Used when the synovectomy is performed in only one compartment and is not part of a more extensive arthroscopic procedure.
• CPT 29876: Arthroscopy, knee, surgical; synovectomy, major, 2 or more compartments (e.g., medial and lateral)
  Used when a medically necessary synovectomy is performed in two or more compartments, not overlapping with other arthroscopic procedures.

Important:

CPT 29875 should not be reported in conjunction with another arthroscopic procedure on the same knee (ipsilateral side), as it is considered part of the primary service. CPT 29876 can be reported only if the synovectomy is performed in compartments not involved in other billed arthroscopic procedures.

Debridement of Synovium vs Articular Cartilage

• CPT 29877: Reported when arthroscopic debridement of articular cartilage is performed.
• CPT 29875 or CPT 29876: Reported when the synovium is debrided this is considered a synovectomy, not cartilage debridement.

Clinical Coding Examples (2025)

• CPT 29875 – A 65-year-old male undergoes arthroscopic debridement of right knee synovitis in the medial compartment only. No other procedure is performed.
• CPT 29876 – A 62-year-old female has arthroscopic debridement of left knee synovitis in both the medial and lateral compartments.
• CPT 29877 – A 55-year-old male diagnosed with primary osteoarthritis undergoes articular cartilage debridement in both medial and lateral compartments of the left knee.

Key Takeaway for 2025

As of 2025, coding guidelines remain consistent with previous years, emphasizing the compartmental specificity and procedure intent. Proper use of knee arthroscopic debridement CPT codes such as CPT 29875, CPT 29876, and CPT 29877 ensures appropriate documentation and reimbursement.

CPT 29875 / CPT 29876 Documentation Audit Checklist

This audit checklist is designed to help coders, auditors, and providers verify that all necessary elements are clearly documented and aligned with CPT coding guidelines. Use this as a quality assurance tool before claim submission to reduce compliance risks and support medical necessity:

1. Operative Report Clarity

• Clearly states “arthroscopic synovectomy” performed.
• Specifies number of compartments involved (1 for 29875; 2 or more for 29876).
• Anatomical locations (e.g., medial, lateral, patellofemoral) are documented.
• Procedure intent: debridement of synovium (not cartilage).

2. Code Appropriateness

• CPT 29875 used only if synovectomy was limited to one compartment.
• CPT 29876 used only if synovectomy was performed in two or more compartments.
• Not bundled with another arthroscopic procedure unless justified with separate compartments or medical necessity.

3. Exclusion Criteria & Bundling Rules

• CPT 29875 not billed with other arthroscopic procedures on same knee (e.g., meniscectomy) unless modifier -59 or appropriate NCCI guidelines support it.
• CPT 29876 only billed if synovectomy is not part of the other primary arthroscopic procedure in the same compartment.

4. Medical Necessity

• Includes a clear diagnosis (e.g., synovitis, rheumatoid arthritis).
• Procedure was medically necessary—not exploratory or incidental.
• Includes pre-operative imaging or findings supporting the need for synovectomy.

5. CPT Language Accuracy

• Use the correct CPT descriptor language in documentation.
  • 29875: “synovectomy, limited”
  • 29876: “synovectomy, major, 2 or more compartments”

6. Laterality

• Indicates right or left knee.
• Matches with ICD-10-CM laterality (e.g., M65.861 – Synovitis, right knee).

7. Modifier Usage

• Modifier -RT or -LT applied as appropriate.
• Modifier -59 used when synovectomy is distinct from other arthroscopic procedures performed on different compartments.

8. Pathology or Findings

• Documentation of inflammation, hypertrophic synovium, or other synovial pathology.
• If biopsy performed, ensure it is also clearly documented (and consider CPT 29879).

9. Billing Support

• All procedure notes, diagnostic imaging, and path reports attached or referenced.
• Consistency between operative notes, billing sheet, and coding submitted.

10. Common Errors to Avoid

• Coding synovectomy for cartilage debridement, should be CPT 29877.
• Using CPT 29876 when only one compartment was involved.
• No documentation of number of compartments, leads to downcoding or denials.