Coding knee arthroscopies can be challenging for both physicians and coders—especially when the surgeon performs multiple procedures, one of which is documented as a synovectomy. Although the rules may seem straightforward, they are not as clear as they appear.

Synovectomy procedures in the knee
Synovium is the smooth lining of the joint that produces synovial fluid to lubricate the joint. Every surgical procedure in the knee includes synovial resections to clean up the joint for visualization. The following CPT codes describe synovectomy procedures in the knee:

• 29875: Arthroscopy, knee, surgical; synovectomy, limited (eg, plica or shelf resection) (separate procedure)
• 29876: Arthroscopy, knee, surgical; synovectomy, major, 2 or more compartments (eg, medial or lateral)

CPT code 29875, limited synovectomy, is described as a “separate procedure.” This means that the work associated with this procedure is inclusive to more extensive procedures performed in the same anatomic site (the knee) and is not separately reportable. This code should only be reported if it is the only procedure performed; separate compartment rules do not apply.

CPT code 29876 describes a major synovectomy and may be reported in two or more compartments when performed. This is where the coding becomes a bit confusing.

Medical necessity
Surgeons commonly perform a synovectomy in addition to other procedures to “clean up” the joint while performing more extensive surgery. Reporting either synovectomy CPT code (29875 or 29876) for these surgical cases would not be appropriate.

For example, a surgeon may document performance of a medial meniscectomy and a tricompartmental synovectomy. Simple documentation, however, does not automatically allow reporting of both the major synovectomy code 29876 and the meniscectomy code 29881 (Arthroscopy, knee, surgical, with meniscectomy [medial OR lateral, including any meniscal shaving] including debridement/shaving of articular cartilage [chondroplasty], same or separate compartment[s], when performed) to payers.

To report both procedures, the surgeon should document the medical necessity and the performance of a “synovial resection” for pathology—not just cleaning up loose synovium that might be fibrillating in the joint.

The AAOS has previously described common diagnoses that support the medical necessity for major arthroscopic synovectomy in two or more compartments (code 29876). This includes, but is not limited to, the following:

• 714.0—Rheumatoid arthritis
• 714.1—Felty’s syndrome
• 714.30—Polyarticular juvenile rheumatoid arthritis, chronic or unspecified
• 714.32—Pauciarticular juvenile rheumatoid arthritis
• 714.33—Monoarticular juvenile rheumatoid arthritis
• 716.96—Arthropathy, unspecified, lower legArthritis (acute) (chronic) (subacute)
• 719.26—Villonodular synovitis, lower leg
• 719.86—Other specified disorders of joint, lower leg Calcification of jointFistula of joint

Coding examples
The following examples illustrate the use and rationale for reporting various arthroscopic knee
procedures.

Example A: The patient is diagnosed with a medial meniscal posterior horn tear and synovitis. The surgeon performs a medial meniscectomy and medial compartment synovectomy. The CPT code that should be reported is 29881.

Rationale: CPT code 29875 is a limited synovectomy (separate procedure) and can’t be reported if any other arthroscopic knee procedure is performed on the same knee in the same session. The rules for surgery in a “separate compartment” do not apply. No pathologic synovial disease requiring a major synovectomy was documented.

Example B: The patient is diagnosed with a lateral meniscal anterior horn tear and synovitis. The surgeon performs a lateral meniscectomy and a synovectomy in the patellofemoral compartment. The CPT code that should be reported is 29881.

Rationale: This situation is similar to the previous example and the same rationale applies.

Example C: The patient is diagnosed with a medial meniscal posterior horn tear, a lateral meniscal anterior horn tear, and synovitis. The surgeon performs a medial and lateral meniscectomy with a medial and lateral compartment synovectomy. The CPT code that should be reported is 29880.

Rationale: No pathologic synovial disease requiring a major synovectomy was documented.

Example D: The patient is diagnosed with a medial meniscal posterior horn tear, a lateral meniscal anterior horn tear, and synovial chondromatosis. The surgeon performs a medial and lateral meniscectomy and a tricompartmental synovectomy to treat the red, swollen, and inflamed synovium. Tricompartmental synovectomy includes the posteromedial and posterolateral portions of the joint accessed through posterior portals. The CPT codes that should be reported are 29876 and 29880.

Rationale: In this case, pathologic synovial disease requiring a major synovectomy was documented.

Example E: The patient is diagnosed with a medial meniscal posterior horn tear and synovial chondromatosis. The surgeon performs a medial meniscectomy and a tricompartment synovectomy to treat the red, swollen, and inflamed synovium. Tricompartmental synovectomy includes the posteromedial and posterolateral portions of the joint accessed through posterior portals. The CPT codes that should be reported are 29876 and 29881.

Rationale: As in the previous example, pathologic synovial disease requiring a major synovectomy was documented.

Reporting surgical procedures for reimbursement must always include documentation of the procedure and the medical necessity for performing the procedure. The diagnosis code communicates the medical necessity to payers, and the CPT code identifies the procedure. Although CPT descriptors may seem straightforward, understanding the nuance of terms such as “separate procedure” and the medical necessity requirement can make coding more difficult.

Action Steps

• Ensure that both the pre- and postoperative diagnoses support the medical necessity of the surgical procedures.
• Document an “Indication for Surgery” paragraph that includes past medical conditions or injuries, radiologic findings, the acute nature of injury, or the failure of conservative therapy.
• Detail each procedure and all findings (including documentation of pathologic synovium) in the body of the operative note.
• Report the synovial resection when medical necessity is present; resist reporting CPT code 29876 unless medical necessity is documented along with a separate ICD-9 code.

Mary LeGrand, RN, MA, CCS-P, CPC, is a consultant with KarenZupko & Associates, Inc., who focuses on coding and reimbursement issues in orthopaedic practices. Information in this article has been reviewed by members of the AAOS Coding, Coverage, and Reimbursement Committee