Orthopedic Coding Alert

Guest Columnist:

Bill Mallon, MD - Know Your Knee Compartments to Select Arthroscopy Codes

Published on Fri Jul 01, 2005

A surgeon's perspective on gleaning codes from op reports

If your practice suffers from the occasional disconnect between the surgeon's notes and the coder's code assignment, you may benefit from a knee coding primer from a physician's perspective. Knowing how the knee is put together can help you select the right code and can help you understand when it's inappropriate to bill certain codes with arthroscopies.

Background: The knee joint is the largest joint in the body. Anatomists and orthopedists usually describe it as having three compartments. A common term in an orthopedist's chart is a patient described as having "tri-compartmental osteoarthritis," meaning that all three compartments are involved with arthritic change.

Separate-Compartment Procedures Can Be Paid

The compartments are important for coding because the National Correct Coding Initiative bundles procedures that surgeons perform in the same compartment. For example, if one performs a medial meniscectomy and a concurrent synovectomy on the medial side of the knee, the surgeon may only charge one code in this situation, because both structures are in the same compartment.

The three compartments are the medial compartment, the lateral compartment, and the patello-femoral compartment. The medial and lateral compartments are described more accurately as the medial femoral-tibial compartment and the lateral femoral-tibial compartment.

The knee includes another anatomic region, termed the intra-articular notch. This is the open posterior area of the femur between the medial and lateral femoral condyles. It is an oft-operated region, because it contains the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL), but it is really not considered a "compartment" for coding purposes.

Know Anatomic Terms to Select Code

Op Report Tip: If you see any of the following terms in your surgeon's operative note, you'll know that the procedure occurred in the medial compartment:

Medial meniscus - anterior and posterior horns

Medial femoral condyle

Medial tibial plateau

Medial ligamentous structures - medial collateral ligament (internally).

Look for the following terms to indicate that the surgeon addressed the lateral compartment:

Lateral meniscus - anterior and posterior horns

Lateral femoral condyle

Lateral tibial plateau

Lateral ligamentous structures - lateral collateral ligament (internally) and the popliteus tendon.

You can rest assured that the surgeon addressed the patello-femoral compartment if he documents the following:

Surgery in the deep surface of the patella or the superficial surface of the anterior femur, usually termed the "trochlear groove."

Be on the lookout: A fibrous structure, termed a "plica," may be found in the knee and is most often located in the patello-femoral compartment, although it could be in any compartment. If you're unsure of the location of the plica that your surgeon documents, ask the physician specifically which compartment he addressed.

1 Compartment Leads to 1 Code

Payers usually interpret the NCCI edits to mean that only one code may be reported for every compartment that the surgeon addresses.

For example: This problem often occurs when a patient has a meniscal tear and a concomitant osteochondral defect in the same compartment, usually a defect on the medial femoral condyle.

During arthroscopy, most surgeons will address both problems, performing a medial meniscectomy (or repair), and shaving the osteochondral defect, termed a "chondroplasty" for coding purposes. The codes for these are 29881 (Arthroscopy, knee, surgical; with meniscectomy [medial OR lateral, including any meniscal shaving]) or 29882 (... with meniscus repair [medial OR lateral]), and 29877 (...debridement/shaving of articular cartilage [chondroplasty]).

But the NCCI bundles 29877 into both 29881 and 29882, and you cannot report them together if the procedures are done in the same compartment.

Exception: If a non-Medicare patient has a medial meniscal tear and a lateral femoral osteochondral defect, you could report 29881 or 29882 with 29877-59 (Distinct procedural service) for the chondroplasty, indicating that you can bypass the NCCI edit because the surgeon addressed two different compartments.

If Medicare covers the patient, you should report 29881 or 29882 with G0289 (Arthroscopy, knee, surgical, for removal of loose body, foreign body, debridement/ shaving of articular cartilage [chondroplasty] at the time of other surgical knee arthroscopy in a different compartment of the same knee). Again, the surgeon must perform the chondroplasty in a different compartment if you want to collect.

Documentation Is the Key to Reimbursement

Thorough documentation is critical in either case, to prove fully that the surgeon performed the procedures in different compartments.

Tip: One of my partners has a nice solution to this. He dictates his notes using separate paragraphs for each compartment, with a header on each paragraph, and places the code at the end of each paragraph. It looks something like this:

Patello-Femoral Compartment. The patello-femoral compartment was inspected fully. No abnormalities were found.

Medial Compartment. In the medial compartment, a flap tear of the medial meniscus was found. This was excised using a motorized shaver (29881).

Lateral Compartment. In the lateral compartment, no meniscal tear was noted. An osteochondral defect was found on the lateral femoral condyle. This was debrided to a smoother surface using a motorized shaver (29877-59).

Intra-Articular Notch. The intra-articular notch was inspected fully and a probe used to test the ACL and PCL. No abnormalities were found.

As you might suspect, he gets reimbursed almost maximally for his knee arthroscopies. Learn your knee compartments and have your surgeons document them separately and you can optimize your op notes to maximize your coding reimbursement.

- About the author: Bill Mallon, MD, is a practicing orthopedic surgeon and the medical director at Triangle Orthopaedic Associates in Durham, N.C.