When the American Medical Association (AMA) published the first edition of Current Procedural Terminology (CPT) to standardize surgical procedure terminology and reporting, modern arthroscopy was in its infancy and no CPT code described it. As the number of arthroscopies for knee, shoulder, and hip conditions has exploded during the past few decades, CPT has attempted to address the reporting needs of these procedures. However, the constant clinical and technological advances, and the fact that CPT is only updated annually, have resulted in codes that lag behind common techniques. This scenario, in turn, has generated a good deal of confusion among surgeons and coders about how to correctly report and bill for these services.

The next CPT code changes to arthroscopic codes are scheduled for January 2019. To ensure correct coding until then, AAOS Now will present essentials for coding the most common arthroscopy codes. This month focuses on the knee; subsequent issues will feature shoulder and hip codes.

Know these modifiers: 51 and 59
One area of confusion for arthroscopic knee, shoulder, and hip coding is modifier usage. The most commonly used modifiers for arthroscopy are 51 (multiple procedures) and 59 (distinct procedural service).

Modifier 51 appended to a code indicates that the procedure is a secondary procedure and it is expected that reimbursement will be reduced. Therefore, for most payers, the code with the greatest number of relative value units (RVUs) should be listed first, followed by the lesser codes with the modifier 51. Medicare, however, does not want codes submitted with the modifier 51, stating that its software will automatically arrange the codes with the greatest value first and the other lesser codes subsequently.

Scrutiny on the use of modifier 59 has increased due to its high frequency usage. When two or more procedures are performed during the same surgical session and the potential for confusion about service overlap or duplication exists, use modifier 59 if the codes meet the criteria for separate reporting and ensuring payment. Specifically, modifier 59 can be used to indicate a different session, a different procedure or surgery, or a different anatomic site or organ system, where there may be a separate incision or excision. Modifier 59 may indicate a separate lesion or a separate injury, not ordinarily encountered or treated on the same day by the same individual.

With so many potential reasons to use modifier 59, the U.S. Centers for Medicare & Medicaid Services (CMS) created "X" subsets (E, S, P, and U) that were to be effective January 2015. CMS has not yet mandated the use of these subsets, but many other carriers are either accepting or mandating that they be used.

The four modifier subsets are as follows:

• XE – separate encounter on the same date of service
• XS – separate structure or organ
• XP – separate practitioner
• XU – unusual nonoverlapping service of the main service provided

These subset codes increase the granularity of modifier 59 usage and permit data collection on the reasons for its use.

As with all modifiers, appending modifiers 51 and 59 with arthroscopy codes depends on a carrier's payment policies, which are generally available on the carrier's web site. In general, carrier policies follow either CPT rules or CMS rules. The fact that there is not one standard is frustrating. But once a coding team learns the requirements for each payer, the practice see improvements in reimbursement and reductions in denials.

Coding for knee arthroscopy
The knee joint has three compartments (medial, lateral, and patellofemoral). The compartment and the type of surgery performed typically determine the bundling and unbundling of codes. For help in coding these and other procedures, refer to the AAOS Global Service Data contained in Code-X, or some other coding product that can assist with understanding the bundling and unbundling of procedures.

The most common knee arthroscopy procedure is a menisectomy, and chondroplasty is also frequently performed at the same time. In 2012, chondroplasty became included with menisectomy (29880 and 29881) regardless of the compartment.

However, chondroplasty is not included when it is performed in a different compartment than a meniscal repair (29882 and 29883). Therefore, if a meniscal repair is performed in the medial compartment, it is permissible to bill for a chondroplasty (29877) in either the lateral compartment or the patellofemoral compartment.

Coding arthroscopic removal of a loose or foreign body can be done in two ways. Under CPT coding, a dedicated code (29874) can be used for arthroscopic removal of a loose or foreign body. If this code is used, the loose or foreign body must be larger than 5 mm or it must be removed through a separate incision.

In 2002, CMS created an add-on code (G0289), which can be used to describe either removal of loose body or débridement of articular cartilage (chondroplasty) at the same time another knee arthroscopy procedure is performed in a different compartment of the same knee. G0289 may only be reported for removal of a loose or foreign body with a menisectomy code if the body was removed from a different compartment of the same knee.

Another area of high usage is a limited synovectomy (CPT code 29875). This procedure is universally considered inclusive to any more extensive procedure performed in the same anatomic site and is not separately reportable. It is only reportable if it is the only procedure performed. Although a second synovectomy code exists (29876 – major synovectomy two or more compartments when performed), it should not be used for a cleanup of hypertrophic synovium. It is to be used only when the synovium has an underlying pathology such as rheumatoid arthritis or pigmented villonodular synovitis.

When submitting codes for reimbursement, make sure that the work being billed is documented as medically necessary, based upon the diagnosis, and that it is not already bundled into another code.

Next month look for Part II – Arthroscopy of the Shoulder and Hip

Michael R. Marks, MD, MBA, is a senior KZA consultant and president of Marks Healthcare Consulting. He serves on the AAOS Patient Safety and Medical Liability committees and cochairs the Communications Skills Mentoring Program. He can be reached at mmarks1988@gmail.com.

Editor's note — This article is the first of a two-part series about arthroscopy coding. The next installment will be published in the March issue of AAOS Now.