Hip and knee arthroplasty procedures have been under scrutiny by both Medicare Administrative Contractors and Recovery Audit Contractors. Although the primary concern has been adequate documentation of medical necessity, accurate coding of primary, revision, and conversion arthroplasty procedures is also important. This article addresses the definitions associated with primary, revision, and conversion arthroplasty procedures and codes specific to hip and knee arthroplasty procedures.

Procedure Codes
Table 1 lists the CPT codes that define primary total hip and knee arthroplasty procedures, revision hip and knee procedures, and conversion to total hip arthroplasty. Note that there is no CPT code for a conversion to total knee arthroplasty.

Table 2 lists the procedure code(s) that may be reported when treating an infected joint. The three codes cover the insertion of an antibiotic-impregnated cement spacer (11981), its removal (19982), and the exchange (11983).

CPT code 11981 should be reported with CPT code 27091 or CPT code 27488 when the implant is removed and an antibiotic-impregnated cement spacer is placed. CPT code 11982 should be reported for the second staged procedure, when the implant is removed and a conversion to either a total hip arthroplasty (27132) or a total knee arthroplasty (27447) is performed.

Definitions
The following definitions describe the terms integral to selecting the appropriate arthroplasty procedure code, especially for revisions or conversions.

A primary arthroplasty occurs when the native joint surface(s) are replaced with artificial implants. For example, a patient with severe osteoarthritis of the hip has a total hip arthroplasty. The surgeon reports CPT code 27130.

A revision arthroplasty occurs when the prior arthroplasty components are removed and replaced with new components in a single surgical procedure. For example, the patient had a total knee arthroplasty 3 years ago. The surgeon removes the femoral component and replaces it with a new component. The surgeon reports CPT code 27486 (revision of total knee arthroplasty, with or without allograft; 1 component).

If the joint is infected, however, and the patient must be treated with antibiotics before a new component can be inserted, the procedure is not considered a revision arthroplasty. For example, the surgeon removes an infected hip prosthesis and places an articulating spacer. The patient will receive 6 weeks of intravenous antibiotics before the surgeon can replace the spacer with a permanent prosthesis. The surgeon reports the following CPT codes:

• 27091 (removal of hip prosthesis; complicated, including total hip prosthesis, methylmethacrylate with or without insertion of spacer)
• 11981-51 (insertion, non-biodegradable drug delivery implant)

CPT code 27134 (revision of total hip arthroplasty; both components, with or without autograft or allograft) should not be used because this is not a revision procedure. It is only the removal of the prosthesis and insertion of spacer.

A conversion occurs when the patient has had prior open surgery with or without retained hardware (eg, plates, screws, dynamic hip screws, antibiotic spacers) that are removed and replaced with arthroplasty components. For example, the surgeon removes an infected hip prosthesis from a patient who had a total hip arthroplasty 2 years ago and places an antibiotic-impregnated cement spacer. The surgeon reports the following CPT codes:

• 27091 (removal of hip prosthesis; complicated, including total hip prosthesis, methylmethacrylate with or without insertion of spacer)
• 11981-51 (insertion, non-biodegradable drug delivery implant)

Six weeks later, the surgeon returns the patient to the surgical suite for a conversion to total hip arthroplasty. The surgeon reports the following CPT codes:

• 27132-58 (conversion of previous hip surgery to total hip arthroplasty, with or without autograft or allograft)
• 11982-58, 51 (Removal, non-biodegradable drug delivery implant)

Modifier 58 is appended because this is a prospectively staged procedure performed during the global period.

An infection may be treated in a single surgical session or it may be treated in two or more stages depending on the organism and its virulence. If the infection is treated in two sessions (staged management), during the first operation the prior prosthesis(es) are removed, with or without insertion of an antibiotic spacer or removal and reinsertion of a spacer.

For example, the surgeon performs a total knee arthroplasty on a 78-year-old male patient. During the global period, the surgeon returns the patient to the surgical suite for an arthrotomy, irrigation, and débridement. The surgeon removes the polyliner to access the posterior knee and replaces it with a new polyliner at the end of the surgery.

The surgeon reports CPT code 27310-78 (arthrotomy, knee, with exploration, drainage, or removal of foreign body [eg, infection]). This is not a revision case or a staged procedure, even though the surgeon exchanged the polyliner. The polyliner was removed to allow access to the posterior knee.

Documentation Tips
Orthopaedic surgeons can avoid coding errors by clearly documenting an indication for surgery and including the procedure title in each operative note. Consider the following documentation tips when dictating the operative notes:

1. Include an indication for surgery paragraph. Include a statement related to subsequent planned procedures in the first operative note and document each stage of the subsequent procedures.
2. Document conservative therapy, or medical reasons for not prescribing conservative therapy.
3. Integrate history notes from the referring physician, if they are relevant.
4. Use key terms such as “revision” and “conversion” in the procedure title. Remember, the knee does not have a conversion CPT code.
5. Document the global period dates.
6. Document increased physician work, complexity, medical comorbidities and time, to support the use of modifier 22 when appropriate.

In addition, remember the Medicare documentation requirements for primary, revision, and conversion joint procedures.

Mary LeGrand, RN, MA, CCS-P, CPC, is a senior 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.