Orthopedic Coding Alert

Case Description

A bipolar arthroplasty of the left shoulder has failed. A surgeon and an assistant surgeon perform a revision bipolar arthroplasty.

The most common problem that warrants revision is instability. For example, the shoulder prosthesis may dislocate repeatedly. The arthroplasty also would be called a failure if excessive scarring caused reduced range of motion. (On rare occasions arthroplasties also fail because of infections or neurovascular damage.)

Procedure

Before reviewing the operative notes below for this specific case, its helpful to understand the difference between a total shoulder revision and a hemiarthroplasty. In a total shoulder revision, the surgeon removes and replaces the surface of the humeral head and the glenoid. In a hemiarthroplasty, only the humeral surface is replaced. But in the following case study, all of the glenoid and only part of the humeral component were replaced; hence, the term bipolar.

Operative Note

The previous incision was utilized. Subcutaneous tissue was divided. The skin was very friable and would tear at the slightest pressure. The deltoid was retracted. The cephalic vein was free but during the procedure it was torn in a manner that required ligation.

The anterior shoulder capsule was exposed and the subscapularis and capsule were removed in one layer. The entire bipolar head was dislocated anteriorly. It was also noted that there had been loss of the superior half of the glenoid. After long tissue dissection and freeing of retractures, the bipolar head was delivered into the wound and removed.

Due to the tightness of the tissue as well as the scarring and friability, long-term mobilization was carried out to regain the ability to expose the glenoid. The glenoid was inspected. The patient was noted to have loss of the superior 30 percent. This was from chronic superior dislocation of the bipolar prosthesis. This was evaluated and options were considered including bone grafting. Because of this patients compromised immune state, it was not felt that this was a viable alternative. It was felt it would be in his best interest to fashion a methyl methacrylate support for the glenoid prosthesis. The glenoid was then sequentially prepared to accept the custom glenoid component. This was quite lengthy in time because of the bulk of the custom implant required to prevent superior migration.

After extensive soft tissue manipulation and lengthening the exposure distally and proximally, the trial was placed. Some modification in the glenoid component was carried out with an Anspach saw to remove areas which were causing impingement. The glenoid was then completed as far as preparation. Trial reductions were carried out and it was initially thought that there would be continued upward subluxation. However, the custom bipolar head which had been prepared seemed to satisfactorily prevent this.

K-wires were placed in the area of the deficit to act as cement anchors. The cement was mixed and the custom glenoid component was cemented in place. There was no area superiorly for screw fixation but a screw was placed in the inferior aspect for initial fixation. At this time, the custom bipolar head was applied and the shoulder was reduced. It was found that the shoulder attempted to migrate superiorly to the maximum extent of the restraining cup but control of this tendency was felt to be satisfactory. The wound was copiously irrigated. The capsule and subscapularis were retracted through pull-out sutures to the bone, followed by closure of the subcutaneous tissue with 3-0 Vicryl and the skin with staples.

Estimated blood loss was 300 cc. The only complication was ligation of the cephalic vein. The patient was placed in a shoulder immobilizer and taken to the recovery room in stable condition.

Coding Principles

Joint replacements are among the most common procedures performed in orthopedicsabout half a million hip and knee arthroplasties are done each year. However, shoulder replacements are performed less frequently. So, as often occurs with newer procedures, coding conventions reflect a lack of options. For example, the CPT does not contain comparable revision codes for shoulders like its revision codes for total hip arthroplasty (27134-27138), or the revision codes for total knee arthroplasty (27486-27488).

The alternative is to use modifiers and select among the following to best represent what occurred during the shoulder revision:

A total shoulder replacement is indicated by 23472 (total shoulder, glenoid and proximal humeral replacement)

A hemiarthroplasty is indicated by 23470 (arthroplasty, glenohumeral joint)

23330-23332 (removal of foreign body, shoulder)

This is a tough call, acknowledges Christine Banks, RRA, CPC, an orthopedic coding specialist, Massachusetts General Hospital in Boston, MA.

In a total shoulder (23472), both the glenoid and the humeral components are replaced. In a hemiarthroplasty (23470) only the humeral component is replaced. But in this procedure the entire glenoid was replaced and only part of the humeral component was replaced, thus causing the coding dilemma.

One approach is to modify the 23470 with -22 (unusual procedural services).

I made this decision [23470 rather than 23472] by carefully comparing the CPT descriptions of the knee and hip procedures we do, says Dawn Carpenter, CPC, billing manager, Ortho Associates of Grand Rapids, MI.

She recommends the use of modifier -22, because the op notes continually use phrases that show how complicated the procedure was. Terms such as tightness, extensive scarring, lengthy procedure, extensive manipulation, modification in the glenoid component justify the additional reimbursement, she explains.

Based on the AMAs CPT Companion, Carpenter would also add 23332 (removal of foreign body, shoulder, complicated) for the removal of the old prosthesis. But, because the procedure was not a total shoulder revision as discussed in the Companions scenario, Carpenter suggests append modifiers -51 (multiple procedures) and -52 (reduced services). (Remember only the glenoid component, not the humeral, was removed and replaced.)

But Banks says code 23331 (removal of foreign body, shoulder, deep) modified by -51 (multiple procedures) better describes the procedure. With this code, you wouldnt have to append the -52 modifier, she says.

She adds that there is a potential argument for using code 23472. The description in the CPT manual represents the procedure as performed several years ago when it did not include just the removal of the ball portion of the humerus.

So you could go with 23472 instead of 23470, using the rationale that 23470 implies that only the humeral surface was replaced. But in reality two separate sites were replaced: one on the glenoid and one on the humerus, she says. If she were to code for the total shoulder replacement, she would not code for the removal of the glenoid and humeral component as well, she adds.

The appropriate diagnosis code would depend on the reason for the failure:

996.5 (mechanical complication of internal orthopedic device);

996.66 (infection or inflammatory reaction due to internal joint prosthesis); or

996.77 (other complications due to internal joint prosthesis).