Rheumatoid and other forms of inflammatory arthritis often have symptomatic destruction of the glenohumeral joint compounded by osteopenic bone, thinning of the rotator cuff tendons, and involvement of the joints of the lower extremity. Patients with disabling glenohumeral inflammatory arthritis may have reverse shoulder arthroplasty (RSA) or anatomic total shoulder arthroplasty (TSA).

RSA may be considered because of glenoid and humeral bone erosion and rotator cuff insufficiency, but acromion and scapular spine fractures are not uncommon following RSA in patients with inflammatory arthropathy, can negatively impact the clinical outcome of this procedure, often go on to non-union, and are often not amenable to surgical repair.

While anatomic TSA may be followed by rotator cuff failure, the survivorship of anatomic arthroplasty for inflammatory arthropathy is better than that for osteoarthritis (data from AOANJRR)

The authors of Comparison of Reverse Shoulder Arthroplasty and Total Shoulder Arthroplasty for Patients with Inflammatory Arthritis report two year clinical outcomes and complications in their patients undergoing RSA (n=43) and TSA (n=43) performed for glenohumeral inflammatory arthritis by an individual high volume surgeon using the same post operative protocol.

Patients had an average age of 72.1 years (range, 31-92 years) with follow-up averaging 51.6 months (range, 22-159 months).

While both groups had similar and poor preoperative comfort and function as reflected by Simple Shoulder Test (SST) scores of 2.4 to 2.5 out of 12, the two patient cohorts were not the same. Patients having RSA were older (average 75 years) than those having TSA (average 69 years). Preoperatively the rotator cuff was intact for all patients having TSA but for only 26% of patients having RSA. Patients having RSA were more likely to have ascending and destructive types of arthritis as opposed to the centered type that was prevalent in the TSA group.

Three patients in TSA group had rotator cuff failure at 5 years, 7 years, and 9 years post-surgery, each of which led to surgical revision at an average of 6.6 year after the TSA. There were two separate cases of glenoid loosening occurring at 2.5 years and 6 years after surgery; these were not revised.

There were four acromion fractures in the RSA group (9%), none of which was treated surgically. One RSA revision was performed for infection.

Excluding the revisions, patients treated with TSA demonstrated significantly greater postoperative final SST scores, VAS function, active elevation, active external rotation, active internal rotation, and SANE score as well as greater improvements in these scores.

The authors concluded that TSA for patients with inflammatory arthritis led to improved clinical outcomes, lower complication rates, and higher revision rates when compared to RSA. RSA outcomes were negatively impacted by a high rate of postoperative acromion fractures.

Comment: In considering the results of this study, it is important to recognize that the patients in each group were different: on average the RSA group was older, had worse pathoanatomy, and were more likely to have rotator cuff tears. These factors - individually or in combination - may make the patient a poorer candidate for anatomic total shoulder arthroplasty. Because the patients were not matched for these important characteristics, the outcomes cannot not be statistically compared.

This paper is important in that it points out that while both TSA and RSA can yield improvements in outcome measures that exceed the minimal clinically important difference (MCID) for patients with inflammatory arthropathy, the two procedures have different vulnerabilities. The TSA carries the risk of rotator cuff failure while RSA carries the risk of acromial/scapular spine fractures. The former can be treated by revision to an RSA; the treatment of the latter can be difficult (see Acromion and spine fractures after reverse total shoulder arthroplasty - what little do we know?).

It is important to warn prospective patients of the complications of the two procedures. It may also be important to advise patients that the outcome of arthroplasty for inflammatory arthropathy may not match that of arthroplasty for osteoarthritis. It is unknown whether modification of activities after surgery may reduce the risks of cuff failure and acromial fractures in patients having arthroplasty for inflammatory arthropathy.

Finally, as pointed out in Cuff tear arthropathy in a young 60 year old woman managed with the CTA hemiarthroplasty TSA and RSA may not be the only options for treating the shoulder with inflammatory arthritis.

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