Commentary & Perspective

Commentary & Perspective on
"Influence of Preoperative Factors on Outcome of Shoulder Arthroplasty for Glenohumeral Osteoarthritis"
by Joseph P. Iannotti, MD, PhD, and Tom R. Norris, MD

Commentary & Perspective by
Louis U. Bigliani, MD*,
The Shoulder Service, New York Presbyterian Medical Center, Columbia University, New York, NY

This is a very important and timely paper, which provides useful information to the orthopaedic surgeon and patient contemplating total shoulder arthroplasty for glenohumeral arthritis. Currently, there is controversy regarding the indications for and results of total shoulder replacement versus hemiarthroplasty. The findings reported by Iannotti and Norris can be used by surgeons and patients in the decision-making process regarding surgical treatment.

Several points in this paper deserve emphasis. First, both total shoulder arthroplasty and hemiarthroplasty provided significant improvement (p < 0.0001) in regard to pain, function, and range of motion, in comparison with preoperative values. There was, however, a trend (p = 0.10) toward a better functional outcome after total shoulder arthroplasty, according to the American Shoulder and Elbow Surgeons function score. These results parallel those of other investigators who have reported the results of total shoulder replacement to be better than those of hemiarthroplasty. One of the most important findings of Iannotti and Norris was the effect of preoperative glenoid erosion on the results of arthroplasty. Patients who had substantial glenoid erosion preoperatively had improved results in terms of range of motion after total shoulder arthroplasty in comparison with those after hemiarthroplasty. Although it is not specifically discussed in this article, one of the possible reasons for this difference in outcomes is that the humeral head is centered in the glenoid cavity during a glenoid replacement whereas it is not in hemiarthroplasty. Very few articles in the past have concentrated on this very important clinical finding in the treatment of osteoarthritis of the shoulder. In my practice, I have found that performing total shoulder arthroplasty in patients with glenoid erosion is a challenge, since it is technically difficult to expose the glenoid, and these patients often have a contracted subscapularis, which requires soft-tissue release. The authors' study would have been strengthened if they had investigated the effects of preoperative glenoid erosion and loss of external rotation and posterior subluxation as dependent variables.

Another factor that was analyzed as an independent variable was posterior subluxation of the humeral head. In patients with posterior subluxation, the results of both hemiarthroplasty and total shoulder replacement were inferior to those in patients without. In our experience, these patients often developed fixed soft-tissue contractures, which may be difficult to reconstruct adequately for the achievement of satisfactory range of motion.

In general, patients with osteoarthritis do not have large rotator cuff tears. In this study, more than 90% of the patients did not have a rotator cuff tear and the ones who did, had reparable tears. If the preoperative anteroposterior radiograph of the shoulder shows that the humeral head is centered in the glenoid fossa, one can infer that the rotator cuff is intact or has only a small tear. Superior migration of the humeral head usually indicates a massive rotator cuff tear. The authors concluded that small reparable tears of the supraspinatus tendon do not adversely affect the outcome of total shoulder arthroplasty. My experience supports this finding.

In conclusion, this paper provides information valuable to orthopaedic surgeons who perform shoulder arthroplasty. It helps both surgeon and patient to anticipate results realistically on the basis of a preoperative evaluation of factors most relevant to the outcome of shoulder arthroplasty for glenohumeral osteoarthritis.

*The author did not receive grants or outside funding in support of the research or preparation of this manuscript. He did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the author is affiliated or associated.