With the exponential rise in the number of total shoulder arthroplasties being performed, the issue of implant longevity continues to concern many orthopaedic surgeons. Clearly, the reported results of total shoulder arthroplasty for primary glenohumeral osteoarthritis are very good in terms of pain relief and function in most cases. This is because, in this disease cohort, the patient’s soft tissues and bone stock are usually well preserved. In spite of even better outcomes as a result of the development of improved and more anatomically designed implants and a better understanding of the importance of proper soft-tissue balancing, many surgeons remain concerned about the long-term outcomes of these total shoulder prostheses. This concern is particularly important because many younger symptomatic patients are now considered to be candidates for these reconstructions more frequently.
Many of these younger patients, who are usually less than fifty years of age, receive a recommendation to have humeral head surface replacement or hemiarthroplasty with or without biologic glenoid resurfacing in an attempt to give pain relief and improve function while avoiding glenoid component failure. Unfortunately, the results of these procedures are less satisfactory both in the short and long term and, for this reason, many more such patients are now receiving a recommendation to undergo primary total shoulder arthroplasty at an earlier age. In these situations, it becomes critically important to understand the inherent risks related to implant longevity in order to appropriately inform and counsel these patients preoperatively.
Historically, glenoid component failures have been the paramount concern with regard to the longevity of total shoulder prostheses1, despite the fact that most recent reports indicate that late soft-tissue failures, including instability and rotator cuff failures, are more prevalent2,3.
To this end, Young et al. have given us important new insight into implant longevity in their excellent moderate-to-long-term multicenter study of rotator cuff dysfunction and glenoid failure in more than 500 patients after total shoulder arthroplasty. This retrospective study, which had a very high percentage of followed patients, is not without flaws by the authors’ own admission. It does, however, enlighten us about the long-term soft-tissue changes that affect outcomes in this patient cohort and gives us another cause for concern in our selection of the proper procedure in younger patients with glenohumeral osteoarthritis. This is especially true since, in multiple studies on revision shoulder arthroplasty, the patients who underwent revision as a result of component failure had significantly better results than patients who underwent revision as a result of soft-tissue failure4.
The strength of the paper by Young et al. is that it sends a clear message to orthopaedic surgeons who perform shoulder arthroplasty—that message being that the procedure must be done precisely in terms of glenoid component positioning, as a superior facing glenoid and preoperative infraspinatus muscle atrophy were predictors of rotator cuff dysfunction in this study. The authors are clear in their explanation of possible reasons for this soft-tissue failure, including the effects of joint constraint, tendon age, and overuse mechanics.
Some might consider the study flawed because of the indirect-plane x-ray method that was used to find rotator cuff dysfunction in these patients; however, this method has been used in other research studies that have been published in major orthopaedic journals5.
Finally, the important “take-home” message of this paper is that surgeons should minimize risk in patients who are candidates for total shoulder arthroplasty by conducting a complete workup, including the acquisition of multidimensional views with use of magnetic resonance imaging and computed tomography, and by paying strict attention to surgical detail when placing the component. In addition, in counseling patients for consideration of total shoulder arthroplasty, surgeons should explain that soft-tissue failure is also a risk in some patients who have underlying rotator cuff disease and in patients who may be inclined to overuse their shoulder following arthroplasty.