CORR Insights®: A Comparison of Revision Rates for Osteoarthritis of Primary Reverse Total Shoulder Arthroplasty to Primary Anatomic Shoulder Arthroplasty with a Cemented All- polyethylene Glenoid: Analysis from the Australian Orthopaedic Association National Joint Replacement Registry

Where Are We Now?

With the growing success of reverse total shoulder arthroplasty (rTSA), the volume of the procedure has increased and the indications for its use have expanded [15]. Surgeons initially used the procedure for rotator cuff tear arthropathy and rotator cuff deficiency, where rTSA has been shown to reproducibly improve pain, function, and patient-reported outcome measures (PROMs) [2]. Now, common indications for the procedure include treatment of acute, displaced proximal humerus fractures in older patients and sequelae of fractures [3], glenohumeral osteoarthritis with an intact rotator cuff and advanced glenoid bone loss or dysplasia [8], and revision shoulder arthroplasty [1]. Primary rTSA is used even more than anatomic total shoulder arthroplasty (aTSA) [9], with both implant designs being utilized in the setting of advanced glenohumeral osteoarthritis (OA).

But there remains limited information on the differences in outcomes and survivorship between rTSA and aTSA when indicated for glenohumeral OA [9, 11, 15]. Some retrospective case control studies have demonstrated similar value and clinical outcomes, including PROMs, when directly comparing both procedures for glenohumeral OA, but have been limited by small sample size and short-term follow-up. There remains a need for longer-term, larger-scale prospective studies that allow for multivariable analysis to control for confounding factors such as age, gender, and medical comorbidities. Large national registries of arthroplasty implants with a high rate of data collection also have the potential to address these limitations to fill in some of these knowledge gaps and help us to better understand differences in outcomes and longevity across different shoulder arthroplasty types.

Enter the study by Gill et al. [5], which used the Australian Orthopaedic Association National Joint Replacement Registry to evaluate the risk of revision for aTSA with an all-polyethylene glenoid component compared to rTSA when indicated for glenohumeral OA and determined whether the revision risk differed based on gender. This large national registry has included shoulder arthroplasty procedures since 2004 and has documented 97.1% of shoulder arthroplasty procedures in the country since November 2007. They performed a multivariable analysis of revision risk that adjusted for patient characteristics like age, gender, American Society of Anesthesiologists score, and BMI. In this large study—their findings drew from the experiences of more than 12,000 patients—the authors found no overall survivorship differences at 4 years between rTSA and aTSA, though in the first 3 months after surgery, there was an increased risk of revision of rTSA compared with aTSA using all-polyethylene glenoids. They also found that men undergoing rTSA had a higher rate of revision than men undergoing aTSA using all-polyethylene glenoids in the first 3 months after surgery, while women undergoing aTSA using all-polyethylene glenoids were at a greater risk of revision than women undergoing rTSA from 3 months after surgery onward.

Based on these discoveries, and despite the rising frequency of rTSA, surgeons may consider the use of either rTSA or aTSA with an all-polyethylene glenoid for surgical treatment of end-stage glenohumeral OA, with gender an important factor to consider in the decision-making process with patients.

Where Do We Need To Go?

While the authors of the current study have provided valuable information on revisions rates in rTSA and aTSA in patients with glenohumeral OA, future studies still need to evaluate measures of pathologic severity and postoperative PROMs. Researchers should also examine shoulder function, complications, and radiologic measures of implant loosening when comparing these procedures to determine how these outcome measures may impact treatment decision-making. Complication profiles, for example, have been shown to differ between rTSA and aTSA [4, 7, 9, 12, 15], and may influence the type of implant chosen for a given patient profile. Additionally, rTSA may be indicated in more advanced pathology, such as more severe preoperative glenoid retroversion and glenoid bone loss (Walch B2 and B3 glenoids), that may be associated with earlier implant loosening and failure in aTSA [8, 10, 14]. However, more information is needed to fully understand the impact of these pathologic factors on implant loosening and longevity. Longer-term follow-up from registries and other large clinical studies will also help to further determine the best indications for rTSA and aTSA in glenohumeral OA. The continued evaluation of factors such as patient age, gender, medical comorbidities, and preoperative pathology, including bony deformity and rotator cuff status, will help us identify whether rates of loosening and revision increase and show stronger associations with certain factors over time.

How Do We Get There?

The ability to successfully perform comparative studies of rTSA and aTSA in glenohumeral OA that are adequately powered and have long-term clinical follow-up is logistically challenging. For that reason, such a study is unlikely to be accomplished at a single institution or center. The continued growth and utilization of shoulder arthroplasty registries and the development of prospective, multicenter longitudinal clinical studies have the potential to best address these challenges by creating large patient cohorts that can be followed for a longer period of time. In addition to the Australian shoulder arthroplasty registry utilized by Gill et al. [5], other national registries have reported on outcomes [3, 6] and continue to be developed, including the American Academy of Orthopaedic Surgeons Shoulder and Elbow Registry, which was launched in 2018 to collect data on shoulder arthroplasty, elbow arthroplasty, and rotator cuff repair. Multicenter longitudinal clinical studies are still relatively uncommon in orthopaedic surgery, but they’re out there. One example is the Multicenter Orthopaedic Outcomes Network Knee Project [13]. The American Shoulder and Elbow Surgeons is also initiating multicenter study groups [7, 10] to address important questions across the field, including those related to rTSA and aTSA. These national registries and societies aim to fill gaps in knowledge, but many are still in the earlier stages of development. Ultimately, successful development and continuation of registries and prospective, multicenter longitudinal clinical studies will depend on long-term funding to support the resources needed to collect large-scale data, maintain these databases, and ensure a high rate of patient follow-up that is essential to carry out these investigations.