There is an opportunity to compare the minimum two year outcomes of anatomic and reverse total shoulders for the treatment of glenohumeral osteoarthritis with intact rotator cuff and glenoid bone loss as indicated by Walch classification A2, B2, B3, or C using two recently published series.
The first is Lateralized Glenosphere Reverse Shoulder Arthroplasty: Inlay and Onlay Designs have Similar Clinical Outcomes in Patients with Glenohumeral Osteoarthritis which presents the outcomes from what the authors characterized as an "off-label indication for RSA" in shoulders with arthritic glenoid bone loss and an intact rotator cuff. The humeral tray design was inlay for 79 patients and onlay for 71 (total 150). The glenoid types were A2 in 85, B2 in 28, B3 in 29, and C in 8. The authors found no significant differences between inlay and onlay implants in any outcome measure at final follow-up.
The second is Anatomic Total Shoulder Arthroplasty with All-Polyethylene Glenoid Component for Primary Osteoarthritis with Glenoid Deficiencies that included patients having a conventional approach to arthritis with an intact rotator cuff and glenoid bone loss (see this link). Glenoid types were A2 in 97, B2 in 83, and B3 in 52 (total 255)
The sex and age distributions for the two series were comparable. The average improvements in the Simple Shoulder Test scores were also comparable (6.7 for RSA and 6.5 for aTSA).
In the reverse total shoulder series the rates of revision were: inlay, 3.8% vs onlay, 1.4%. The rates of scapular notching were: inlay, 5.1% vs onlay, 7.0%. The rates of acromial stress fracture were: inlay, 0% vs onlay, 2.8%, and the rates of tuberosity resorption were: inlay, 25% vs onlay, 27%.
In the anatomic total shoulder series the revision rate was 1% (3/255).
Comment: This comparison does not provide evidence that the reverse total shoulder is of greater benefit to patients with intact cuffs and arthritic bone loss in comparison to a conventional anatomic total shoulder. In that "value" can be defined as benefit recognized by the patient (e.g. in the patient self-assessed Simple Shoulder Test) divided by the cost, it is relevant that the cost of a reverse total shoulder is substantially higher than that of an anatomic total shoulder (graphic from Orthopedic Network News Volume 30, Number 1 January 2019)
This is obviously not a randomized controlled trial with long term followup. But it does seem to suggest that the burden of proof may lie with those advocating the RSA for patients with intact cuffs and arthritic bone loss.
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Here are some videos that are of shoulder interest
