Dr. Jobin: We’re going to define osteoarthritis glenoid bone loss and posterior subluxation. We’re going to talk about decades of success with the anatomic total shoulder with retroverted glenoids. And we’re going to show why the reverse is fraught with complications. Reverse has tons of complications. And when you do it correctly, your function is less and your satisfaction is less than with a total shoulder.
So, my opponent, Dr. Sperling, lots of experience, lots of textbooks, etc., but even his own research supports total shoulder over reverse.
So, John, don’t underestimate the new kid on the block.
What do we know about bone loss and osteoarthritis? About 42% of glenoids are B2 and will undergo arthroplasty. There’s posterior bone erosion, humeral subluxation and capsular redundancy (Churchill, JSES 2015).
What about anatomic total shoulder with posteriorly worn glenoids? Patients need surgery to correct and balance the joint. We’re very successful if we can correct within 10 degrees of retroversion. We do know that excessive reaming does cause risk of polyethylene loosening. And if you leave the glenoid in retroversion, and Dr. Iannotti showed this (JBJS 2013), you have five times the chance of developing radiolucent lines.
Can we balance? Of course. There are some great studies showing how we were able to correct subluxation. Gerber (JSES 2009)—91% corrected. Habermeyer (CORR 2007)—80 patients, 2-year follow-up, 100% of his posterior subluxation was corrected. Same thing with Bigliani—41 patients, 3.5 years follow-up, all B glenoids, 100% balanced.
What about retroversion correction? Can we really do this? Hot off the presses this year (Mehta, et al., JSES, 2018) our group demonstrated that about 60% of our patients were corrected to within 10 degrees of retroversion.
What are the limits of high side reaming? Well, some anatomic studies have shown 18 to 15 degrees is probably your limit for reaming the high side (Nowak, JSES, 2009; Calvert, JSES, 2007). If you have pre-operative retroversion greater than 27 degrees—a lot—you do risk glenoid loosening and Walch shows this at 6-year follow-up with about 40% of his glenoids loosening (JSES, 2010).
Aggressive reaming does remove the subchondral bone and we’ve seen in finite element analysis that this does compromise the cement interface (Walch, JSES, 2011).
What about bone grafting? It does not work, failure rates of 30-50%.
How about wedge or augmented glenoid components? Well, here’s an opportunity to restore some balance, restore cuff tension, preserve glenoid vault, and change some of these forces from shear to compression.
What are their clinical outcomes? A 3-year follow-up study, 22 patients, pre-operative retroversion about 24 degrees; 66% had bone ingrowth around the central peg fins, and radiolucent scores were really minimal—0.5 (Favorito, JSES, 2016). This was really encouraging.
