The images above show a shoulder with extensive glenoid erosions before surgery (left) and the same shoulder after reverse total shoulder arthroplasty.
Bone loss, especially in the glenoid side of the shoulder, can be a challenge for shoulder arthroplasty. Anatomical total shoulder arthroplasty in a glenoid with major bone loss is associated with loosening, which can occur in a very short period of time and require revision surgery. Bone grafting has been used to make up for the bone loss, but it is associated with failure rates as high as 20% to 30%.
“Part of the problem,” says Edward McFarland, professor of orthopaedic surgery, “is that the glenoid does not have a lot of soft bone; therefore, bone grafting can be very technically demanding. The bone graft also has to be protected for three to six months, which is why healing can be difficult.”
One of the major advances in the past 15 to 20 years has been a reverse prosthesis, in which the glenoid side is resurfaced with a metal baseplate through which screws can be inserted into the glenoid and scapula to stabilize the implants. The sphere can then be placed on top of this baseplate using a Morse taper connection. The advantage of this type of reverse shoulder implant is that it can be used effectively in a glenoid with severe bone loss.
“At Johns Hopkins, we use a reverse total shoulder prosthesis with a 28-millimeter-diameter baseplate, a large central screw, and four peripheral locking screws. The glenoid is reamed flat to provide a good, sturdy surface behind the baseplate,” says McFarland.
He has found that bone can be removed with little risk of the glenoid fracturing or the baseplate loosening.1 This also obviates the need for augmented baseplates, which have a beveled surface and require bone removal for implantation.
This technique of reaming the glenoid surface flat was met with skepticism by those who thought that bone should never be removed from the glenoid. McFarland has since published studies showing that he is able to obtain strong fixation in patients with osteoarthritis and an intact rotator cuff. However, the procedure is not limited to those patients.
“We have found that this approach works really well regardless of the patient’s diagnosis,” he says. This approach has been used in patients with rotator cuff tear arthropathy, dislocation arthropathy, immunologic arthritis, glenoid dysplasia and revision arthroplasty.
A recent five-year review of a cohort of patients treated with this approach found a failure rate of only 5%.2 “That compares favorably to other studies that show a failure rate of 10% to 15% at 15 years,” says McFarland. “This approach offers a lot to the surgeon who performs moderately complex cases, and it eliminates the need for bone grafting or technically challenging bone grinding. It is a simple, straightforward way to accomplish the goal of achieving a stable socket.”
Most importantly, McFarland has found that patients are happy with the postoperative outcomes, namely good range of motion and noticeable pain relief.
“For patients with bone loss, this is a really great option,” says McFarland. “It is very rewarding to see these patients have a fairly fast recovery despite no bone grafting. Many of them have very little socket bone remaining, but with this technology, we are able to put the screws through the baseplate into the bone. It is a really great salvage procedure for people who have glenoid bone loss found in primary and revision shoulder replacement.”
1 McFarland EG, Huri G, Hyun YS, et al. Reverse total shoulder arthroplasty without bone grafting for severe glenoid bone loss in patients with osteoarthritis and intact rotator cuff. J Bone Joint Surg Am 2016;98:1801-7.
2 McFarland EG, Meshram P, Rojas J, et al. Reverse Total Shoulder Arthroplasty without Bone-Grafting for Severe Glenoid Bone Loss in Patients with Osteoarthritis and Intact Rotator Cuff: A Concise 5-Year Follow-up of a Previous Report. J Bone Joint Surg Am 2021;103:581-5.