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Inferior overhang of glenosphere yielded excellent range of motion in reverse shoulder arthroplasty
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NEW YORK — Results presented at the American Shoulder and Elbow Surgeons Annual Meeting showed a larger glenosphere implanted with inferior overhang may be associated with excellent postoperative range of motion after reverse shoulder arthroplasty.
Robert U. Hartzler, MD, and colleagues determined preoperative and postoperative range of motion among 180 patients who underwent reverse shoulder arthroplasty and had a minimum of 1-year follow-up. Hartzler noted they performed a risk factor analysis to compare excellent vs. poor range of motion outcomes.
“Excellent range of motion was defined as forward elevation greater than 140° and external rotation greater than 30° or was defined as forward elevation less than 100° or external rotation less than 15°,” Hartzler said in his presentation here.
According to Hartzler, 75 of the 180 patients had either excellent or poor outcomes. Of the 36 patients with poor outcomes, Hartzler noted 16 patients had a lack of forward elevation and external rotation, 11 patients had poor external rotation alone and nine patients had poor forward elevation.
“Those with poor range of motion outcomes also had worse pain relief and improvement in ASES score,” Hartzler said.
In a univariate risk factor analysis, Hartzler noted an association between higher BMI and excellent range of motion, while young age trended toward significance. He added poor range of motion outcomes were associated with smaller glenospheres and anterior offset positioning of the humeral cup.
Hartzler reported an association between glenosphere overhang and excellent range of motion, according to univariate analysis of radiographic outcomes.
“The odds of excellent range of motion were nine-times and five-times higher with 39-[mm] and 42-[mm] glenospheres vs. a 36-mm glenosphere,” Hartzler said. “Each millimeter of glenosphere overhang resulted in a 1.6-times odds of an excellent outcome, and anterior cup offset was highly associated with poor range of motion outcomes in this model.” – by Casey Tingle
Reference:
Denard PJ, et al. Paper 42. Presented at: American Shoulder and Elbow Surgeons Annual Meeting; Oct. 17-19, 2019; New York.
Disclosure: Hartzler reports he is a paid consultant and paid presenter or speaker for Arthrex Inc.; is a board or committee member for the Arthroscopy Association of North America; and received publishing royalties, financial or material support from Wolters Kluwer Health – Lippincott Williams & Wilkins.
Perspective
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Robert J. Gillespie, MD
Range of motion outcomes continue to be a challenging following reverse shoulder replacement. Since the original Grammont design of the reverse shoulder replacement utilizing a valgus humeral neck angle and a medialized and inferior center of rotation, much work and innovation has been done to optimize range of motion and function after reverse shoulder replacement.
Robert Hartzler, MD, and colleagues present a large cohort of patients from a prospective database 1 year after surgery in their study “Radiographic parameters associated with excellent vs. poor range of motion (ROM) outcomes following reverse shoulder arthroplasty.” They examined specific radiographic and implant parameters that may lead to improved range of motion with their specific implant design. Among many factors, they found that increased glenosphere size and inferior overhang of the glenoid were associated with excellent outcomes and anterior overhang of the humeral component was seen more commonly in poor outcome patients. Interestingly, they did not see an association with lateralization of the glenoid component and range of motion outcomes which has been seen in other reverse implant designs.
The authors should be congratulated on this prospective study examining factors leading to improved outcomes with this specific, innovative design of a reverse shoulder replacement. It emphasizes that unlike anatomic shoulder replacement, specific design and radiographic considerations among implant manufacturers may lead to different outcomes in our patients undergoing reverse shoulder replacement.
University Hospitals Cleveland Medical Center
Program director for the orthopedic surgery residency
Associate professor in orthopedic surgery
Cleveland
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