Comparison of Clinical and Radiological Results according to Glenosphere Position in Reverse Total Shoulder Arthroplasty: A Short-term Follow-up Study

BACKGROUND: In a previous biomechanical study, eccentric glenospheres with more inferior position of the center of rotation were shown to improve range of motion and reduce the incidence of scapular notching after reverse total shoulder arthroplasty (RSA). The purpose of this study was to compare the clinical and radiological results of RSA using an eccentric glenosphere to those using a concentric glenosphere and to determine the usefulness of the eccentric glenosphere. METHODS: From 2009 to 2015, we performed a retrospective review of 20 consecutive patients who underwent RSA using a deltopectoral approach. Nine patients underwent RSA using a concentric glenosphere (group A) while 11 had an eccentric glenosphere (group B). The average follow-up period was 13.9 months (range, 12 to 18 months). All glenoid components were placed with 15° of inferior tilt. Clinical results were assessed using the visual analog pain scale score (VAS), the American Shoulder and Elbow Surgeon (ASES) score, the Korean shoulder scoring system (KSS), and the Constant score. On radiological evaluation, prosthesisscapular neck angle (PSNA), peg-glenoid rim distance (PGRD), scapular neck-inferior glenoshere rim distance (inferior glenoshpere overhang), acromion-greater tuberosity (AT) distance, glenoid-greater tuberosity (GT) distance, and severity of notching according to the Nerot-Sirveaux classification were assessed. RESULTS: The clinical results improved significantly in both groups, but there was no statistically significant difference between the two groups. A significant intergroup difference was observed with regard to PGRD (24.8 ± 1.6 mm for group A vs. 22.2 ± 1.9 mm for group B; p = 0.002) and inferior glenosphere overhang (2.0 ± 1.7 mm for group A vs. 5.8 ± 1.6 mm for group B; p = 0.000). Seven of 9 patients in group A developed notching compared with 2 of 11 patients in group B (p = 0.022). The other radiological parameters such as inferior tilt and AT and GT distances were not significantly different between two groups. Complications such as loosening and scapular fractures did not occur. CONCLUSIONS: The eccentric glenosphere in RSA was more effective in reducing the rate of notching than the concentric glenosphere although clinical outcomes were not significantly different in the short-term follow-up.

Evaluating Scapular Notching after Reverse Total Shoulder Arthroplasty

BACKGROUND: Scapular notching can happen at diverse location depending on implant design or operative technique, therefore, it is easily misdiagnosed. Thus, this study purposed to suggest a method helpful to assess scapular notching. METHODS: The subjects were 73 cases of reverse shoulder arthroplasty (RSA) for cuff tear arthropathy during the period from May 2009 to April 2014 and followed-up for over a year. There was medialized RSA in 22 cases, bone increased offset RSA (BIO-RSA) in 36 cases, and metal increased offset RSA (metal-RSA) in 15 cases. Scapular notching was not determined by bone defect at the inferior of glenosphere as Sirveaux's classification, but scapular notching at the site where the rotational route of the polyethylene of humeral implant met the scapular neck were examined. The results were compared with conventional method. RESULTS: By conventional method, scapular notching was observed in 10 cases (45.5%) in medialized RSA, 12 cases (33.3%) in BIO-RSA, and none in metal-RSA. By new method, it was observed in 9 cases (40.9%) in medialized RSA, 10 cases (27.8%) in BIO-RSA, and none of metal-RSA. The site of scapular notching was apart from glenoshpere in 18 cases, and at inferior of glenosphere in 1 case. Absorption of bone graft was observed in 4 (11.1%) out of 36 cases of BIO-RSA. CONCLUSIONS: It is hard to distinguish scapular notching from absorption of bone graft in BIO-RSA, and bone absorption at the lateral lower end of glenoid in medialized RSA. Thus, it is considered useful to assess scapular notching at the site where the rotational route of the polyethylene insert meets scapular neck.

Evaluating Scapular Notching after Reverse Total Shoulder Arthroplasty

BACKGROUND: Scapular notching can happen at diverse location depending on implant design or operative technique, therefore, it is easily misdiagnosed. Thus, this study purposed to suggest a method helpful to assess scapular notching. METHODS: The subjects were 73 cases of reverse shoulder arthroplasty (RSA) for cuff tear arthropathy during the period from May 2009 to April 2014 and followed-up for over a year. There was medialized RSA in 22 cases, bone increased offset RSA (BIO-RSA) in 36 cases, and metal increased offset RSA (metal-RSA) in 15 cases. Scapular notching was not determined by bone defect at the inferior of glenosphere as Sirveaux's classification, but scapular notching at the site where the rotational route of the polyethylene of humeral implant met the scapular neck were examined. The results were compared with conventional method. RESULTS: By conventional method, scapular notching was observed in 10 cases (45.5%) in medialized RSA, 12 cases (33.3%) in BIO-RSA, and none in metal-RSA. By new method, it was observed in 9 cases (40.9%) in medialized RSA, 10 cases (27.8%) in BIO-RSA, and none of metal-RSA. The site of scapular notching was apart from glenoshpere in 18 cases, and at inferior of glenosphere in 1 case. Absorption of bone graft was observed in 4 (11.1%) out of 36 cases of BIO-RSA. CONCLUSIONS: It is hard to distinguish scapular notching from absorption of bone graft in BIO-RSA, and bone absorption at the lateral lower end of glenoid in medialized RSA. Thus, it is considered useful to assess scapular notching at the site where the rotational route of the polyethylene insert meets scapular neck.