The association of incomplete glenoid component seating and periprosthetic glenoid radiolucencies after total shoulder arthroplasty

Background Radiolucent lines surrounding prosthetic glenoid components are commonly seen after unconstrained total shoulder arthroplasty and can be a harbinger of subsequent glenoid component failure. Whether less than 100% glenoid seating is associated with the development of radiolucent lines around glenoid prostheses is unknown. This study investigated the association between incomplete glenoid component seating and periprosthetic glenoid radiolucencies. Methods Thirty-six unconstrained total shoulder arthroplasties were performed in 29 patients for primary glenohumeral osteoarthritis with a minimum 2-year follow-up. All were implanted with a partially cemented all-polyethylene glenoid prosthesis. Patients were evaluated with standardized plain films preoperatively and postoperatively and with thin-cut computed tomography (CT) scans at the latest follow-up. The Lazarus and Yian classifications were used to assess radiolucency and seating on radiographs and CT scans. Ratings were calculated for intraobserver and interobserver reliability and given κ, the Kendall coefficient, and interclass correlation coefficient values. Results At a mean of 43 months (range 24-26 months) after surgery, neither Lazarus plain film radiolucency scores ( P = .78) nor Yian CT radiolucency scores ( P = .68) were associated with Lazarus plain film seating scores. Neither Lazarus plain film radiolucency scores ( P = .25) nor Yian CT radiolucency scores ( P = .91) were associated with modified Lazarus CT scan seating scores. CT allowed for better intraobserver and interobserver reliability in all categories. Conclusion Radiolucencies around a partially cemented glenoid component were not associated with the degree of component seating. Complete seating of the glenoid component is not necessary to achieve radiographic implant stability at a mean follow-up of 43 months.