Radiographic analysis of polyethylene glenoid components using modern cementing techniques

The purpose of this study was to examine the initial radiographic appearance and changes occurring over time in patients who have undergone total shoulder arthroplasty by modern methods of bone preparation and current cement techniques. Sixty-five patients underwent seventy total shoulder arthroplasties by use of a cemented all-polyethylene, keeled glenoid component. The surface radius was equal to the radius of a one-piece humeral component. The mean clinical follow-up was 4.18 years (range, 2-8.6 years); radiographic follow-up averaged 3.9 years (range, 2-8.6 years). Three observers evaluated radiographs 1 to 2 months postoperatively and at final follow-up. The glenoid component was considered at risk for clinical problems if there was a complete lucent line surrounding the component and some part of the line was 1.5 mm or greater in width or two of three or all three observers identified a shift in component position. Similarly, a humeral component was judged to be at risk if three or more zones had lucent lines 2 mm or greater in width or a shift in component position had occurred. On the early radiographs, 10 glenoid components had incomplete lucencies behind the keel. On the most recent radiographs, 59 glenoid components had incomplete lucent lines and 3 had complete lucent lines. Eight components were judged to have shifted in position. When data for lucent lines and shifting were combined, 10 (14%) of the glenoid components were at risk. At follow-up, no cemented humeral components were at risk whereas 3 (6%) of the 54 tissue ingrowth components were at risk for clinical loosening. Given the number of shoulders in this study, there were no associations between radiographic changes and clinical results. Improvements have occurred in glenoid component fixation. However, additional advances are possible and may occur from improved surgical technique, decreased particle-related osteolysis, enhanced joint kinematics, or novel fixation methods.