Optimizing humeral stem fixation in revision reverse shoulder arthroplasty with the cement -within -cement technique

Background: The purpose of this study was to report on the clinical outcomes of patients undergoing revision reverse shoulder arthro-plasty (RSA) by the cement-within-cement technique, as well as to identify whether surgical technique can affect subsequent humeral loosening. Methods: In 98 patients, cemented humeral components that were revised to RSA using the cement-within-cement technique were identified and included in this study. We compared 8 patients in whom humeral stem loosening developed with 90 patients whose stem remained fixed. Preoperative and postoperative radiographs of each patient were downloaded in DICOM (Digital Imaging and Communications in Medicine) format and analyzed in Mimics. The total area of the cement mantle (in square millimeters) and of the stem (in square millimeters), as visualized on 2-dimensional plain films, was measured in each subject on both preoperative and postoperative radiographs. Outcomes at a minimum of 2 years of follow-up were analyzed. Results: Clinical outcomes were available in 57 patients, with a mean follow-up period of 54 months (range, 21-156 months). Patients demonstrated significantly improved functional outcome scores and shoulder range of motion. In the group without loosening, the mean increase in the cement mantle area was 4380 +/-12701 mm(2) (P < .0001). In the group with loosening, the mean increase in the cement mantle area was only 811 +/- 4014 mm(2) (P = .484). Conclusions: Use of the cement-within-cement technique for fixation of the humeral component in revision RSA is effective in improving functional outcome scores and shoulder range of motion. Furthermore, these findings suggest that efforts to maximize the cement volume during reimplantation may lessen the chance of humeral stem loosening requiring additional revision. Level of evidence: Level III; Retrospective Cohort Comparison; Treatment Study (C) 2020 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.