Methods

Between April 2012 and April 2014, 17 joints in 17 patients (male 4, female 13) were included in this study. Sixteen patients were rheumatoid arthritis and one was osteoarthritis and the average age at the time of the procedure was 61 years (range 28–88). Unlinked K-NOW total elbow system (Teijin-Nakashima Medical. Co. Ltd.) was used in all cases and 3D planning was performed by Zed View (Lexi.Co.). After the appropriate size and position of the prosthesis were decided on the 3D images [Figure 1], the position of the bone tunnel made for the insertion of humeral and ulnar stem was recorded on axial, sagittal, and coronal plane (4 point measurements for humerus, and 6 points for ulna, See Figure 2). After the elbow was exposed via a posterior approach, bone resection and reaming was performed according to the 3D planning. The surgeon took an appropriate adjustment to align the prosthesis properly during the surgery. The final position of the stem insertion was recorded immediately prior to set the prostheses. We analyzed the accuracy of stem size prediction, the correlation between preoperative and final measurements, and postoperative complications.