Abstract
Objective
Computed tomography based three-dimensional surgical preoperative planning (3D-planning) has been expanded to achieve more precise placement of knee and hip arthroplasties. However, few reports have addressed the utility of 3D-planning for the total elbow arthroplasty (TEA). The purpose of this study was to assess the reliability and precision of 3D planning in unlinked TEA.
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.
Results
The sizes of humeral stems and ulnar stems were estimated exactly in 70% (12/17) and 94 % (16/17) of all cases, respectively. All of the stem sizes were estimated accurately within one size. There was a strong correlation between the preoperative measurements around stem insertion and final position of the humerus with the correlation coefficient of 0.96–0.99, whereas the correlation was varied widely 0.48–0.97 for the ulna stem. The mean error in 3D orientation of the stem position was 0.56 mm for the humeral stem and 1.03 mm for the ulnar stem. There were no technical difficulties related to use of 3D-planning and the prostheses were properly placed in 16 cases, however posterior penetration of the ulnar stem occurred in 1 case.
Conclusion
This study demonstrated the reliability and precision of preoperative 3D planning for unlinked TEA. Proper positioning of the prosthesis is extremely important to prevent maltracking and instability since postoperative instability has been a major complication of the unlinked TEA. This technique will potentially reduce the postoperative complications.
