This article evaluates the position and orientation of the elbow flexion axis following linked and non-linked total elbow arthroplasty. The rationale for the study is that the design of the elbow implant should allow a degree of freedom in the axis of flexion and extension, which would result in a lower failure rate. The authors evaluated the capitellocondylar implant, the Kudo implant, and the linked GSP-3 prosthesis.
The study includes 16 patients. Eight were treated with the Kudo implant, 6 with the capitellocondylar implant, and 2 with the GSP-3 implant. Radiostereometric analysis was performed, as well as standard radiographic imaging. The results demonstrate a significant variation in the maximum extended position that the patient could achieve following surgery. The Kudo prosthesis showed the greatest variability in the direction of the mean axis. The linked prosthesis demonstrated significant dispersion in the frontal plane, but significantly less dispersion in the horizontal plane, as would be expected due to the link mechanism.
This study demonstrates that there is much greater dispersion of flexion in postoperative patients than was seen in the normal elbow in vivo, which would be expected following rheumatoid arthritis and total elbow arthroplasty. The finding was especially true in an unlinked prosthesis. The results further indicate that the Kudo prosthesis has the greatest degree of laxity, followed by the capitellocondylar implant. The authors recommend use of this prosthesis with caution in the face of ligamentous laxity.