Study on stability of resurfacing total elbow arthroplasty: a cadaver study

Abstract

Background

Although excellent clinical results have been reported for resurfacing total elbow arthroplasty, also known as K-elbow, there are still reports of complications due to postoperative instability of the elbow joint. Appropriate implant selection, proper implant placement, and establishment of soft tissue repair methods are necessary to prevent complications, but these requirements have not fully undergone scientific verification. Surgical techniques such as the extent of bone resection of the distal humerus and soft tissue repair methods require technical skill, but the extent to which these techniques contribute to joint stability is unclear. This study aimed to investigate the factors contributing to elbow joint stability after elbow arthroplasty using K-elbow and fresh-frozen cadavers.

Methods

Six upper limbs of fresh-frozen cadavers were used in this study. The resurfaced unlinked-type elbow prosthesis (K-elbow) was placed using a posterior approach. The distal humerus was resected at 0 mm, 2 mm, and 4 mm on the articular surface, and the artificial elbow joint was installed. Anchors were inserted into the olecranon, the biceps tuberosity, and the coronoid process to simulate the triceps, biceps, and brachialis muscles, and traction forces of 20 N, 10 N, and 10 N, respectively, were applied. In addition, a digital angle meter was attached to the forearm, and varus and valgus stress tests were performed at all elbow joint ranges of motion using forearm weight to evaluate the spacer effect. Furthermore, a stress test was performed for each soft tissue repair process at the 2-mm bone resection site to evaluate the stability of the procedure.

Results

As the extent of bone resection of the distal humerus increased, the extension angle tended to improve. Furthermore, as the extent of bone resection increased, elbow joint instability due to varus and valgus stress increased. Soft tissue repair did not affect elbow instability due to varus stress, but it tended to reduce elbow instability due to valgus stress. In addition, the triceps fascia suture reduced the external rotation angle of the elbow joint in response to valgus stress.

Conclusion

This cadaver study demonstrated that bone resection of the distal humerus significantly affects both the range of motion and stability of the elbow joint after K-elbow arthroplasty. The triceps fascia suture was identified as the most critical soft tissue repair procedure for ensuring elbow joint stability, particularly against valgus stress.