Monitoring and robotizing shoulder arthroplasty for training and optimization of suturing techniques

Abstract

Objective

Shoulder arthroplasty with a humeral head prosthesis is used to treat complex proximal humeral fractures, and the outcome depends on the placement and integrity of sutures. The object of this research is to determine the forces supported by sutural filaments that bind the tuberosities to the prosthesis in proximal humeral fractures. Knowledge of these forces facilitates comparison of different suturing strategies that may improve the surgical procedure and provide better outcomes.

Method

A robotic workstation and a set of sensor modules were designed and built to emulate post-surgery rehabilitation geometry and forces with the required precision and repeatability. This system allows monitoring the forces supported by each sutural thread, as well as measurement of the millimeter scale displacements between the bone fragments produced postoperatively during rehabilitation movements. Several common suturing strategies carried out by orthopedists in shoulder arthroplasty with placement of a humeral head prosthesis were emulated using the robotic system.

Results

Based on in vitro laboratory experiments, the shoulder arthroplasty suture that supports higher strains was identified. The sutural band with maximum stress was not the same when the humerus is immobilized after surgery and in the postoperative rehabilitation phase.

Conclusion

The robotic system for shoulder arthroplasty with humeral head prosthesis placement provides biomechanical insight with quantitative analysis of the force distribution regarding the suturing strategy used in the procedure. The suture most likely to fail early when increasing tension in the rotator cuff muscles is the one passed through both tuberosities. The clinical significance of these findings is identification of the need to avoid shortening the humeral height or increasing retroversion in this procedure.