Optimizing tension in first carpometacarpal prosthesis using tenodesis effect.

Optimal intraprosthetic tension is critical for function and longevity of dual‑mobility thumb carpometacarpal (CMC1) arthroplasty. The objective of this work is to describe and formalize the use of the tenodesis effect as a reliable, reproducible intraoperative test to optimize tensioning of dual‑mobility CMC1 prostheses and reduce complications related to over tensioning. The tenodesis‑based assessment performed after trial implantation is detailed: with the prosthesis in place, passive wrist flexion/extension is used to observe thumb interphalangeal (IP) joint movement. Excessive resistance to IP passive flexion during wrist flexion or to IP extension during wrist extension indicates over tensioning; corrective options include selecting a shorter neck or advancing the metacarpal stem. Using the tenodesis effect yields a dynamic, stable assessment that reflects postoperative biomechanics better than the piston test, improving restoration of natural thumb motion and reducing risks of polyethylene wear, cup migration, and early failure. The tenodesis effect is a simple, reproducible intraoperative tool to optimize tension in dual‑mobility CMC1 arthroplasty, enhancing functional outcomes and prosthesis durability.