Effect of tendon-to-bone gap on adjustable-versus fixed-loop biceps tendon fixation

Abstract

Background Distal biceps tendon ruptures significantly impair forearm flexion and supination strength, particularly in active individuals. Suspensory fixation using cortical button devices is a widely accepted surgical approach. Adjustable-loop techniques allow maximal tendon-to-bone apposition, while fixed-loop methods are simpler but may leave a gap. Biomechanical differences between these techniques specific to the distal biceps tendon remain poorly investigated, especially given the unique loading patterns of the elbow compared to other joints. Methods Finite element analysis was performed using ANSYS software. Three-dimensional models of the radius and distal biceps tendon were constructed from computed tomography data. Three configurations were compared: Model 1 (adjustable-loop with dense tendon-to-bone contact, 0 mm gap), Model 2 (fixed-loop with 1.0 mm gap), and Model 3 (fixed-loop with 5.0 mm gap). Cortical bone, tendon, suture, and titanium button properties were assigned based on literature values. A 500 N tensile load was applied at the proximal tendon boundary simulating 90° elbow flexion. Stress, strain, and displacement distributions were analyzed in the fixation system and tendon.