Biomechanical evaluation of subpectoral biceps tenodesis: dual suture anchor versus interference screw fixation

Abstract

Subpectoral biceps tenodesis has been reliably used to treat a variety of biceps tendon pathologies. Interference screws have been shown to have superior biomechanical properties compared to suture anchors; although, only single anchor constructs have been evaluated in the subpectoral region. The purpose of this study was to compare interference screw fixation with a suture anchor construct, using 2 anchors for a subpectoral tenodesis. A subpectoral biceps tenodesis was performed using either an interference screw (8×12 mm; Arthrex) or 2 suture anchors (Mitek G4) with #2 FiberWire (Arthrex) in a Krackow and Bunnell configuration in seven pairs of human cadavers. The humerus was inverted in an Instron and the biceps tendon was loaded vertically. Displacement driven cyclic loading was performed followed by failure loading. Suture anchor constructs had lower stiffness upon initial loading (P=.013). After 100 cycles, the stiffness of the suture anchor construct "softened" (decreased 9%, P<.001), whereas the screw construct was unchanged (0.4%, P=.078). Suture anchors had significantly higher ultimate failure strain than the screws (P=.003), but ultimate failure loads were similar between constructs: 280±95 N (screw) vs 310±91 N (anchors) (P=.438). The interference screw was significantly stiffer than the suture anchor construct. Ultimate failure loads were similar between constructs, unlike previous reports indicating interference screws had higher ultimate failure loads compared to suture anchors. Neither construct was superior with regards to stress; although, suture anchors could withstand greater elongation prior to failure.