All-Suture Anchor Techniques for Biceps Tenodesis Are Noninferior in End-Cycle Stiffness to an Interference Screw Technique; However, Secondary Outcomes, Such as Ultimate Failure Load, Yield Load, Creep, and Load-to-Failure Stiffness, Are Inferior in an Ovine Model

Abstract

PurposeThe purpose of this study was to assess the biomechanical performance of two simplified loop and tack biceps tenodesis techniques, all-suture anchor and all-suture anchor with a button, compared to the interference screw technique in an ovine model. MethodsTwenty-one biceps tenodesis procedures were executed on the humeri and flexor digitorum profundus tendons of skeletally mature, female sheep. Limbs were evenly randomized into two experimental groups (all-suture anchor with/without button) and one control group (interference screw). Cyclic loading followed by a load-to-failure test was conducted.The primary outcome metric was end-cycle stiffness, or stiffness measured at the end of cyclic loading, as it modeled the resistance of the construct to the lower-force activities of postoperative physical therapy. Secondary metrics included ultimate failure load (UFL), yield load, creep, and load-to-failure stiffness. End-cycle stiffness difference-of-means testing was conducted with a minimal clinically significant difference (MCID) threshold of -15N/mm (1.5kg/mm). Groups were compared using ANOVA for all recorded variables. ResultsBoth the all-suture anchor and all-suture anchor with button techniques were found to be noninferior in end-cycle stiffness compared to the interference screw technique (-5.2N/mm, 95% CI [-13.6, 3.3] and –3.8N/mm, 95% CI [-12.5, -4.9]) for -15N/mm MCID. The all-suture techniques showed significantly lower UFL, lower yield load, greater creep, and lower load-to-failure stiffness (P<0.001, P<0.001, P=0.002, P<0.001, respectively). Tendon dimensions did not vary significantly across groups. ConclusionsUnder subfailure loading conditions, the all-suture anchor with/without button techniques demonstrated end-cycle stiffness noninferiority with an interference screw technique, however, these techniques were inferior in all secondary outcomes, including significantly lower UFL, lower yield load, greater creep, and lower load-to-failure stiffness. Clinical RelevanceThe all-suture anchor with/without button approaches may retain the natural length-tension dynamics of the long head biceps tendon as fixation can occur before releasing the tendon origin. Additionally, it may offer a simpler and more cost-effective alternative to prevailing arthroscopic methods.