Knotted single lasso loop has a lower stiffness and comparable ultimate failure strength compared with knotless whipstitch fixation in onlay tenodesis.

Background: Suture and knotless anchor onlay tenodesis are two common treatments for biceps lesions; however, there is a paucity of biomechanical studies evaluating the efficacy and structural integrity of these techniques.

Methods: Tendons were harvested from four lower extremity fresh cadaver specimens, including the extensor digitorum longus, peroneus longus, peroneus brevis, and anterior tibialis tendons. Each tendon diameter was recorded using a digital Vernier caliper. Sixteen 3D printed proximal humeri models were allocated to either the single lasso loop with suture anchor (SLL) group or the whipstitch with knotless suture anchor (WSA) group. Each tenodesis model was initially tested on an electrodynamic material testing instrument under a cyclic load ranging from 5 to 70 N at a speed of 1.25 mm/s. The force on the tendon was then returned to 5 N, which was pulled until the ultimate failure of the construct. Displacement during cyclic loading, ultimate failure load, stiffness, and failure modes were assessed.

Results: Fourteen tenodesis models were validated, and two models were discarded due to technical errors. No significant differences between the two groups were observed regarding tendon diameter, ultimate failure load, and displacement at ultimate failure load. However, the construct stiffness for the SLL group was lower than that of the WSA group (58.02 ± 5.62 N/mm vs. 72.24 ± 15.63 N/mm, P = 0.043).

Conclusion: The SLL group had a lower construct stiffness than the WSA group, whereas construct displacement and ultimate failure load were similar in both groups. Therefore, SLL biceps tenodesis may offer a convenient alternative, with lower tendon migration fixation, while performing an arthroscopic biceps tenodesis.

Level of evidence: Basic Science Study.