2025 ISAKOS Congress in Munich, Germany

2025 ISAKOS Biennial Congress Paper


Onlay Fixation with an All-Suture Anchor Provides Sufficient Biomechanical Stability for Lateral Extra-Articular Tenodesis

Marcos Tejada, B.S., Naples, Florida UNITED STATES
Rachel M. Frank, MD, Englewood, CO UNITED STATES
Brian C Werner, MD, Charlottesville, VA UNITED STATES
Oliver L Hauck, M.S., Naples, FL UNITED STATES
Coen Abel Wijdicks, PhD, Naples, Florida UNITED STATES

Arthrex, Naples, Florida, UNITED STATES

FDA Status Cleared

Summary

Knotless all-suture anchors were found to be a viable alternative to conventional, onlay fixation techniques in the setting of a modified Lemaire lateral extra-articular tenodesis.

Abstract

Introduction

Spiked ligament staples (SLS) and suture anchors are often used in onlay repair for modified Lemaire lateral extra-articular tenodesis (LET). However, associated hardware prominence, footprint size, and irritation are documented issues. Knotless all-suture anchors (ASA) are a promising alternative to SLS that mitigate these issues. However, there is a paucity of studies comparing the performance of various onlay techniques. The study objective was to compare the biomechanical behavior of ASA to SLS and biocomposite suture anchors (BSA) under simulated anterolateral forces. The hypothesis was that ASA would demonstrate comparable fixation strength to SLS and BSA with comparable survival rates under cyclic loading.

Methods

Iliotibial band (ITB) grafts were harvested, whipstitched, and fixed onto fresh-frozen porcine femurs using ASA, SLS, or BSA (n=6/group). Each femur was placed in a custom fixture at the base of an electromechanical testing machine, oriented at 60° of flexion with ITB grafts parallel to the load axis, simulating a worst-case scenario. Specimens were pre-tensioned for 10 minutes at 20 N; afterward, specimens were cyclically loaded through the following load ranges for 100 cycles each at 0.5 Hz before loading to failure at 25 mm/min: 10-50 N, 10-75 N, 10-100 N, 10-125 N. Five millimeters of displacement was determined as the threshold for clinical failure and survivorship analysis. Biomechanical outcomes included cyclic displacement (mm), survivorship (%), ultimate load to failure (N), and mode of failure. Statistical analyses (P<0.05) included one-way analysis of variance (ANOVA) for all cyclic displacement and ultimate load.

Results

Cyclic displacement values after all load ranges were 4.25 ± 0.28 mm, 3.94 ± 0.71 mm, and 8.14 ± 1.68 mm for ASA, SLS, and BSA, respectively. No significant differences in cyclic displacement were found between ASA and SLS within each load range, whereas significant differences were found in each load range between BSA and both ASA and SLS (P<0.05). Survivorship was 100% for ASA, 83% for SLS, and 0% for BSA. The ultimate loads were 257 ± 40 N, 300 ± 47 N, and 205 ± 24 N for ASA, SLS, and BSA, respectively; only SLS and BSA were significantly different (P=0.002). All failure loads exceeded the anterolateral ligament’s failure load of 175 N for a relative comparison of adequate strength in the anterolateral compartment. Failure modes were anchor pullout (2/6) or graft pullout (4/6) for ASA, graft pullout (6/6) for SLS, and anchor pullout (5/6) or graft pullout (1/6) for BSA.

Conclusion

All-suture anchor onlay fixation demonstrated comparable displacement to SLS and significantly lower displacement to BSA with greater survival to both conventional techniques during cyclic loading. ASA had comparable failure loading, with all groups exceeding the native anterolateral ligament failure load.

Clinical Relevance: All-suture anchors are a biomechanically viable alternative to spiked staples and biocomposite suture anchors for LET onlay fixation, which may mitigate potential complications associated with the conventional techniques.