Independent Suture Augmentation With All-Inside Anterior Cruciate Ligament Reconstruction Reduces Peak Loads on Soft-Tissue Graft. A Biomechanical Full-Construct Study

Abstract

Purpose: To evaluate the effect of suture augmentation (SA) of 7-mm and 9-mm diameter graft on load sharing, elongation, stiffness, and load to failure for all-inside anterior cruciate ligament reconstruction (ACLR) in a biomechanical Study was funded by Arthrex ID: EMEA-16020. full-construct porcine model.

Methods: Bovine tendon grafts, 7-mm and 9-mm diameter, with and without SA were tested using suspensory fixation (n = 8). The independent SA was looped over a femoral button and knotted on a tibial button. Preconditioned constructs were incrementally increased loaded (100N/1,000 cycles) from 100N to 400N for 4,000 cycles (0.75 Hz) with final pull to failure (50 mm/min). Isolated mechanical and optical measurements during construct loading of the SA allowed to quantify the load and elongation range during load sharing. Construct elongation, stiffness and ultimate strength were further assessed.

Results: Load sharing in 7-mm grafts started earlier (200N) with a significant greater content than 9-mm grafts (300N) to transfer 31% (125N) and 20% (80N) of the final load (400N) over the SA. Peak load sharing with SA reduced total elongation for 7-mm (1.90 ± 0.27 mm vs 4.77 ± 1.08 mm, P < .001) and 9-mm grafts (1.50 ± 0.33 mm vs 3.57 ± 0.54 mm, P < .001) and adequately increased stiffness of 7-mm (113.4 ± 9.3 N/mm vs 195.9 ± 9.8 N/mm, P < .001) to the level of augmented 9-mm grafts (208.9 ± 13.7N/mm). Augmentation of 7-mm (835 ± 92N vs 1,435 ± 228N, P < .001) and 9-mm grafts (1,044 ± 49N vs 1,806 ± 157N, P < .001) significantly increased failure loads.

Conclusions: Load sharing with SA occurred earlier (200N vs 300N) in lower stiffness 7-mm grafts to carry 31% (7-mm) and 20% (9-mm) of the final load (400N). Loads until peak load sharing were transferred over the graft. Augmented constructs showed significantly lower construct elongation and increased stiffness without significance between variable grafts. Failure load of augmented grafts were significantly increased.

Clinical relevance: Suture tape ligament augmentation may potentially protect biological grafts from excessive peak loading and elongation, thus reducing the risk of graft tears.