Does the 5-strand-graft have superior biomechanical behaviour than 4-strand-graft during ACL reconstruction?

Abstract

Purpose. This study aimed to compare the biomechanical proprieties of 4 and 5-strandgrafts. Methods. For the present study, fresh-frozen bovine common digital extensor tendons were used. Tendon grafts were prepared and sized to have a length of almost 27 cm and a cylinder 4 strand diameter of 8 mm. In half of all samples (Group A, n=12,), the graft was formed by 2 bundles duplicated around a metallic rod creating a 4-strand-tendon construct. In the other half of samples (Group B, n= 12,) 5-strand-tendon construct was created duplicating a single tendon around the rod, and tripling the other one. The grafts were preconditioned at 50 N for 10 min, followed by 1,000 cyclic loading between 50 and 250 N. Load-to-failure test was then carried out at a rate of 1 mm/s. Results. No statistically significant differences were found between two groups concerning cyclic elongation at the 500 th cycle and at the final cycle. An increased stiffness was observed in the Group B during cyclic loads and at pull-out (p<0.05). Significant differences were noted at the ultimate load-to-failure between Group A (1533 ± 454 N) and Group B (1139 ± 276 N) (p< 0.05). Conclusion. This study showed that both graft construct appears to be biomechanically effective in a bovine tendon model. 5-strand-graft showed an increased stiffness and a decreased ultimate load-to-failure comparing to the 4-strand-graft construct. Biomechanically, no real benefit could be observed in the clinical setting increasing the numbers of strands used for the ACL reconstructive surgery.

Hamstring Graft Preparation for ACL Reconstruction

“…Specifically, no advantages in terms of graft elongation were observed comparing four-strand and five-strand graft, even an increased stiffness of the five-strand graft was observed during cyclic load. 26 During graft preparation, each tendon ends should be separately whipstitched with no. 2 non-absorbable sutures.…”

Similar biomechanical properties of four tripled tendon graft models for ACL reconstruction

“…In case of undersized tendons, one potential way to provide an adequate graft diameters is to triple hamstring grafts. Several authors [12][13][14][15][16][17][18] have presented mechanical assessment to clarify the properties of tripled grafts but the question remains open as to what is the best configuration that can maximize the cooperation effect between the strands.…”