Five‐Strand Hamstring Grafts are Biomechanically Comparable to Four‐Strand Grafts and Offer Greater Diameter for Anterior Cruciate Ligament Reconstruction

Purpose The purpose of this study was to compare the biomechanics of 4‐strand and 5‐strand hamstring constructs for anterior cruciate ligament grafts. Methods Thirty‐six human cadaveric hamstring grafts were tested in 3 different conditions: (1) graft femoral fixation complex, (2) graft femoral and tibial fixation (GFTF) complex using a human model, and (3) GFTF complex using a porcine model. Grafts were tested on a tensile testing machine. Four‐stranded grafts served as the control group, and 5‐stranded grafts served as the experimental group. Cyclic elongation, ultimate load to failure, stiffness, and diameter of the grafts were analyzed. Results Average 4‐strand graft diameter was 7.96 mm compared to 9.32 mm for the 5‐strand graft ( P  = .00017). Average stiffness of grafts ≥8 mm was 105.04 N/mm compared to 85.05 N/mm for grafts <8 mm ( P  = .04988). There was a positive correlation between graft diameter and stiffness (13.4 N/mm per every 1 mm increase in diameter, r 2 value of 13.1%, and F‐significance of 0.02778). There were no significant differences in terms of ultimate load to failure, cyclic elongation, or stiffness between the experimental groups. Conclusion Five‐strand hamstring grafts offer greater diameter and are biomechanically comparable to 4‐strand equivalents at time 0. Grafts >8 mm offer significantly greater stiffness compared to grafts sized <8 mm. There is a weak positive correlation between graft diameter and stiffness. Clinical Relevance A potential drawback to hamstring grafts is their variability in size. Five‐strand hamstring grafts provide increased diameter in comparison to 4‐strand equivalents and might be used when quadrupled graft diameter is <8 mm.