Quadriceps tendon (QT) grafts have recently gained interest as autografts for anterior cruciate ligament (ACL) reconstruction. A systematic review demonstrated that soft-tissue QT grafts showed less postoperative rotatory instability and fewer complication profiles than QT grafts with a bone block. In ACL reconstruction using soft-tissue QT, the graft preparation strategy is important; however, there is no established method for this. Graft failure rate may differ depending on the suture method used. Therefore, this study aimed to compare the biomechanical strength of various QT fixation configurations using adjustable loops in soft-tissue QT grafts for ACL reconstruction. We hypothesized that the method using the SpeedWhip rip stop technique would exhibit the lowest elongation and highest maximum load to failure. Compared with previous reports, this study is more in line with clinical situations. Therefore, the results of this study may provide surgeons with new insights into femoral fixation of soft tissue QT grafts in ACL reconstruction.
Material And Methods
Thirty fresh-frozen bovine Achilles tendons (10 mm width, 50 mm length, and 4 mm thickness) were used in this study. Tendons were assigned to three groups (n = 10 per group) with different suture configurations using adjustable loops with a suspensory button. In group A, the threads of the adjustable loop were fixed by crossing them at the tip of the loop and the entire loop based on Hughes et al.; in group B, the continuous loops with hanging buttons were directly sutured to the tendon with eight simple sutures; and in group C, the SpeedWhip rip stop technique was used for fixation. A No.2 FiberWire was used by an experienced surgeon for Groups A and B, while a FiberTag was used for Group C. All knots were tied five times and fixed.
The tensile tests were performed for five cycles of preloading at 50 N and by holding this force for 1 minute; the load-to-failure testing was conducted 5 mm/min until the rupture. The difference in the total length (elongation) of the tendon before and after preloading and the ultimate failure load at breaking point were measured using a material analysis software. Data were presented as the mean and standard deviation. Statistical significance was set at P< 0.05.
The average elongation was 10.3 ± 2.4 mm in group A, 16.6 ± 2.2 mm in group B, and 10.0 ± 1.0 mm in group C, and group B had a significantly longer elongation than groups A and C (p <0.001). The ultimate failure load was 157.5 ± 33.4 N on average in group A, 253.4 ± 45.5 N in group B, and 337.7 ± 21.0 N in group C, and there was a significant difference between all groups (p<0.001).
Fixation using SpeedWhip rip stop technique to fix the suspensory button and soft tissue transplant tendon results in minimal elongation and higher fixation strength. Simple devices that use this method have already been developed. Since the method of fixation relatively simple, using soft-tissue QT for femoral fixation is advantageous in ACL reconstruction.