Mechanical assessment of tripled hamstring tendon graft when using suspensory fixation for cruciate ligament reconstruction

Abstract

BackgroundTripling semitendinosus tendon for ACL graft preparation facilitates creation of longer and thicker grafts. Our objective was to evaluate the mechanical difference between tripled tendon grafts, prepared by three methods, by comparing with quadrupled tendon graft.MethodsBovine hind-foot hoof extensors were allocated to four groups. Group I had quadrupled graft construct. Tripled graft constructs were prepared by passing the tendon to the Endobutton CL loop and stitching the third strand to (i) the loop (in Group II) or (ii) to one strand(in Group III) or (iii)to loop and both tendon strands (in Group IV). The constructs were preloaded from 10 to 50 N at 0.1 Hz for 10 cycles, followed by 1000 cycles of sinusoidal loading between 50 and 250 N at a frequency of 0.5 Hz. The specimens were then subjected to load to failure test at the rate of 50 mm/min. Displacement with cyclic loading, load at failure and the mode of failure were noted.ResultsThe load at failure was 957 ± 23.30 N (Mean ± Standard Deviation) in Group I, 590.8 ± 24.40 N in Group II, 682.6 ± 59.28 N in Group III and 963.4 ± 21.72 N in Group IV. The displacement with cyclic loading was 1.13 ± 0.11 mm in Group I, 4.908 ± 0.55 mm in Group II, 1.822 ± 0.55 mm in Group III and 1. 126 ± .018 mm in Group IV. There was no significant difference between the Groups I and IV with respect to the load at failure and displacement (p > 0.05). The values were significantly different in Group II and Group III (p < 0.01), when compared to groups I and IV.ConclusionsTripled grafts have mechanical properties equivalent to quadrupled grafts only when the three strands are sutured together. Caution may be warranted when using suspensory fixation device with tripled tendons and the third strand must be securely attached to the loop of fixation device and to the other two strands.

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

“…In our study, eight samples were tested for each group and this number is in line with current literature [16,17,30]. To standardize the graft preparation method, tendons were sized to have a diameter of 8 mm when the graft was folded in a tripled configuration.…”

“…An original aspect of our work is that the parameters collected not only concern the behavior at failure, but also monitor the biomechanical response evolution during cyclic loading. To the best of our knowledge, in the literature cyclic loads are applied to simulate a rehabilitation program, but only data related to ultimate failure load are generally available concerning tripled grafts [ 16 , 17 ]. We believe that these measures, describing the dynamic behavior of grafts, allow a better characterization of the grafts and a more faithful comparison between the triplication methods.…”

“…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.…”

Anterior Cruciate Ligament Reconstruction with 4-Strand Hamstring Tendon Construct May be Biomechanically Superior to 5-Strand Hamstring Tendon Construct When Using Femoral Suspensory Fixation

“…Geethan et al. 14 also compared doubled with tripled bovine tendon grafts with different suture configurations (using cortical buttons and clamping the tibial end) and found significantly increased displacement of the tripled graft compared to the doubled graft only if the third limb was not sewn to the other limbs. Vaillant et al.…”

“… 11 , 12 However, existing biomechanical studies are limited as they do not closely replicate the in vivo scenario, either due to graft choice (bovine vs human tissue), omittance of the additional doubled-over tendon (i.e., 3-strand instead of 5-strand), or omittance of standard tibial fixation. 13 , 14 , 15 , 16 The purpose of this study was to compare stiffness, strain, and load to failure of 4- versus 5-strand hamstring ACLR human tendon allografts with femoral suspensory and tibial interference screw fixation. Our hypothesis was that in this biomechanical model, the extra fifth strand would demonstrate better stiffness, strain, and load to failure than the 4-strand constructs.…”