The single-suture technique for anterior cruciate ligament graft preparation provides similar stability as a three-suture technique: a biomechanical in vitro study in a porcine model

Scaffold-induced compression enhances ligamentization potential of decellularized tendon graft reseeded with ACL-derived cells

Anterior cruciate ligament (ACL) reconstruction is often performed using a tendon graft. However, the predominant synthesis of fibrotic scar tissue (type III collagen) occurs during the healing process of the tendon graft, resulting in a significantly lower mechanical strength than that of normal ACL tissue. In this study, ACL-derived cells were reseeded to the tendon graft, and scaffold-induced compression was applied to test whether the compressive force results in superior cell survival and integration. Given nanofiber polycaprolactone (PCL) scaffold-induced compression, ACL-derived cells reseeded to a tendon graft demonstrated superior cell survival and integration and resulted in higher gene expression levels of type I collagen compared to non-compressed cell-allograft composites in vitro. Translocation of Yes-associated protein (YAP) into the nucleus was correlated with higher expression of type I collagen in the compression group. These data support the hypothesis of a potential role of mechanotransduction in the ligamentization process.

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

PURPOSE

The present study tested and compared the biomechanical properties of four different triplicate graft tendon techniques.

METHODS

32 tripled tendons from the common extensor muscle of bovine fingers were tested on a material testing machine, passing the end loop over a metal rod of a clevis connected to the load cell on the upper side, and fixing the lower end to a clamp. The samples were divided into four groups: (A) tripled with a free end sutured only to one of the two fixed bundles (B) tripled with a free end positioned between the two fixed strands and sutured to both (C) tripled with an S-shape and all the three strands sutured together at the upper and lower extremities of the graft (D) partially quadrupled with the free end sutured together with the other three bundles at the upper extremity. Each sample was pretensioned at 50 N for 10 min and then subjected to 1000 load control cycles between 50 and 250 N. Finally, each sample was subjected to a load to failure test. Authors also present some preliminary results on the feasibility of a non-contact and full-field Thermoelastic Stress Analysis technique, based on Infrared Thermography, to evaluate the level of stress on the whole graft, and hence on each strand, during fatigue loading.

RESULTS

Eighty five percent of the samples failed at the level of the clamp. The cyclical elongation progressively decreased in all the samples and there was a simultaneous increase in stiffness. An increased stiffness was noted between Group 2 vs Group 3 and Group 2 vs Group 4 at the 500th and 1000th cycle. The failure loads were as follows: (a) 569.10 N, (b) 632.28 N, (c) 571.68 N, (d) 616.95 N. None of the parameters showed a statistically significant difference between the four groups.

CONCLUSION

This study reported similar biomechanical behavior of four different models of tripled grafts suitable for ACL reconstruction. In addition, the biomechanics of overall tripled tendon grafts seems more affected by the viscoelastic property of the tendon itself rather than the preparation method.

Does using high-tensile strength tape improve the fixation strength in tendon graft fixation with needleless suture wrapping techniques compared to a suture?

PURPOSE

To compare the biomechanical properties of a high-tensile strength suture and high-tensile strength tape in tendon graft fixation using two needleless suture wrapping techniques, the modified Prusik knot and modified rolling hitch.

METHODS

Two needleless suture wrapping techniques, the modified rolling hitch (MR) and modified Prusik knot (MP), were utilized. Meanwhile, two kinds of suture materials, a No. 2 braided nonabsorbable high-strength suture (S) and a 1.3 mm high-tensile strength tape (T), were used. A total of 40 porcine tendons were used, which were randomly divided into four groups. Each group was assigned to one of the following groups: MRS, MRT, MPS, and MPT. Each specimen was pretensioned to 100 N for three cycles, cyclically loaded from 50 to 200 N for 200 cycles, and finally loaded to failure.

RESULTS

The MRT group (34.1 ± 3.5%) had a significantly higher value compared with the MRS (29.7 ± 2.3%), MPS (27.1 ± 3.6%) and MPT (29.5 ± 4.0%) groups in term of elongation after cyclic loadings (p = 0.002). In terms of ultimate failure load, there were no significant differences in the MRS (401 ± 27 N), MRT (380 ± 27 N), MPS (398 ± 44 N) and MPT (406 ± 49 N) values (p = 0.539). All specimens failed due to suture breakage at the knots.

CONCLUSION

Compared with the high-tensile strength suture, using the high-tensile strength tape lead to greater elongation after cyclic loading when the modified rolling hitch was used. No differences in terms of elongation after cyclic loading and load to failure were found between the high-tensile strength suture and tape using the modified Prusik knot.