[Artificial ligaments applied in anterior cruciate ligament repair and reconstruction: Current products and experience]

Early clinical outcomes of all-inside arthroscopic anterior cruciate ligament reconstruction with autograft tendon augmentation using the LARS internal brace ligament

Objective

The aim of this study was to compare the early clinical outcomes of all-inside anterior cruciate ligament (ACL) reconstruction using hamstring tendons augmented using the ligament augmentation and reconstruction system (LARS) versus hamstring tendons alone as a control.

Methods

This study included 99 patients with ACL injuries who underwent all-inside arthroscopic ACL reconstruction using either the LARS internal brace ligament combined with hamstring tendon (augmentation group, n = 48) or hamstring tendon alone (hamstring group, n = 51). Postoperative follow-up was conducted using Lysholm, International Knee Documentation Committee (IKDC), Tegner, KOS-ADLS, and ACL-RSI scores to evaluate functional recovery of patients at 1, 3, and 6 months. If necessary, MRI findings obtained at postoperative 3 months were also analyzed to evaluate graft integration and healing dynamics. Tensile strength of the augmented graft was measured through tensile testing. Moreover, to evaluate the postoperative healing status of the augmented tendon, an ACL reconstruction model was established using New Zealand white rabbits. At 4 and 8 weeks postimplantation, rabbit knees were harvested, decalcified, embedded in paraffin, and stained to evaluate new tissue formation. All statistical analyses were conducted using the GraphPad Prism and SPSS software, with appropriate statistical tests applied for comparison between groups.

Results

At 1-month postoperative follow-up, the LARS augmentation group demonstrated significantly higher Lysholm, IKDC, and KOS-ADLS scores than the hamstring group, with P < 0.01 for all comparisons. At 3-month postoperative follow-up, the augmentation group exhibited significantly higher Tegner, Lysholm, IKDC, and KOS-ADLS scores than the hamstring group, with P < 0.05 for all measurements. In the tensile testing, the tendons + LARS and LARS groups showed significantly higher maximum loads and lower elongation than the tendon group with P < 0.001 for maximum load and P < 0.05 for elongation. Examination of the histological sections at 4 and 8 weeks showed that the LARS ligament exhibited excellent biocompatibility, with abundant collagen fibers and neovascularization identified between its fibers.

Conclusion

The combination of LARS internal brace ligaments with autograft tendons in ACL reconstruction provides superior early postoperative outcomes, improving knee stability and patient satisfaction with no remarkable complications. The augmented graft exhibited reliable tensile strength and favorable tissue integration.

Establishment of near and non isometric anterior cruciate ligament reconstruction with artificial ligament in a rabbit model

Background

Tunnel position deicide the isometry of graft attachment in synthetic anterior cruciate ligament (ACL) reconstruction. Near-isometric tunnel position may have advantage in graft integration and knee function in ACL reconstruction (ACLR) with polyethylene terephthalate (PET) ligament. Few studies focused on tunnel position isometry when conduct ACLR with an animal model. This study aimed to establish a preclinical rabbit model of near and non isometric ACLR with PET ligament and investigate the advantage of near-isometric ACLR compared to non-isometric ACLR.

Methods

Nine hind limbs of rabbit were used in tunnel position study. Two femoral(anatomic, nonanatomic) tunnels and three tibial(anterior, middle, posterior) tunnels were used to measure tunnel position isometry during knee full range of motion. The tunnel position combination with minimal isometry was considered as near-isometric tunnel position. Then, 48 rabbits divided into two groups were conducted near or non isometric ACLR with PET ligament with graft fixation angle of 30° and constant tension of 5N. PET ligament isometry, range of motion(ROM) restriction, knee laxity were recorded after operation and followed up with macroscopic observation, microcomputed tomography (micro-CT) analysis, histology assessment and biomechanical test at 4 and 8 weeks postoperatively.

Results

The tunnel combination with minimal isometry was femoral anatomic position and tibial posterior position(5.19 ​± ​1.78%) and considered as near-isometric tunnel position. ROM restriction were observed in non-isometric group (22.50 ​± ​14.14°) while none in near-isometric group. However, no ROM restriction observed at 8 weeks in both group. Knee laxity compared to contralateral knee were better in near-isometric group than non-isometric group (stable/slack/total 10/2/12 VS 3/9/12, p ​= ​0.012) at 8 weeks postoperatively. Supeiror PET ligament integration were also observed in near-isometric group through macroscopic observation, micro-CT analysis, histology assessment at both 4 and 8 weeks. The failure load in the Near-Isometric group at 8 weeks were higher than timezero reconstruction with statistical difference (156.8N ​± ​25.98N vs.102.6 ​± ​22.96N, p ​= ​0.02).

Conclusion

A rabbit model of ACLR based on tunnel position isometry was successfully established in this study. The near-isometric tunnel position in rabbit model was femoral anatomic position and tibial posterior position. A near-isometric ACLR with PET ligament did not cause ROM restriction and had a better graft integration and follow-up stability than non-isometric ACLR with ROM restriction.

The Translational Potential of this Article

The study demonstrate the establishmentof near-isometric tunnel position and non-isometric tunnel position with significant difference of ROM restriction and graft-bone integration. The described tunnel positions with differential isometry in a rabbit ACLR provides a reproducible and translational small animal model and enables preclinical research between tunnel position isometry and its affection on variable grafts, graft integration and knee function.