Borjali, A. | bioRxiv Science

bioRxiv2021

Core bone diameter in an organic implant-less technique affecting the biomechanical properties of the anterior cruciate ligament fixation; an in-vitro study

BackgroundBone and site hold tendon inside (BASHTI) is an implant-less technique that can solve some of the problems associated with other anterior cruciate ligament (ACL) reconstructive methods. This study aims to investigate the effect of core bone diameter variation on the biomechanical properties of a reconstructed ACL using BASHTI technique. MethodsA number of 15 laboratory samples of reconstructed ACL were built using bovine digital tendons and Sawbones blocks. Samples were divided into three groups with different core bone diameters of 8 mm, 8.5 mm, and 9 mm. The double-stranded tendon size and bone tunnel diameter were 8 mm and 10 mm, respectively. A loading scenario consisting of two cyclic loadings followed by a single cycle pull-out loading was applied to the samples simulating the after-surgery loading conditions to observe the fixation strength. ResultsResults showed that the core bone diameter had a significant effect on the failure mode of the samples (P = 0.006) and their fixation strength (P < 0.001). Also, it was observed that the engaging length and the average cyclic stiffness (ACS) of them were influenced by the core bone diameter significantly (engaging length: P = 0.001, ACS: P = 0.007), but its effect on the average pull-out stiffness was not significant (P = 0.053). ConclusionsIt was concluded that core bone diameter variation has a significant impact on the mechanical properties of ACL reconstruction when BASHTI technique is used, and it should be noted for surgeons who use BASHTI technique. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=103 SRC="FIGDIR/small/452098v1_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@33ca50org.highwire.dtl.DTLVardef@276f38org.highwire.dtl.DTLVardef@f6e66forg.highwire.dtl.DTLVardef@192b117_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIA new implant-less technique was used to reconstruct anterior cruciate ligament. C_LIO_LIArtificial bone and fresh animal soft tissue used to simulate the fixation process. C_LIO_LILoading condition were carefully chosen to simulate the post-operation. C_LIO_LIComponents geometry had direct effect on biomechanical properties of the fixation. C_LIO_LIOptimum geometry was found trough an experimental examination. C_LI

bioengineering↗

bioRxiv2020

Biomechanical Modeling of a Bone Tunnel Enlargement Post ACL Reconstruction

BackgroundBone tunnel enlargement is considered as a potential problem following ACL reconstruction and can cause a fixation failure and complicate its revision surgery. This study evaluates post tibial tunnel expansion in ACL reconstruction using an interference screw. MethodsA series of in-vitro experimental tests on animal bone and tissues were used to simulate post ACL reconstruction. The study believes an unbalanced lateral force can cause a local enlargement on the contact zone inside the tunnel. Grayscale X-ray images were used to assess the screw alignment inside the tunnel. ResultsThey showed a slight misalignment between the screw and the tunnel axis as the tendon strands moved along the side of the tunnel, and the screw had partial contact with the tendon and bone along the tunnel. According to the results, increased stress in the tunnel wall causes tunnel enlargement. Although the tunnel created away from the tibial central axis produced a higher strength, it results in higher stress on the wall of the tunnel which can increase the risk of tunnel expansion. ConclusionsThe current study believes the use of an unguided interference screw insertion potentially increases risks of the misaligned fixation and cause a tunnel enlargement. This risk may be controlled by restricting the post-operative rehabilitation.

bioengineering↗