Effect of geometry on the fixation strength of anterior cruciate ligament reconstruction using BASHTI technique

© 2020 Thieme Publishing Group. This is an accepted manuscript of an article accepted for publication in Journal of Knee Surgery; https://dx.doi.org/10.1055/s-0040-1716371.The goal of this study is to investigate the effects of tendon and cannulated drill bit diameter on the strength of the bone and site hold tendon inside (BASHTI) fixation technique for an anterior cruciate ligament (ACL) reconstruction. Bovine digital tendons and Sawbones blocks were used to mimic the ACL reconstruction. Mechanical strength of the specimens was measured using a cyclic loading continued by a single cycle pull-out load until failure to simulate the real post-surgical loading conditions. Finally, failure modes of specimens and ultimate failure load were recorded. The maximum possible tendon surface strain (i.e. tendon compression) for tendon diameters of 6, 7, 8, and 9 mm were 0.73, 0.8, 0.7, and 0.65, respectively. 80% of the specimens with tendon diameter of 6 mm and 20% of specimens with tendon diameter of 7 mm failed on the torn tendon. All samples with larger tendon diameters (i.e. 8 and 9 mm) failed on the fixation slippage. The maximum fixation strength according to the most suitable core bones for 6, 7, 8 and 9 mm tendons were 148±47 N (core 9.5 mm), 258±66 N (core 9.5 mm), 386±128 N (core 8.5 mm) and 348±146 N (core 8.5 mm), respectively. The mode of tendon failure was significantly influenced by the tendon diameter. Also, an increase in tendon compression (TC) raised the fixation strength for all tendon diameters; however, tendon over compression decreased the fixation strength for the 8 mm tendon group. Finally, an empirical equation was proposed to predict BASHTI fixation strength.Peer reviewedFinal Accepted Versio

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

© 2021 The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Background Bone 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. Methods A 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. Results Results 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). Conclusions It 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.Peer reviewe

Comparison of mechanical properties in interference screw fixation technique and organic anterior cruciate ligament reconstruction method: a biomechanical study

© 2021 The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Background Bone and Site Hold Tendon Inside (BASHTI) technique is an organic implant-less technique for anterior cruciate ligament (ACL) reconstruction with some clinical advantages, such as speeding up the healing process, over implantable techniques. The study aims to compare the mechanical properties of BASHTI technique with the conventional interference screw technique. Methods To investigate the mechanical properties, 20 in-vitro experimental tests were conducted. Synthetic dummy bone, along with fresh digital bovine tendons, as a graft, were used for experiments. Three loading steps were applied to all specimens, including a preconditioning, a main cyclic, and a pull-out loading. Results The mechanical characters of an interference screw technique using an 8 mm tendon diameter, including fixation strength, average cyclic stiffness (ACS), and average pull-out stiffness (APS) were found to be 439 ± 132 N, 10.3 ± 5.3 kN/mm, and 109 ± 40 N/mm, respectively. In the case of an interference screw using a 9 mm tendon, the fixation strength, ACS, and APS were obtained 549 ± 87 N, 10.3 ± 4.7 kN/mm, and 91 ± 13 N/mm, respectively. In parallel, the fixation strength, APS, and ACS of BASHTI technique using an 8 mm tendon were 360 ± 123 N, 3.3 ± 0.6 kN/mm, and 79 ± 27 N/mm, respectively, while, for 9 mm tendon 278 ± 103 N, 2.4 ± 1.2 kN/mm, and 111 ± 40 N/mm, were reported for fixation strength, APS, and ACS respectively when BASHTI technique was used. Conclusion About 50% of interference screw samples showed superior mechanical properties compared to BASHTI technique, but in another half of the samples, the differences were not significant (N.S.). However, due to organic advantages of BASHTI technique and lower cost, it could be used as a substitute for interference screw technique, especially where fast recovery is expected.Peer reviewe

Proceedings of Abstracts, School of Physics, Engineering and Computer Science Research Conference 2022

© 2022 The Author(s). This is an open-access work distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. For further details please see https://creativecommons.org/licenses/by/4.0/. Plenary by Prof. Timothy Foat, ‘Indoor dispersion at Dstl and its recent application to COVID-19 transmission’ is © Crown copyright (2022), Dstl. This material is licensed under the terms of the Open Government Licence except where otherwise stated. To view this licence, visit http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3 or write to the Information Policy Team, The National Archives, Kew, London TW9 4DU, or email: [email protected] present proceedings record the abstracts submitted and accepted for presentation at SPECS 2022, the second edition of the School of Physics, Engineering and Computer Science Research Conference that took place online, the 12th April 2022

Effect of the core bone engaged length on the BASHTI fixation strength, an in-vitro study on bovine tendons using identical-density surrogate bones

Abstract Background BASHTI is an implant-less anterior cruciate ligament (ACL) reconstruction technique, which resolves the problems caused by implants such as interference screws. This study aims to investigate the effect of the drill bit and tendon’s diameter on the Core Bone Engaged Length (CBEL) and the fixation strength. CBEL is the length of core bone which has a full engagement with both tunnel and graft at the same time. Methods 60 in-vitro tests were conducted for 6, 7, 8, and 9 mm tendon sizes with a 10 mm bone tunnel. In this study bovine tendons and dummy bone blocks were used to model the fixation. Drill bits were used to extract the core bone for securing the auto-graft. A three-stage tensile test including a force-controlled cyclical preloading of 10–50 N with a frequency of 0.1 Hz for 10 cycles, followed by the main force-controlled cyclical loading of 50–200 N with a frequency of 0.5 Hz for 150 cycles, and immediately a displacement-controlled single cycle pull-out load with a rate of 20 mm/min were carried out to discover the fixation strength of each sample. Results The 6 mm group had the greatest CBEL. However, all cases in this group failed in loadings below 200 N, which is the minimum required strength after ACL reconstruction. The fixation strength of cases with more than 200 N fixation strength for 7, 8, and 9 mm tendon diameters were 275 ± 42, 330 ± 110, and 348 ± 93 N, respectively, showing insignificant difference between groups (P-value = 0.45). Nevertheless, CBELs for these groups were 16.6 ± 3.4, 9.6 ± 2.4, and 11.7 ± 3.8 mm, respectively, implying a significant increase in CBEL in the 7 mm group than that for 8 and 9 mm groups (P-value = 0.002 and 0.049, respectively). Conclusion Results showed that CBEL could assess the quality of BASHTI technique. However, CBEL was an inverse function of tendon compression, so it was not an independent parameter to determine BASHTI strength. Also, the CBEL of 7 mm group which fulfilled the 200 N threshold was higher than that of 8 and 9 mm groups, so its healing process speed may be higher, which is recommended for a future study in this field

Biomechanical analysis of different osteosynthesis configurations in the pin and plate fixation method for distal humerus fractures

Abstract Distal humerus fractures commonly occur in adults with low bone mineral density causing major technical challenges for orthopedic surgeons. Persian fixation method was introduced as a novel technique to stabilize small fragments in comminuted distal humerus fractures using a set of K-wires and a reconstruction plate. The present study aims to measure this technique's stiffness and stability of this technique and analyze the effect of influential parameters with numerical simulation and biomechanical testing on a cadaveric specimen. Validation of the finite element (FE) model was conducted based on results of experiments. The results indicated that Delta configuration mainly led to a higher stiffness in the case of axial loading and anterior bending compared to L configuration. Analyzing the influential factors of this technique suggests that changes in diameter and number of K-wires have a similarly significant effect on the construct stiffness while the height of plate had a slight influence. Also, the diameter of wires was the most effective parameter for implant failure, particularly in the 3-pin construct, which caused a reduction in failure risk by about 60%. The results revealed that the Persian fixation method would achieve suitable stability compared to the dual-plating technique