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Effect of Geometry on the Fixation Strength of Anterior Cruciate Ligament Reconstruction Using BASHTI Technique

Moeinnia, Hadi | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53176 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Nourani, Amir; Chizari, Mahmoud
  7. Abstract:
  8. BASHTI is a new implant-less ACL reconstruction surgery which has recently been considered for its advantages. This study aimed to investigate the effects of tendon and cannulated drill bit diameter on the BASHTI fixation strength and core bone engaged length (CBEL) in an anterior cruciate ligament (ACL) reconstruction. It is believed that CBEL may affect both bone healing process and fixation strength in this technique. Bovine digital tendons and Sawbones blocks were used to mimic the ACL reconstruction. Tendons were sized to 6, 7, 8, 9, and 10 mm and the hole size for the 6-9 mm tendons was set to 10 mm while for the 10 mm tendon was set to 12 mm. Mechanical strength of the specimens was measured using a cyclic loading followed by a single cycle pull-out load to failure to simulate the real post-surgical loading conditions. Finally, failure modes of specimens, ultimate failure load as well as CBELs were recorded. The maximum possible tendon surface strain (i.e. tendon compression) for tendon diameters of 6, 7, 8, 9 and 10 mm were 0.73, 0.8, 0.7, 0.66 and 0.46, 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), 248±81 N (core 9.5 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. Moreover, the CBEL was influenced by both tendon diameter and tendon compression. Also, an increase in hole diameter (10 to 12 mm), did not significantly affect BASHTI fixation strength while caused an significant increase in CBEL (60% increase). Finally, a finite element model of the BASHTI fixation process was developed and its results were used to design an artificial neural network in order to anticipate the BASHTI fixation strength according to the geometrical parameters
  9. Keywords:
  10. Bashti Bone Plug Method (BBPT) ; Geometric Parameters ; Anterior Cruciate Ligament (ACL) ; Core Bone Plug ; Biomechanical Models ; Fixation Strength ; Extensional Loading

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