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Effects of Using Sheath on Fixation Strength of Bashti Bone Plug Technique (BBPT) in an Anterior Cruciate Ligament (ACL) Reconstruction

Borjali, Amir Hossein | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50690 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Farrahi, Gholamhossein; Chizari, Mahmoud
  7. Abstract:
  8. Bashti Bone Plug Technique (BBPT) is a novel implant-less surgical methodology for Anterior Cruciate Ligament (ACL) reconstruction. The technique uses the core bone plug belonging to the patient, cut during tunneling with hole saw drill bit, to fix the ends of the tendon graft. Results show that when fitting the bone plug in this method, a large strike is required for fixation which leads to breaking the bone plug and consequently reducing the effective length of the bone plug inside the tunnel during fixation. Therefore, it was decided to use the sheath which covers the bone plug to overcome said challenges since during fixation with the sheath, Due to the low friction coefficient in these sheaths, the bone plug enters the tunnel more easily, does not require heavy strikes and fixation is done better. Moreover, the bone plug does not diverge from the path and causes less injury to the graft tissue and less widening in the fixation tunnel. Hence, in order to perform a controlled study, a synthetic bone with the density correlated with young people was used as a model for human bone. Additionally, bovine tendons with certain length were used as the graft tissue. PVC and PTFE polymers with two different thickness values were used. Oscillating load and simple tension tests were performed. Loading was done with preconditioning 5-20 N for 10 cycles with 1 Hz frequency, 40-120 sinusoidal loading for 100 cycles with 1 Hz frequency and simple tensile test with an incremental rate of 20 mm/s until failure. The final mechanical strength and stiffness in the PTFE sheath with 0.1 mm was 343.86 N and 114.62 N/mm and in the PVC sheath with similar thickness, 235.95 N and 93.36 N/mm. Therefore, the sheath which was superior based on mechanical properties was selected and compared with the 0.2 mm PTFE sheath. The final force and stiffness of the sheath with 0.2 mm thickness was categorized into two groups based on the length the bone plug has entered the tunnel into incomplete and complete, which was 221.6 N and 66.99 N/mm for the former and 420.02 N and 126.16 N/mm for the latter. Statistical analysis showed that the PTFE sheath was the better choice. Additionally, it was found that the length of the bone plug inside the tunnel has a large effect on fixation strength and if the plug enters the tunnel completely, the best possible outcome can be expected. Hence, using sheath in this technique is highly recommended for ACL reconstruction
  9. Keywords:
  10. Knee ; Bashti Bone Plug Method (BBPT) ; Anterior Cruciate Ligament (ACL) ; Sheath Flow ; Implant Less ; Core Bone Plug

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