AccScience Publishing / IJB / Volume 9 / Issue 6 / DOI: 10.36922/ijb.0117
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Biomechanical evaluation of an anatomical bone plate assembly for thin patella fracture fixation fabricated by titanium alloy 3D printing  

Chi-Yang Liao1,2,3 Shao-Fu Huang1,4 Wei-Che Tsai1 Yu-Hui Zeng1 Chia-Hsuan Li1,4 Chun-Li Lin1,4*
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1 Department of Biomedical Engineering, National Yang Ming Chiao Tung University, Taipei, Taiwan
2 Department of Orthopedics, Tri-Service General Hospital Songshan Branch, National Defense Medical Center, Taipei, Taiwan
3 Department of Surgery, Tri-Service General Hospital Songshan Branch, National Defense Medical Center, Taipei, Taiwan
4 Medical Device Innovation and Translation Center, National Yang Ming Chiao Tung University, Taipei 112, Taiwan
Submitted: 5 April 2023 | Accepted: 17 June 2023 | Published: 18 July 2023
© 2023 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( )

This study established and evaluated the feasibility of a three-dimensional (3D)- printed titanium anatomical surface with adjustable thin bone plate assembly (AATBP) for patella fracture fixation. The AATBP was 1.6 mm in thickness and divided into a proximal plate (PP) with locking screw holes and a distal plate (DP) (0.4 mm in thickness) with compressive screw holes for assembly using a ratchet mechanism to adjust the total fixation height according to the patella size. Two pairs of hooks were designed on the proximal/distal edges to allow passage through the tendon to grip the fractured fragments. 3D printing combined with Computer Numerical Control (CNC) drilling was performed to manufacture the AATBP. Four-point bending and surface roughness tests were performed to evaluate the AATBP mechanical behavior. A cyclic (300 times) load test with 15-kg weights was adopted to compare the biomechanical stability between the AATBP and conventional tension band wiring (TBW) fixations. A parallel finite element (FE) analysis was achieved to understand the fracture gap and bone stress in the two different fixations on a transverse patella fracture. The result showed that the maximum AATBP manufacturing error was 3.75%. The average fracture gaps on the medial/lateral sides after cyclic loads were 2.38 ± 0.57 mm/2.30 ± 0.30 mm for TBW and 0.03 ± 0.01 mm/0.06 ± 0.03 mm for AATBP fixations. The same trend occurred in the FE simulation. This study confirmed that a complicated thin bone plate, including the anatomical surface, hooks, and ratchet with size-adjustable characteristics, can be fabricated using metal 3D printing with acceptable manufacturing error and reasonable anatomical surface/ thin bone plate assembly fitness. Biomechanical cyclic tests and FE simulation showed that the AATBP fixation is superior to the conventional TBW for patella transverse fractures.

Metal 3D printing
Anatomical surface
Patella fracture
Bone plate
This study is supported in part by MOST project 108-2622-E-010-001-CC2 and 110-2222-E-032-003-MY2, Taiwan.
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Conflict of interest
The authors declare no conflicts of interest.
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International Journal of Bioprinting, Electronic ISSN: 2424-8002 Print ISSN: 2424-7723, Published by AccScience Publishing