Biomechanical evaluation of an anatomical bone plate assembly for thin patella fracture fixation fabricated by titanium alloy 3D printing

Chi Yang Liao, Shao Fu Huang, Wei Che Tsai, Yu Hui Zeng, Chia Hsuan Li, Chun Li Lin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish
Pages (from-to)171-186
Number of pages16
JournalInternational Journal of Bioprinting
Volume9
Issue number6
DOIs
StatePublished - 2023

Keywords

  • Anatomical surface
  • Assembly
  • Bone plate
  • Metal 3D printing
  • Patella fracture

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