Investigation of a heirarchical collagen scaffold/3D printed lattice structure designed for use in total knee replacements
type: CreativeWork
description: Aseptic loosening is a common cause of late-stage failure in total knee replacement (TKR) surgery. This multifactorial condition is exacerbated by stress shielding and micromotion at the bone/implant interface. Stress shielding can be reduced using implant materials with a similar modulus to that of the surrounding bone, such as Ultra High Molecular Weight Polyethylene (UHMWPE). Micromotion is reduced by improved implant osseointegration. A new design for the tibial component of a prosthesis based on macromolecular materials was therefore proposed. A fused deposition modelling (FDM) 3D printed poly ether ketone ketone (PEKK) lattice structure formed the load bearing component of the construct. This contained a lyophilised collagen scaffold filling the lattice voids, to encourage osseointegration. To understand the effects of printing parameters on the structure and properties of prepared samples, the bonds formed between FDM printed rasters were explored. Samples printed from poly lactic acid (PLA) and PEKK polymers were investigated. X-ray microtomography provided information on structural defects (including porosity) and tensile testing was used to investigate the relationships between printing parameters and the ultimate tensile strength (UTS) and modulus. The rasters of dumbbell specimens were aligned perpendicular to the applied load, such that the inter-raster bonds were strained during testing. Increased print speed and raster width were associated with reduced porosity and increased UTS and modulus in both PLA and PEKK. Based on these findings, optimised printing parameter sets were defined. Next, a lattice design was developed to match the compressive modulus of cancellous bone. Based on a combination of theoretical modelling and experimental testing, the effects of lattice volume fraction and geometry on compressive modulus were determined for a range of different lattice morphologies. A sheet diamond lattice morphology exhibited the highest modulus over a…
abstract: Aseptic loosening is a common cause of late-stage failure in total knee replacement (TKR) surgery. This multifactorial condition is exacerbated by stress shielding and micromotion at the bone/implant interface. Stress shielding can be reduced using implant materials with a similar modulus to that of the surrounding bone, such as Ultra High Molecular Weight Polyethylene (UHMWPE). Micromotion is reduced by improved implant osseointegration. A new design for the tibial component of a prosthesis based on macromolecular materials was therefore proposed. A fused deposition modelling (FDM) 3D printed poly ether ketone ketone (PEKK) lattice structure formed the load bearing component of the construct. This contained a lyophilised collagen scaffold filling the lattice voids, to encourage osseointegration. To understand the effects of printing parameters on the structure and properties of prepared samples, the bonds formed between FDM printed rasters were explored. Samples printed from poly lactic acid (PLA) and PEKK polymers were investigated. X-ray microtomography provided information on structural defects (including porosity) and tensile testing was used to investigate the relationships between printing parameters and the ultimate tensile strength (UTS) and modulus. The rasters of dumbbell specimens were aligned perpendicular to the applied load, such that the inter-raster bonds were strained during testing. Increased print speed and raster width were associated with reduced porosity and increased UTS and modulus in both PLA and PEKK. Based on these findings, optimised printing parameter sets were defined. Next, a lattice design was developed to match the compressive modulus of cancellous bone. Based on a combination of theoretical modelling and experimental testing, the effects of lattice volume fraction and geometry on compressive modulus were determined for a range of different lattice morphologies. A sheet diamond lattice morphology exhibited the highest modulus over a…
author: Meek, Matthew
language: eng
keywords: 3D printing, collagen, orthopaedics, PEKK, total knee replacement
license: https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/3a81ff7d-5e23-40ef-bb7c-9e991a3a9be4/download
license: https://www.rioxx.net/licenses/all-rights-reserved/
date published: 2023-07-24
date modified: 2026-07-22T22:24:28Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.100237