In vitro degradation, flexural, compressive and shear properties of fully bioresorbable composite rods

R.M. Felfel; I. Ahmed; A.J. Parsons; G.S. Walker; C.D. Rudd

doi:10.1016/j.jmbbm.2011.05.016

In vitro degradation, flexural, compressive and shear properties of fully bioresorbable composite rods

R.M. Felfel^*, I. Ahmed, A.J. Parsons, G.S. Walker, C.D. Rudd

^*Corresponding author for this work

Mechanical And Aerospace Engineering

Research output: Contribution to journal › Article › peer-review

56 Citations (Scopus)

Abstract

Several studies have investigated self-reinforced polylactic acid (SR-PLA) and polyglycolic acid (SR-PGA) rods which could be used as intramedullary (IM) fixation devices to align and stabilise bone fractures. This study investigated totally bioresorbable composite rods manufactured via compression moulding at ~100 °C using phosphate glass fibres (of composition 50P ₂O ₅-40CaO-5Na ₂O-5Fe ₂O ₃ in mol%) to reinforce PLA with an approximate fibre volume fraction (vf) of 30%. Different fibre architectures (random and unidirectional) were investigated and pure PLA rods were used as control samples.The degradation profiles and retention of mechanical properties were investigated and PBS was selected as the degradation medium. Unidirectional (P50 UD) composite rods had 50% higher initial flexural strength as compared to PLA and 60% higher in comparison to the random mat (P50 RM) composite rods. Similar initial profiles for flexural modulus were also seen comparing the P50 UD and P50 RM rods. Higher shear strength properties were seen for P50 UD in comparison to P50 RM and PLA rods. However, shear stiffness values decreased rapidly (after a week) whereas the PLA remained approximately constant. For the compressive strength studies, P50 RM and PLA rods remained approximately constant, whilst for the P50 UD rods a significantly higher initial value was obtained, which decreased rapidly after 3 days immersion in PBS.However, the mechanical properties decreased after immersion in PBS as a result of the plasticisation effect of water within the composite and degradation of the fibres. The fibres within the random and unidirectional composite rods (P50 RM and P50 UD) degraded leaving behind microtubes as seen from the SEM micrographs (after 28 days degradation) which in turn created a porous structure within the rods. This was the main reason attributed for the increase seen in mass loss and water uptake for the composite rods (~17% and ~16%, respectively).

Original language	English
Pages (from-to)	1462-1472
Number of pages	11
Journal	Journal of the Mechanical Behavior of Biomedical Materials
Volume	4
Issue number	7
Early online date	13 May 2011
DOIs	https://doi.org/10.1016/j.jmbbm.2011.05.016
Publication status	Published - 31 Oct 2011

Funding

The authors would like to acknowledge the financial support of the Egyptian Government and the EPSRC . The authors would also like to thank Dr. Derek Irvine and Ms. Natasha Birkin for their help with the GPC.

Keywords

composite rods
compressive and shear stress properties
flexural
phosphate glass fibres
polylactic acid

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10.1016/j.jmbbm.2011.05.016

Cite this

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title = "In vitro degradation, flexural, compressive and shear properties of fully bioresorbable composite rods",

abstract = "Several studies have investigated self-reinforced polylactic acid (SR-PLA) and polyglycolic acid (SR-PGA) rods which could be used as intramedullary (IM) fixation devices to align and stabilise bone fractures. This study investigated totally bioresorbable composite rods manufactured via compression moulding at ~100 °C using phosphate glass fibres (of composition 50P 2O 5-40CaO-5Na 2O-5Fe 2O 3 in mol%) to reinforce PLA with an approximate fibre volume fraction (vf) of 30%. Different fibre architectures (random and unidirectional) were investigated and pure PLA rods were used as control samples.The degradation profiles and retention of mechanical properties were investigated and PBS was selected as the degradation medium. Unidirectional (P50 UD) composite rods had 50% higher initial flexural strength as compared to PLA and 60% higher in comparison to the random mat (P50 RM) composite rods. Similar initial profiles for flexural modulus were also seen comparing the P50 UD and P50 RM rods. Higher shear strength properties were seen for P50 UD in comparison to P50 RM and PLA rods. However, shear stiffness values decreased rapidly (after a week) whereas the PLA remained approximately constant. For the compressive strength studies, P50 RM and PLA rods remained approximately constant, whilst for the P50 UD rods a significantly higher initial value was obtained, which decreased rapidly after 3 days immersion in PBS.However, the mechanical properties decreased after immersion in PBS as a result of the plasticisation effect of water within the composite and degradation of the fibres. The fibres within the random and unidirectional composite rods (P50 RM and P50 UD) degraded leaving behind microtubes as seen from the SEM micrographs (after 28 days degradation) which in turn created a porous structure within the rods. This was the main reason attributed for the increase seen in mass loss and water uptake for the composite rods (~17% and ~16%, respectively).",

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AU - Ahmed, I.

AU - Parsons, A.J.

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AU - Rudd, C.D.

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N2 - Several studies have investigated self-reinforced polylactic acid (SR-PLA) and polyglycolic acid (SR-PGA) rods which could be used as intramedullary (IM) fixation devices to align and stabilise bone fractures. This study investigated totally bioresorbable composite rods manufactured via compression moulding at ~100 °C using phosphate glass fibres (of composition 50P 2O 5-40CaO-5Na 2O-5Fe 2O 3 in mol%) to reinforce PLA with an approximate fibre volume fraction (vf) of 30%. Different fibre architectures (random and unidirectional) were investigated and pure PLA rods were used as control samples.The degradation profiles and retention of mechanical properties were investigated and PBS was selected as the degradation medium. Unidirectional (P50 UD) composite rods had 50% higher initial flexural strength as compared to PLA and 60% higher in comparison to the random mat (P50 RM) composite rods. Similar initial profiles for flexural modulus were also seen comparing the P50 UD and P50 RM rods. Higher shear strength properties were seen for P50 UD in comparison to P50 RM and PLA rods. However, shear stiffness values decreased rapidly (after a week) whereas the PLA remained approximately constant. For the compressive strength studies, P50 RM and PLA rods remained approximately constant, whilst for the P50 UD rods a significantly higher initial value was obtained, which decreased rapidly after 3 days immersion in PBS.However, the mechanical properties decreased after immersion in PBS as a result of the plasticisation effect of water within the composite and degradation of the fibres. The fibres within the random and unidirectional composite rods (P50 RM and P50 UD) degraded leaving behind microtubes as seen from the SEM micrographs (after 28 days degradation) which in turn created a porous structure within the rods. This was the main reason attributed for the increase seen in mass loss and water uptake for the composite rods (~17% and ~16%, respectively).

AB - Several studies have investigated self-reinforced polylactic acid (SR-PLA) and polyglycolic acid (SR-PGA) rods which could be used as intramedullary (IM) fixation devices to align and stabilise bone fractures. This study investigated totally bioresorbable composite rods manufactured via compression moulding at ~100 °C using phosphate glass fibres (of composition 50P 2O 5-40CaO-5Na 2O-5Fe 2O 3 in mol%) to reinforce PLA with an approximate fibre volume fraction (vf) of 30%. Different fibre architectures (random and unidirectional) were investigated and pure PLA rods were used as control samples.The degradation profiles and retention of mechanical properties were investigated and PBS was selected as the degradation medium. Unidirectional (P50 UD) composite rods had 50% higher initial flexural strength as compared to PLA and 60% higher in comparison to the random mat (P50 RM) composite rods. Similar initial profiles for flexural modulus were also seen comparing the P50 UD and P50 RM rods. Higher shear strength properties were seen for P50 UD in comparison to P50 RM and PLA rods. However, shear stiffness values decreased rapidly (after a week) whereas the PLA remained approximately constant. For the compressive strength studies, P50 RM and PLA rods remained approximately constant, whilst for the P50 UD rods a significantly higher initial value was obtained, which decreased rapidly after 3 days immersion in PBS.However, the mechanical properties decreased after immersion in PBS as a result of the plasticisation effect of water within the composite and degradation of the fibres. The fibres within the random and unidirectional composite rods (P50 RM and P50 UD) degraded leaving behind microtubes as seen from the SEM micrographs (after 28 days degradation) which in turn created a porous structure within the rods. This was the main reason attributed for the increase seen in mass loss and water uptake for the composite rods (~17% and ~16%, respectively).

KW - composite rods

KW - compressive and shear stress properties

KW - flexural

KW - phosphate glass fibres

KW - polylactic acid

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DO - 10.1016/j.jmbbm.2011.05.016

M3 - Article

C2 - 21783156

AN - SCOPUS:79960557137

SN - 1751-6161

VL - 4

SP - 1462

EP - 1472

JO - Journal of the Mechanical Behavior of Biomedical Materials

JF - Journal of the Mechanical Behavior of Biomedical Materials

IS - 7

ER -

In vitro degradation, flexural, compressive and shear properties of fully bioresorbable composite rods

Abstract

Funding

Keywords

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