Porous poly(para-phenylene) scaffolds for load-bearing orthopedic applications

DiRienzo, Amy L.; Yakacki, Christopher M.; Frensemeier, Mareike; Schneider, Andreas; Safranski, David L.; Hoyt, Anthony J.; Frick, Carl P.

doi:10.1016/j.jmbbm.2013.10.012

Cited by 20 publications

(14 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…All samples demonstrated similar stress-strain responses and there were no observed differences in deformation behavior over the range of pore sizes considered here. This is in agreement with previous studies on porous polymers that showed that the percent porosity had a greater influence on properties than pore size within certain size ranges [28]. While pore size showed little effect, the compressive response of the porous architecture was different for the two architecture depths.…”

Section: Compression Testing and Microct Analysis Demonstrated Three supporting

confidence: 92%

Local deformation behavior of surface porous polyether-ether-ketone

Evans

Torstrick

Safranski

et al. 2017

Journal of the Mechanical Behavior of Biomedical Materials

Self Cite

View full text Add to dashboard Cite

Surface porous polyether-ether-ketone has the ability to maintain the tensile monotonic and cyclic strength necessary for many load bearing orthopedic applications while providing a surface that facilitates bone ingrowth; however, the relevant deformation behavior of the pore architecture in response to various loading conditions is not yet fully characterized or understood. The focus of this study was to examine the compressive and wear behavior of the surface porous architecture using micro Computed Tomography (micro CT). Pore architectures of various depths (~0.5-2.5mm) and pore sizes (212-508µm) were manufactured using a melt extrusion and porogen leaching process. Compression testing revealed that the pore architecture deforms in the typical three staged linear elastic, plastic, and densification stages characteristic of porous materials. The experimental moduli and yield strengths decreased as the porosity increased but there was no difference in properties between pore sizes. The porous architecture maintained a high degree of porosity available for bone-ingrowth at all strains. Surface porous samples showed no increase in wear rate compared to injection molded samples, with slight pore densification accompanying wear.

show abstract

Section: Compression Testing and Microct Analysis Demonstrated Three supporting

confidence: 92%

Local deformation behavior of surface porous polyether-ether-ketone

Evans

Torstrick

Safranski

et al. 2017

Journal of the Mechanical Behavior of Biomedical Materials

Self Cite

View full text Add to dashboard Cite

show abstract

“…Metallic implants provide high strength but are associated with medical imaging artifacts and unwanted bone resorption due to their high modulus and corresponding stress shielding [2]. Current porous polymer scaffolds can facilitate bony ingrowth but lack the strength necessary for high load-bearing environments experienced in clinical soft tissue reconstructions, spinal fusions, and arthrodesis applications [3, 4]. Bioresorbable polymers and composites facilitate osseointegration and implant resorption, but are clinically limited to soft tissue reconstructions and have cited incidences of prolonged inflammation, migration, incomplete degradation, and implant breakage [5].…”

Section: Introductionmentioning

confidence: 99%

High-strength, surface-porous polyether-ether-ketone for load-bearing orthopedic implants

Evans

Torstrick

Lee³

et al. 2015

Acta Biomaterialia

Self Cite

177

140

View full text Add to dashboard Cite

Despite its widespread clinical use in load-bearing orthopaedic implants, polyether-ether-ketone (PEEK) is often associated with poor osseointegration. In this study, a surface porous PEEK material (PEEK-SP) was created using a melt extrusion technique. The porous layer thickness was 399.6±63.3 µm and possessed a mean pore size of 279.9±31.6 µm, strut spacing of 186.8±55.5 µm, porosity of 67.3±3.1%, and interconnectivity of 99.9±0.1%. Monotonic tensile tests showed that PEEK-SP preserved 73.9% of the strength (71.06±2.17 MPa) and 73.4% of the elastic modulus (2.45±0.31 GPa) of as-received, injection molded PEEK. PEEK-SP further demonstrated a fatigue strength of 60.0 MPa at one million cycles, preserving 73.4% of the fatigue resistance of injection molded PEEK. Interfacial shear testing showed the pore layer shear strength to be 23.96±2.26 MPa. An osseointegration model in the rat revealed substantial bone formation within the pore layer at 6 and 12 weeks via µCT and histological evaluation. Ingrown bone was more closely apposed to the pore wall and fibrous tissue growth was reduced in PEEK-SP when compared to non-porous PEEK controls. These results indicate that PEEK-SP could provide improved osseointegration while maintaining the structural integrity necessary for load-bearing orthopaedic applications.

show abstract

“…where E s is the modulus of the solid material, E c is the elastic modulus of the porous material, and f is the porosity [25][26][27]. Based on this relationship, PPP with 70% porosity was assigned an elastic modulus of 450 MPa, which falls within the range measured experimentally [24].…”

Section: Methodsmentioning

confidence: 68%

“…Porous PPP can be manufactured via hot press sintering of PPP powder with the desired amount of salt (NaCl) crystals needed to produce the desired level of porosity. After sintering, the salt is leached out, leaving an open-cell foam structure with a pore size dictated by the size of the NaCl crystals [25]. For the models in this study, PPP was simulated with 70% porosity by calculating the apparent elastic modulus of the porous PPP (Eq.…”

Section: Methodsmentioning

confidence: 99%

Interbody Spacer Material Properties and Design Conformity for Reducing Subsidence During Lumbar Interbody Fusion

Chatham

Patel

Yakacki

et al. 2017

Journal of Biomechanical Engineering

Self Cite

View full text Add to dashboard Cite

There is a need to better understand the effects of intervertebral spacer material and design on the stress distribution in vertebral bodies and endplates to help reduce complications such as subsidence and improve outcomes following lumbar interbody fusion. The main objective of this study was to investigate the effects of spacer material on the stress and strain in the lumbar spine after interbody fusion with posterior instrumentation. A standard spacer was also compared with a custom-fit spacer, which conformed to the vertebral endplates, to determine if a custom fit would reduce stress on the endplates. A finite element (FE) model of the L4–L5 motion segment was developed from computed tomography (CT) images of a cadaveric lumbar spine. An interbody spacer, pedicle screws, and posterior rods were incorporated into the image-based model. The model was loaded in axial compression, and strain and stress were determined in the vertebra, spacer, and rods. Polyetheretherketone (PEEK), titanium, poly(para-phenylene) (PPP), and porous PPP (70% by volume) were used as the spacer material to quantify the effects on stress and strain in the system. Experimental testing of a cadaveric specimen was used to validate the model's results. There were no large differences in stress levels (<3%) at the bone–spacer interfaces and the rods when PEEK was used instead of titanium. Use of the porous PPP spacer produced an 8–15% decrease of stress at the bone–spacer interfaces and posterior rods. The custom-shaped spacer significantly decreased (>37%) the stress at the bone–spacer interfaces for all materials tested. A 28% decrease in stress was found in the posterior rods with the custom spacer. Of all the spacer materials tested with the custom spacer design, 70% porous PPP resulted in the lowest stress at the bone–spacer interfaces. The results show the potential for more compliant materials to reduce stress on the vertebral endplates postsurgery. The custom spacer provided a greater contact area between the spacer and bone, which distributed the stress more evenly, highlighting a possible strategy to decrease the risk of subsidence.

show abstract

Porous poly(para-phenylene) scaffolds for load-bearing orthopedic applications

Cited by 20 publications

References 59 publications

Local deformation behavior of surface porous polyether-ether-ketone

Local deformation behavior of surface porous polyether-ether-ketone

High-strength, surface-porous polyether-ether-ketone for load-bearing orthopedic implants

Interbody Spacer Material Properties and Design Conformity for Reducing Subsidence During Lumbar Interbody Fusion

Contact Info

Product

Resources

About