Soft bone cement for brittle bone
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Soft bone cement for brittle bone Cecilia Persson 1 , Alejandro López 1,2 , Malin Nilsson 2 1 Department of Materials Science and Engineering, Uppsala University, Sweden. 2 Inossia AB, Sweden.
Transcript of Soft bone cement for brittle bone
Soft bone cement for brittle bone
Cecilia Persson1, Alejandro López1,2, Malin Nilsson2
1 Department of Materials Science and Engineering, Uppsala University, Sweden. 2 Inossia AB, Sweden.
Background
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Standardcement
Softcement Bone
Averageelasticm
odulus
(MPa
)
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Standardcement
Softcement Bone
Averagecompressive
strength(M
Pa)
newfractures40%Success
60%
Nonadjacentfractures33%
Adjacentfractures67%
Incidenceofosteoporosisinadults>50yearsoldworldwide
%PatientsVertebralaugmentation %fractures
Standardcementtoostiff!
Controlling the mechanical properties of bone cement using
cement softener
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100012001400160018002000
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Elasticm
odulus(M
Pa)
%CementSoftener
Standardcement
mediumstiffnesscement
softcement
Handling properties
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Standardcement Softcement
settingtim
e(m
in)
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doughingtime(m
in)
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Standardcement Softcement
maxim
umte
mpe
rature(°C)
Slightlylongersettingtimeforsafeinjectability
Lowsettingtemperaturefor
reducedriskoftissuenecrosis
Behavior and injectability Polymerizationtemperatureatvariousroom
temperatures
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Force(N)
Time(min)
Standardcement(1.5mm/min)
Softcement(1.5mm/min)
Standardcement(5mm/min)
Softcement(5mm/min)
Easierandsaferinjectabilityattwodifferentspeeds
Cohesion StandardcementSoftcement
Nosignificantdifferenceincementspread(sphericity)=
goodcohesion!
Mechanical properties
24h 24h2w 2w4w 4w0
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Standardcement Softcement
Elasticm
odulus(M
Pa)
24h 24h2w 2w4w 4w0
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Standardcement Softcement
Compressivestrength(M
Pa)
Rodent in vivo model
Representativehistologicalsectionsoftissueexplantsfrom1,4and12weeks,stainedwithhematoxylinandeosin(ISO10993-6).• Notoxicreaction• Nodifferenceintissueresponsebetweenstandardandsoftcements• Noabnormaltissueorganizationapartfromnecessarywoundhealing
RepresentativeCT-scansofimplantsinvivoandexvivo.Fiveimplantsoutofeightareobservedinthis
image.
Sprague-Dawleyratsharvestedat1,4and12weeks• 8implants/animal• Histology• Flowcytometry
Rodent in vivo model
• No statistical differences (p > 0.05) were found between the populations of immune cells present in the tissue surrounding the different materials, indicating that there was no significant differences in the immune response to the modified PMMA cements compared to the base cement.
• The leukocyte population decreased between 1-week and 12-week (p=0.04). • The granulocyte population decreased between 4-week and 12-week (p=0.009). • The macrophage population showed no significant change in presence over time.
Sheep in vivo model NAMSA(Lyon):7sheep:defectsizeØ=4mmandh=9-12mmharvestedat4and12weeks8implants/animalImplantedinthebone
A. B.
LEFT
C. D.
RIGHT
Thepurposeofthestudywastoevaluate:• thelocaltissueeffects• thedegradation• theperformance
Sheep in vivo model X-Rayimagesofmodifiedcement(AandB)andcontrol(CandD)at4weeks
Tissueresponseanalysedinregionofinterest
Sheep in vivo model A-modifiedcementB-control.C-modifiedcementat4weeksD-controlat4weeksE-modifiedcementat12weeksF-controlat12weeksBT:Bonetissue(pink),IG:Implantgranules(blackdots)I:Implant(white)FB:fibroustissue(navyblue)BM:Bonemarrow(grey)
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Test Control Test Control
ImplantAreaDensity(%)LacunaeAreaDensity(%)FibrousAreaDensity(%)BoneAreaDensity(%)
4weeks 12weeks
Conclusions • Low stiffness of soft cement matches trabecular bone
• Low setting temperature making it a safer product
• Longer injection time giving improved injectability and safer handling
• Easy to mix and use, does not alter known mixing procedure for bone cements • No toxic reaction, no significant difference in tissue or immune response, no delayed immune response,
and generally biocompatible in rodent and sheep in vivo model • Bone healing response observed around the soft cement was similar to that noted around the control
over time, both qualitatively and histomorphometrically.
Conclusions
The new cement showed safe biological response in combination with more adequate mechanical properties for osteoporotic bone, making it a promising material for improved outcomes of vertebroplasty in osteoporotic patients.
Acknowledgements • MedTech4Health• VINNOVA(VINNMER2010-02073)• EU(FP7-PEOPLE-2010-268134)
Contact:[email protected]
