Biomechanics + BIOEN+520+|+ME+527+ Session+9A + Biomechanics + - - PowerPoint PPT Presentation

Musculoskeletal+ Biomechanics+

BIOEN+520+|+ME+527+

Session+9A +

Biomechanics +

• f+Bone

+

…Structure,)Func,on, ) and)Proper,es )

Bone...+

[Q]: +What+do+we+know+about+bone?+

Jeopardy…+ Bone

$200 $400 $1000 $600 $800

Jeopardy...+

206 +

What+is+the+(average)+ number+of+bones+in+the+ adult+human+body?+

Jeopardy…+ Bone

206

$400 $1000 $600 $800

Jeopardy...+

Support,+protect,+homeostasis,+ hematopoiesis… +

What+is+the+funcSon+of+bone?+

Jeopardy…+ Bone

206

$1000 $600 $800

Support, protect, ...

Jeopardy...+

CorScal+and+Cancelleous… +

What+are+the+ two+primary+ types+of+bone?+

Jeopardy…+ Bone

206 Cortical and Cancellous

$1000 $800

Support, protect, ...

Jeopardy...+

Osteoblasts,+osteoclasts,+

• steocytes…

+

What+are++++++ + the+types+of+ bone+cells?+

Jeopardy…+ Bone

206 Cortical and Cancellous

$1000

Support, protect, ... Osteoblasts,

• steoclasts, ...

Who+is+Julius+ Wolff?+

Jeopardy...+

This+German+anatomist+developed+ the+theory+on+the+funcSonal+ adaptaSon+of+bone.++

Session+9A+Discussion+QuesSons...+

[Q]:+What+is+the+mechanical+funcSon+of+bone?+ [Q]:+What+is+the+structure+(macro/micro)+of+bone?+ [Q]:+How+do+the+mechanical+properSes+of+bone+ compare+to+other+materials?+ [Q]:+How+does+the+structure+of+bone+relate+to+its+ funcSon+and+properSes?+ [Q]:+Why+should+we+care+about+the+properSes+of+ bone+(…how+could+they+help)?+

Bone:+By+the+Numbers…+

Bones+by+Region+

28+]+Head/Face/Ear+ 64+]+Upper+Extremity+ 26+]+Spine+ 26+]+Chest+(ribs,+ sternum,+and+ hyoid)+ 62+]+Lower+ ExtremiSes+

Bone:+Macrostructure...+

• Epiphysis:++
• Physis:+
• Metaphysis:+
• Diaphysis:+
• Periosteum:+

[Q]: +What+and+where+are+the+general+regions+

• f+long+bones?+

trabecular bone w/ cortex growth plate trabecular bone w/ cortex cortical bone (shaft) fibrous membrane

Bone:+Macrostructure...+

Examples:+

Bone:+Microstructure...+

[Q]: +What+is+the+fundamental+structural+unit+

• f+corScal+bone?+

Osteon+

Bone:+Microstructure...+

Mow+and+Hayes+(1997)+

Bone:+CorScal…++

+Compact+bone+composed+of+ Sghtly+packed+osteons+

! Osteon+Dia.:++100]300+µm+ ! Density:++1.7]2.0+gm/cc+ ! Volume+FracSon:+85]90%+

Jee+(1983)+

Bone:+Cancellous+/+Trabecular…+

+Porous+“spongy”+bone+

! Trabeculae:++100]300+µm+(thick)+

x+600]1000+µm+(long)+

! Density:++0.09+to+1.26]g/cc+ ! Vol.+FracSon:+~25]30%+(young)+ ! High+surface+area+to+volume+

raSo+

Yeh+and+Keaveney+(1999),++Jee+(1983)+

Bone:+TesSng...+

[Q]: +How+would+you+prepare+and+test+bone+ samples?+

Garnier+(1999),+Mimon+(1997)++

Bone:+TesSng...+

Mimon+(1997),+Garnier+(1999)+

Cancellous+Bone...+

Bone:+TesSng...+

Kemper+(2007)+

+CorScal+ Bone...+

Bone:+TesSng...+

Wam+(2014)+

+NaSve+ Metacarpal+in+ 3]pt+bending+

Bone:+ProperSes...+

[Q]: +To+fulfill+its+role,+what+kind+of+mechanical+

properSes+does+bone+have?+

!

support & protect...

• Comp. Stress (MPa)

(⊥ grain)

Bone:+ProperSes...+

Yes!+

[Q]: +Does+fiber+orientaSon+affect+properSes?+

Bone:+ProperSes...+

[Q]: +Is+bone+strain]rate+sensiSve?+

Yes!+

Bone:+ProperSes...+

Typical+Values...+

Cortical Trabecular Modulus 15-20 GPa 0.2-0.5 GPa Strength 150-200 MPa 2-10 MPa Modulus 10-15 GPa 0.2-0.5 GPa Strength 100-150 MPa 2-10 MPa Modulus 2-5 GPa ? Strength 50-75 MPa 2-10 MPa

Compression Tension

Mow+&+Hayes+(1997),+Kopperdahl+and+Keaveney+(1998),++Ciarelli+(1991)+

Shear

Bone:+ComposiSon...+

[Q]: +What+in+the+composiSon+(structure)+of+

bone+would+give+it+these+properSes?+

! Extracellular+matrix...+(2+phases)+

• Organic+phase:+Collagen++++++++++++++++++++++++++++++++++++++

(50]60%+of+bone+vol.,+25]35%+of+bone+wt.)+

• Mineral+phase:+HydroxyapaSte+crystals+++++++++++++

(40]50%+of+bone+vol.,+65]75%+of+bone+wt.)+

! A+“bio]composite”+material…+

Mow+and+Hayes+(1997)+

Bone:+Structure]FuncSon]Property...+

[Q]: +In+summary,+how+does+the+structure+of+

bone+relate+to+its+properSes+and+funcSon?+

Its structure (a strong bio-composite material) and properties (stiff and strong) enables it to perform its necessary function (support the weight of the body and protect vital organs)…

FuncSon+ Property+ Structure+

Bone:+Summary...+

• +A+biological+“living”+Sssue+(…not+staSc)+
• +Two+primary+types:+corScal+and+trabecular+
• +A+“bio]composite”+material+consisSng+of+
• rganic+(collagen)+and+mineral+(HA)+phases+
• +RelaSvely+strong+and+sSff+and+remodels+in+

response+to+funcSonal+loads+

• +Fiber+orientaSon+results+in+different+properSes+

for+different+loading+direcSons+(anisotropic)+

• +ViscoelasSc+(strain]rate+dependent)++

Bone:+Test+ConsideraSons...+

• Storage+/preservaSon+
• Temperature+
• HydraSon+
• Sample+size+and+type+
• Strain+rate+
• Mode+of+loading+
• OrientaSon+
• Age/gender+

[Q]: +What+factors+should+be+considered+when+

tesSng?+

Bone:+Why+Study?+

[Q]: +Why+should+we+care+about+the+properSes+

• f+bone?+

Need+naSve+properSes+for:+

• Medical+device+development+
• SubsStute+materials+(bone+grass/fillers)++
• Tissue+engineering++

Bone:+Case+Study+#1+(Bone+gras+subsStute)+

Bone+Gras+Materials:+

• Autograph+Bone+
• Allograph+Bone+
• Ceramics+
• Polymers+

PolyGraft, OsteoBiologics, Inc.

Bone:+Case+Study+#1+(Bone+gras+subsStute)+

Interpore+Pro+Osteon...+

• Coralline hydroxyapatite

(Similar composition and pore structure)

• Biocompatible
• Sterilizable

" Properties???

hmp://www.interpore.com+

Bone:+Case+Study+#1+(Bone+gras+subsStute)+

Interpore+Pro+Osteon

+ [VF = 31.4 ± 2.0%]

Vertebral+Trabecular+Bone +

[VF = 14.2 ± 1.5%]

Femoral+Trabecular+Bone +

[VF = 29.8 ± 0.4%]

Smaller pore size...

Bone:+Case+Study+#1+(Bone+gras+subsStute)+

Property + Pro+Osteon + Femoral+Bone + Vertebral+ Bone + Modulus+[Mpa] + 2900+±+1290 + 441+±+271 + 309+±+109 + Strength+[Mpa] + 5.87+±+1.92 + 6.76+±+4.84 + 2.23+±+0.95 + UlSmate+Strain + 0.0022+±+0.03 + 0.011 + 0.019 + Permeability+ [x10]9m2] + 0.49+±+0.19 + 0.12+±+0.11 + 3.59+±+1.90 +

[Haddock+et+al,+1999]+

Bone:+Case+Study+#1+(Bone+gras+subsStute)+

Pro+Osteon+in+canine+ humeri+(3,+6,+12,+and+24+ weeks)

Summary:

• Stiff (…6x bone)
• Dense (...smaller pore size)
• Brittle (...low ultimate strain)
• Permeability (...ok)

Okay for some applications... Not well matched for vertebral trabecular bone...

[Resnick,+2002]+