Spine biomechanics2

Spine BiomechanicsSpine Biomechanics
Jayant SharmaJayant Sharma
M.S.,D.N.B.,M.N.A.M.SM.S.,D.N.B.,M.N.A.M.S..

Cervical SpineCervical Spine
 Seven vertebraeSeven vertebrae
– C 1-7C 1-7
 More flexibleMore flexible
 Wide range of motionWide range of motion
– RotationRotation
– FlexionFlexion
 Peripheral NervesPeripheral Nerves
– ArmsArms
– Shoulder, Chest and diaphragmShoulder, Chest and diaphragm

Cervical SpineCervical Spine
 Spinous processes increase in length distallySpinous processes increase in length distally
C 1-2 almost transverse,C 1-2 almost transverse,
C 2- T 1 --45º to transverseC 2- T 1 --45º to transverse
 Occipito Atlantoaxial complexOccipito Atlantoaxial complex ––
specialized articulation,specialized articulation,
large ROM,large ROM,
no diskno disk
– 60% axial rotation – C 1-2,60% axial rotation – C 1-2,
– difficult for occipital condyles to slide on C 1,difficult for occipital condyles to slide on C 1,
– no loss with agingno loss with aging
– Lateral bending – small, alar ligamentLateral bending – small, alar ligament
––Inter axial rotation(IAR)-- close to cord, rotate without impingementInter axial rotation(IAR)-- close to cord, rotate without impingement

 C 3-7 – flexion -extension predominates, lateralC 3-7 – flexion -extension predominates, lateral
bendingbending
– IAR – lower vertebra (flex-ex); upper vertebra (lateralIAR – lower vertebra (flex-ex); upper vertebra (lateral
bending)bending)
– Distinct coupling pattern – lateral bending & axialDistinct coupling pattern – lateral bending & axial
rotation,rotation,
– spinous process point opposite to lateral bendspinous process point opposite to lateral bend
– Axial rotation – limited by uncinate processes & facetsAxial rotation – limited by uncinate processes & facets
 Intradural sagittal diameterIntradural sagittal diameter
– 2-3mm lower in extension2-3mm lower in extension
– Posteroinferior margin of upper vertebra &Posteroinferior margin of upper vertebra &
ligamentum flavumligamentum flavum
– Cord thicker in extension> less play in extensionCord thicker in extension> less play in extension
– Canal widest at C 1-2, narrows at C 5Canal widest at C 1-2, narrows at C 5

Thoracic SpineThoracic Spine
 Mid-back or dorsal regionMid-back or dorsal region
 Ribs attached to vertebraeRibs attached to vertebrae
 Relatively immobileRelatively immobile
 Peripheral nervesPeripheral nerves
– IntercostalIntercostal

Thoracic SpineThoracic Spine
 Rigid, transition between Cervical & LumbarRigid, transition between Cervical & Lumbar
regionsregions
 Facet orientation changes, may be abrupt T 9-12Facet orientation changes, may be abrupt T 9-12
 Flexion-extension – upper: 4º, middle: 6º, lower:Flexion-extension – upper: 4º, middle: 6º, lower:
12º12º
 Lateral bending – upper: 6º, lowerLateral bending – upper: 6º, lower 2/32/3:: 9º9º
 Axial rotation – upperAxial rotation – upper 1/21/2: 8º, lower 3 segments:: 8º, lower 3 segments:
2º each2º each
 Upper & lower region – lateral bending & axialUpper & lower region – lateral bending & axial
rotation strongly coupledrotation strongly coupled
 Middle – variable coupled motionMiddle – variable coupled motion

Lumbar SpineLumbar Spine
 Lower backLower back
 Carries the the weight of the upperCarries the the weight of the upper
bodybody
– Larger, broaderLarger, broader
 Peripheral nervesPeripheral nerves
– LegsLegs
– PelvisPelvis

Lumbar SpineLumbar Spine
 Flexion-ExtensionFlexion-Extension
– large, due to sizable disks & lack of facetlarge, due to sizable disks & lack of facet
restraintrestraint
– IAR – posterior half of disk, moves withIAR – posterior half of disk, moves with
flexion-extensionflexion-extension
 Centrode – path of moving IARCentrode – path of moving IAR
 Lateral bending – IAR on left side ofLateral bending – IAR on left side of
disk with right benddisk with right bend
 Axial rotation – IAR in posterior nucleusAxial rotation – IAR in posterior nucleus
 Disk degeneration – IAR spread outDisk degeneration – IAR spread out

 Sagittal plane TranslationSagittal plane Translation
– 2-3 mm, normal in symptom free pts2-3 mm, normal in symptom free pts
– Up to 5 mm in L 3-4 & L4-5, 4 mm in L5-S1Up to 5 mm in L 3-4 & L4-5, 4 mm in L5-S1
 Lateral bending & Axial Rotation couplingLateral bending & Axial Rotation coupling
– Spinous processes point in same direction asSpinous processes point in same direction as
lateral bendinglateral bending
– Opposite of cervical, upper thoracic,Opposite of cervical, upper thoracic,
lumbosacrallumbosacral

Sacral and Coccygeal regionSacral and Coccygeal region
 SSacrumacrum
– Triangular structureTriangular structure
– Base of the spineBase of the spine
– Connects spine to pelvisConnects spine to pelvis
– Nerves to pelvic organsNerves to pelvic organs
 CoccyxCoccyx
– Few small bonesFew small bones
– Remnant of tailRemnant of tail

Sacroiliac RegionSacroiliac Region
 Poorly understoodPoorly understood
 Partly synovial, partly syndesmoticPartly synovial, partly syndesmotic
 Stiff, coarse interdigitating articular surfacesStiff, coarse interdigitating articular surfaces
 IAR scatteredIAR scattered
 Complete ankylosis in up to 76% over age of 50Complete ankylosis in up to 76% over age of 50
 Joint motion – overcome ligamentous resistance,Joint motion – overcome ligamentous resistance,
1 leg stance1 leg stance

General KinematicsGeneral Kinematics
 CurvatureCurvature
– SagittalSagittal
– Shape of vertebrae & disks, rib cage, inclination ofShape of vertebrae & disks, rib cage, inclination of
sacral end platesacral end plate
– Developmental phenomenon, posture, rate of growthDevelopmental phenomenon, posture, rate of growth
– Add flexibility & shock absorbing capabilityAdd flexibility & shock absorbing capability
 6 degrees of freedom6 degrees of freedom
– Translation & RotationTranslation & Rotation
– 3 orthogonal planes3 orthogonal planes
– Motion usually coupledMotion usually coupled
 Center of gravityCenter of gravity – in front of 2– in front of 2ndnd
sacral segmentsacral segment

Types of motionTypes of motion

 ROMROM
– Facet joints & Intervertebral disksFacet joints & Intervertebral disks
– C spineC spine
 Flexion-extension predominates, midcervicalFlexion-extension predominates, midcervical
 Axial rotation, upper cervicalAxial rotation, upper cervical
 Lateral bendingLateral bending
– T spineT spine
 Little motion, rib cage.Little motion, rib cage.
– L spineL spine
 Lateral bending, mid portionLateral bending, mid portion
 Flexion-extension, lumbosacralFlexion-extension, lumbosacral
 Rotation, minimalRotation, minimal
– Greater mobility at C & L spine> more stress> moreGreater mobility at C & L spine> more stress> more
clinical complaintsclinical complaints

Shear & Tensile CharacteristicsShear & Tensile Characteristics
 In direct shear testsIn direct shear tests
– Shear stiffness in horizontal directionShear stiffness in horizontal direction
 260 N/mm260 N/mm22
 Spine rarely fails in pure shearSpine rarely fails in pure shear
 Similarly under normal physiologic activitiesSimilarly under normal physiologic activities
– Pure tensile loading doesn’t occurPure tensile loading doesn’t occur
– But annulus undergoes tensile loading duringBut annulus undergoes tensile loading during
 BendingBending
 Axial rotationAxial rotation
 ExtensionExtension

Compressive load characteristicsCompressive load characteristics
 Cancellous boneCancellous bone
– Large deformationLarge deformation
 Up to 9.5% before failureUp to 9.5% before failure
 Cortical boneCortical bone
– Small deformationSmall deformation
 Up to 2% before failureUp to 2% before failure

Measurements of In vivo LoadsMeasurements of In vivo Loads
 Needle pressureNeedle pressure
transducertransducer
 CalibratedCalibrated
– Introduced intoIntroduced into
nucleus pulpous ofnucleus pulpous of
cadaveric functionalcadaveric functional
unitunit
 Inserted in vivo inInserted in vivo in
L3-4 discL3-4 disc

The Motion SegmentThe Motion Segment
 Functional Spinal UnitFunctional Spinal Unit
– 2 adjacent vertebrae & intervening soft tissue2 adjacent vertebrae & intervening soft tissue
 AnteriorAnterior
– Vertebral bodyVertebral body
– DiskDisk
– ALL, PLLALL, PLL
 Support, absorb impact, restrict vertical translationSupport, absorb impact, restrict vertical translation
 PosteriorPosterior
– Neural arch & its processesNeural arch & its processes
– Facet jointFacet joint

Vertebral BodyVertebral Body
 Primary load-transmitting element, 80-90%Primary load-transmitting element, 80-90%
 Bone Mineral Content--Bone Mineral Content-- Osteoporosis> lossOsteoporosis> loss
of horizontal trabeculaeof horizontal trabeculae
 SizeSize
– Increasing size from C to L spineIncreasing size from C to L spine
 Compressive load> pressure higher inCompressive load> pressure higher in
center of end plates than peripherycenter of end plates than periphery
 In vivo, filled with blood> greater strength,In vivo, filled with blood> greater strength,
hydraulic shock absorberhydraulic shock absorber
 Weaker anterior trabeculae, Wolff’s lawWeaker anterior trabeculae, Wolff’s law

Posterior ElementsPosterior Elements
 Pedicles, lamina, facet joints, spinous &Pedicles, lamina, facet joints, spinous &
transverse processestransverse processes
 Bony processes> lengthen moment arms ofBony processes> lengthen moment arms of
musclesmuscles
 Forces on processes> transmitted to LaminaForces on processes> transmitted to Lamina
 Forces on posterior elements> transmitted toForces on posterior elements> transmitted to
vertebral bodies from Pediclesvertebral bodies from Pedicles
 Pars InterarticularisPars Interarticularis
– Large bending forces; excessive extensionLarge bending forces; excessive extension
– Thicker than rest of laminaThicker than rest of lamina
– Common site of stress/fatigue fractures> weakensCommon site of stress/fatigue fractures> weakens
motion segment> spondylolithesismotion segment> spondylolithesis

 Facet JointsFacet Joints
– Major role in controlling motionMajor role in controlling motion
– Resist torsion & shear, role in compressionResist torsion & shear, role in compression
– Lumbar FSU – facets 40% torque resistence,Lumbar FSU – facets 40% torque resistence,
40% disk, 20% ligaments40% disk, 20% ligaments
– Load sharing varies with flexion & extensionLoad sharing varies with flexion & extension
 Seated position> decreased lumbar lordosis>Seated position> decreased lumbar lordosis>
increased intradiscal pressure & decreased load-increased intradiscal pressure & decreased load-
bearing of the facetsbearing of the facets
– Orientation of facetsOrientation of facets
 C spine - 45º transverse, parallel frontalC spine - 45º transverse, parallel frontal
 T spine - 60º transverse, 20º frontalT spine - 60º transverse, 20º frontal
 L spine - 90º transverse, 45º frontalL spine - 90º transverse, 45º frontal
– Capsules lax> allow glidingCapsules lax> allow gliding

LigamentsLigaments
 Nonsegmental longitudinal (ALL, PLL,Nonsegmental longitudinal (ALL, PLL,
supraspinous)supraspinous)
 Segmental longitudinal (interspinous,Segmental longitudinal (interspinous,
intertransverse, ligamenta flava)intertransverse, ligamenta flava)
 Capsular ligamentsCapsular ligaments
 Limit motion, provide stability/equilibriumLimit motion, provide stability/equilibrium
 ALLALL
– Interlinked to disksInterlinked to disks
– Resists extensionResists extension
– 2X tensile strength of PLL2X tensile strength of PLL

 PLLPLL
– Narrow over vertebral bodies, flare out over disks;Narrow over vertebral bodies, flare out over disks;
thin lateral extensionthin lateral extension
– Resists flexionResists flexion
– Ossification> spinal stenosisOssification> spinal stenosis
 Ligamentum FlavumLigamentum Flavum
– Elastic & strongElastic & strong
– ““shingled” configuration with laminaeshingled” configuration with laminae
– Lengthen w/ flexion, shorten w/ extensionLengthen w/ flexion, shorten w/ extension
– Loss of disk height or hyperextension> buckle intoLoss of disk height or hyperextension> buckle into
spinal canalspinal canal
 Interspinous & SupraspinousInterspinous & Supraspinous
– Resist flexionResist flexion
– Long moment armsLong moment arms

MECHANISMS OFMECHANISMS OF
LIGAMENTOUS INJURYLIGAMENTOUS INJURY
 Strain rates appear toStrain rates appear to
affect which tissue isaffect which tissue is
damaged.damaged.
 Reports of high incidenceReports of high incidence
of ruptured interspinousof ruptured interspinous
ligamentsligaments
 Interspinous ligamentsInterspinous ligaments
could be injured by fallingcould be injured by falling
backward and applyingbackward and applying
posterior shear forces withposterior shear forces with
the spine flexed.the spine flexed.

 Forward-bending with aForward-bending with a
flexed spine increasesflexed spine increases
the shear forces on thethe shear forces on the
spine because of stretchspine because of stretch
of the interspinousof the interspinous
ligaments and theligaments and the
superincumbent weight.superincumbent weight.
 Extensor muscles thatExtensor muscles that
cancan prevent anteriorprevent anterior
shearshear on superioron superior
vertebrae are silentvertebrae are silent
when lumbar spinewhen lumbar spine
flexion is far enough toflexion is far enough to
void protection againstvoid protection against
shear.shear.

Functional Consideration for theFunctional Consideration for the
Interspinous andInterspinous and
Supraspinous LigamentsSupraspinous Ligaments
 Supraspinous ligaments areSupraspinous ligaments are
parallel to the compressiveparallel to the compressive
axis.axis.
 Importance of ligaments inImportance of ligaments in
resisting flexion appears to beresisting flexion appears to be
overstated.overstated.
 Supraspinous ligament appearsSupraspinous ligament appears
to beto be most importantmost important
ligamentous restraint to flexion.ligamentous restraint to flexion.

 Interspinous ligamentsInterspinous ligaments areare
oblique to the compressiveoblique to the compressive
axis of the spine, perhapsaxis of the spine, perhaps
providing restraint toproviding restraint to
flexion throughout theflexion throughout the
ROM.ROM.
 Interspinous ligamentsInterspinous ligaments
protect against posteriorprotect against posterior
shear forces of theshear forces of the
superior vertebra on thesuperior vertebra on the
inferior vertebra.inferior vertebra.

Failure Strength of Spinal LigamentsFailure Strength of Spinal Ligaments

Vertebral MusclesVertebral Muscles
 Spine buckles with small compressiveSpine buckles with small compressive
forces without musclesforces without muscles
 Anterior, posterior, lateralAnterior, posterior, lateral
 Gross-function – span several motionGross-function – span several motion
segssegs
 Fine-function – span 1 or 2 segsFine-function – span 1 or 2 segs
 Deep back muscles are major spineDeep back muscles are major spine
movers; many other groupsmovers; many other groups

MultifidiMultifidi
 Multifidi span only aMultifidi span only a
few segments andfew segments and
run parallel to therun parallel to the
compression axis.compression axis.
 There forces onlyThere forces only
effect specific areaseffect specific areas
of the spine.of the spine.
 Extensor of theExtensor of the
spinespine

Abdominal MusclesAbdominal Muscles
 RECTUSRECTUS
ABDOMINISABDOMINIS
 Major trunk flexorMajor trunk flexor
 Sections preventSections prevent
buckling of musclebuckling of muscle
during trunk flexion.during trunk flexion.
 Some say no functionalSome say no functional
difference in upper anddifference in upper and
lower segmentslower segments
 My next studyMy next study

Special Case of the Quadratus Lumborum andSpecial Case of the Quadratus Lumborum and
Psoas MajorPsoas Major
 Psoas major appearsPsoas major appears
to be primarily a hipto be primarily a hip
flexor, with little role inflexor, with little role in
lumbar stabilization.lumbar stabilization.
 Psoas major dispersesPsoas major disperses
bending stressesbending stresses
across the wholeacross the whole
lumbar spine during hiplumbar spine during hip
flexion.flexion.

Special Case of the Quadratus Lumborum andSpecial Case of the Quadratus Lumborum and
Psoas MajorPsoas Major
 QuadratusQuadratus
lumborum appearslumborum appears
to be important asto be important as
lumbar stabilizer.lumbar stabilizer.

Motion of Entire SpineMotion of Entire Spine

Weight bearing properties ofWeight bearing properties of
motion segment unitmotion segment unit

Compressive Strength of SpineCompressive Strength of Spine

Stress-Strain CurveStress-Strain Curve

Intervertebral DiscIntervertebral Disc
 Soft fibro-cartilaginous cushionsSoft fibro-cartilaginous cushions
– Between two vertebraBetween two vertebra
– Allows some motionAllows some motion
– Serve as shock absorbersServe as shock absorbers
 Total – 23 discsTotal – 23 discs
 ¼¼ thth
of the spinal column's lengthof the spinal column's length
 AvascularAvascular
 Nutrients diffuse through end platesNutrients diffuse through end plates

Intervertebral Disc AnatomyIntervertebral Disc Anatomy
 Spongy centerSpongy center
– NucleusNucleus
pulposuspulposus
 Surrounded bySurrounded by
a tougher outera tougher outer
fibrous ringfibrous ring
– Anulus fibrosusAnulus fibrosus

Nucleus PulposusNucleus Pulposus
 Has more water and PGsHas more water and PGs
 PG are macro-moleculesPG are macro-molecules
– Attract and retain waterAttract and retain water
– Hydrophilic gel–like matterHydrophilic gel–like matter
 Resists compressionResists compression
 Amount of waterAmount of water
– Activity relatedActivity related
– Varies throughout the dayVaries throughout the day

 Nucleus PulposusNucleus Pulposus
– Eccentrically positioned posteriorlyEccentrically positioned posteriorly
– Young & healthyYoung & healthy
 50% cross-sectional50% cross-sectional
 90% water, bound to proteoglycans90% water, bound to proteoglycans
– Aging> dessication> increase viscosity> fissuringAging> dessication> increase viscosity> fissuring
– Pascal’s lawPascal’s law
 Fluid mass within closed container> local increase inFluid mass within closed container> local increase in
pressure> transmit around entire side wall (annulus)pressure> transmit around entire side wall (annulus)
 Young nucleus> even distribution of loadYoung nucleus> even distribution of load
 Old nucleus> undue concentration on vertebral body edgesOld nucleus> undue concentration on vertebral body edges
– Small displacement w/ ROM, ball-bearing likeSmall displacement w/ ROM, ball-bearing like
– Compressive stress predominatesCompressive stress predominates

Anulus FibrosusAnulus Fibrosus
 Strong radial tire–like structureStrong radial tire–like structure
 Series of lamellaeSeries of lamellae
 Concentric sheets of collagenConcentric sheets of collagen
fibersfibers
– Connected to end platesConnected to end plates
– Orientated at various anglesOrientated at various angles
– Under compressionUnder compression
 Become horizontalBecome horizontal
 Encloses nucleus pulposusEncloses nucleus pulposus

 Annulus FibrosusAnnulus Fibrosus
– 90 collagen sheets90 collagen sheets
– Fibers of adjacent sheets 30º to each otherFibers of adjacent sheets 30º to each other
– Hyaline cartilage plates & bony ring epiphysesHyaline cartilage plates & bony ring epiphyses
of vertebral bodiesof vertebral bodies
– Vertical component – tension resistor duringVertical component – tension resistor during
flex-ex & lateral bendingflex-ex & lateral bending
– Horizontal component – rotary stressHorizontal component – rotary stress
– Axial load – tensile stressAxial load – tensile stress

AnnulusAnnulus
 In BendingIn Bending
– Increased tensile force posteriorlyIncreased tensile force posteriorly
– Increased compressive force anteriorlyIncreased compressive force anteriorly
 In RotationIn Rotation
– Reorientation of collagenous fibersReorientation of collagenous fibers
– Tightening of fibers traveling in oneTightening of fibers traveling in one
directiondirection
– Loosening of fibers traveling in oppositeLoosening of fibers traveling in opposite
directiondirection

DiskDisk
 Major restraint to motionMajor restraint to motion
 Viscoelastic behavior, demonstrates Creep &Viscoelastic behavior, demonstrates Creep &
HysteresisHysteresis
 AvascularAvascular
– End-plate microfractures> vascular ingrowth &End-plate microfractures> vascular ingrowth &
granulation tissue> altered mechanical behaviorgranulation tissue> altered mechanical behavior
– End-plates influence the nutrition; diffusionEnd-plates influence the nutrition; diffusion
 Lumbar FSULumbar FSU
– Disk – 40% of torque resistanceDisk – 40% of torque resistance
– Rest by posterior element and ligamentsRest by posterior element and ligaments
 Diurnal change in heightDiurnal change in height
– 1% shorter at night; 2% for children; 0.5% for elderly1% shorter at night; 2% for children; 0.5% for elderly
– 50% of height lost during first 2 hours in upright50% of height lost during first 2 hours in upright
 Healthy disks creep slowerHealthy disks creep slower

Intervertebral Disc FunctionsIntervertebral Disc Functions
 Movement of fluid within the nucleusMovement of fluid within the nucleus
– Allows vertebrae to rock back and forthAllows vertebrae to rock back and forth
– FlexibilityFlexibility
 Act to pad and maintain the spaceAct to pad and maintain the space
between the twenty-four movablebetween the twenty-four movable
vertebraevertebrae
 Act as shock absorbersAct as shock absorbers
 Allow extension and flexionAllow extension and flexion

 Intradiscal PressureIntradiscal Pressure
– Compressive loads in vivo: 500N standing,Compressive loads in vivo: 500N standing,
700N sitting700N sitting
– Increased to 3000 to 6000N during lifting ofIncreased to 3000 to 6000N during lifting of
moderate weights, decreases with load closermoderate weights, decreases with load closer
to bodyto body
– Estimate of P = 1.5X compressive loadEstimate of P = 1.5X compressive load
divided by the cross sectional areadivided by the cross sectional area
– Disk pressure is usually uniformDisk pressure is usually uniform
– Pressure lowest in supine positionPressure lowest in supine position
– Disk usually does not fail, but end platesDisk usually does not fail, but end plates
fracturefracture

Creep CharacteristicsCreep Characteristics
Grade 0 - Non-degenerative disc ( more viscoelastic)
Grade 2 – Mild degenerative disc (less sustenance)
Grade 3 – Severe degenerative disc ( more deformation)

Pathology of Intervertebral DiscPathology of Intervertebral Disc
InjuryInjury
 Annular InjuryAnnular Injury
– Annular ringsAnnular rings
 SoftenedSoftened
 OverstretchedOverstretched
 TornTorn
– Normal viscoelasticity is exceededNormal viscoelasticity is exceeded
– Cannot stabilize or limit motionCannot stabilize or limit motion
– Nucleus pulposus exerts pressure onNucleus pulposus exerts pressure on
weak partweak part
– Buckling occurs -Buckling occurs - Disc BulgeDisc Bulge

InjuryInjury
 ExtrusionExtrusion
– Fragmentation ofFragmentation of
nucleus pulposusnucleus pulposus
– Nuclear materialNuclear material
dissects its waydissects its way
through breaches inthrough breaches in
annulus fibrosusannulus fibrosus

InjuryInjury
 ProlapsesProlapses
– Fissures provideFissures provide
pathway forpathway for
irritating nuclearirritating nuclear
fluid to escapefluid to escape
onto perineuralonto perineural
tissue *tissue *
 Persistent andPersistent and
chronic back painchronic back pain
** -- Hampton et alHampton et al

Theory of weight bearingTheory of weight bearing
 Nucleus pulpousNucleus pulpous imbibes waterimbibes water
 Develops internal pressureDevelops internal pressure
 Pressure exerted in all directionsPressure exerted in all directions
– Lateral forcesLateral forces
 Against annulusAgainst annulus
– Superiorly and inferiorly directed forcesSuperiorly and inferiorly directed forces
 Against end platesAgainst end plates
– Increases stiffnessIncreases stiffness
 Of end plate and annulus fibrosusOf end plate and annulus fibrosus

 Sagittal plane translationSagittal plane translation
– 2-3 mm, normal in symptom free pts2-3 mm, normal in symptom free pts
– Up to 5 mm in L 3-4 & L4-5, 4 mm in L5-S1Up to 5 mm in L 3-4 & L4-5, 4 mm in L5-S1
 Lateral bending & axial rotation couplingLateral bending & axial rotation coupling
– Spinous processes point in same direction asSpinous processes point in same direction as
lateral bendinglateral bending
– Opposite of cervical, upper thoracic,Opposite of cervical, upper thoracic,
lumbosacrallumbosacral

Theory of weight bearingTheory of weight bearing
(cont’d)(cont’d)

Mechanical CharacteristicsMechanical Characteristics
Tensile stiffness of the disc annulus in different directions
Highest along – 150
Lowest along – the disc axis

StrengthStrength
Highest – Along normal direction of annulus fibers
( 3 times stronger than that along horizontal direction)

Back PainBack Pain
 Pain is a protective mechanismPain is a protective mechanism
 Nerve endings near the spine receiveNerve endings near the spine receive
abnormal stimulationabnormal stimulation
 Signals are transmitted from affected areaSignals are transmitted from affected area
to the brainto the brain
– They are interpreted as painThey are interpreted as pain
 A reflex action follows in the backA reflex action follows in the back
– Muscles go into spasmMuscles go into spasm
 To protect the backTo protect the back
 To keep the damaged area immobileTo keep the damaged area immobile

Types of painTypes of pain
 Based on sourceBased on source
– MechanicalMechanical
– ChemicalChemical
 Based on affected regionBased on affected region
– LocalLocal
– ReferredReferred
 Based on natureBased on nature
– TransientTransient
– AcuteAcute
– ChronicChronic

Causes of LBPCauses of LBP
 DysfunctionDysfunction
 Predisposing factorsPredisposing factors
– Postural stressPostural stress
– Work related stressWork related stress
– Disuse and loss of mobilityDisuse and loss of mobility
– ObesityObesity
– Debilitating conditionsDebilitating conditions
 Precipitating factorsPrecipitating factors
– MisuseMisuse
– OveruseOveruse
– Abuse or traumaAbuse or trauma

ScoliosisScoliosis
 A medio-lateralA medio-lateral
curve of thecurve of the
vertebral columnvertebral column
Exceeding 10Exceeding 1000
– TypesTypes
 StructuralStructural
 NeuromuscularNeuromuscular
 IdiopathicIdiopathic
 Non-structuralNon-structural
– TreatmentTreatment
 ExercisesExercises
 BracingBracing

Detection of ScoliosisDetection of Scoliosis

LordosisLordosis
 In the sagittal planeIn the sagittal plane
– ‘‘S’ shapeS’ shape
 As a small childAs a small child
– When starts to sitWhen starts to sit
– Cervical lordosisCervical lordosis
 Toddler and adultToddler and adult
– When starts to standWhen starts to stand
– Lumbar lordosisLumbar lordosis
– Allows spring-like actionAllows spring-like action

KyphosisKyphosis
 An exaggerated curvature in theAn exaggerated curvature in the
sagittal planesagittal plane
 Long rounded curveLong rounded curve
((round backround back))
 Sharp posterior angulationSharp posterior angulation
((hump backhump back))
 Possible causesPossible causes
– Wedge compression fractureWedge compression fracture
– Ankylosing spondylitisAnkylosing spondylitis
– Senile osteoporosisSenile osteoporosis
– Destructive tumors of spineDestructive tumors of spine

Intervertebral DiscIntervertebral Disc
 Intervertebral disk make up 20-30% ofIntervertebral disk make up 20-30% of
the height of the column and thicknessthe height of the column and thickness
varies from 3mm in cervical region,varies from 3mm in cervical region,
5mm in thoracic region to 9 mm in the5mm in thoracic region to 9 mm in the
lumbar region.lumbar region.
 Ratio between the vertebral body heightRatio between the vertebral body height
and the disk height will dictate theand the disk height will dictate the
mobility between the vertebra –mobility between the vertebra –
– Highest ratio in cervical region allows forHighest ratio in cervical region allows for
motionmotion
– Lowest ratio in thoracic region limits motionLowest ratio in thoracic region limits motion

Lumbar Foramen
http://www.spineuniverse.com/displayarticle.php/article1973.html
Spinal CordNerve Root

Lateral ViewLateral View Posterior ViewPosterior View
RodWire Bar CagePlate Screw
Pedicle Screw
Threaded Cage
Facet Screw
Arthrodesis = surgical fixation of a jointArthrodesis = surgical fixation of a joint
Stiffer arthrodesis = better healing environment (currently believed)Stiffer arthrodesis = better healing environment (currently believed)

Mechanical CausesMechanical Causes
Biological CausesBiological Causes
Stimulating stressesStimulating stresses
No slide between bone fusion interfaceNo slide between bone fusion interface
No separation between bone fusion interfaceNo separation between bone fusion interface
OsteoinductionOsteoinduction
Blood supplyBlood supply
OsteoconductionOsteoconduction
NOTE: FBI stands for Fusion Bone Interface
OsteoinductionOsteoinduction The ability to mediate the induction of osteosis exceptionally in a nonbony location
OsteoconductionOsteoconduction The ability to act as a scaffold for new osteosis in a bony environment
Blood supplyBlood supply Provide sufficient nutrition for osteosisStimulating stressesStimulating stresses Bone is laid down where needed and resorbed where not needed  Wolff’s lawWolff’s law
Separation at FBISeparation at FBI Bone contact surfaces are separated by external load  bone non-union
Slide at FBISlide at FBI Bone contact surfaces slide along each other causing by external load  bone non-union
Bone To Be FusedBone To Be Fused Bone FusionBone FusionBone FusionBone Fusion

Low Back Pain DisordersLow Back Pain Disorders

Spondylolysis
Spondylolisthesis

What is the CORE?What is the CORE?
 Lumbo-pelvic-hip complexLumbo-pelvic-hip complex
 Location of center of gravity (CoG)Location of center of gravity (CoG)
 Efficient core allows forEfficient core allows for
 Maintenance of normalMaintenance of normal length-tension relationshipslength-tension relationships
 Maintenance of normalMaintenance of normal force couplesforce couples
 Maintenance of optimal arthrokinematicsMaintenance of optimal arthrokinematics
 Optimal efficiency in entire kinetic chain duringOptimal efficiency in entire kinetic chain during
movementmovement
 Acceleration, deceleration, dynamic stabilizationAcceleration, deceleration, dynamic stabilization
 Proximal stability for movement of extremitiesProximal stability for movement of extremities

Core Stabilization ConceptsCore Stabilization Concepts
 A specific core strengthening program can:A specific core strengthening program can:
 IMPROVEIMPROVE dynamic postural controldynamic postural control
 EnsureEnsure appropriate muscular balanceappropriate muscular balance && jointjoint
arthrokinematicsarthrokinematics in the lumbo-pelvic-hip complexin the lumbo-pelvic-hip complex
 AllowAllow for expression offor expression of dynamic functional performancedynamic functional performance
throughout the entire kinetic chainthroughout the entire kinetic chain
 Increase neuromuscular efficiencyIncrease neuromuscular efficiency throughout the entirethroughout the entire
bodybody
 Spinal stabilizationSpinal stabilization
 Must effectively utilize strength, power, neuromuscular control &Must effectively utilize strength, power, neuromuscular control &
endurance of the “prime movers”endurance of the “prime movers”
 Weak core = decreased force production & efficiencyWeak core = decreased force production & efficiency
 Protective mechanism for the spineProtective mechanism for the spine
 Facilitates balanced muscular functioning of the entire kineticFacilitates balanced muscular functioning of the entire kinetic
chainchain
 Enhances neuromuscular control to provide a more efficient bodyEnhances neuromuscular control to provide a more efficient body
positioningpositioning

Core Stabilization TrainingCore Stabilization Training
ProgramProgram
 Level I: StabilizationLevel I: Stabilization

Level II: Stabilization andLevel II: Stabilization and
StrengthStrength

Level III: Integrated StabilizationLevel III: Integrated Stabilization
StrengthStrength

Level IV: Explosive StabilizationLevel IV: Explosive Stabilization

SciaticaSciatica
- radiating pain down the leg- radiating pain down the leg
RadiculopathyRadiculopathy
- radiating pain down the leg as a result of nerve root irritationradiating pain down the leg as a result of nerve root irritation
Back PainBack Pain
 irritation of the posterior primary ramusirritation of the posterior primary ramus
- facet capsule, local musculature- facet capsule, local musculature
 sinuvertebral branch - posterior annulussinuvertebral branch - posterior annulus
 change in disc loading and shape, biomechanicschange in disc loading and shape, biomechanics
 loss of viscoelasticity.loss of viscoelasticity.
 90% of radiating pain have long-standing prior episodic low back90% of radiating pain have long-standing prior episodic low back
painpain

 Straight-leg raising : L5, S1 rootStraight-leg raising : L5, S1 root
 Contralateral SLR : sequestrated or extrudedContralateral SLR : sequestrated or extruded
discdisc
 Femoral stretching, reverse SLR : L3, L4 rootFemoral stretching, reverse SLR : L3, L4 root
Root Tension SignsRoot Tension Signs

Epidural steroid injectionEpidural steroid injection
 If leg pain persist beyond 4 weeksIf leg pain persist beyond 4 weeks
 Maximum 3 injection per yearMaximum 3 injection per year
 Response vary greatlyResponse vary greatly
- Hagen,2002 : short-term effect 40%. no significant- Hagen,2002 : short-term effect 40%. no significant
long-term effectlong-term effect
- Wiesel, 1995 : 82% relief for 1 day, 50% for 2 weeks,- Wiesel, 1995 : 82% relief for 1 day, 50% for 2 weeks,
16% for 2mo.16% for 2mo.
- White 1983 : 77% avoid surgery after injection- White 1983 : 77% avoid surgery after injection
- Carette, 2002 : neither significant functional- Carette, 2002 : neither significant functional
benefit nor reduction in need forbenefit nor reduction in need for
surgerysurgery

Indication of SurgeryIndication of Surgery
Ideal candidateIdeal candidate
 history, physical examination, radiographic finding, are consistenthistory, physical examination, radiographic finding, are consistent
with one anotherwith one another
 when discrepancy exist, the clinical picture should serve as thewhen discrepancy exist, the clinical picture should serve as the
principal guide.principal guide.
Absolute surgical indicationAbsolute surgical indication
 cauda equina syndromecauda equina syndrome
 acute urinary retension/incontinence,acute urinary retension/incontinence,
saddle anesthesia, back/buttock/leg pain, weakness, difficultysaddle anesthesia, back/buttock/leg pain, weakness, difficulty
walkingwalking
Relative indicationRelative indication
 progressive weaknessprogressive weakness
 no response to conservative treatmentno response to conservative treatment

Facet JointFacet Joint
 Synovial jointSynovial joint
 Rich innervation with sensory nerve fiberRich innervation with sensory nerve fiber
 Same pathologic process as other large synovial jointSame pathologic process as other large synovial joint
 Load share 18% of the lumbar spineLoad share 18% of the lumbar spine

Vital FunctionsVital Functions
 Restricted intervertebral joint motionRestricted intervertebral joint motion
 Contribution to stabilityContribution to stability
 Resistence to axial, rotational, and bending loadResistence to axial, rotational, and bending load
 Preservation of anatomic relationshipPreservation of anatomic relationship
Biochemical CompositionBiochemical Composition
 Water : 65 ~ 90% wet wt.Water : 65 ~ 90% wet wt.
 Collagen : 15 ~ 65% dry wt.Collagen : 15 ~ 65% dry wt.
 Proteoglycan : 10 ~ 60% dry wt.Proteoglycan : 10 ~ 60% dry wt.
 Other matrix protein : 15 ~ 45% dry wt.Other matrix protein : 15 ~ 45% dry wt.

Vertebral End-PlateVertebral End-Plate
 Cartilaginous and osseous componentCartilaginous and osseous component
 Nutritional support for the nucleusNutritional support for the nucleus
 Passive diffusionPassive diffusion

Neurologic ExaminationNeurologic Examination

Spine biomechanics2

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