spine biomechanics, intervertebral disc &lbp. spine
Post on 20-Dec-2015
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Cervical SpineCervical Spine
Seven vertebrae Seven vertebrae – C 1-7C 1-7
More flexibleMore flexible Supports the headSupports the head Wide range of motionWide range of motion
– Rotation to left and rightRotation to left and right– FlexionFlexion
Up and downUp and down
Peripheral nervesPeripheral nerves– ArmsArms– Shoulder, Chest and diaphragmShoulder, Chest and diaphragm
Thoracic SpineThoracic Spine
Mid-back or dorsal regionMid-back or dorsal region Twelve vertebrae Twelve vertebrae
– T 1-12T 1-12
Ribs attached to vertebrae Ribs attached to vertebrae Relatively immobileRelatively immobile Peripheral nervesPeripheral nerves
– IntercostalIntercostal
Lumbar SpineLumbar Spine
Lower backLower back Five vertebrae Five vertebrae
– L 1-5L 1-5
Carries the the weight of the upper body Carries the the weight of the upper body – Larger, broader Larger, broader
Peripheral nervesPeripheral nerves– LegsLegs– PelvisPelvis
Sacral and Coccygeal regionSacral and Coccygeal region
SSacrumacrum – Triangular structure Triangular 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
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
Motion SegmentMotion Segment
Two adjacent vertebraeTwo adjacent vertebrae Intervertebral discIntervertebral disc Six degrees of freedomSix degrees of freedom
– Flexion-extensionFlexion-extension– Lateral flexionLateral flexion– Axial rotationAxial rotation
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 length of the spinal column's length Avascular Avascular Nutrients diffuse through end platesNutrients diffuse through end plates
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 space between Act to pad and maintain the space between the twenty-four movable vertebraethe twenty-four movable vertebrae
Act as shock absorbersAct as shock absorbers Allow extension and flexion Allow extension and flexion
Intervertebral Disc AnatomyIntervertebral Disc Anatomy
Spongy center Spongy center – Nucleus pulposusNucleus pulposus
Surrounded by a Surrounded by a tougher outer tougher outer fibrous ring fibrous ring – Anulus fibrosusAnulus fibrosus
Anulus FibrosusAnulus Fibrosus
Strong radial tire–like structure Strong radial tire–like structure Series of lamellaeSeries of lamellae Concentric sheets of collagen Concentric sheets of collagen
fibers fibers – 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
AnnulusAnnulus
In Bending In Bending – Increased tensile force posteriorly Increased tensile force posteriorly – Increased compressive force anteriorlyIncreased compressive force anteriorly
In Rotation In Rotation – Reorientation of collagenous fibersReorientation of collagenous fibers– Tightening of fibers traveling in one directionTightening of fibers traveling in one direction– Loosening of fibers traveling in opposite Loosening of fibers traveling in opposite
directiondirection
Nucleus PulposusNucleus Pulposus
Has more water and PGsHas more water and PGs PG are macro-molecules PG are macro-molecules
– Attract and retain waterAttract and retain water– Hydrophilic gel–like matter Hydrophilic gel–like matter
Resists compressionResists compression
Amount of waterAmount of water– Activity related Activity related – Varies throughout the day Varies throughout the day
Theory of weight bearingTheory of weight bearing
Nucleus pulpous Nucleus pulpous imbibes waterimbibes water Develops internal pressureDevelops internal pressure Pressure exerted in all directionsPressure exerted in all directions
– Lateral forces Lateral forces Against annulusAgainst annulus
– Superiorly and inferiorly directed forces Superiorly and inferiorly directed forces Against end platesAgainst end plates
– Increases stiffness Increases stiffness Of end plate and annulus fibrosusOf end plate and annulus fibrosus
Mechanical CharacteristicsMechanical Characteristics
Tensile stiffness of the disc annulus in different directionsHighest along – 150
Lowest along – the disc axis
StrengthStrength
Highest – Along normal direction of annulus fibers( 3 times stronger than that along horizontal direction)
Creep CharacteristicsCreep Characteristics
Grade 0 - Non-degenerative disc ( more viscoelastic)Grade 2 – Mild degenerative disc (less sustenance)
Grade 3 – Severe degenerative disc ( more deformation)
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
Bending Bending 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 pressure Needle pressure transducer transducer
CalibratedCalibrated– Introduced into nucleus Introduced into nucleus
pulpous of cadaveric pulpous of cadaveric functional unitfunctional unit
Inserted in vivo in L3-Inserted in vivo in L3-4 disc4 disc
Pathology of Intervertebral Disc InjuryPathology of Intervertebral Disc Injury
Annular InjuryAnnular Injury– Annular rings Annular rings
SoftenedSoftened Overstretched Overstretched Torn Torn
– Normal viscoelasticity is exceededNormal viscoelasticity is exceeded– Cannot stabilize or limit motionCannot stabilize or limit motion– Nucleus pulposus exerts pressure on weak partNucleus pulposus exerts pressure on weak part– Buckling occurs - Buckling occurs - Disc BulgeDisc Bulge
Pathology of Intervertebral Disc InjuryPathology of Intervertebral Disc Injury
ExtrusionExtrusion– Fragmentation of Fragmentation of
nucleus pulposusnucleus pulposus– Nuclear material Nuclear material
dissects its way dissects its way through breaches in through breaches in annulus fibrosusannulus fibrosus
Pathology of Intervertebral Disc InjuryPathology of Intervertebral Disc Injury
ProlapsesProlapses– Fissures provide Fissures provide
pathway for irritating pathway for irritating nuclear fluid to nuclear fluid to escape onto escape onto perineural tissue *perineural tissue * Persistent and chronic Persistent and chronic
back painback pain
** - - Hampton et alHampton et al
Back PainBack Pain
Pain is a protective mechanismPain is a protective mechanism Nerve endings near the spine receive abnormal Nerve endings near the spine receive abnormal
stimulation stimulation Signals are transmitted from affected area to the Signals are transmitted from affected area to the
brainbrain– 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 spasm Muscles 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– Acute Acute – Chronic Chronic
CausesCauses of LBP 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
Examinations to locate back painExaminations to locate back pain
StandingStanding– Observation and Palpation Observation and Palpation
Iliac crestIliac crest Posterior superior iliac spine (PSIS)Posterior superior iliac spine (PSIS) Anterior superior iliac spine (ASIS)Anterior superior iliac spine (ASIS) Spinous processesSpinous processes Muscle tightnessMuscle tightness GaitGait
Examinations of back painExaminations of back pain
Movement TestingMovement Testing– Forward bendingForward bending– Backward bendingBackward bending– Lateral bendingLateral bending– RotationRotation– Leg extension and backward bendingLeg extension and backward bending
Forward bendingForward bending
Hands are pushing in Hands are pushing in opposite directionopposite direction
Tissues from skin to Tissues from skin to central corecentral core– Elongate posterior Elongate posterior – Compress anteriorCompress anterior
Assessing lumbo-pelvic Assessing lumbo-pelvic congruencycongruency– Palpation from cervical spine Palpation from cervical spine
to pelvisto pelvis
Back ExaminationBack Examination
Nerve tension signsNerve tension signs Nerve compression signsNerve compression signs
Examination of back painExamination of back pain
Supine TestingSupine Testing– Passive hip flexionPassive hip flexion– Faber positionFaber position– Straight leg raise (SLR)Straight leg raise (SLR)– Force is directed to right femurForce is directed to right femur
Posterior to anterior force directed to femur Posterior to anterior force directed to femur – In flexed and vertical positionIn flexed and vertical position
– Passive knee flexion in a prone positionPassive knee flexion in a prone position– Passive internal and external hip rotation Passive internal and external hip rotation
knee at 90knee at 9000 of flexion of flexion
Passive hip flexionPassive hip flexion
Hip hyperflexedHip hyperflexed– Lumbar spine flattened Lumbar spine flattened
Over 90Over 9000 of flexion of flexion
Force transmissionForce transmission– To extensor of hipTo extensor of hip
Posterior rotary Posterior rotary movement on iliummovement on ilium
– Spinal flexionSpinal flexion
Straight leg raise (SLR)Straight leg raise (SLR)
Straight leg raisedStraight leg raised Femoral flexionFemoral flexion AdductionAdduction Internal rotationInternal rotation Increase in tensile Increase in tensile
forceforce– On sciatic nerveOn sciatic nerve
Related to ischial Related to ischial tuberositytuberosity
Phases of Treatment for Phases of Treatment for lumbopelvic disorderslumbopelvic disorders
Treatment of painTreatment of pain Modalities Modalities MedicationMedication
– Support the regionSupport the region– Biomechanical counseling / restBiomechanical counseling / rest
Continue supportContinue support– Begin non-destructive movementBegin non-destructive movement– Decrease destructive behaviorDecrease destructive behavior
Phases of Treatment for Phases of Treatment for lumbopelvic disorders (cont’d)lumbopelvic disorders (cont’d)
Discontinue supportDiscontinue support– Begin proprioceptive and kinesthetic strength trainingBegin proprioceptive and kinesthetic strength training
Neuromuscular efficiencyNeuromuscular efficiency Dynamic stabilizationDynamic stabilization
Establishment of limitsEstablishment of limits MovementMovement LoadsLoads PositionsPositions Frequencies Frequencies
Treatment OptionsTreatment Options
CryotherapyCryotherapy ThermotherapyThermotherapy
– Superficial heatingSuperficial heating– Deep HeatDeep Heat
Injection Therapy & Soft tissue injectionsInjection Therapy & Soft tissue injections ElectrotherapyElectrotherapy
– Transcutaneous electrical nerve stimulation Transcutaneous electrical nerve stimulation (TENS)(TENS)
Treatment Options (cont’d)Treatment Options (cont’d)
ManipulationManipulation Traction Traction MassageMassage Physical therapy and exercisesPhysical therapy and exercises AcupunctureAcupuncture Corsets and bracesCorsets and braces Surgerical treatmentSurgerical treatment
ScoliosisScoliosis
A medio-lateral A medio-lateral curve of the curve of the vertebral columnvertebral column Exceeding 10Exceeding 1000
– TypesTypes Structural Structural NeuromuscularNeuromuscular IdiopathicIdiopathic Non-structuralNon-structural
– TreatmentTreatment ExercisesExercises BracingBracing
KyphosisKyphosis
An exaggerated curvature in the An exaggerated curvature in the sagittal planesagittal plane
Long rounded curveLong rounded curve ((round backround back))
Sharp posterior angulation Sharp 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
Video on description of Spinal ColumnVideo on description of Spinal Column
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