KIN 330KIN 330

Structural and Functional

Analysis

of Human Movement

Structure of ClassStructure of Class

divided into three parts– tissue– movement patterns and analyses– application of physics to movement

What is Kinesiology?What is Kinesiology?

Components of Kinesiology

What is Biomechanics?What is Biomechanics?

...the application of physics and engineering principles to the study of motion.

Components of BiomechanicsComponents of Biomechanics

Kinematics - the description of motionKinetics - the study of forces on motion

Who can use biomechanics?Who can use biomechanics?

Biomechanics of BoneBiomechanics of Bone

Purposes of skeletal system– protection– provides rigid links and attachments for

muscles– facilitates muscle action and body movement

BoneBone

metabolically active highly vascular responds to mechanical demands among the body’s hardest structures

Distinguishing FeaturesDistinguishing Features

Organic component Inorganic component Interface of two components

Mechanical PropertiesMechanical Properties

Functionally speaking:– strength– stiffness

Load/Deformation CurveLoad/Deformation Curve

Regions– A - B: Elastic Region:– B: Yield Point– B - C: Plastic Region:– C: Ultimate Failure Point

Parameters displayed on curveParameters displayed on curve

load

deformation

energy

Usefulness of L-D CurveUsefulness of L-D Curve

determines the mechanical properties of the entire structure of the bone.

Strength

Stiffness

Classification of BoneClassification of Bone

Depends on the extent of deformation before failure– reflected in the fracture surfaces

Brittle -

Ductile -

Bone’s behaviorBone’s behavior

more brittle or more ductile behavior depending on:– age of bone– rate at which bone is loaded

Characteristic Unique to BoneCharacteristic Unique to Bone

Anisotropy– bone exhibits different mechanical properties

when loaded along different axes

Types of LoadingTypes of Loading

Forces are applied to bone using Newton’s 3rd Law of Motion.

These loads are equal in magnitude and oppositely directed.

Types of LoadingTypes of Loading

Tension– loads applied outward along longitudinal axis of

bone.Compression

– loads applied inward along longitudinal axis of bone.

Shear– loads applied parallel to cross-sectional surface of

structure.

Bone loads cont.Bone loads cont.

Bending– loads applied that cause bone to bend.

Torsion– loads applied that cause bone to twist about

longitudinal axis.Combination

– two or more loads are applied to bone.

Behavior of bone variesBehavior of bone varies

Rate of bone loading is importantWhen loaded at higher rates:

– bone is stiffer, sustaining higher load to failure, and

– bone stores more energy before failure.

Clinical Importance of Clinical Importance of Loading RateLoading Rate

Influences the fracture pattern and amount of soft tissue damage at the fracture site.

Three general categories of bone fracture.– Low energy fracture

– High energy fracture

– Very high energy fracture

Fractures caused by:Fractures caused by:

a single load that exceeds the ultimate strength of the bone, or

repeated applications of a load of lower magnitude.

Fatigue FracturesFatigue Fractures

Produced by:– few repetitions of a high load, or

– by many repetitions of a relatively normal load.

Factors affecting theFactors affecting thefatiguing processfatiguing process

Amount of Load

Number of repetitions

Frequency of Loading

When do fatigue fractures When do fatigue fractures occur?occur?

When remodeling process is outpaced by the fatigue process.

Examples?Affect of muscle fatigue?

– Implications?

Bone RemodelingBone Remodeling

bone remodels by altering its size, shape and structure to meet the mechanical demands placed on it.

Wolff’s Law:

Degenerative changesDegenerative changes

reduction in amount of cancellous bone, thinning of cortical bone, decrease in total amount of bone tissue, and slight decrease in the size of bone.

Direct implications?

Bone SummaryBone Summary

Identify eight major points presented.