KIN 330 Structural and Functional Analysis of Human Movement
Structure of Class • divided into three parts • tissue • movement patterns and analyses • application of physics to movement
What is Kinesiology? • Components of Kinesiology
What is Biomechanics? • ...the application of physics and engineering principles to the study of motion.
Components of Biomechanics • Kinematics - the description of motion • Kinetics - the study of forces on motion
Who can use biomechanics?
Biomechanics of Bone • Purposes of skeletal system • protection • provides rigid links and attachments for muscles • facilitates muscle action and body movement
Bone • metabolically active • highly vascular • responds to mechanical demands • among the body’s hardest structures
Distinguishing Features • Organic component • Inorganic component • Interface of two components
Mechanical Properties • Functionally speaking: • strength • stiffness
Load/Deformation Curve • Regions • A - B: Elastic Region: • B: Yield Point • B - C: Plastic Region: • C: Ultimate Failure Point
Parameters displayed on curve • load • deformation • energy
Usefulness of L-D Curve • determines the mechanical properties of the entire structure of the bone. • Strength • Stiffness
Classification of Bone • Depends on the extent of deformation before failure • reflected in the fracture surfaces • Brittle - • Ductile -
Bone’s behavior • more brittle or more ductile behavior depending on: • age of bone • rate at which bone is loaded
Characteristic Unique to Bone • Anisotropy • bone exhibits different mechanical properties when loaded along different axes
Types 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 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. • 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 varies • Rate of bone loading is important • When loaded at higher rates: • bone is stiffer, sustaining higher load to failure, and • bone stores more energy before failure.
Clinical Importance of Loading 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: • a single load that exceeds the ultimate strength of the bone, or • repeated applications of a load of lower magnitude.
Fatigue Fractures • Produced by: • few repetitions of a high load, or • by many repetitions of a relatively normal load.
Factors affecting thefatiguing process • Amount of Load • Number of repetitions • Frequency of Loading
When do fatigue fractures occur? • When remodeling process is outpaced by the fatigue process. • Examples? • Affect of muscle fatigue? • Implications?
Bone Remodeling • bone remodels by altering its size, shape and structure to meet the mechanical demands placed on it. • Wolff’s Law:
Degenerative 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 Summary • Identify eight major points presented.
