KIN 330 Structural and Functional Analysis of Human Movement

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

What is Kinesiology? H Components of Kinesiology

What is Biomechanics? H...the application of physics and engineering principles to the study of motion.

Components of Biomechanics H Kinematics - the description of motion H Kinetics - the study of forces on motion

Who can use biomechanics?

Biomechanics of Bone H Purposes of skeletal system –protection –provides rigid links and attachments for muscles –facilitates muscle action and body movement

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

Distinguishing Features H Organic component H Inorganic component H Interface of two components

Mechanical Properties H Functionally speaking: –strength –stiffness

Load/Deformation Curve H Regions –A - B: Elastic Region: –B: Yield Point –B - C: Plastic Region: –C: Ultimate Failure Point

Parameters displayed on curve H load H deformation H energy

Usefulness of L-D Curve H determines the mechanical properties of the entire structure of the bone. H Strength H Stiffness

Classification of Bone H Depends on the extent of deformation before failure –reflected in the fracture surfaces H Brittle - H Ductile -

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

Characteristic Unique to Bone H Anisotropy –bone exhibits different mechanical properties when loaded along different axes

Types of Loading Types of Loading H Forces are applied to bone using Newton’s 3rd Law of Motion. H These loads are equal in magnitude and oppositely directed.

Types of Loading H Tension –loads applied outward along longitudinal axis of bone. H Compression –loads applied inward along longitudinal axis of bone. H Shear –loads applied parallel to cross-sectional surface of structure.

Bone loads cont. H Bending –loads applied that cause bone to bend. H Torsion –loads applied that cause bone to twist about longitudinal axis. H Combination –two or more loads are applied to bone.

Behavior of bone varies H Rate of bone loading is important H 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 H Influences the fracture pattern and amount of soft tissue damage at the fracture site. H Three general categories of bone fracture. –Low energy fracture –High energy fracture –Very high energy fracture

Fractures caused by: H a single load that exceeds the ultimate strength of the bone, or H repeated applications of a load of lower magnitude.

Fatigue Fractures H Produced by: –few repetitions of a high load, or –by many repetitions of a relatively normal load.

Factors affecting the fatiguing process H Amount of Load H Number of repetitions H Frequency of Loading

When do fatigue fractures occur? H When remodeling process is outpaced by the fatigue process. H Examples? H Affect of muscle fatigue? –Implications?

Bone Remodeling H bone remodels by altering its size, shape and structure to meet the mechanical demands placed on it. H Wolff’s Law:

Degenerative changes H reduction in amount of cancellous bone, H thinning of cortical bone, H decrease in total amount of bone tissue, and H slight decrease in the size of bone. H Direct implications?

Bone Summary H Identify eight major points presented.