Biomechanics Session 1 POST PDF

Movement Science I Course Intro Adapted with permission from Dr. Cole, George Washington University Program in Physical  Thank you! Acknowledgements –Dr. Keith Cole –Dr. Kenneth Harwood ...

Movement Science I Course Intro Adapted with permission from Dr. Cole, George Washington University Program in Physical  Thank you! Acknowledgements –Dr. Keith Cole –Dr. Kenneth Harwood  Syllabus Part 1 Part 2 Reflection and Free Body Diagram Reflection #2 Assignment –2% – 3% Final Exam Biomechanics Lab #1 and #2 – 5% each –30% – Graded for completeness –Cumulative with an emphasis – Key will be released on the second half of the course Quizzes –Multiple choice – 2 worth 5% each Gait Analysis Assignment Exam #1 –15% – 30% –Show your ability to apply your – Free Response!! Solve FBDs, draw graphs or figures, etc biomechanical knowledge!  Course Learning Objectives Apply basic biomechanical & kinesiological principles to human structures and anatomical structures. Discuss physiological and biomechanical consequences of mechanotransduction and tissue injury. Analyze kinetic and kinematic (motion) factors influencing human movement Apply kinesiological principles of kinematics and biomechanics to movement dysfunction More of a lay language objective: Have the foundational language and problem solving skills to assess how tissues are being loaded, and then decide how and whether or not to load or unload the tissue  Importance of Kinesiology & Biomechanicst? How will kinesiology and/or biomechanics help you as a Physical Therapist?  Movement Science I Session 1: Essentials of Biomechanics & Kinesiology Adapted with permission from Dr. Cole, George Washington University Program in Physical Kinematics, Rotation, Translation  Overview Kinesiology: –The study of movement –Essential for rehabilitation, MSK prevention, ergonomics, device and equipment design –Integrates: anatomy, biomechanics and physiology Kinematics (motion) and Kinetics Anatomical Study of a Knee The Vitruvian Man (forces) School of Michelangelo Buonarroti Italian Leonardo DaVinci 1475–1564  Kinematics Kinematics: –Branch of mechanics concerned with motion of a body without reference to the forces which cause the motion –Two types of motion: Translation Rotation  Translation Translation: –Movement of a body without change in its orientation –Types: Rectilinear: Linear motion, straight line motion Curvilinear: Curved line motion Variables: –Position/displacement (meters, feet, inches) –Velocity (m/sec) –Acceleration (m/sec2)  Rotation Rotation: –Movement of a body in a circular path around a pivot point –All points of the body rotate the same angular direction, across the same number of degrees –Variables Distance (degrees, radians) Velocity (degrees/sec) Acceleration (radians/sec2) Rotation vs. Translation A B Rotation vs. Translation Does our body rotate or translate? 5:07-5:16 Does our body rotate or translate? During gait, what parts of our body –Translate? –Rotate? –Translate and rotate?  Motion and Osteokinematics vs. Arthrokinematics  Osteokinematics Osteokinematics: motion of bones relative to the three cardinal planes. Examples: – Flexion and extension (Sagittal plane) – Abduction and adduction (frontal plane) – Internal and external rotation (horizontal plane) Assumptions: –You know motions of the cardinal planes –Understand axes of rotation –Please review  Axis of rotation Bones rotate around a joint in a plane that is perpendicular to an axis of rotation –The axis can be assumed to pass through the convex member of the joint but this is a rough estimate –In reality, the center of axis moves during rotation (subtly most of the time)  Degrees of freedom Degrees of freedom are the number of permitted planes of angular motion at a joint (corresponding to cardinal planes) – Clinician: look at angular motion about a joint Joints have up to 3 degrees of freedom (3 cardinal planes) How many degrees of free does the shoulder have? Wrist? – Engineering: includes angular AND translational motion. Consider 6 degrees of freedom (3 angular, 3 linear)  Open Chain vs. Closed Chain Open Kinematic Chain: Closed Kinematic Chain: Distal segment is NOT Distal segment is fixed to the ground or immovable fixed to the ground or object immovable object Examples? Examples?  Osteokinematics: OKC and CKC Open kinetic chain: Distal segment rotates on fixed proximal segment Closed kinetic chain: proximal segment rotates on fixed distal segment Usually both are happening at the same time!  Arthrokinematics: Arthrokinematics describes the motion that occurs between the articular surfaces of joints Joint movement usually involves two curved surfaces, one typically convex and one concave. Three main types of movements between joint surfaces: – Roll – Glide – Spin  Arthrokinematic Motions Roll: Multiple points of one articular surface contacting multiple points on the other (tire on road). Slide/Glide: Single point on one articular surface contacts multiple points on another articular surface (tire skidding) Spin: A single point on one articular surfaces rotates on a single point of the other articular surface (rotating top)  Rotation vs Translation Rotation Translation  Joint Motion Primary Motion: the predominant arthrokinematic component to achieve the joint motion Accessory Motion: the secondary and tertiary arthrokinematic component(s) to achieve the joint motion Maitland, 2005  Convex-Concave Rule If a convex surface moves on a concave surface, roll and slide are in opposite directions (A) If a concave surface moves on a convex surface, roll and slide are in the same directions (B) Also called the Kaltenborn rule  Convex-Concave Rule Arthrokinematics at the glenohumeral joint during abduction. The glenoid fossa is concave, and the humeral head is convex. A, Roll-and-slide arthrokinematics typical of a convex articular surface moving on a relatively stationary concave articular surface. B, Consequences of a roll occurring without a sufficient offsetting slide.  Convex-Concave Rule Concave on Convex Convex on Concave Kiminstitute.c om  Exercise Using your hands (one hand being convex and one being concave) describe the concave/convex rule for: 1) Concave on convex 2) Convex on concave  Spin as the primary motion Shoulder –IR/ER when in 90 degrees abduction Hip –Flexion/extension Humeroradial joint –Supination/pronation  Combination: Roll and Slide with Spin. Some joints combine roll and slide with spin. One example is during terminal knee extension: – Knee extension in CKC: Some joints combine roll and slide with spin. During the last 30◦ the femur –Rolls anteriorly –Slides posteriorly –Spins internally – Knee extension in OKC During the last 30◦ the tibia –Rolls anteriorly –Slides anteriorly –Spins externally  Evidence for the Convex/Concave Rule An evidence-based review on the validity of the Kaltenborn rule as applied to the glenohumeral joint (Brandt, Sole, Krause & Nel, 2007) found that – In 28 studies, the humeral head rolled and slid in the same direction – In 10 studies, the humeral head rolled and slid in opposite directions The evidence indicates – (i) different arthrokinematic behavior for normal and dysfunctional joints and – (ii) that not only the passive subsystem, but also the active and control subsystems may determine intra-articular gliding motion. Following rule to treat restricted joint motion still effective to help stretch tight capsule or ligaments  Breakout Questions Question 1: Describe the arthrokinematics of the following: Knee flexing from 30 to 40 degrees, closed chain Femur (vex) moving on stable tibia (cave) Vex on Cave Posterior roll, anterior glide Elbow extending, open chain Ulna (Cave) moving on a stable humerus (vex) Cave on vex Posterior roll, posterior glide Question 2: 64 year old patient with gradual onset of “stiffness” in the R shoulder.. PMH: diabetes and HTN Patient complaint: Stiffness and pain on raising arm in abduction Question: Considering the concave/convex rule, what accessory motion might be deficient? What tissues might restrict that motion? What tissues might be causing the pain and why? What would you do to increase the such accessory motion? M  Closed packed and open packed positions Close packed positions: maximal congruency (“fits the best”), usually in or near the end of range of motion – Most ligaments and parts of the capsule are pulled taut – Position of stability – Minimal accessory movement Open packed: Less congruency (“loose” packed) – Ligaments and capsule are relatively slack – Less stability – Relatively more accessory movement For example, for the knee – Closed pack: full extension with external rotation of the tibia – Open pack: 30 degrees flexion – Question: When assessing your patient’s knee, would you expect more anterior/posterior glide with or without a bolster under their knee? Expect more glide because the knee is put in an open packed position  Kinematics Review What are the two types of kinematic motion? –Translation and rotation What are the three types of arthrokinematic motions? –Spin, roll, glide/slide Name one way we apply the principles of kinematics to patient care? –Joint mobilizations Kinetics  Center of Mass Center of mass: Point at the exact center of an object’s mass. –Mass is evenly distributed in all directions Center of Gravity: point about which the effects of gravity are completely balanced. CoM closely coincides with CoG –For the purposes of this class CoM = CoG  Review: Vector vs Scalar Scalar: Quantity that has a magnitude and no direction –Examples? Temperature, mass, distance, speed Vector: Quantity that has both magnitude and direction –Examples ?oooooo answers are at the end of the powerpoint Vectors have both x and y components A smaller angle has a greater x component and a smaller y component A larger angle has a smaller x component and a larger y component The angle of application of a force matters!  Kinetics Branch of mechanics that describes the effects of forces on the body. Definitions: –Force: mechanical disturbance or load (push or pull) In Newtons (N) – 1 N = 1 kg × m/sec2 F = ma Defined by: – Point of application – Spatial orientation – Direction – Magnitude  Force Vector Defined by: –Spatial Orientation –Direction –Point of Application –Magnitude Fg  Force and Acceleration F=ma, force is equal to the mass of the object times the acceleration or acceleration is equal to force Fg divided by mass Types of Forces/Loads Who creates more linear acceleration? 10 N of Force 10 N of Fo rc e Who creates more linear acceleration? 10 N of Force Horizontal Vertical 10 N of Fo rc e  Internal vs External Forces Internal: –Produced by structures within the body –Passive: Ligaments, joint capsule, muscle (off), joint reaction force etc. –Active: Muscle (on) External –Produced by forces outside the body –Examples: Gravity or external load (weight held in hand, therapist applying resistance to a limb, etc)  Torque Torque (moment) is a measure of how Moment arm much a force acting on an object causes the object to rotate Torque (τ) is the rotary equivalent to force Torque = Force x moment arm: τ = Fd – Moment arm is the perpendicular distance between the axis of rotation and the line of action of a force Moment arm For our purposes, Moment and Torque are the same  Rotatory motion Torque (moment) is a measure of how much a force acting on an object causes the object to rotate Torque (τ) is the rotary equivalent to force Torque = Force x moment arm: τ = Fd – Moment arm is the perpendicular distance between the axis of rotation and the line of action of a force For our purposes, Moment and Torque are the same  Moment Arm Think about the biceps muscle exerting a force on the forearm. Note: the length of both arrows is the same Describe the difference in force in these two scenarios Describe the difference in torque in these two scenarios Ignore gravity  Discussion Question Using Biomechanics, explain why holding luggage in your hand generates greater torque about the elbow when the elbow is at 90 degrees (shoulder in 0 degrees) compared to when the elbow is at 10 degrees of flexion. FB FL  Decomposition of Forces When the angle of the force changes, the torque generating capacity changes Break down force into x and y components  Internal and External Torque Internal Torque: –Produced by structures within the body –Passive: Ligaments, joint capsule, muscle (off) –Active: Muscle (on) External Torque –Produced by forces outside the body –Examples: Gravity or external load (weight held in hand, therapist applying resistance to a limb, etc)  Internal and External Torque Establish your reference frame. By convention, CCW is 𝐹𝐽 typically considered positive y x Discussion Question Is the internal torque greater than, less than or equal to the external torque during the following types of muscle contractions? Concentric Isometric Eccentric Levers  Lever Systems Lever: Simple machine consisting of a rigid rod suspended across of pivot point Internal and external forces produce torques through bony levers Classified as first, second and third class levers –The body takes advantage of all three levers for each of their advantages. Image credit: dreamstime.com  First Class Levers Axis of rotation between opposing forces. Internal External Forces Forces Body example of 1st class level  Second Class Levers Axis of rotation located at one end of the lever and Internal forces have greater leverage Internal Forces External Forces Body Example of 2nd Class Lever  Third Class Levers Axis of rotation located at one end of the lever and external forces have greater leverage Internal Forces External Forces body example of 3rd class lever  Mechanical Advantage The efficiency of a lever is based on its’ mechanical advantage –Mechanical advantage of the internal force = –Mechanical advantage of the external force= Internal Externa Forces l Forces Interna Intern l al Extern Extern Forces Forces al al Forces Forces  Mechanical Advantage For each type of lever, is the mechanical advantage for the muscle greater than 1, less than 1 or unkown? –Mechanical advantage of the internal force = Internal Externa Forces l Forces Interna Intern l al Extern Extern Forces Forces al al Forces Forces Why is a 3rd class lever the most common? Questions?? Importance of Kinesiology & Biomechanics Image credit: https://www.vargopt.com Importance of Kinesiology & Biomechanics  Breakout Questions Question 1: Describe the arthrokinematics of the following: Knee flexing from 30 to 40 degrees, closed chain – Femur (vex) moving on stable tibia (cave) – Vex on Cave – Posterior roll, anterior glide Elbow extending, open chain – Ulna (cave) moving on a stable Humerus (vex) – Cave on Vex – Posterior roll, posterior glide Question 2: 64 year old patient with gradual onset of “stiffness” in the R shoulder.. PMH: diabetes and HTN Patient complaint: Stiffness and pain on raising arm in abduction Question: Considering the concave/convex rule, what accessory motion might be deficient? What tissues might restrict that motion? What tissues might be causing the pain and why? What would you do to increase the such accessory motion? Hummers (vex) moving on glenoid fossa (cave) Abduction: superior roll, inferior glide (opposite) At risk for adhesive capsulitis Inferior mobilizations of humeral head  Closed packed and open packed positions Close packed positions: maximal congruency (“fits the best”), usually in or near the end of range of motion – Most ligaments and parts of the capsule are pulled taut – Position of stability – Minimal accessory movement Open packed: Less congruency (“loose” packed) – Ligaments and capsule are relatively slack – Less stability – Relatively more accessory movement For example, for the knee – Closed pack: full extension with external rotation of the tibia – Open pack: 30 degrees flexion – Question: When assessing your patient’s knee, would you expect more anterior/posterior glide with or without a bolster under their knee? More glide with a bolster (Open pack)  Review: Vector vs Scalar Scalar: Quantity that has a magnitude and no direction –Examples? mass, distance, temperature, speed Vector: Quantity that has both magnitude and direction –Examples? force, moment , velocity, acceleration  Moment Arm Think about the biceps muscle exerting a force on the forearm. Note: the length of both arrows is the same Describe the difference in force in these two scenarios Describe the difference in torque in these two scenarios Ignore gravity  Moment Arm (Alternate solution) Think about the biceps muscle exerting a force on the forearm. Note: the length of both arrows is the same Describe the difference in force in these two scenarios Describe the difference in torque in these two scenarios Ignore gravity  Answer Using Biomechanics, explain why holding luggage in your hand generates greater torque about the elbow when the elbow is at 90 degrees (shoulder in 0 degrees) compared to when the elbow is at 10 degrees of flexion.  Answer (Alternate) Using Biomechanics, explain why holding luggage in your hand generates greater torque about the elbow when the elbow is at 90 degrees (shoulder in 0 degrees) compared to when the elbow is at 10 degrees of flexion.  Decomposition of Forces When the angle of the force changes, the torque generating capacity changes Break down force into x and y components Re-draw to depict point of application  Internal and External Torque Establish your reference frame. By convention, 𝐹𝑏 CCW is 𝐹𝐽 𝑦 typically considered positive y 𝐹𝑏 𝑥 x  Mechanical Advantage For each type of lever, is the mechanical advantage for the muscle greater than 1, less than 1 or unknown? –Mechanical advantage of the internal force = Internal Externa Forces l Forces Interna Intern l al Extern Extern Forces Forces al al Forces Forces >1