Fundamental Biomechanics

Which is more likely to produce more joint torque with maximal effort from patient? (MVC= maximal voluntary contraction)? Isokinetic: Triceps brachii at A) -60 deg/sec B) 30 deg/sec

-60 deg/sec Eccentric motion produces more force

Coefficient of Friction Kinetic Dry bone on bone

0.3

Free Body Diagram

1) identify the object and forces that are action on objects including the reference frame 2) identify the axis of motion (if applicable) 3) Identify all forces acting on the object indicating direction and magnitude, and point of application 4) Determine moment arms 5) Sum of moments=0; sum of force=0 (in equilibrium)

Coefficient of Friction Kinetic Synovial Joint

0.003

Role of Capsules and Ligaments- Passive

1. Augment mechanical stability of joint 2. Guide joint motion 3. Prevent excessive motion Ligaments help to limit the extremes of motion Bones create the path, muscle do the moves, ligaments complete the stops Ligaments= passive tissue

Articular Cartilage Purposes

1. Distribute joint loads 2. Allow movement

Mechanical Lever System Classifications

1st class lever 2nd class lever 3rd class lever

Closed vs. Open (loose) packed joint position Knee Open (loose) position

20-30 degrees of flexion

Mechanical Advantage (AKA leverage) Force efficiency vs. speed potential

2nd class levers have a greater mechanical advantage + greater torque "stronger" 3rd class levers have a mechanical disadvantage, but a greater speed/ROM

Stress-Strain Different Zones Complete Failure

8% strain in ligament Stress decreases slightly

Tendons and Ligaments Composed largely of collagen

1. the mechanical stability of collagen gives both elements of strength and flexibility 2. Some ligaments do have significant amount of elastin present to give them more elasticity, e.g., ligaments flavor and ligaments niche. Relatively rare. 3. 60% of wet weight is water 4. Also contains glycolipids and proteoglycan Resist tensile loads

Which is more likely to produce more joint torque with maximal effort from patient? (MVC= maximal voluntary contraction)? Isokinetic: Quadriceps at A) 120 deg/sec B) 300 deg/sec

120 deg/sec Increased velocity decreases force production

Which is more likely to produce more joint torque with maximal effort from patient? (MVC= maximal voluntary contraction)? Isokinetic: Triceps brachii at speed of A) 30 deg/sec B) 180 deg/sec

30 deg/sec increasing contractile speed decreases force production

Muscle structure Order from outside to inside

Epimysium Perimysium: surrounding of a fascicle Endomysium: wrapping of an individual muscle fiber

Length-Tension Relationship

Especially important in muscles that cross multiple joints hamstrings biceps triceps some hand musculature...

Ligaments and Tendons Makeup

Fibroblasts (20%) Extracellular matrix (80%) -type I collagen: white, strength of steel, Ehlers-Danlos Syndrome (connective tissue disorder- laxity in joints) More collagen than elastin Ground substance= jelly like filler

Mechanical Advantage (AKA leverage) 2nd Class levers

Have a mechanical advantage of greater than 1 wheelbarrow

Muscle Characteristics Excitability

Ability to respond to a stimulus

Mechanical Lever System Classification Second Class lever

Advantage to the effort Whenever two resultant forces are applied so that the resistance force lies between the effort force and axis of rotation Calf MMT example- raising on toes. Resistance= weight down toward ground, effort= gastrocs

What is the greatest determinate of stability of a joint?

Bony congruency Decreased bony congruency=less stable

Hormones PT relevance Relaxin

Hormone Produced during pregnancy and during a small window of days in menstrual cycle Increase extensibility of ligaments Makes pubic ring loosen up

Arthrokinematics at the glenohumeral joint during abduction. The glenoid fossa is concave, and the humeral head is convex.

Humeral head (convex) moving on glenoid fossa (concave)= roll and slide in opposite direction. Roll= superior, slide= inferior PT must complete inferior glide of humerus on glenoid fossa

Maximum power

Is midway between the concave maximum isometric force on the y axis and maximum velocity on the x axis

Closed vs. Open (loose) packed joint position "Locked Position"

Joint surfaces are most congruent, capsule and ligaments most taut, probably the position of greatest intra-articular pressure Considered the greatest stability

Closed vs. Open (loose) packed joint position "Unlocked position"

Joint surfaces are not as congruent, capsule and ligaments are not as tight, allowing for more motion between joint surfaces Often the position used to assess joint play

Osteokinematics Abd/Add

Lateral flexion, side bending, ulnar and radial deviation, eversion/inversion

Newton's 1st Law of motion

Law of Inertia An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force

Anisotropic

Most tissues are anisotropic Differenty types or directions of stress create different strains on tissues Bone: great to resist compressive force, not as good with torsion, not so good with shear

Production of muscle force

Passively and actively

Moment arm or lever arm

Perpendicular distance from the axis to the line of action of force

PRICE

Protect Relativerest Ice Compress Elevate

Mechanical Lever System Classification

Related to location of forces with respect to axis E= effort R=resistance

Mechanical Lever System

Relatively rigid object rotating about an axis

Stress-Strain Different Zones Plastic Region

Reverse in slope magnitude- strain begins to increase more rapidly than stress Plastic deformation starts Permanent change, no recovery.

Types of Contractions Isotonic

Same tonus or same tension is produced with same external weight

Classifications of Joints Diarthrosis Ball and Socket Joint

Spheric convex surface that is paired with a cuplike socket Primary angular motions: Triplanar- flexion/extension, abd/add, int./ext/ rotation ex. glenohumeral joint, coxofemoral (hip joint) 3 DOFs

Active Insufficiency

The diminished ability of a muscle to produce or maintain active tension Read more about

Torque (aka the moment)

Torque= Force* perpendicular distance

Viscoelastic Materials Hysteresis- Energy Lost

Viscoelastic materials do not store and then return all of their energy that is transferred to them when deformed by an applied force (e.g. some of the energy is lost to heat) Material might not return to its original dimensions Loss of energy between expended and regained is called hysteresis Plastic range Example Balloon

Response to Injury Scar tissue Art of PT

We have a lot to learn Wide variety of opinion and expectations for healing speed or the need to protect healing issue

Closed Kinematic Chain

Weight bearing movement occurs at multiple joints- concurrent movement distal segment is fixed- invites compensation loading may be proximal or distal ex. squat, pushup

Types of Collagen Type XI

articular cartilage

Osteokinematics Flexion/extension

dorsiflexion/plantar flexion forward bending/backward bending

Y axis

forward/backward

Which of the following biomecahnical terms describes the 'study of forces effects on a body? a. kinetics b. kinematics c. kinesiology d. cybernetics e. cacophony

kinetics

Moment

moment= force*moment arm

Trigonometry Review tan

tangent= opposite/adjacent

Pt can't extend knee Should the PT administered glide be done posteriorly or anteriorly

Tibia (concave) moving on femur (convex)= concave on convex= same direction. roll= anterior, slide= anterior glide must occur in opposite direction Stabilize tibia (bolster)- holding tibia in place, move convex (femur) on concave (tibia) with a posterior glide of femur on tibia

Types of Collagen

Type I Type II Type III Type XI +28 types of collagen

Z axis

Up and down

Work-Energy Relationship

Used to study energy expenditures Simple way to look at metabolic demand Limited- no time component Need another term with time component

Co-contraction

When both the agonist and antagonist contract at same time Used for joint stability Think of a 1st class lever

Muscle Roles or Actions Synergist

When two or more muscles work together to produce movement

Mechanical Work Concentric

Work= + (positive work)

Mechanical Work Isometric

Work= 0 (no work)

Mechanical Work Eccentric

Work=- (negative work)

Trigonometry Review Pythagorean theorem

a2+b2=c2

Muscle Characteristics Adaptability

ability to change structure

Trigonometry Review cos

cos= adjacent/hypotenuse

Muscle Funciton Shape of fibers Fusiform

fibers run in parallel with the tendon or line of pull of the muscle e.g., biceps brachii increased speed and ROM

Mechanical Lever System Classification Resistance force

force opposing the motion

Connective Tissue Organic extracellular matrix Ground substance

glycoproteins and proteoglycans

Forces External

gravity, wind, water, other people Measure with ground reaction force plate

Mechanical Advantage (AKA leverage) 3rd class levers

have a mechanical advantage that is less than 1 most muscle actions (speed tradeoff)

Long Fibers, Small PCSA

higher contractile velocity, but lower maximum titanic tension Muscle force decreases as muscle velocity increases slight negative slope

Classifications of Joints Diarthrosis Hinge joint

hinge of a door, formed by a central pin surrounded by a larger hollow cylinder Primary angular motions: flexion/extension Ex. humeroulnar joint, interphalangeal joint 1 DOF

Osteokinematics Motions

horizontal abd/add circumduction

Closed vs. Open (loose) packed joint position Knee Locked position

hyper extended

Factors of velocity of movement and length of muscle

influence force production

Types of Contractions Isotonic Eccentric

lengthening contraction (AKA negative)

Osteokinematics Internal/external rotation

medial and lateral rotation axial rotation (right and left)

Arthrokinematics "accessory motion" Roll

multiple points along one rotating articular surface contact multiple point on another articular surface A tire rotating on a stretch of pavement Bone rotating in space

Moment arm

perpendicular distance from the axis to the line action of force

Arthrokinematics "accessory motion" Types of accessory motion

roll slide spin

Types of Contractions Isokinetic

same or equal motion concentric eccentric

X axis

side to side

Trigonometry Review sin

sin= opposite/hypotenuse

Arthrokinematics "accessory motion" Joint play motion

small movements at the joint can relay to large motion of the bones. Typically cannot be performed voluntarily- these are passive motions usually requires pt's relaxation of muscles and/or the application of a passive movement by an examiner These small motions at the joint are essential for normal, pain-free joint function

Articular Cartilage Anatomy Middle zone

squishes and moves Padding

Mechanical Lever System Classification Effort force

the force causing the motion

Reverse Action

the origin moves toward the insertion Distal end is typically fixed pull-ups

Mechanical Lever System Classification First Class lever

two resultant forces are applied on either side of an axis of rotation Teeter totter C1= Resistance of head to fall forward, looking up= effort of posterior muscles

Mechanical Work

work=force*distance work= torque*angular displacement

Hip when walking is on which axis?

y axis: abd/add

Joint moments

A change of angle of an applied force will change the torque Force can be broken into Joint reaction forces and rotational components No torque is produced by a force through the axis Split vector into x and y, if either is parallel to lever, it has no impact on the axis of rotation- either compresses or distracts joint

Arthrokinematics "accessory motion" Slide

A single point on one articular surface contacts multiple points on another articular surface A non-rotating tire skidding across a stretch of icy pavement AKA glide

Arthrokinematics "accessory motion" Spin

A single point on one articular surface rotates on a single point on another articular surface A toy top rotating on one spot on the floor

2 Types of Motion

A solid structure or body (i.e. bone) has really two types of motion. 1. Translation 2. Rotation

Epitenon

A synovial layer found where tendons are subjected to high friction forces-e.g. in the palm and digits AKA tenosynovium Actually contains synovial cells that produce synovial fluid to facilitate tendon gliding

Muscle Characteristics Contractility

Ability to modify length (shorten)

NSAIDs

Alive, Advil, ibuprofen Frequently used in TX of tendon/ligament problems to reduce inflammation Treatment with some NSAIDs can lead to decrease tensile strength of tendons and a decrease in collagen We need that early inflammatory process to lay down the building blocks to repair ligament and maintain LONG-TERM strength Don't take within first 48 hrs of injury Studies show tissue strength decreases with NSAIDs taken within first 48 hrs.

Connective Tissue Visoelastic Materials

All biological materials exhibit viscoelastic behaviors Viscosity is the resistance to flow, due mainly to the fluids within the tissues An elastic material will deform and return to its original shape- not immediate as its not purely elastic like a superball Due primarily to elastin fibers

Joint Classification Stability vs. mobility

All joints are balance between mobility and stability GH joint: sacrifices stability for mobility Humeroulnar joint: mobile in sagittal plane only, stable in others

Production of muscle force Passive

All the layers of CT (epi, peri, endo) the titian structure The tendon- all in all, a lot of elastic components

Articular Cartilage Purposes 2. Allow mvoement

Allow movement of opposing joint surfaces with essentially no friction and/or wear

Passive insufficiency

An inactive process, potentially antagonistic muscle is of insufficient length to permit completion of the full ROM available at the joints crossed by the passive muscle - Make fist with wrist flexed -straighten knee with hip flexed to 90- can't kick leg all the way out due to inadequate length

Factors affecting torque

Angle of insertion, and subsequent magnitude of M(y), muscle length, type of activation (i.e. isometric, concentric, or eccentric), and velocity of shortening or elongation of the activated muscle

Which of the following options best describes the position of the axis of rotation for shoulder abduction motion? a. longitudinal axis b. vertical axis c. medial-lateral axis d. anterior-posterior axis e. geometric axis

Anterior-posterior axis

Active + Passive= Length-tension relation Active force

As length increases, tension increases to an apex before decreasing linearly

How can the type of contraction influence the amount of muscle force production

As the angle increases, the torque increases until a point when the tension begins to decrease with increased angle Lowest torque= concentric-> isometric-> eccentric Active elements are strongest in eccentric motion because of the way the cross bridges of actin and myosin lick in- stronger than when they slide against each other as in concentric

Stress-Strain Different Zones Nonlinear Region "toe"

Assessed clinically Ligament/tendon Stress is approximately equal to strain

Muscle architecture Pennate muscles

At peak speeds, short muscles stop producing force As short fibers lengthen, they initially produce large amounts of force, but once a short fiber has doubled its length, its ability to produce force decreases linearly As the length of long muscles increases, the force production increases in a much less dramatic fashion (slight slope). Once a long muscle has stretched 1/2 of its original length, the muscles ability to produces force begins to decrease

Functions of Tendons

Attach muscle to bone Transmit tensile loads from muscle to bone, thereby producing joint motion Forces transmitted with relatively little loss of force

Center of Rotation

Axis of rotation b/w two limb segments at a given instant in time Change in axis due to 'imperfect' joint shape COG does not mean COR typically COR is located in the convex half of the joint coupling

Classifications of Joints Diarthrosis 6 categories

Ball and Socket Hinge Pivot Saddle Ellipsoid (condyloid) Plane or Gliding

Pressure Ulcers

Bed sores or pressure ulcers occur when a pt is placed in the same position for an extended amount of time in which a large amount of pressure is placed over a small area. To avoid bed sores, increase the area of contact.

Which is more likely to produce more joint torque with maximal effort from patient? (MVC= maximal voluntary contraction)? Isometric contractions: A) biceps femoris B) Biceps brachii

Biceps femoris greater CSA

Muscle, tendon, bone. Which is the most stiff?

Bone

Rolls and slides go wrong

Bone movements occurring in the absence of normal arthrokinematic movement cause impingement or dislocation. Ex. The glenoid fossa is concave and the humeral head is convex. During ABD of glenohumeral joint, the head of the humerus glides down in glendoid fossa during elevation, allowing the greater tuberosity f the humerus to clear the acromion process, preventing bone on bone contact that limits motion Striking the acromion process would also impact on adjacent soft tissue, thus producing injury and pain Also, allows the muscles to maintain a good length-tension relationship

Classification of Stiffness Steep stress strain curve

Brittle Very little strain causes high amounts of stress (vertical)

Center of Gravity

COG is the point of application of gravity on a body (hypothetical point) Average COG of the human body bisect the midline of the transverse and frontal planes and is at about the level of S2.

Stability

COG must stay within BOS to maintain stability The closer the COG is to the BOS surface the more stable Moment arms are greater on a ladder

Cross-sectional area

CSA is directly related to the maximal force potential of a muscle Greater thickness=greater force CSA is the sum of the thickness of all the available muscle fibers

Reducing friction

Cartilage on cartilage Tenosynovium Bursa Synovial fluid

Connective Tissue All connective tissue made of three things

Cells Organic extracellular matrix: Fibers and ground substance

Connective Tissue Organic extracellular matrix Fibers

Collagen and elastin

Classification of Stiffness Gradual strain-stress curve

Compliant Increased strain causes gradually increased stress (more horizontal)

Articular Cartilage Water Mechanics

Compressed articular cartilage- fluid squished out of the cartilage is exuded through pores in the outermost layer The fluid flows back into cartilage after the motion or compression ceases Force is sustained over a long period of time then permeability of cartilage is decreased- basically loose water and cartilage becomes more like a solid Fluid flow, either in or out, after compressed down is decreased as well and takes some time to recover

Viscoelastic Materials Creep

Continued deformation of material over time with constant load Continued strain; same stress Load is constant, tissue gives to load over time a constant state of stress with an increasing amount of strain.

Joint Reaction forces Compression

Contributes to joint stability Pull lever into joint

Creep vs. stress relaxation Prone knee hang

Creep

Frozen shoulder Theraband moves arm into elevation and external rotation. Over time, stretch will give

Creep

Joint Classification DOF's

DOF implies the number of planes a joint is capable of moving in There are 6 DOF's but we focus on angular only for osteokinematics (just three)

Viscoelastic Materials Stress Relaxation

Decrease in stress in a deformed structure with time when deformation is held constant the observed decrease in stress in response to the same amount of strain generated in the structure

Immobilization

Decreases tensile strength of ligaments Causes disorganization of collagen Eight weeks of immobilization can cause up to 50% loss of collagen Most critical weakness is at site of attachment to bone (osteoclastic) Rest of the tissue becomes more. pliable decreasing maximal load

Principle (or Cardinal) Planes of the Body

Defined anatomical position as starting point in most cases Sagittal Plane Frontal Plane Transverse Plane

Articular Cartilage Physiology

Devoid of blood vessels and nerves Nourishment solely from the back and forth flow of fluid into and out of cartilage Flow of fluid is essential for the health of cartilage and as an aid for reducing friction motion is the lotion of the joint

Classifications of Joints Synarthroses Fibrous Joints

Direct union- fibrous tissue- little to no motion Suture- skull, edges interlock Gomphosis- tooth (peg in a hole) Syndemosis- membrane, e.g., interosseous membrane

Classifications of Joints Synarthroses Cartilaginous Joints

Direct union-cartilage No joint capsule some movement Symphysis- fibrocartilage- pubic symphysis, intervertebral disc Synchondrosis- hyaline cartilage- manubriosternal joint Generally exist in the midline of the body

Articular Cartilage Purposes 1. Distribute joint loads

Distribute joint loads over wide area, thus dereasing the stresses sustained by the contracting joints

Hormones PT relevance Estrogen

Down regulation of type I collagen synthesis ACL injury

Theoretical Force Velocity Curve

Eccentric- as the lengthening velocity decreases, force decreases- lengthening velocity doesn't really change force- kind of a plateau- but eccentric always results in more force than isometric or concentric. At 0 cm/sec of lengthening (ISOMETRIC) force is held constant. As the shortening velocity increases, force decreases. trying to decrease force= test quickly and concentrically

Mechanical Advantage (AKA leverage)

Efforts moment arm/ Resistance moment arm

Muscle Characteristics

Excitability Conductivity Adaptability Contractility

Fatigue Failure

Failure of the structure from repeated loading and unloading below its peak complete failure point from a single application of stress Paper clip: bend it back and forth enough times and it fails

Immobilization Continued

Fewer cross links of collagen and more immature collagen following immobilization Less fluid context in tendon/ligament with loss of matrix material (consistent with contractures/poor mobility) Position of immobility is important- positioned in some tension helps to preserve the health of tendon and ligament Providing stress to the tissue to help it heal well- no load/no stress= not healthy. want optimal stress.

Fiber orientation

Fiber orientation influences cross-sectional area (muscle thickness) Anatomically, the cross sectional area of a fusiform (tibias anterior) and Penniform (rectus femoris bipenate) may be the same, but due to the senate structure of the rectus femurs, its physiological cross sectional area is larger. More muscle in a small speace= less length, can't generate as much velocity

Muscle Funciton Shape of fibers Penniform

Fibers run diagonally with respect to the tendon running through the muscle Allows you to stack more fibers in a given place, but force is applied on tendon at an angle Unipennate- semimembranous Bipennate- gastrocnemius Multipennate- deltoid Smaller distance, higher tension, more force

Classifications of Joints Synarthroses Two categories

Fibrous Joints Cartilaginous Joints

Fundamental elements that comprise all connective tissue

Fibrous proteins, cells, ground substance

Bursae

Flat sacs of synovial membrane with synovial fluid lying between tendon and bone, muscle and bone, ligament and bone or skin and bone

Newton's 3rd Law of Motion

For every action there is an equal and opposite reaction

Classifications of Joints Diarthrosis Pivot joint

Formed by a central pin surrounded by a larger cylinder Unlike a hinge, the mobile member of a pivot joint is oriented parallel to the axis of rotation- this mechanical orientation produces the primary angular motion of spin, similar to a doorknobs spin around a central axis Primary angular motion: spinning of one member around a single axis of rotation ex. humeroradial joint, Atlanto-axial joint 1 DOF

Types of Collagen Type II

Found in hyaline cartilage and annulus fibrosis- make a frame to maintain shape and consistency in CT

Types of Collagen Type I

Found in tendons, ligaments and stratum fibrousum- the RUGGED REBAR Most common

Classifications of Joints Diarthrosis

Freely moveable filled with joint fluid ends are covered with cartilage articular (joint) capsule synovial membrane capsular ligaments blood vessels sensory nerves

Friction

Friction force acts to oppose movement between two surfaces in contact with one another F(friction)=u*Force of contraction

Active force generation

Fucntion of length type of contraction internal structure

Muscle Roles or Actions Synergist Stabilizer

Functions to fixate an area so another movement can occur Muscle that stabilize the scapula during shoulder abduction

Muscle Roles or Actions Synergist Neutralizer

Functions to prevent undesired movement Rectus abdominas activating while lifting thigh into flexion to avoid anterior rotation

Connective Tissue

Give support and form to the body

Classifications of Joints Diarthrosis Saddle Joint

Has two surfaces: one surface is concave, and the other is convex- these surfaces are oriented at approximate right angles to each other and are reciprocally curved Primary angular motions: Biplanar motion- spin b/w bones is possible, but may be limited by interlocking nature of joint ex. carpometacarpal joint of the thumb, sternoclavicular joint 2 DOFs

Normal Healing of Ligaments

Heal by fibrous scar- not as strong as normal ligament Partial tears heal somewhat better provided ligament is protected and a blood supply is present Complete tears- gap between shredded ends-only heals with scar Time to healing depends on many factors including the size of ligament as well as the forces applied to it after injury- use your PRICE principles If can apply ideal stress= scar that is smaller, stronger, and aligns with fibers

Impulse and Force

Impulse and force are directly related.. more force means more impulse Double the force, double the impulse Triple the force, triple the impulse Impulse does not equal force- impulse also depends on how long the force is applied More time= more impulse 2X time= 2X impulse Impulse is a vector quantity, has direction and magnitude

Implications of impulse momentum relationships

Impulse=F*T Tennis serve- fallow through- longer time racket in contact with ball= increased impulse= increased velocity Landing from jump- increasing landing time decreases force Running shoes- foam/padding to increase time which decreases force.

Impulse

Impulse=force*time=F*T When you apply a force on an object, you also exert an impulse on it. When something exerts a force on you, it also exerts an impulse on you. Forces and impulses always go together.

Closed vs. Open (loose) packed joint position Open (Loose) Packed

In all other positions, the surfaces do not fit perfectly but are incongruent and called open packed or loose packed (most room in the joint for accessory motion) The ligamentous and capsular structures are slack and the joint surfaces may be distracted several millimeters Loose packed positions allow for the most accessory motions of spin, roll, and glide and may decrease joint friction

Fatigue Failure Bone

In bone, a fatigue failure is called a stress fracture

Stiffness of Visoelastic material is Rate or Speed dependent

In general, the faster a material is loaded the more brittle it is Walking vs. running walking= force applied over a longer period of time= less brittle material running= force applied quickly, over a shorter period of time= more brittle material

Rate Dependent "loading Rate"

In general, the faster a material is loaded the more brittle it will become Example- hoe do you rip pieces of tape? Fast Excessive stress= tear in tendon/ligament OR avulsion fracture

Don't 'overload the joint' Should we avoid the loading stress? Loading to cartilage will stimulate

Increased chondrocyte activity Upregulate the amount of matrix turnover (i.e. more proteoglycans- the bottle brushes)

Types of Contractions

Isometric Isotonic Isokinetic

2 Types of Motion Translation

Linear (straight) motion in which all parts of a rigid body move parallel to and in the same direction as every other part of the body Straight (rectilinear-2D) Curvilinear (3D)

Mechanical Lever System Classification

Location of forces with respect to an axis

Torque and moment arm

Longer moment arm= increase torque

Forces Vector quantity

Magnitude (length of vector) Direction (direction of arrow) Point of application (point where vector force is applied) Line of action (dotted line continued past point of application)

Pathological Mechanical Advantage Repair of massive rotator cure muscle at the shoulder

Make new insertion for tendon to insert= moment arm messed up= decreased muscle strength

Articular Cartilage Hyaline

Matrix: primarily type II collagen, proteoglycans, water Hydrophilic- water loving Keep viscous/slippery matrix of cartilage winds 3D- all different directions Base holds sulfates

Mechanical Lever System Classification Third class lever

Mechanical advantage to resistance Whenever two resultant forces are applies so that the effort force lies between the resistance force and axis of rotation Most of the muscles in the body are 3rd class levers Biceps (effort) when trying to raise a weight (resistance)

Momentum

Momentum=M*V (mass*velocity) What makes an object difficult to stop? its mass, more speed means more momentum Momentum is a vector quantity- its direction is the same as the direction of the object's velocity

2 Types of Motion Rotation

Motion in which a rigid body moves in a circular path about some pivot point or axis of rotation All points rotate in the same direction

Osteokinematics

Motion of bony levers with respect to one another defined in principal planes of motion Whats measured by goniometry

Classifications of Joints Diarthrosis Ellipsoid Joint

One partner with a convex elongated surface in one dimension that is mated with a similarly elongated concave surface on the second partner. Primary Angular Motion: Biplanar motion- flexion/extension, abd/add ex. radoiocarpal joint 2 DOFs AKA condyloid

What position would the knee be in to test the MCL?

Open packed position allows for isolation. A closed position would result in all ligaments being taut If there is motion in the close packed position, more than one ligament may be torn

What position would the joint be in if there was fluid in the joint due to injury?

Open packed position for comfort- more room for fluid

Would you do a strength assessment on the quad in the close packed or open packed position?

Open packed position. In the closed packed position there is a high amount of passive stability (very difficult to 'beat' quad). The open or loose packed position down regulates that passive stability because it has a much lower passive stability due to non-taut ligaments

Pennation Angle

Orientation between the muscle fibers and the tendon Muscle that is parallel with tendon= 0 degrees Reduction in transfer of force as muscular attachment is oblique to the tendon

Classifications of Joints Diarthrosis Plane or Gliding Joint

Pairing of two flat or relatively flat surfaces Primary angular motion: biplane motion- side translation OR combined slide and rotation ex. carpometacarpal joints (digits II to IV), inter carpal joints, inter tarsal joints 3 DOFs

Transverse (horizontal) Plane

Parallel to horizon and divides body into upper and lower section internal (med)/ext (lat) rotation, axial rotation

Power

Power= force*speed Speed=Distance/time Power=work/time More functional than work, since it factors in time

Classifications of Joints Diarthrosis Joint capsule Synovial Fluid

Present in small amounts in all synovial joints Looks like blood plasma as a clear or pale yellow viscous fluid Helps keep the joint lubricated and articular cartilage nourished The viscosity of the fluid allows it to resist loads that produce a shearing force- fluid becomes less viscous and more watery in the case of arthritis

Pressure

Pressure= force/area Increase the area to reduce the pressure on a joint surface or skin surface Force increases with flexion, but so does area

Agonist

Prime mover The muscle responsible for producing the desired motion at a joint

Production of muscle force Passive force generation

Product of muscle length Elastic- some stored energy: if you stretch muscle, it will bounce back the longer muscle is stretched out, the more force it generates

Muscle Characteristics Conductivity

Propagate a stimulus

Pathological Mechanical Advantage Patellectomy

Quad tendon moves- loose mechanical advantage

Which is more likely to produce more joint torque with maximal effort from patient? (MVC= maximal voluntary contraction)? Isometric contractions: A) quadriceps Femoris B) Hamstrings

Quadriceps femoris Greater CSA

Anatomical Pulleys

Redirect muscle forces Optimize the moment arm Optimize muscle's length-tension relationship

Pulleys

Redirects forces without changing the magnitude

Response to Injury Scar tissue

Reduced mechanical properties Random orientation Contracts or grows shorter as it grows Responds to loading- parallel fiber orientation Stretching and lengthening must occur early on to generate change

Articular Cartilage Morphology

Relatively thin covering (usually 5mm or less) Comprised of cells within an extracellular medium (matrix) Significant water content in matrix Avascular and aneural- implications on healing and sour of pain

Principle (or Cardinal) Planes of the Body Sagittal Plane

Runs parallel to sagittal suture of the skull, dividing the body into right and left sections Flexion/extension, dorsiflecion/plantar flexion, forward/back bend

Principle (or Cardinal) Planes of the Body Frontal Plane

Runs parallel to the coronal suture of the skull, dividing the body into front and back sections Abd/add, lateral flexion, ulnar/radial deviation, eversion/inversion

Articular Cartilage Anatomy Deep zone

Runs perpendicular like tent spikes- anchors to the calcified one

Isotropic

Same stiffness in every direction Not true of any of the CT really ex. silly puddy, possibly fat

Joint Reaction forces Distraction

Separate joint surface which may contribute to instability Pull lever away from joint

Muscle Function

Shape of fibers Fusiform Penniform

Osteokinematics affected by:

Shape of joint surfaces ligaments muscles tendinous restraints pain edema soft tissue (e.g. fat)

Theraband example Hav e along and and short band. Strain is set equal Both people walk back to a length that doubles their initial length, then complete shoulder abduction in the ant/pos plain. Which has more change in ROM

Short band Short band= more strain change= most force change Greater % of movement of initial length during short band abduction than long band Doubling initial length= 100% strain

Types of Contractions Isotonic Contraction

Shortening contraction

Muscle length and speed vs. force

Shorter muscle length + fusiform= speed!

Moment arms Right hand rule

Shortest distance. between the line of action (LOA) and the axis Clockwise (-) (into page)- taking away from you Counter Clockwise (+) (out of page)- adding to you

Types of Collagen Type III

Skin and stratum synovium

Articular Cartilage Anatomy Articular surface

Skin like Control water in and out

Stress-Strain Different Zones Major Failure

Some functionality, not yet torn Stress=Strain

SAID

Specific Adaptation Imposed Demands

Aging

Start with connective tissue not fully matured and physical strong- youth= weak (growth plate) Decline in mechanical properties of tendons and ligaments in aging Tensile strength, load to failure, elastic modulus Best physical properties of connective tissue at skeletal maturity

Newton's 2nd Law of motion

The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. F=ma Net force= mass * acceleration

Stability Base of Support

The area enclosed by the outermost edges of the body in contact with the support surface Must keep COG in BOS or will fall

Center of Gravity (COG)

The center of gravity is the average location of the weight of an object (i.e. balance point)

Impulse-Momentum Relationship

The impulse applied by the net force on a system= the change of momentum of the system

Does pinnation angle result in an increase or decrease in force??

The increased force that results from the increased CSA is greater than the loss of force with indirect pull on the tendon, so pinnation results in an increase in force

Fatigue Limit

The maximal stress that a material can undergo indefinitely without fatigue failure

Closed vs. Open (loose) packed joint positions Close packed position (the best fit)

The maximum area of surface contact occurs the attachments of ligaments are farthest apart and under tension Capsular structures are taut The joint is mechanically compressed and difficult to distract (separate)-ligaments are taut= limited accessory motion

Antagonist

The muscle directly opposite the motion being performed

Areolar "loose" Connective Tissue

The packing material CT- very delicate and not resistant to stress Surrounds both ligament and tendons Decreases friction on tissues In tendons is called paratenon and is a sheath-like structure that may include the entire tendon or that position in contact with joint or bone (sheath for tendon with synovial fluid to reduce friction)

Concave-Convex Rule Convex on concave

The roll and slide are in opposite direction Ex. femur (convex) rotating on tibia (concave) as in a squat roll= posterior, slide= anterior

Concave-Convex Rule Concave on convex

The roll and slide are in the same direction Ex. knee flexion as when bringing the heel to the gluteal Tibia (concave) on femur (convex) Roll=posterior, slide= posterior

Closed vs. Open (loose) packed joint positions

The surfaces of joint pairs match each other in one preferred position, the point of maximum congruency called the close packed position (the best fit)

Muscle Moment Arms Size change with Movement

There are points in a joints ROM where you are weak or strong Elbow 10 degrees flexion: 24# 40 degrees flexion: 44# 130 degrees flexion: 130 degrees

Temperature Dependent

Thermal transition The time to achieve 2.6% strain for a given load at various temperatures: as time progresses, temperature rises Efficacy or modalities: warm-up Applying heat to tissue makes them more compliant to stretching

Joint Reaction forces

These forces do NOT equal rotational motion BUT they aren't wasted force Compression Distraction Most muscle have line of pull relatively parallel to bones during ROM -majority of muscle force is translational not rotational Need to produce even greater forces to cause rotation Muscle force creates a LOT of compression in the joint when moving

Stress

Stress=force/area (CSA) (like pressure)

Example: Max is seated at my muscle test chair. Quadriceps muscle testing isometrically (MVIC=maximal voluntary isometric contraction) and exceed max measurable force output produced by my kin COM dynamometer (2000N=450 lbs). I would like to compare side-to-side as he has a knee injury You may adjust seat angle position, knee position, position of shin pad force transducer, contraction speed. I use the maximal force production during a trial as part of my test Can you change the testing set up to allow for an accurate measure of Max's strength for a side to side comparison?

Move seat forward= shorten muscle (active insufficiency) Knee fully extended or fully flexed (active insufficiency) Increase speed to decrease force produced Move tibial attachment distally

Arthrokinematics "accessory motion"

Movement of one joint surface in relation to the other joint surface

Muscle, tendon, bone Which is the most compliant?

Muscle

Factors affecting muscle force

Muscle fiber length CSA Velocity of movement Directional movement

Short muscle fibers, Large PCSA

Muscle force decreases as muscle velocity increases, dramatically. Steep slope

Types of Contractions Isometric

Muscle produces force but maintains the same length

Forces Internal

Muscles, ligaments, bones

Muscle morphology (structure)

Myosin- thick filaments actin- thin filament troponin, topomyasin, titian- elastic portion

Arrangement of Collagen Fibers

Nearly parallel in tendons to allow them to withstand high unidirectional loads Less parallel in ligaments to allow these structures to sustain predominant tonsil strength in one direction and smaller stresses in other directions Ligaments capable of providing stability in multiple directions but one direction will predominate Injury most likely to occur when stressed in one of the secondary support direction (ACL)

Active + Passive= Length-tension relation Passive force

No tension is experienced until a point is reached, at which point tension increases with length

Open Kinematic Chain

Non weight bearing Movement occurs at a single joint: only one joint is moving Distal segment is free to move- allows for isolation Distal segment is loaded ex. resisted knee extension for quad strengthening

Stress-Strain Different Zones

Nonlinear region "toe" Linear or elastic region Plastic Region Major failure Complete failure

Degrees of Freedom

Number of permitted planes of angular motion Translation- 3 DOFs: A/P axis, M/L axis, S/I axis Rotation- 3 DOFs: A/P axis, M/L axis, Longitudinal axis (along the length of the bone)

Don't 'overload the joint' Should we avoid the loading stress? Immobilization

Nutrition compromised- no fluid exchange Often results in degeneration of cartilage Loss of proteoglycans in the matrix Increased permeability the matrix with greater deformations during impact loading

Classification of Stiffness Intermediate curve

Stiff As strain increases stress increases incrementally. (more vertical)

Stress-Strain Different Zones Nonlinear or elastic region

Stiffness Young's modulus Modulus of elasticity Similar to spring Ligament can recover from 4% strain.. no problem. Between nonlinear or elastic region and plastic region is the happy place before the bad place

Strain

Strain= change in length/initial length "normalized stretch' How much a material deforms relative to a given stress.

Classifications of Joints Diarthrosis Joint capsule Inner layer

Stratum Synovium Highly vascularized poorly innervated Produces hyaluronic acid (a major component of synovial fluid) Also responsible for the removal of waste products and allows nutrients in

Classifications of Joints Diarthrosis Joint capsule Outer layer

Stratum fibrousum Dense fibrous tissue encloses the ends of the bone; attached to the periosteum via Sharpey's fibers Poorly vascularized Richly innervated for incoming neural input related to motion- movement rate, direction, compression and tension, vibration and pain

Creep vs. stress relaxation Drop out cast- Cast that puts knee into extension but can be taken off over time, tissue lengthens- cast doesn't change

Stress Relaxation

Kinetics

Study of forces and torques that produce motion

Kinematics

Study of motion w/o regard to forces or torques that may produce the motion

Kinesiology

Study of movement Requires anatomy, biomechanics, physiology

Connective Tissue Tendons, Ligaments and Joint Capsules Three principle structures that

Surround Connect Stabilize Joints

Classifications of Joints

Synarthroses Diarthrosis

Tendons and Ligaments Deformation

Tendons and ligaments undergo deformation before failure When ultimate tensile strength of structures is surpassed, complete failure occurs rapidly Load-bearing ability is substantially decreased During normal activity, tendons are subjected to much less than 25% of ultimate stress Area of weakness: particularly vulnerable at the insertion of tenon or ligament into stiffer bone and the transition from tendon to muscle Tendons can handle a higher level of strain than ligaments- more stiff

Forces Types

Tension- load on a rope Compression- most common on bones Shear- slipping off Torsion- twist Bending Combined- have all the time