Exam 4 (Biomechanics) Flashcards
What determines the type and function of connective tissue?
1) Composition and percentage of cells (fibroblasts, chondrocytes, osteoblasts)
2) Extracellular matrix (ECM) components (fibers, proteoglycans, glycoproteins, tissue fluid)
Collagen General Function
· Resists tensile (stretch) forces (minimal elongation under tension)
· Types I- VI are most abundant
Collagen Types (I-IV) , Function, and Synthesis
1) TYPE I: “crimped”/ overlapping layout, resists tensile loads, most abundant
· Bone
· Ligament
· Tendons
· Reinforces Fibrocartilage
· Joint Capsule
· Intervertebral discs
* “Uncrimping” occurs in Toe-region of stress-strain curve
2) Type II: withstands tensile/compressive forces
· Articular cartilage
· Hyaline Cartilage
· Nucleus pulposus
· Eye
· SYNTHESIZED BY: chondroblasts
3) Type III: most pliable, greater ability to stretch, synthesized during wound repair
· Blood vessels
· Bladder
· Uterus
· Skin
· GI Tract
· Embryonic tissue
* Pliable for tissues that need to expand
· SYNTHESIZED BY: Fibroblasts
4) Type IV:
* Separates tissue compartments and surrounds smooth muscle and nerve cells
Collagen Fiber Arrangements/Alignments and Mechanical Stress
· Arrangements/alignment reflects the mechanical stress acting on the tissues
· Can form:
- fibrils to resist tensile loads
- sheets/mesh to anchor/link tissues
Why is re-injury more prominent in early healing stages? (Type III vs Type I Collagen Fibers)
· Type III (more pliable/weaker) is laid down initially and then replaced by Type I (stiff)
Result of Collagen Synthesis
· Formation of Tropollagen (from Procollagen) which joins together to form fibrils with distinct cross bands (transverse and longitudinal)
· Fibrils then form fibers and bundles of fibers
*Cross bands are what provides resistance to tensile loads
Connective Tissue Diseases/Disorders
1) Marfan Syndrome: gene mutation that affects elastin fibers
· Results in lack of resistance in tissues
· Prone to aortic rupture (decreased resistance causes increased risk of rupture)
2) Ehlers-Danlos Syndrome (13 Types): gene mutation that affects Type III collagen
· Joint pain/hyper-mobility/instability/hyper-extensibility/organ prolapse, etc.
3) Osteogenesis Imperfecta (8 Types): genetic mutation of Type I collagen
· Easily fracture bones, bone deformities, barrel-chest, scoliosis, hearing loss, discolored teeth, respiratory issues, short stature, etc
Impact of the Loss of PGs during early stages of Osteoarthritis?
· PGs (combined to hylauronic acid) are lost during early stages of Osteoarthritis resulting in:
- decreased ability of tissue to absorb water - decreased ability to withstand compressive forces
- Increased subchondral bone stress (bone on bone)
Clinical Significance of PGs and early Osteoarthritis
· PGs are lost during early OA
· DECREASED ability of tissues to absorb water and withstand compressive forces results in INCREASED stress on subchondral bone (bone on bone with no cartilage so bones are now weight bearing)
Classification of Connective Tissue
1) Proper
· Dense (Regular vs Irregular)
· Loose
2) Supportive
· Cartilage
· Bone
3) Special Properties
· Adipose
· Hematopoietic
· Mucous
Kinematics vs. Kinetics
· Kinematics: study of motion WITHOUT regard to the forces contributing to that motion
· Kinetics: study of the effect of forces on the body and resulting motions they created
Biomechanics
Forces acting on and with biological systems
Newtons 1st Law of Motion: Law of Inertia
· Law of Inertia: a body will remain at rest or constant motion until acted upon by an external force
· Inertia: Energy required to displace an object/body, directly proportional to object’s mass (ex: bigger person is harder to push over vs. smaller person)
Newton’s 2nd Law of Motion: Law of Acceleration
· Law of Acceleration (Linear): Linear acceleration is directly proportional to the force causing it, occurs in same direction as force, and is inversely proportional to mass of object
· Law of Acceleration (Angular):
Angular acceleration is directly proportional to the torque causing it and inversely proportional to mass moment of inertia
· If acceleration = 0 then sum of forces = 0 (ex: when standing still or moving at constant speed)
* ex: more torque required to push escalade vs. mini cooper)
* Mass moment on inertia changes based on mass distribution around axis of rotation
Newton’s 3rd Law: Law of Action-Reaction
· Law of Action-Reaction: For every action (force/torque) there is an equal and opposite reaction (force/torque)
*ex: force from pt pulling TB apart and force from TB pulling together
* ex: ground reaction force while standing
Internal vs External Force
· Internal: act within the body
(ex: muscles)
· External: Act on the body
(ex: gravity, ground reaction forces, etc.)
Types of Forces on MSK
1) Unloaded
2) Tension (ends pull in opposite directions)
3) Compression (ends push in same direction) (present during weight bearing)
4) Bending (one side stretches and other compresses)
5) Shear (body segments go in opposite directions)
6) Torsion (twist)
7) Combined Loading (combo. of any or all above forces)
Stress-Strain Curve
· Strain on tissue when a stress/stretch/force is applied
· All tissues have this
· 4 Regions:
1) Nonlinear Toe Region: uncrimping of collagen fibers (Type I)
2) Elastic Region/Linear Region: tissue stretches and then returns to original shape
3) Plastic Region: tissue stretches and then change/deformation in tissue occurs
* Ideal region for PTs
4) Ultimate Failure Point: stretch resulting in rupture/damage
Importance of Time on Viscoelastic Tissues during the Stress-Strain Curve
· Viscoelastic tissues change with time during the stress-strain curve
· Slope increases as rate of loading and rate of force increase (how fast/slow a stretch/force is applied)
Ground Reaction Force (GRF)
· Force that is equal and opposite to force exerted by the foot (tri-planar)
Center of Pressure (CoP)
· Point of application of GRF (then needs to be absorbed)
· Multi-directional
· Changes throughout movement
* ex: heel strike during gait means COP at heel
Center of Mass (CoM) vs Center of Gravity (CoG)
· CoM: point where mass is equally distributed
- changes with movement
- depends on shape, mass distribution, and density
- can be inside or outside of object
- Normal CoM: Anterior to S2 (static standing)
* ex: pole vaulting would shift CoM posteriorly
· CoG: point where weight is evenly distributed (balance with response to gravity)
Dense Connective Tissue (Regular vs Irregular)
· Dense Regular: high stress resistance in a SINGLE direction (due to organized collagen arrangement)
- innervated but poorly vascularized
*ex: Tendons and ligaments
· Dense Irregular: mechanical stress resistance in ALL directions and protects organs (due to woven collagen arrangement)
*ex: Fascia, periosteum, peri and endomysium, dermis, glands, organs
Loose Connective Tissue
· Multi-directional stress resistance (NOT mechanical stress) due to meshwork of collagen and elastin arrangement
· Well vascularized and innervated
* ex: Viscera, fascia, endothelia
Base of Support (BOS)
· All points at which the body contacts a supporting surface (ex: sitting in chair- ischial tuberosity, butt, feet on floor, etc)
· Equilibrium occurs when COM is within BOS
Resultant Joint Force (RJF) / Joint Reaction Force (JRF)
· Net muscle forces and bony contact forces (primary internal forces) acting at a joint
Torque Formula
· Torque = Force x Moment Arm
** Angle at which force is applied and muscle attaches to bone is CRITICAL for Net Torque**
· Internal Moment Arm: distance from internal force/ tendon insertion to joint (axis of rotation)
ex: distance from bicep tendon insertion to elbow joint
· External Moment Arm: distance from external force to axis of rotation
(ex: distance from free weight in hand to elbow joint)
** Longer moment arm = greater torque
* Internal torque > external torque in order to lift a weight
* Force that passes through axis of rotation does not produce torque (bc moment arm = 0)
Translation vs Rotation
· Translation: linear motion where all parts of body move in same direction (parallel) to other parts of body
(ex: skiing down mountain)
· Rotation: angular/circular motion about a pivot point where all points in body rotate simultaneously in the same angular direction (CW vs CCW)
(ex: tumbling down mountain)
Normal vs Tangential (Compression and Distraction) Force
· Normal Force: acts perpendicular to body segment
- creates a moment/torque, AKA moves the joint
· Tangential Force: acts parallel to a segment (acts along the axis)
- Compression forces stabilize a joint
* PT application: WB through arm to compress shoulder to promote muscle recruitment
- Distraction forces create traction (pull away from each other)
* PT application: cervical traction
MSK Levers
· 1st Class: axis of rotation is in the middle of opposing forces
(ex: c-spine axis of rotation in between extensors/internal moment arm and head weight/external moment arm)
· 2nd Class: axis of rotation is at one end of bone and muscle has greater advantage
- Internal Moment Arm > External Moment Arm
- ex: Calf raise bc GSC is at advantage over gravity
· 3rd Class (MOST COMMON): axis of rotation at one end of bone and external force has greater advantage over muscle
- External Moment Arm > Internal Moment Arm
- ex: 90° elbow flexion and holding a dumbbell
Mechanical Advantage
· Ratio of internal moment arm (IMA) to external moment arm (EMA)
· Most muscles are at mechanical disadvantage (EMA > IMA)
Force-Couples
· 2 or more muscles contract simultaneously and produce SAME amount of force but in OPPOSITE direction
· ex: opening a jar, turning a steering wheel
-ex in the body: PPT where hamstrings pulls ischial tuberosity down, rectus abdominis pulls pubic symphisis up
ECM Components (Fibers, Fluid, and Ground Substance)
1) Fibers (Collagen, Elastin)
2) Proteoglycans (PGs)
· Aggrecan: main PG in articular cartilage for skeletal growth and function
3) Glycosaminoglycans (GAGs)
· Hydrophillic
· Stiff and inflexible
· Resist compressive forces in cartilage
· Ex: Hylauronic Acid combines with PGs to resist compressive forces in cartilage, high vsicosity to lubricate synovial joints
4) Tissue Fluid
5) Glycoproteins
· Allow adhesion of fibroblasts, chrondroblasts/cytes, osteoblasts/cytes
· ex: laminin, fibronectin
- Ground Substance is PGs, GAGs, and Glycoproteins
Elastin
· High recoil (but decreases with age)
· In tissues that accommodate large volume changes (ex: ligamentum flava (in SC) arteries, bladder, uterus, aorta)
· Thinner than collagen, yellow
Attenuation and Radiodensity
· Attenuation: Reduction of x-ray beam as it traverses matter
(ex: bone attenuates (absorbs) matter greater than air)
· Radiodensity: determined by how tissue attenuates/absorbs x-ray signal (ex: bone attenuates more than air and thus has higher radiodensity and appears whiter on film)
ABCS of Radiography (X-Rays and CT)
·A: Alignment
- skeletal alignment, joint alignment
- Can identify fractures, spurs, etc
·B: Bone integrity/density
- excessive sclerosis (bone hardening)
·C: Cartilage Spaces
- joint space
- subchondral bone
·S: Soft Tissues
- joint capsule effusions
- periosteum
- muscle swelling or atrophy
T1 vs T2 Weighting for Imaging
· T1: highlights tissues with high fat content (for good anatomical detail)
- Tissues with quick longitudinal magnetization times will appear brighter (Fat)
·T2: good for detecting inflammation
- Tissues with longer transverse magnetization times will appear brighter (Fluid)
Functional MRI (FMRI)
· Used to visualize blood flow in the brain because blood flow usually follows nerve activity
Ligament Function
· Connects bone to bone
· Made of dense regular connective tissue
· Limits excessive motion
· Guides normal joint movement
· Innervated but limited vascular supply
Tendon Function
· Connects muscle to bone
· Made of dense regular connective tissue
· Transmits force
· Innervated with some vascular supply
Joint Capsule (2 Layers and Function)
· Fibrous Layer:
- Made of dense irregular connective tissue that’s continuous with periosteum
- Surrounds tendons and ligaments that insert near the joint
- Innervated and vascularized
·Synovial Membrane Layer:
- Lines fibrous capsule
- Lubricates joint
- Contains Type A Cells (remove debris, important for inflammation)
- Contain Type B Cell (produce hyaluron and PGs to help lubricate and resist compressive forces)
Cartilage Function
· Load-bearing, resist force in multiple directions
· Mostly avascular (Medial Meniscus is highly vascularized though)
· Dense irregular connective tissue
3 Types of Cartilage
1a) Simple Hyaline
- on articular surfaces
- prone to calcificaiton
* WEAKEST
1b) Articular Hyaline
- avascular and anueral
- nutrient supply from synovial fluid
- zone 1 fibers are horizontal and zone 2-4 are vertical
* Tidemark (between zones 3 and 4) advances with age/increases in size thus thinning the cartilage and causing degeneration
2) Fibrous
- at tendon insertions, IV discs, menisci
- multi-direction strength and limits motion
3) Elastic
- Found in nose and ears
- highly flexible
Regeneration vs Repair
· Regeneration: regrowth of original tissue
· Repair: formation of connective tissue scar (occurs when regeneration is not possible)
Static Equilibrium vs Dynamic Equilibrium
· Static: No linear or angular acceleration (0)
- Translational Equilibrium
- Rotational Equilibrium
· Dynamic: When linear or rotational velocity is constant (NOT zero)
Relationship between joint angle, moment arm, and torque generation
As body segment moves through ROM, the angle of insertion of muscle changes thus changing the internal moment arm
Osteokinematics and Open Kinetic Chain vs Closed Kinetic Chain
· Motion that occurs at a joint between the BONES that compromise the joint
- cardinal planes used for frame of reference
· OKC: proximal segment is fixed, distal segment is free to move
- ex: bicep curl
· CKC: distal segment is fixed, proximal segment is free to move
- ex: squat
Arthrokinematics
· Motion that occurs between articular surfaces of joints
· 3 Main Movements:
- Roll
- Spin
- Glide/slide
Concave-Convex Rule
· Direction of the roll of a joint always occurs in same direction of osteokinematic (bone) motion
· Direction of the arthrokinematic (joint) glide depends on shape of moving bone
- Concave-on-Convex: concave component rolls and glides in SAME directions (ex: elbow flexion)
- Convex-on-Concave: convex component rolls and glides in OPPOSITE directions (ex: dorsiflexion, shoulder ABD)
Myofibril (skeletal muscle structure)
· Smallest part of muscle fiber
· Made up by sarcomeres (which are made up of actin and myosin)
· Contains sarcomeres (contractile part)
H-Band
· Region of sarcomere where there is no overlap of the actin and myosin (important bc space allows for overlap to occur during contraction)
* Longer sarcomere and more space to connect = greater force generation
Contractile Proteins
1) Myosin: multiple flexible head that helps connect with actin
2) Actin: regulates tension generation
Structural (Non-Contractile) Proteins
1) Desmin: holds sarcomeres together
2) Titin
3) Nebulin
4) Dystrophin: helps get nutrients inside and contributes to parallel force production
How does muscle get activated?
Increase in the overlap of actin and myosin
Energy System Exertion
1) ATP Storage (0-2sec)
2) ATP-CP (2-10s)
3) Lactic Acid (10s-2min)
4) Aerobic (2min +)
Fiber Types
· Type I (Slow Oxidative):
- fatigue resistant
- slow contractile speed
- low intensity contraction (that allows for long contraction)
· Type IIA (Fast Oxidative Glycolytic):
- fast and high intensity contraction
- fatigues quickly
- low vascularization (bc we dont need as much O2)
· Type IIB/IIx (Fast Glycolytic):
- fastest twitch and high intensity
- fatigues quickly
Motor Unit
· Alpha motor neuron and all the fibers it innervates
· “All On/ All Off” principle: either all fibers of MU contract or none contract
Summation (relationship between frequency of stimulation to strength of contraction)
1) Increases frequency
2) Increases Ca+ inside the cell
3) Increases myosin and actin connections
4) Increases force
- Increase in frequency results in increase in force
Electromechanical Delay (EMD)
· Time between onset of activation and onset of force production
· Dependent on:
1) Muscle
2) Activation Type (electrical vs voluntary)
3) Muscle length
4) Mvmnt velocity
· Delay is greater for more caudal muscles (bc signal must travel further)
How do motor units regulate force production?
1) Rate coding (Increase frequency of stimuli)
2) Recruitment/ Synchronization (recruit additional units)
- Smaller units/Type I Fibers recruited first then bigger units/Type II
3) Muscle Length
Process of Force Generation
1) Action Potential
2) Excitation-Contraction Coupling
3) Cross-bridge Cycling
Isometric/Concentric/Eccentric Contractions related to Internal/External Torque and Resulting Movement
1) Isometric:
· Int = Ext
· No rotation occurs
2) Concentric:
· Int> Ext
· Segment and RJT move in same direction
3) Eccentric:
· Ext> Int
· Segment and RJT move in opposite directions
Where would you find Type I vs Type II vs both collagen in the body?
· Type I- tendons
· Type II- nose and ears
· Type I AND II- fibrocartilage that makes up intervertebral discs
Prime Mover
· Muscle that produces the RJT
· Propulsive/ Concentric: when joint and acceleration are in same direction
- ex: push off during gait
- ex: pushing up into a bridge
· Braking/Eccentric: joint moving in opposite direction of muscle/decelerating
- ex: standing to sitting
- ex: lowering down from a bridge
-ex: lowering down of a pushup
Power
· Ability to generate force quickly
· Concentric contractions generate power
· Eccentric contractions absorb power
Impulse and Momentum
· Impulse: force applied over time
· Momentum: amount of motion possessed by an object (impulse leads to a change in momentum)
Positive vs Negative Work
· Positive: muscle and joint = same direction (muscle and joint move in same direction)
- concentric contractions
- generates power
- ex: calf raise
· Negative: muscle and joint = opposite directions
-eccentric
-absorbs power
- ex: quads during descent of a squat
Bone Function
· Load bearing
· Tensile and compressive strength
· Lever
· Stores Ca+, fat, and proteins
· Produces blood cells
Bone Classification (5 Types)
1) Long (femur, metacarpals)
2) Short (carpals)
3) Flat (sternum, cranial bones, rubs, scapulae)
4) Irregular (facial bones, vertebrae)
5) Sesamoid (patella, pisiform)
Bone Anatomy
· Epiphysis: spongy bone (red bone marrow)
· Metaphysis: growth plate
· Diaphysis (compact bone)
· Medullary Cavity: endosteum (yellow bone marrow and adipose)
Lamellar vs Woven vs Compact/Cortical Bone
· Lamellar: mature bone, highly calcified
· Woven: in developing or growing bones, newly calcified
Sharpeys Fibers
Collagen fibers that tether periosteum to bone
Bone Loading
· Stress is distributed along cancellous bone to cortical structure
Wolff’s Law
Bone is laid down in areas of high stress and reabsorbed in areas of low stress
Bone Composition
· Type I Collagen: provides strength and spacing for mineral deposition
· Osteocytes
· Osteoblasts
· Osteoclasts
· Osteogenic
·PGs
· Glycoproteins to bind to Ca+
Haversian System (Osteons) in Cortical Bone (Central and Perforating Canals)
· Haversian/Central Canal in center of cortical bone that allows for passage of neurovascular bundles
· Volkmann’s/Perforating Canal: allows communication between osteons
· Good blood flow allows bone to withstand compression
Bone Cell Functions
1) Osteogenic/Osteoprogenitor: develop into osteoblasts, help with healing
2) Osteoblasts: bone formation
* Decrease with age
3) Osteocytes: maintain mineral matrix
4) Osteoclasts: bone resorption stable with age
* Stable with age
Osteosarcoma
· Primary bone cancer
· From osteoprogenitor cells
· Lose structural integrity
Paget’s Disease
· Overactive osteoclasts resulting in osteoblasts compensating by laying down weak/unorganized bone
· Result: headaches, hearing problems, increased skull size
2 Primary Methods of Bone Formation/Growth
1) Intramembranous Officiation: direct formation
2) Endochondral Ossification: bone replaces hyaline cartilage
- more time consuming
- RESULT OF BOTH:
1) Mesenchymal tissue converts to bone
2) Woven bone initially laid down and then matures to lamellar bone
Hypercalcemia vs Hypo
· Hypercalcemia (> 10.5mg/dl)
- proximal muscle weakness
- bone fractures
· Hypocalcemia (<8.5)
- NM excitability
- muscular tetany, flexion of UE
- numbness/tingling of hands/feet/face
3 Main Calcium Metabolism Hormones
1) Parathyroid Hormone (PTH)
2) Calcitrol
3) Calcitonin
Calcium Homeostasis
· Senses hypercalcemia:
1) Thyroid release calcitonin
2) Osteoclasts are inhibited
3) Kidney Ca+ reabsorption decreases
4) Ca+ blood level decerases
· Sense Hypocalcemia:
1) Parathyroid gland releases PTH
2) Osteoclasts release Ca+ from bone
3) Kidneys reabsorb Ca+
4) Ca+ blood levels increase
Primary treatment for Osteoporosis?
Calcitonin due to its ability to inhibit osteoclasts and inhibit kidney reabsorption of Ca+
Calcitonin vs Calcitriol
· Calcitonin: Inhibits osteoclasts and kidney reabsorption (when Ca+ blood levels are too high)
- stimulates ca+ uptake to bones
· Calcitriol: activated in the kidney to increase GI tract Ca+ uptake and kidney reabsorption
Hyperparathyroidism vs Hypo
· Hyper: excessive PTH produced (increases blood Ca+ but decreases bone density)
· Hypo: not enough PTH produced thus resulting in low blood calcium levels
Rickets vs Osteomalacia
· Rickets: reduced sunlight exposure resulting in low Ca+ blood level and high PTH
· Osteomalacia: hyperthyroidism resulting in low Ca+ blood level and high PTH
Normal vs Shear Stress
· Normal: acts perpendicular (tension or compression)
· Shear: acts parallel
Normal vs Shear Strain
· Normal: measure of deformation/change in length from normal forces (tensile or compressive)
· Shear: measure of deformation from shear forces
Stress-Strain Curve Graph Properties
· Stiffness: increased stiffness results in decreased compliance
- steepest curve
· Resiliency: returns to shape after being stretched
- longest elastic region
· Ductility:
- longest palstic region
· Brittleness:
- shortest plastic region
· Toughness:
-largest area under the curve
Hysteresis Loop
· Stress-Strain loop is different during loading vs unloading
· Inside the loop is total amount of energy lost
Viscoelastic Tissues
· Depend on strain and strain rate
· Creep: constant stress applied (will result in gradual increase in strain and gradual decrease when stress is removed)
Stress-Strain Properties for Bone vs Tissue
1) Bone
· Rate of loading
· Direction of torque
· Temperature
2) Tissue
· Direction of load
· Tissue composition
· Rate of loading
· Duration and history of deformation
Endogenous vs Exogenous Tissue Injury
· Endogenous: inside the body
- tissue necrosis
- immune reactions (allergies)
· Exogenous: outside the body
- infections
- trauma
- physical or chemical agents
Reversible vs Irreversible Cell Injury
· Reversible:
- nucleus is not damaged
- homeostasis can be restored
- adaptations can occur and be reversible
· Irreversible:
- altered nucleus, mitochondria, and lysosomes with rupture of cell membrane
- cell can’t adapt
- necrosis
Necrosis vs Apoptosis
1) Necrosis
- Active cell degradation
- inflammation can occur and fluid can leak out (can be measured in lab test)
- ex: Coagulative: caused by ischemia (decreased blood flow) resulting in nucleus shrinking and solidification of organs
2) Apoptosis
- normal cell death
- no inflammation
- contents dont leak out (cant be measured in lab test)
Inflammation
· Response of vascularized tissue toward injury
· Acute: sudden and short
- has platelets and neutrophils
- more intense in younger people due to responsiveness of inflammatory system
· Chronic: gradual and persistent
- has lymphocytes and plasma cells
Transudate vs Exudate (Vascular Phase of Acute Inflammation)
· Transudate: protein poor fluid that leaks out of capillary into interstitial space, tight junctions dont allows proteins or RBCs to pass
· Exudate: protein rich bc endotheleal cells seperate to allow proteins and RBs to pass through
Effusion
· Accumulation of fluid in a joint cavity/capsule
· Type of edema
Cellular Phase of Acute Inflammation
· Chemical Mediators (cell or plasma derived) function to vasodialte/constrict, permeability, activate inflammatory cells, chemotaxis, pain, fever, etc.
Bone Fracture Classifications
· Complete vs Incomplete
· Displace vs Non-displaced
· Open vs Closed
Pathologic vs Stress Fracture
· Pathologc: normal stress in abnormal bone
· Stress:abnormal stress to a normal bone
Dislocation vs Subluxation of Joints
· Dislocation: complete loss of contact between articular cartilage and complete displacement of 2 bones
· Subluxation: partial loss of contact between articular cartilage
Strain vs Sprain vs Avulsion Injuries
· Strain: tear of injury of tendon
· Sprain: tear of injury of ligament
· AvulsionL complete seperation of either tendon or ligament from its bony attachment site
Pennation Angle
Angle of orientation between muscle fibers and tendon
