Bio mechanics content

what position is this

anatomical reference point:

• erect standing position with all body parts facing forwards

• body segment movement starting point

fill in the blanks

1. medial

2. deep

3. superficial

4. lateral

fill in the blanks

1. transverse plane

2. frontal plane

3. sagittal plane

4. posterior (dorsal)

5. anterior (ventral)

6. superior

7. inferior

8. proximal

9. distal

fill in the blanks

1. sagittal axis

2. frontal axis

3. longitudinal axis

movements in frontal plane

1. abduction, adduction

2. lateral flexion

3. radial deviation, ulnar deviation

4. eversion, inversion

5. elevation, depression

fill in the blanks

abduction, adduction

fill in the blanks

lateral flexion

fill in the blanks

radial deviation, ulnar deviation

fill in the blanks

eversion, inversion

fill in the blanks

elevation, depression

movements in transverse plane

1. medial rotation, lateral rotation

2. pronation, supination

3. horizontal abduction, horizontal adduction

fill in the blanks

medial rotation, lateral rotation

fill in the blanks

pronation, supination

fill in the blanks

horizontal abduction, horizontal adduction

movements in sagittal plane

1. flexion, extension, hyperextension

2. dorsiflexion, plantarflexion

fill in the blanks

flexion, extension, hyperextension

fill in the blanks

dorsiflexion, plantarflexion

fill in the blanks

circumduction:

a conical body movement that combines four basic motions: flexion, extension, abduction, and adduction

Specific weight

Force due to weight per meter cube

N/m³

fill in the blanks

compression

fill in the blanks

tension

fill in the blanks

shear

fill in the blanks

bending

fill in the blanks

torsion

what is the axis

x: load frequency

y: load magnitude

fill in the blanks

x: deformation

y: load

elastic region, yield point, plastic region, ultimate failure point

what happens when deformation reaches past ultimate failure point

tissue tear / breaks

acute loading

application of a single force of sufficient magnitude to cause injury to biological tissue

repetitive loading

repeated application of a subacute load that is usually of relatively low magnitude

what is human gait

translatory progression of the human body as a whole produced by coordinated, rotatory movements of the body segments

major tasks of gait

1. maintenance of support of head, arms and trunk

2. maintenance of posture and balance of the body

3. control of foot trajectory to achieve safe ground clearance and gentle heel/toe landing

4. generation of mechanical energy to maintain/increase forward velocity

5. absorption of mechanical energy for shock absorption and stability or to decrease forward velocity

modern gait laboratories consist of

• motion analysis system

• force platform

• EMG system

Gait cycle of normal walking

• Phases

  • 60% stance phase

  • 40% swing phase

• Support

  • 20% double limb support

  • 80% single limb support

• GRF: 1.25BW

Running gait (fill in the blanks)

1. heel strike

2. toe off

3. heel strike

4. stance phase

5. swing phase

6. float phase

7. float phase

Running gait characteristics

• requires more muscle strength, balance and range of motion

• reduced base support and stance phase

• absence of double limb support period and presence of float periods

• GRF: 2.5BW

Stair gait (fill in the blanks)

1. 64% stance phase

2. 36% swing phase

3. weight acceptance

4. pull up

5. forward continuance

6. foot clearance

7. foot placement

Stair gait characteristics

• weight acceptance: initial point of contact is anterior and travels posteriorly to midfoot

• pull up: single limb support with knee extensors producing majority of energy

• greater range of motion of hips & knee joints required

Treadmill gait advantages

• small footprint

• available weight support

• metabolic analysis

• embedded force platform

Treadmill gait characteristics

• higher cadence

• shorter stance time

• shorter stance time

• joint range of motion and moments similar

• push off forces and GRF lower

• higher metabolic costs

What is orthosis

externally applied device used to influence structural and functional characteristics of the neuromuscular and skeletal system

functions of orthoses

• support normal alignment

• prevent unwanted motion

• prevent deformity

• reduce unwanted forces or moments

• augments joint power

indications of orthoses

• assists motion

• correct flexible deformity

• prevents progression of fixed deformity

• stabilizes gait

• decreases pain

• decreases energy expenditure

• transfer weight

causes of lower limb abnormalities

• congenital

• diseases

• trauma

congenital conditions which cause lower limb abnormalities

• cerebral palsy

• long bone malformations

• osteogenesis imperfecta

• club foot

disease conditions which cause lower limb abnormalities

• arthritis/osteoarthritis

• muscular dystrophy

• scoliosis

trauma conditions which cause lower limb abnormalities

• fractures

• head injuries

• muscle/cartilage/tendon ruptures

• spinal cord injuries

ideal orthosis is graded by

• function

• comfort

• cosmesis

• fabrication

• cost

function of ideal orthoses

• meets individual’s mobility need and goals

• maximizes stance phase stability

• minimizes abnormal alignment

• minimally compromises swing clearance

• effectively prepositions the limb for initial contact

• energy efficient

comfort of ideal orthoses

• can be worn for long periods without damaging skin or causing pain

• easy to put on and off

cosmesis of ideal orthoses

• meets individual’s need to fit in with peers

fabrication of ideal orthoses

• made in shortest time possible

• use minimally complex designs

• has some degree of adjustability

• children: responds to growth

• durable

cost of ideal orthoses

• minimal initial and maintenance cost

types of orthoses

• foot orthoses (FO)

• ankle-foot orthoses (AFO)

• knee-ankle-foot orthoses (KAFO)

• hip-knee-ankle-foot orthoses (HKAFO)

• reciprocating gait orthoses (RGO)

foot orthoses (FO)

• shoe brace which corrects abnormal foot and lower extremity function

• corrects flat foot and plantar fasciitis

ankle-foot orthoses (AFO)

• surrounds ankle and at least part of foot

• L shaped and applied externally to ankle and foot

• stabilizes ankle and subtalar joint caused by adult acquired flat foot

• types: static and dynamic

knee-ankle-foot orthoses (KAFO)

• prescribed when there is a need for knee control and foot orthosis

hip-knee-ankle-foot orthoses (HKAFO)

• prescribed for paraplegia

• gross trunk movements are employed to initiate flexion of hips and thereby achieve a very laborious form of bipedal gait

reciprocating gait orthoses (RGO)

• a HKAFO that allows for one leg to be placed in front of another

• achieved by linking 2 KAFOs together with a band, two cables or push pull rod

• if one flexes the other extends

• allows for smoother gait with lesser effort

what is a prothesis

artificial device that replaces a missing body part, restoring normal function of said body part

types of amputees/orthoses

• transtibial

• transfemoral

• hemipelvectomy

transtibial orthoses consist of

• socket

• shank

• foot

transtibial orthoses socket

• patellar bar is built at center of patellar ligament

• socket is aligned at ~5ᵒ of knee flexion for patellar bar to act as weight bearing surface and 5ᵒ adduction

• other major weight bearer is medial tibial flare

transtibial orthoses shank

• tube of aluminum alloy/titanium

• for aesthetic purpose, foam is shaped and skin colored polyester covering is chosen to match amputee’s sound leg

transtibial orthoses foot

• usually use solid ankle cushion heel (SACH) foot

• advantages of SACH foot

  • no moving parts

  • requires little maintenance

  • good appearance

  • quiet in operation

  • manufacturability for different shoe heel height

• disadvantage

  • limited range of plantar and dorsiflexion

ideal prosthoses

compromises weight vs function

what is a biomaterial

substance that is engineered to interact with biological systems for medical purpose

what is biocompatibility

ability of a material to perform with an appropriate host response in a specific application

adsorption vs absorption

adsorption: particles stick to the surface of another phase

absorption: particles soak into the bulk of another phase

cell attachment on material’s surface

cell adhesion ligaments on cell adhesion substrate attaches to cell’s adhesion receptors

natural silk as a biomaterial

• advantages

  • biocompatible, biodegradable, mechanically strong and versatile in its form

  • can support tissue growth, drug delivery and regenerative medicine without causing toxicity

  • optical transparency and low autofluorescence

  • piezoelectric and dielectric

  • thermal stability

• risk and limitations

  • processing sensitivity

  • batch variability

  • slower degradation

what is tissue engineering

develops biological substitutes that restore, maintain or improve tissue function

tissue engineering scaffold

• provides structural support and shape of construct

• provides place for cell attachment and growth

• usually biodegradable and biocompatible, not intended for permanent stay

scaffold design criteria

• appropriate mechanical and physical properties

• promotes cell adhesion

• proper degradation rate

• no production of toxic degradation products

• integration into surrounding native tissue

• minimal inflammatory/immune response

scaffold materials

• polymeric: foams, hydrogels and thin films

  • chitosan, alginate

• natural: hydrogels

  • collagen, elastin, fibrin

• ceramic: porous structures

  • calcium phosphate

artificial tissue interface

• material response: material responding to living system

• host response: other than intended effects of living systems

  • local (site of implant)

    • protein adhesion

    • coagulation of blood

    • platelets adhesion

    • hemolysis

    • inflammation

    • infection

  • systemic (throughout whole body)

    • thrombus formation

    • embolization

    • hypersensitivity

    • elevation of implant elements in blood that could cause cancer

    • lymphatic particles transport to other tissues/organs

    • system toxicity

artificial skin

• tissue engineering products have been applied to chronic skin wounds

• current technology is partially effective in their ability to restore other skin structures

• future trend is to regenerate skin appendages

bioreactors

• mimics in-vivo conditions to what actually happens in the body

• various forces acting on cells of our body that helps them grow and proliferate