EXSS 288- Mechanics and Classification of Injuries

what is an acute injury?

mechanical failure of soft tissue due to excessive force occurring in a single bout

describe the onset and duration of an acute injury

sudden onset of short duration

what is a chronic injury?

mechanical failure of soft tissue due to repeated micro-trauma occurring over an extended period of time

decribe the onset and duration of a chronic injury

gradual onset and prolonged duration

what is an open fracture?

• exposed

• breaks the surface of the skin

what is a closed injury?

• unexposed

• any injury that does not involve disruption of the skin surface

what is stress?

external or internal force acting on the tissue

what is strain?

the extent of deformation under loading

what does the degree of deformation depend on?

• tissue composition

• speed of applied load

• frequency of loading

• direction of loading

what is the yield point?

load is greater than mechanical capabilities of the tissue; where mechanical failure begins to occur

what are the six primary mechanical forces that cause injury?

• tension

• compression

• shear

• bending

• torsion

  • combined

what is tension?

creates a pulling action trying to elongate the structure

what is compression?

creates a pushing action tending to shorten the structure

what is shear force?

• forces that acts parallel to the cross section or surface of a body

• two forces are in opposite directions

what is bending force?

• loading about an axis

• combination of tension and compression

what is torsion?

load applied causing structure to twist about an axis

what is combined loading?

• tissue is seldom loaded in one mode only

• subjected to multiple indeterminate loads

• geometric structure is irregular

what are the two main parts of the bone?

• epiphysis

• diaphysis

what increases as bone mass increases?

bone strength

why is bone size important?

distribution of mechanical stresses

what is Wolff’s law?

healthy bones remodel and adapt to the mechanical loads (stresses) placed upon them

where are mechanical stresses most concetrated?

where there are sudden shape changes in the bone

in what order does the direction of loading tend to go for bone?

compression → tension → shear

what is considered when naming a fracture based on site?

• bone name

• diaphysis, epiphysis

how do you describe a fracture based on extent?

• partial

• complete

how do you describe a fracture based on configuration?

• transverse

• oblique

• spiral

• etc.

how do you describe a fracture based on relationship of fragments?

• displaced

• nondisplaced

how do you describe a fracture based on relationship to environment?

• open

• closed

what is the first fx called?

transverse

what is the second fracture called?

oblique

what is the third fracture called?

spiral

what is the fourth fracture called?

comminuated

what is the fifth fracture called?

avulsion

what is the sixth fracture called?

impacted

what is the seventh fracture called?

fissure

what is the eighth fracture called?

greenstick

what is the etiology of a transverse fracture?

direct blow

what is the etiology of spiral fx?

rotation on planted foot

what is the etiology of an oblique fx?

one end fixed, other sudden torsion

what is the etiology of a comminuted fx?

blow or fall in awkward position

what is the etiology of a depressed fx?

flat bones, direct blow

what is the etiology of a greenstick fx?

incomplete Fx, skeletally immature (convex)

what is the etiology of longitudinal fx?

splits along length, jumping from height

what is the etiology of a serrated fx?

direct blow, jagged edges

what is the etiology of a contrecoup?

ide opposite to point of impact

what is the etiology of impacted fx?

compressive force on long axis of bone

what is typically involved in fracture healing?

• immobilization for most cases

  • casting/splinting/ORIF

what does length of immobilization time depend on?

• vascularity of bone

• stress on bone

what is the typical healing timeline for a fx?

6-8 weeks

what is the healing process of fx healing?

• osteoblasts lay extra bone called “callus”

• need stimulus to re-gain compressive, tensile strength

• osteoclasts reshape bone

what is a dislocation?

bone is forced out of the joint

where is dislocation more common?

the upper extremity

what is subluxation?

partial dislocation

what is the S/S of dilocations?

deformity; almost always present

what can happen with deformity from a dislocation?

occasionally obscured by heavy musculature; requires palpation to determine normal contours

what are the additional concerns with a dislocation?

• avulsion fractures

• growth plate separation

  • “once a dislocation, always a dislocation”

how should dislocations be considered?

should always be considered and treated as fracture until ruled out

what is the only absolute diagnostic technique for dislocations?

x-ray

what is return to play determined by?

extent of soft tissue damage

what is the function of a tendon?

execute joint motion by transmitting mechanical forces from muscles to bones

what is the function of ligaments?

join bones and provide stability to joints

what are passive tissues?

non-contractile structures

what are inert structures?

unable to actively generate forces

what is a sprain?

disruption of a ligament

what is a strain?

disruption of a muscle/tendon

what does tendon attach?

muscle to bone

what does a tendon usually do?

usually double the strength of the muscle it serves

what are tendons in composition?

highly collagenous

what are tendons highly resistant to?

tensile forces

where are tendons strongest?

mid-substance

where are tendons weakest?

myo-tendinous and osteo-tendinous junctions

what are the two MOIs for tendons?

• high magnitude, single load, tensile forces

• low magnitude, repetitive load, tensile forces

what are compressive forces wit tendons?

• bony structures

  • external compression

what are more rare MOIs for tendons?

• vascular “wringing out” (prolonged compression)

• friction

what are five common tendon injuries?

• tendinitis

• tenosynovitis

• tendinosis

• strain/rupture

• contusion

what are common MOIs for ligaments?

• high magnitude, single load, tensile forces

• low magnitude, repetitive load, tensile forces

what do constant tensile forces lead to?

ligamentous deterioration

what forces mainly impact the ACL and intercondylar notch?

compression/shear

what is the etiology, end feel, and instability of a first degree sprained ligament?

• mild overstretching, no tissue disruption

• firm

• none

what is the etiology, end feel, and instability of a second degree sprain?

• partial disruption or macro tearing of the ligament

• definite (soft)

• slight to moderate

what is the etiology, end feel, instability of a third degree sprain?

• complete disruption

• none

• severe

what are the 4 MOIs for ligaments?

• high magnitude, single load, tensile forces

• low magnitude, repetitive load, tensile forces

• contraction induced

• compressive forces

what is another name for muscle guarding?

spasm

what is the MOI of muscle guarding?

neurological, repetitive trauma, other injury

what is a special consideration for muscle guarding?

myofascial trigger points

what is another name for muscle soreness?

DOMS

what is the MOI for DOMS?

eccentric muscle contraction

when do you feel DOMS?

2 days after working out

what is a special consideration for DOMS?

Rhabdomyolysis

what is another name for muscle cramping?

heat cramps

what is the MOI for muscle cramping?

dehydration, electrolyte imbalance, fatigue

what are two skeletal muscle acute injuries?

contusions and strains

what is a contusion?

• sudden traumatic blow with compressive force

• superficial or deep tissue affected

• rated by the ability of muscle to produce ROM

what is a strain?

• stretch or tear in muscle

• abnormal muscle contractions

what can cause a strain?

• mineral imbalance from sweat

• fatigue

• strength imbalance

what are the S/S of a first degree strain?

mild loss of strength, swelling, ecchymosis, point tenderness

what are the S/S of a second degree strain?

symptoms are more severe, greater function loss

what are the S/S of a third degree strain?

severe symptoms, loss of muscle function, possible palpable defect

what are three chronic muscle injuries?

• myositis

• fasciitis

• myositis ossificians

what is myositis?

inflammation of muscle