STATICS AND COMPENSATION HIGH YIELD Flashcards
name this stance:
state of bipedal support of body weight during which all bones of the foot remain nearly motionless
static stance
in the static stance, what is the distribution of body weight supported by:
forefoot?
heel?
mid foot?
metatarsals?
1/4 of BW supported by forefoot
1/4 of BW supported by the heel
1/2 of BW supported by the midfoot
2:1:1:1:1
what is the loading axis for normal distribution?
shifted medially
caused by?
shifted laterally
caused by?
*this is static stance
center of trochlea of talus
2nd inter metatarsal space
1st and 2nd metatarsals bear more of the weight
abducted foot
lateral metatarsal heads bear more of the weight
adducted foot
what muscle must fire to 1/4 of BW on forefoot? what about the remaining?
so base of support is made of?
*this is static stance
gastrocnemius
feet anterior to the ankle joint
MTP joints
lateral margins of feet
posterior margins of feet
what is the joint orientation in static stance for STJ and MTJ?
what else is affected?
why is the gastro imp?
neutral
locked in fully pronated positions
legs and sagittal bisection of the calcaneus are perpendicular to the ground and parallel to each other
it exerts plantarflexion moment force at ankle joint loading forefoot, but remember that no muscle support is necessary to keep structural integrity
bones of the forefoot are moving while they bear weight, what is this called?
dynamic gait
so when the faster a person walks, or heavier they are, what is the affect of the forces on the foot?
the greater the forces acting on the joints of the foot during gait
what are the forces acting on the foot during gait? effects?
compression (linear) force
-stability
bending (tension) force
-instability
how does normal foot function during stance phase achieve stability?
bone compression
muscle contraction
no ligament tension
*ligament tension helpful during structural support
so because we know the dynamic gait is phasic activity, is muscular contraction important? the phasic activity of muscles resist?
yes
rotatory movements at joints and ground reactive forces
during dynamic gait, in a pronated foot, what increases the most at joints?
rotational motion increases at most joints
and so muscles work harder in an unstable pronated foot to resist the rotational forces and opposite is true for supinated foot
these serve as emergency stability when a sudden unanticipated motion of one or more joints occurs?
ligaments
what is the relation between ligament and subluxation?
so the joint starts tension in the ligament and joint capsule of the involved joint and so as ligament lengthens, resistance to emergency rotational forces increases
what is the effect of stretch on ligaments or the capsule?
it stimulates the propioceptors
function of the ligament during emergency instability?
decelerates motion of subliming joint
start increased contraction of muscle to stabilize joint
keeps joint integrity intact until muscle function re-establishes the joint
what does ligamentous failure result in?
ligament sprain or rupture
avulsion fracture
joint damage due to compression of articular surfaces
total joint dislocation
what is the primary cause of mechanical trauma to foot?
kinetic instability during locomotion
what is the cause/effect of kinetic instability during locomotion?
causes internal tissue damage which eventually manifests in external symptoms
corns, calluses, neuromas
subluxation results in? how to fix this?
ligament strain muscle fatigue jont deformities abnormal structure degenerative joint disease
improvement in stability of the foot
what are the main causes of kinetic instability during locomotion?
hypermobility
subluxation
what are the two forms of compensation?
normal
abnormal
these joints are the primary sites for compensation due to triplanar motion available?
which one is the primary joint in the lower extremity for compensation?
STJ and MTJ
STJ
pronatory and supinators compensation are used to describe?
direction of compensation
what is the effect of pronation and supination on normal compensation?
pronation of STJ everts rear foot
supination of STJ inverts the rear foot
what is the effect of normal compensation on the mid tarsal joint?
MTJ locks on rear foot when both the long. and oblique axis are maximally pronated
what are the factors that determine the MTJs ability to compensate for rear foot position?
ROM
locking position
compensation for STJ pronation (rear foot eversion) is?
forefoot inversion (supination of LMTJ)
same number of degrees of forefoot inversion as rear foot eversion
same number of degrees of forefoot inversion as rear foot eversion, if this doesn’t happen than what?
rearfoot pronation is only partially compensated
what is the result when the STJ (moving the forefoot) attempts to remain in contact with the ground?
1st ray dorsiflexion
MTJ unlocks
foot bears weight on 2nd metatarsal head
T/F, forefoot cannot compensate for rear foot supination?
true
what does the locking mechanism of the MTJ do? what happens to the calcaneus? what about the MTJ axis?
prevents eversion of the forefoot
calcaneus inverts with STJ supination and so forefoot also inverts
MTJ axis is loaded maximally pronated and so locked and so no more forefoot motion can occur
refer to MTJ and STJ compensation for terrain!!!
in notes
what are the types of abnormal compensation?
forefoot varus
rearfoot varus
forefoot supinatus
rigid plantar flexed first ray
