5/13 INTRO TO PROSTHETICS AND ORTHOTICS | COMPLETE QUESTIONS WITH 100% RATED
CORRECT ANSWERS | GRADED A+ | 2025/2026 LATEST UPDATE
ideal orthosis no orthosis can restore "normal" function to the person with impairment but
it may enhance mobility and other functioning through biomechanical control mechanisms;
keep in mind that orthoses can be heavy and costly!
major determinants of an ideal orthosis (5 C's) Control (biomechanical)
Comfort
Cosmesis
Cost (metabolic)
Cost (monetary)
control (biomechanical) 1. limits undesirable motions
2. enhances desired motions
3. example on slide 20: 3 point force system: articulated AFO
articulated AFO -Hold the toe, hold ankle in, and push on the back of the calf to keep the
foot up
-Depending on the pathology - design orthoses appropriately depending on the force
-Push on the proximal tibia to get extension in stance (knee extension)
more on control (biomechanical) slide 21 1. manipulation of the ground reaction force
vector
,2. relationship of the vector to the joint axis
3. external torque production
*causes the patient to be more stable (prosthetics and orthotics - alignment goals are the same
to promote stability)
*standing in slight DF to get extension at the knee
torque defined torque = tendency of a force to rotate an object (to twist or move a joint)
torque (T) = force x lever arm length
crouch gait large magnitude of external torque producing ankle DF, knee flexion, and hip
flexion; will see this with CP, spina bifida, etc; DF contractures, knee flexion contractures - really
need them to be more extended
more on crouch gait 1. hip flexion external torque
2. knee flexion external torque
3. ankle dorsiflexion external torque
even more on control (biomechanical) 1. Anterior ground reaction AFO restores external
torque producing knee extension during stance
2. Solid ankle design prevents external torque of ankle dorsiflexion during stance
3. Torque is also known as a "moment"
, **ground reaction AFOs with an extended foot plate, solid ankle, needs to be a stop at the
ankle to get extension at the knee (slide 24)
the 7 types of orthotic controls Free - No type of resistance against DF (ex) - free DF can
move
Resist - resistance to the movement
Assist - assist the movement; springs inside the joints to help bring the foot up; tamerac joints
to build in some DF so the AFO is in a resting position of DF
Stop - stopping at a certain angle
Hold - hold in alignment; not allowing any motion
Lock - lock the motion; in sitting not locked but once the patient is standing, can lock in to get
the knees extended
Variable - can vary the amount of resistance if they have a contracture and tune it depending
on the extent of the contracture (getting a stretch overnight)
comfort slide 26
1. Subjective patient experience
2. Influenced by perception, peripheral sensation, tissue tolerance
3. Factors influencing comfort
-Interface stresses (pressure, shear, friction)
-Suspension
-Bulk, weight, thermal insulation
If they aren't comfortable - the patient will never wear it; help make it look good too
CORRECT ANSWERS | GRADED A+ | 2025/2026 LATEST UPDATE
ideal orthosis no orthosis can restore "normal" function to the person with impairment but
it may enhance mobility and other functioning through biomechanical control mechanisms;
keep in mind that orthoses can be heavy and costly!
major determinants of an ideal orthosis (5 C's) Control (biomechanical)
Comfort
Cosmesis
Cost (metabolic)
Cost (monetary)
control (biomechanical) 1. limits undesirable motions
2. enhances desired motions
3. example on slide 20: 3 point force system: articulated AFO
articulated AFO -Hold the toe, hold ankle in, and push on the back of the calf to keep the
foot up
-Depending on the pathology - design orthoses appropriately depending on the force
-Push on the proximal tibia to get extension in stance (knee extension)
more on control (biomechanical) slide 21 1. manipulation of the ground reaction force
vector
,2. relationship of the vector to the joint axis
3. external torque production
*causes the patient to be more stable (prosthetics and orthotics - alignment goals are the same
to promote stability)
*standing in slight DF to get extension at the knee
torque defined torque = tendency of a force to rotate an object (to twist or move a joint)
torque (T) = force x lever arm length
crouch gait large magnitude of external torque producing ankle DF, knee flexion, and hip
flexion; will see this with CP, spina bifida, etc; DF contractures, knee flexion contractures - really
need them to be more extended
more on crouch gait 1. hip flexion external torque
2. knee flexion external torque
3. ankle dorsiflexion external torque
even more on control (biomechanical) 1. Anterior ground reaction AFO restores external
torque producing knee extension during stance
2. Solid ankle design prevents external torque of ankle dorsiflexion during stance
3. Torque is also known as a "moment"
, **ground reaction AFOs with an extended foot plate, solid ankle, needs to be a stop at the
ankle to get extension at the knee (slide 24)
the 7 types of orthotic controls Free - No type of resistance against DF (ex) - free DF can
move
Resist - resistance to the movement
Assist - assist the movement; springs inside the joints to help bring the foot up; tamerac joints
to build in some DF so the AFO is in a resting position of DF
Stop - stopping at a certain angle
Hold - hold in alignment; not allowing any motion
Lock - lock the motion; in sitting not locked but once the patient is standing, can lock in to get
the knees extended
Variable - can vary the amount of resistance if they have a contracture and tune it depending
on the extent of the contracture (getting a stretch overnight)
comfort slide 26
1. Subjective patient experience
2. Influenced by perception, peripheral sensation, tissue tolerance
3. Factors influencing comfort
-Interface stresses (pressure, shear, friction)
-Suspension
-Bulk, weight, thermal insulation
If they aren't comfortable - the patient will never wear it; help make it look good too
