9/9c Base of Support Lab

Question 1

which device provides the most stability: cane, crutches, walker and why?

Answer 1

walker because it has the largest base of support

Question 2

what plane of motion does the walker provide the most support?

Answer 2

sagittal

Question 3

what kinds of impairments would you recommend a walking device for?

Answer 3

any impairment that causes lack of control

when the external environment is unusual terrain

Question 4

when using crutches, which position is easiest for your patient to bear full weight on the device and take a step?

Answer 4

20 degrees is the best position to bear weight on because the external moment arm is smaller than in 90 degrees thus the internal force needed to initiate movement is less

Question 5

what happens at 0 degrees when you try and move a crutch

Answer 5

at 0 degrees, the muscle cross bridge fibers are already the most flexed that they can be, so it is really hard to generate the torque/muscle force to initiate movement foreward

Question 6

which is a more natural gait pattern when using crutches?

• one cane/crutch progressing with ipsilateral foot
• one cane/crutch progressing with contralateral foot
• one cane/crutch progressing before the contralateral foot

Answer 6

• one cane/crutch progressing with the contralateral foot provides a more natural gait pattern and increases the base of support

Question 7

how should a patient progress with two crutches and one foot?

Answer 7

progressing forward and beyond the base of the crutch generates a larger base of support in more directions

Question 8

If a patient has a bunionectomy on both feet, what is th e best modality using crutches>

Answer 8

two crutches, each progressing separately with the ipsilateral foot because there are bilateral weightbearing issues

Question 9

understand the parts of a wheelchair

Answer 9

review the diagram

Question 10

where is a patient’s COM when sitting on a wheel chair

Answer 10

their thighs and hips

Question 11

where does the COM lie wrt the base of support on a wheelchair?

Answer 11

directly in the center

Question 12

when the front wheels of a wheelchair are lifted up 2 inches where is the COM and what is the lever system?

Answer 12

COM is moving back a bit, the system becomes a first class lever system because there is a force pushing down in the back and a force pulling up in the front while the axis of rotation is in the center

Question 13

what is the axis of rotation of a wheelchair?

Answer 13

its back wheels

Question 14

why is the wheelie position easier to maintain than the 2-in off the floor?

Answer 14

because the external moment arm from the body weight is shorter at the wheelie position than at the 2in off the ground one

Question 15

when passing the wheelie position, what kind of lever system is generated?

Answer 15

a second class lever position because the axis of rotation is closer to the external force than the internal force

Question 16

when using the tipping maneuver to get into a wheelie, what tactic are you using?

Answer 16

force couples

Question 17

mechanics of a patient in a wheelchair if the patient had transfemoral amputations

Answer 17

center of mass moves further back, so patient is in danger of tipping back
solve with anti-tipping bars and reclining wheel chairs

Question 18

mechanics of a patient in a wheelchair if the patient had bilateral long leg cases holding legs in nearly full extension?

Answer 18

harder to tip backward and the center of mass would move forward
solve by hanging weights on the back of the chair to adjust the center of mass so tipping is less