Q1: TT Gait Deviation & Dynamic Alignment

Question 1

Initial Contact Goals

Answer 1

• knee in 5-10 deg flexion
• step length equal to sound side

Question 2

Initial Contact Deviation: Knee fully extended

Answer 2

• faulty suspension
• insufficient socket flexion
• Foot too anterior

Question 3

Initial Contact Deviation: Excessive knee flexion

Answer 3

• faulty suspension
• flexion contracture

Question 4

Initial Contact Deviation: Unequal Step Length

Answer 4

• faulty suspension
• patient cause (pain, fear, etc.)

Question 5

Loading Response Goals

Answer 5

• controlled knee flexion of approximately 20 deg
• no pistoning in socket

Question 6

Possible Causes of Knee remaining extended in loading response

Answer 6

• heel too soft
• PF bumper too soft (result in foot slap)
• Heel lever too short (socket too posterior, foot too anterior)
• Insifficient socket flexion
• Shoe heel height lower than foot heel height
• excessive activation of knee or hip extensors

Question 7

Possible causes of abrupt knee flexion in loading response

Answer 7

• heel to stiff
• PF bumper to firm
• heel lever too long
• excessive socket flexion
• shoe heel height higher than foot heel height
• weak quads

Question 8

Goals of Midstance

Answer 8

• vertical pylon in sagittal plane
• slight varus moment:socket displaces laterally approximately 1/2
• 2-4” base of support
• no lateral trunk leaning

Question 9

Causes of Excessive Varus Moment at Midstance

Answer 9

• Foot too inset
• Socket ML too large
• Excessive Socket abduction

Question 10

Causes valgus moment at midstance

Answer 10

• foot outset or insufficient inset
• excessive socket adduction
• antalgic gait

Question 11

Terminal Stance Goals

Answer 11

• sufficient forefoot leverage to maintain weight bearing until contralateral weight acceptance
• prevention of excessive knee extension moment in terminal stance
• smooth heel off
• knee flexion following heel-off to prepare for toe-off

Question 12

Excessive Extension in Terminal stance causes

Answer 12

• foot too anterior
• insifficient socket flexion or foot too plantar flexed
• keel too rigid
• foot too long
• heel of shoe too low
• weak quads

Question 13

Abrupt Knee Flexion in terminal stance causes

Answer 13

• foot too posterior
• socket too flexed; foot too dorsiflexed
• keel too soft
• foot too short
• heel of shoe to high (anterior lean)

Question 14

Stance phase preswing goals

Answer 14

• smooth transfer of body weight to sound side
• adequate socket suspension entering swing phase