Gait

Question 1

Prerequisites of normal gait

Answer 1

1. Stability in stance: this requires a stable foot position and good control of body segments above the lower limbs whilst still achieving clearance and forward propulsion.
2. Adequate foot clearance in swing: this requires appropriate positioning of hip, knee and ankle in the stance limb with adequate flexion at the hip and knee and adequate ankle dorsiflexion in the swing limb.
3. Adequate step length: this follows from good balance and stability on the stance side with appropriate flexion on the swing side.
4. Appropriate pre-positioning of the foot in terminal swing: this follows
   from all the above.
5. Energy conservation: this is achieved by minimizing vertical excursion of
   the body during gait and by ensuring that joint stability is achieved wherever possible by the position of the GRF rather than by muscle activity.

Question 2

How may a person compensate for a leg length discrepancy?

Answer 2

1. Circumduction of the longer limb: the hip abducts and the limb swings around outside the normal line of progression, effectively shortening the limb.
2. Hip hitching: abdominal and paraspinal muscles are activated to hitch the pelvis up on the longer side to gain the same advantage.
3. High stepping: exaggerated hip and knee flexion increases the clearance of the longer limb in swing.
4. Vaulting: plantarflexion of the ankle in the shorter limb during stance increases clearance of the longer limb whilst maintaining a level pelvis

Question 3

What are the three rockers of gait?

Answer 3

(a) the heel (first) rocker
(b) the ankle (second) rocker
(c) the forefoot (third) rocker

Question 4

Causes of positive Trendelenburg gait

Answer 4

weakness in the hip abductor muscles: gluteus medius and gluteus minimus