Learning and understanding gait cycle is very important in evaluating lower limb problems, as much can be learnt by carefully studying the way the patient walks and moves.
- A single gait cycle consists of a stance phase (60%) and a swing phase (40%).
- Stride: it’s one full gait cycle from heel strike to another heel strike.
- It’s measured from initial contact at the start of stance to the next initial contact of the same foot.
- Each stride is composed of a stance phase and a swing phase.
- Stance Phase: it’s the period of time when the foot is on the ground, in which the leg accepts body weight and provides single limb support.
- 60% of one gait cycle.
- Swing phase: it’s the period of time that the foot is off the ground, in which the limb advances forward.
- 40% of one gait cycle
- Step: it is the distance between initial contacts of the alternating feet.
- Walking: it’s a period of double limb support in addition to always having one foot in contact with the ground throughout the gait cycle.
- Ground reaction forces (GRF): it is the force exerted by the ground on a body in contact with it.
- GFR is approximately 1.5 times body weight during walking and 3 to 4 times body weight during running.
See Also: Ankle and Foot Anatomy
Stance phase forms 60 % of gait cycle. It starts from the heel strike to toe off phase of the same foot.
- Defined as the initial contact of the foot heel on the ground.
- Muscles actions:
- Hip extensors contract to stabilize the hip.
- Quadriceps and tibialis anterior muscles contract eccentrically.
- Controls the rate at which foot strikes the ground.
- Hindfoot is locked/inverted at initial strike allows for energy absorption
- Gastrocnemius-soleus complex eccentrically contracted during flat foot position.
- Controlling forward progression of body over the foot.
- Hindfoot is unlocked/everted for ground accommodation.
- From elevation of opposite limb until both ankles are aligned in coronal plane.
- Hip extensors and Quadriceps muscles has a concentric contraction.
- Begins when the supporting heel is of the ground, and continues until the opposite heel touches the ground.
- Toe flexors and tibialis posterior muscles contract (the most active muscles during this phase).
- Defined as the time from elevation of limb (toes are off the ground) to maximal knee flexion.
- Gastrocnemius-soleus complex has a concentric contraction.
- Hindfoot supinates, with activating the posterior tibialis tendon.
- Transverse tarsal joint locks and provides a rigid lever arm for toe-off
- Defined as the time from maximal knee flexion to where the tibia is vertical to the ground.
- Ankle dorsiflexor muscles contract to ensure foot clearance.
- Defined as the time from where the tibia is vertical to just prior to another initial contact (heel strike).
- Hamstring muscles decelerate forward motion of the thigh.
Center of gravity (COG)
- In standing position: it’s located 5 cm anterior to S2 vertebral body.
- During gait cycle COG displaces vertically.
- While it displaces 5 cm horizontally during normal gait cycle.
Abnormal Gait patterns
- A markedly shortened stance phase on one side.
- Pain makes the patient move off the affected limb as quickly as possible.
- The step length may be short
- A stiff-legged gait with the legs crossing each other is often associated with the muscle imbalance found in cerebral palsy.
- Often, there is also a crouched posture with flexed hips and knees, feet that are in equinus and both limbs internally rotated.
- During swing phase, there is no ‘pick up’ of the foot so it effectively ‘drops’ into equinus; if the foot was not lifted higher than usual to accommodate this, the toes would drag along the floor.
- This is caused by disorder or damage to the peripheral nerves supplying the foot dorsiflexors (peroneal nerve)
- This could be due to a bilateral foot drop or it may signify problems with balance or proprioception.
Waddling (Trendelenburg) gait
- The trunk is thrown from side to side with each step.
- The mechanics are similar to those that produce a positive Trendelenburg test as seen in patients with functionally weak abductor muscles of the hip, perhaps due to dislocation or simply pain.
See Also: Trendelenburg Test
- Ataxia produces a more obvious and irregular loss of balance, which is compensated for by a road-based gait, or sometimes uncontrollable
- Dystonia refers to abnormal posturing (focal or generalized) that may affect any part of the body and is often aggravated when the patient is concentrating on a particular motor task such as walking.