Gait Kinematics

Question 1

Phases and Tasks

Answer 1

Stance
* initial contact (weight acceptance)
* loading response (weight acceptance)
* mid stance (Single limb support)
* terminal stance (single limb support)
* pre swing (swing limb adavncement)

Swing
* initial swing (swing limb advancement)
* mid swing (swing limb advancement)
* terminal swing (swing limb advancement)

Question 2

Torque: angular force or joint moment

Answer 2

• Torque is a measure of the force that can cause an object to rotate about an axis. In human biomechanics, the joint is the rotational axis
• In gait the term for torque is joint moment: the amount of force that is required to stabilize or create movement in a joint axis.
• The essential aspect: is the limb in a contact or loaded position (stance) which is to stabalize or absorb force or is the joint freely moving (swing)

Question 3

Rockers

Answer 3

midstance biomechanics: Fixed foot (ankle rocker) with tibial advancement. Talocrural joint serves as the fulcrum.
1. Heel rocker: initial contact of calcaneus with ground
2. Ankle rocker: Fixed foot with full foot contact
3. Forefoot rocker: calcaneus moves out of contact, forefoot contact.
4. (toe rocker: great toe serves as the base of contact)

*rockers only in stance phase

Question 4

Sagittal Plane Pelvic Tilt

Answer 4

• anatomically the pelvis sits at 10 degrees of anterior pelvic tilt
• With ambulation, the pelvis tilts an additional 4 degrees anteriorly (unseen by vision) during terminal stance.
• In early single leg stance, a posteior tilt occurs

Question 5

Frontal Plane Pelvic Tilt

Answer 5

• During weight acceptance the contralateral side of the pelvis drops 4 degrees (downward tilt)

Question 6

Frontal Plane Kinematics: Hip

Answer 6

• On the stance phase limb (right): pelvis in frontal plane
• Hip: stabalize the hip & pelvis in the frontal plane from initial contact through pre swing
• small frontal plane movement of the hip from initial contact to the end of the loading response 0 degrees to 10 degrees adduction

Question 7

Frontal plane Kinematics: Knee

Answer 7

• On stance phase: knee must remain in alignment with hip and ankle (no overt varus or valgus)

Question 8

Frontal Plane: Subtalar Joint

Answer 8

• Subtalar joint is responsible for supination and pronantion
• Supination occurs during late terminal stance. The calcaneus reduces from 5 to 2 degrees of eversion. This action increases the stability of the midtarsal joints and creates a rigid forefoot level moving towards supination. This action helps promote the third rocker (forefoot rocker)
• Pronation occurs during loading response. The calcaneus everts 5 degrees and the subtalar joint moves into pronation. Pronation unlocks the mid tarsal joints and assists in ankle shock absorption reducing stress of the loading impact. Moves the tibia slightly into internal rotation.

Question 9

Transverse plane: pelvis rotation

Answer 9

• terminal stance: pelvis retraction 5 degrees
• Midswing: pelvis neutral
• Terminal swing: pelvis forward rotation 5 degrees
• pelvis rotation allows for longer step/stride length

Question 10

Transverse plane: trunk rotation

Answer 10

• thoracic rotation results in shoulder forward rotation and creates arm swing
• Thoracic forward rotation coincides with contralateral pelvis retraction