Lecture 62 - Biomechanics III Flashcards
Gait
Cyclic motion of lower and upper limbs that aim to move body forward
5 goals of gait
- forward progression
- shock absorption
- lower quarter mobility
- stance stability
- energy conservation
What are the 2 phases of gait
- Stance phase
- Swing phase
Full gait cycle
Time between contact to contact of same foot (stride)
What are the 5 events of stance phase
- Initial contact: moment when foot contacts ground (heel)
- Loading response: Weight is transferred to limb
- Mid-stance: Body progresses directly over limb
- Terminal Stance: Weight is transferred to forefoot and body moves forward
- Pre-swing: Limb is unloaded and weight is shifted to opposite extremity (toe-off)
What are the 3 parts of the swing phase
- Initial-swing: Foot comes off floor and femur begins to advance forward
- Mid-swing: Knee begins to extend and foot clears the ground as femur continues to advance
- Terminal Swing: Knee begins to extend and foot clears the ground as femur continues to advance
What are the 3 functional domains of the gait cycle
Stability
Ability of system to return to original state
Static vs dynamic stability
Joint stabilit
Ability of joints to move effectively without undue stress or risk of injury that is influenced by ligaments, muscles, tendons and other anatomical structures.
What are the 3 components of joint stability
- Structural factors
- Neuromuscular Control
- Proprioceptive feedback
What is the base of support and line of gravity
Stability vs instability
How does wider base of support impact line of gravity
Wider base of support may lower line of gravity and increase stability
When the base of support is large….
The COG has more freedom to move without going outside the base of support
Examples of modifying COG when carry a load
What factors affect spinal stability (5)
What are the 3 major contributors to ankle stability
- Congruity of articular surfaces when joints are loaded
- Static ligamentous restraints
- Musculotendinous units
Ankle sprains occur when
rearfoot undergoes excessive inversion/supination on an externally rotated leg
Chronic sprains are likely due to (2)
- Mechanical Instability
- Functional instability
What are the 3 lateral ankle ligaments that provide stability
What are 2 tests to measure ankle ligament tears
- Anterior drawer test: Positive test = laxity compared to other ankle
- Talar tilt test: Tilt calcaneus on talocalcaneal joint
Positive test = pain or increased laxity on either side
Eversion = deltoid ligament
Inversion = calcaneal talar ligament
Does anterior drawer test have higher specificity or sensitivity and what does it mean
High sensitivity, low specificity
-> rule out the disease (high specificity and negative test) -> ADT
-> if positive you don’t know if you have ligament problems and you have to switch to test with high specificity
Does talar tilt test have higher specificity or sensitivity and what does it mean
High specificity, low sensitivity (talar tilt diagnostic)
-> rule in the test
-> if positive test = has disease
What are the movements and planes that occur in pronation
What are the movements and planes that occur in supination
Describe the gait cycle in terms of tibial rotation and pronation or supination
Explain pronation and supination at ankle
What happens to the talus during pronation - closed chain
What are the 3 basic mechanisms that make up supination of the foot
Explain the metatarsal break angle
Explain the windlass mechanism
Explain contralateral swing
