Biomechanical principles & gait Flashcards
What does Wolff’s law state?
That a bones shape and structure is a reflection of its mechanical loading history eg a tennis players racket are will have greater bone density than the other arm.
What does Wolff’s law state?
That the shape and structure of a bone is a reflection of its mechanical loading history.
What six different mechanical forces can bone be subjected to?
Unloaded, tension, compression, shear, bending and torsion.
Vertebral fractures are commonly a result of which force being applied to the bones?
Compression.
Pulled muscles and avulsion fractures are commonly a result of what type of force being applied to bones?
Tensile forces.
A common ACL/MCL injury sustained by american football players is caused by which force acting on the bones?
Shear Force (planted/strapped foot and opposing tackle).
Which two bones are frequently subjected to bending forces, especially when skiing?
Fibula, Tibia and femur.
What makes up the menisci?
Fibrocartilagenous tissue.
What operation can cause an increase in the incidence of OA in the knee?
Meniscectomy
By what % does a menisci increase congruency in the knee joint?
50%.
Tendons connect what to what?
Muscle to bone.
Ligaments connect what to what?
Bone to bone.
What type of collagen to tendons contain?
Type 1 collagen.
What structure resists tensile forces and stores up energy in order to act as a spring during locomotion, complementing muscle force?
Tendons.
What are the main functions of ligaments?
To guide and limit joint mobility and to maintain congruence and act as strain sensors.
Why do strained ligaments hurt?
They have a good nerve supply - complete rupture results in no pain - surgery needed.
What are the four major properties of skeletal muscle?
Irritability - responds to nervous stimulation
Contractibility
Extensibility
Elasticity
Which globular protein is involved in muscle contraction?
Troponin (and tropomyosin in the thin filaments).
Plyometrics refers to what type of action?
Repeated and rapid muscle stretches and contractions, ie jumping up and down.
An agonist muscle is defined as…
the muscle responsible for producing the movement.
An antagonist muscle is defined as…
the muscle that opposes the agonist in a particular movement ie relaxes to allow an agonist to act, or contracts proportionally to produce a slow movement.
A Fixator or stabiliser muscles is defined as…
a muscle which provides an immobile base for a join on which other prime movers act.
A synergist muscle is defined as…
a muscle that prevents unwanted movements which would be produced if the prime movers (agonist) acted alone.
What types of mechanical forces can bones be put under?
Unloaded, tension, compression, shear, bending and torsion.
What are the three muscle mechanism components?
Swing
Shunt
Spin
What is passive insufficiency?
A factor limiting biarticular muscles that span two joints, i.e. hamstring. Don’t allow movement at both joints at the same time.
What is active insufficiency?
A factor limiting movement due to a muscles inability to contract by more than a fixed amount. There’s insufficient ‘shortening’ ability when another joint is already flexed.
What defines the concurrent movement of muscles?
When two muscles are acting together, shortening at one end, but lengthening at the other.
What defines COUNTERcurrent movement of muscles?
The opposite of concurrent movement, where the muscles involved either lengthen at both ends or shorten at both ends.
What is gait?
The movement pattern associated with human locomotion - running and walking.
The gait cycle is defined as the interval between…
Two successive heel strikes of the same foot.
Stance phase and swing phase make up what?
The Gait Cycle.
What is the stance phase defined as?
Heel strike to toe off.
What is the swing phase defined as?
Foot is off the group and is moving away from toe-off to the heel strike - the weight baring phase.
Over pronation of the foot can be caused by, and can result in what conditions.
Subtular joint hypermobility, collapsed medial longitudinal arch. Causes increased susceptibility to achilles tendon problems and hallux valgus.
What is hallux valgus?
A bunion.
What characterises a hemiplegic gait?
One leg swung out laterally.
What pathology is a common cause of a hemiplegic gait?
Stroke
A parkensonian gait can also be described like?
A shuffle - small, tentative steps with little peripheral movement, do not have a natural arm swing.
An antalgic gait is used to describe what type of walk?
A limp/movement away from the side of pain.
What is an ataxic gait caused by?
Cerebellar dysfunction.
Tipping of the pelvis during the stance phase of the gait cycle is suggestive of which pathology?
Trendelenburg.
