Biomechanics and locomotion

Question 1

How is unilateral stance maintained

Answer 1

Body in counter torque from glute of standing leg
Stabilise the pelvis and stop it dropping/weakness
Hip adductors maintain stance (3xBW)
Abductors forced to keep upright- dec force- SB to standing leg= counter torque
Loading= result of ground reaction forces and muscular contraction
Weight is an equal ground reaction force through acetabulum= stationary, with muscular contraction (glutes, hamstrings, quads)
Popliteus- locks knee in flexion/standing to maintain stability

Question 2

Significance of femoral angle of inclincation

Answer 2

Ideal= 120-130
Ensures weight of upper body is transferred down axis of femur biomechanically transfers forces to acetabulum
Deformity= incongruency= OA/wear and tear

Question 3

Significance of Q angle

Answer 3

Healthy hips/pelvis/Q angle= straight force down during running, abnormalities cause problems
Healthy= dynamic
Angle from quad to patella tendon

Question 4

Role of talus in gait mechanics

Answer 4

No muscular attachments, point of contact between tibia and fibula as well as calcaneus
Torque converter- causes rotation of leg to be converted to inversion and eversion vectors in foot
Helps adapt foot to reaction forces
Locking of talus during toe off phase creates stable base for weight bearing
Tibia and fibula movement on talus is a sliding movement which acts in opposite movement to talus which rolls on calcaneum

Question 5

Understand the determinants involved in gait cycle

Answer 5

1 foot- Heel strike- foot flat- midstance (unilateral stance)
Other foot- Heel off- toe off
Acceleration in toe off, deceleration in midswing- prep for heel strike

Question 6

Functional relationship of opposing pelvic muscles

Answer 6

Hip flexors will anteriorly rotate pelvis, when hamstrings and abdominal wall are weak
Hamstrings posteriorly rotate pelvis, when erector spine group are weak

Question 7

Pelvis role in locomotion

Answer 7

Force coupling- occurs around acetabular socket (pivot point)
Ant/post musculature= push/pull motion, directly effects locomotion
Need to look at these structures to identify where problem is
SIJ- modified synovial- L-shaped provides stable structure to adapt downward force of gravity, ligaments reinforce

Question 8

Artho-kinetics involved in patella malt racking

Answer 8

Inc leverage for quads
Provides maximum amount of torque available during 20-60 flex
During knee flexion there is compression of patellofemoral Jt- if patella is not sitting right evenly between condyles erosion may occur of condyles + post surface of patella
Stabilised by cruciate ligament

Question 9

Kinetic principles of roll and slide

Answer 9

Convex, concave roll
Helps maintain auricular surface contact
Maintains Jt congruity through ROM
Knee is example of- both bones roll and slide in same direction

Question 10

Kinetic principles of force coupling

Answer 10

Coordinated activation and use of muscles and forces to produce movement
2 opposing forces rotating around pivot point
Can be equal or unequal

Muscle synergies- refers to coordinated activation of multiple muscles working together to produce movement and stabilise the Jt
Force direction and alignment- aligning diff forces from muscles to prod movement
Co-contraction and stabilisation- refers to simultaneous activation of opposing muscle groups around Jt to provide stability

Question 11

Kinetic principles of form closure

Answer 11

Stability of Jt or body segment based on congruence between articulating surfaces

Congruence- relies on congruence, perfect fit= stable
Interlocking- form closure can be achieved through interlocking. involves interlocking of jt surfaces to create stability
Containment- object should be completely enclosed or contained, preventing movement or displacement

Question 12

Kinetic principles of force closure

Answer 12

Muscular or external factor to maintain Jt stability

Tension and compression- needed for stability, tension forces tighten and secure Jt, compression forces push surfaces together to create stability
Muscle activation- requires activation of muscles to generate necessary forces. contraction= tension and compression= security
External forces- provide additional stability or force transmission. Prevent undesired movement

Question 13

Kinetic principles of roll and slide

Answer 13

Interaction of a rolling and sliding between surfaces during movement

Roll- one surface rolls along the surface of other without slipping, allows smooth and controlled motion
Slide- sliding of one surface across another= even force distribution reducing friction

Lubrication= important (synovial fluid)