BIOMECHANICS & LOCOMOTION Flashcards
BIOMECHANICS DEFINITION
A field that combines disciplines of biology and engineering mechanics and utilises tools of physics, maths and engineering to qualitatively derive the properties of biological molecules
LOCOMOTION MEANING
Movement of the body
DIFFERENCE BETWEEN WALKING AND RUNNING
At least one lower limb is always in contact with the ground when walking
WALKING
There is a lower limb in contact with the ground at any given time
RUNNING
There are periods of time where both lower limbs are off of the ground
CYCLING
The lower limbs don’t touch the ground. You are using the mechanism of the bike and the rotation of your legs to drive the bike
VECTORS OF MOVEMENT IN STAGE 1 OF GAIT
Hip flexion - 20
Knee flexion - 0
Ankle dorsiflexion - 0
MOVERS IN STAGE 1 OF GAIT
Quads
Glute max/hamstrings
Tibialis anterior
Extensor digitorum
STABILISERS IN STAGE 1 OF GAIT
Quadratus lumborum/obliques
IT band
Thoracolumbar fascia
Glutes min/med
Latissimus dorsi
Adductors
ACCESSORY MOVEMENTS IN STAGE 1 GAIT
Pelvis lateral tilt
Pelvis posterior rotation
Sacrum counter nutated
Trunk left rotated
CLIMBING STAIRS AND CENTRE OF GRAVITY
Differs when going up and down, the body concisely shifts
OA changes/injury interferes with its process
PELVIS ROLE IN LOCOMOTION
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 problem
SIJ- modified synovial- L-shaped provides stable structure to adapt to downward force of gravity, ligaments reinforce
FUNCTIONAL RELATIONSHIP OF OPPOSING PELVIC MUSCLES
Hip flexors anteriorly rotate pelvis, when hamstrings and abdominal wall are weak
Hamstrings posteriorly rotate pelvis when erector spine group are weak
UNILATERAL STANCE
To maintain single limb support must be counter torque of equal weight of head and torso and other leg to stop pelvis dropping
Hip abductors must generate 3xBW to maintain stance
SB toward stance leg reduces need for hip abductor force (produces counter torque)
Loading occurs as result of both ground reaction force and muscular contraction
Primary weight bearing area on acetabulum located on superior portion, thus area must accommodate both ground reactions races and muscular contraction
DYNAMIC Q-ANGLE MEANING
Quadratus angle
Healthy hip/pelvis/Q-angle= straight force down during running, abnormalities cause problems
Healthy= dynamic
PURPOSE OF PATELLA
Increases leverage for quads
Provides maximum amount of torque available during 20-60 flexion
During knee flexion there is compression of patellofemoral Jt- if patella is not sitting even;y between condyles erosion may occur of condyles + post surface of patella
Stabilises cruciate ligament
BODY WEIGHT UP STAIRS
3.3x going up
BODY WEIGHT DOWN STAIRS
7.7x going down
CONVEX AND CONCAVE ROLL AND SLIDE
Convex= rugby ball
Helps maintain articular surface contact
Maintains Jt congruity through ROM
Knee is example of convex of concave- both bones roll and slide in same direction
SCREW-HOME MECHANISM OF KNEE
Stabilising mechanism for tibiofemoral Jt during extension (standing)
Requires 10 of ER during last 30 of ext
Mechanically linked to ext and flex of knee and cannot be performed independently
Maximises overall contact area of knee- between fibula and tibia
Increase Jt congruence and stability
Popliteus is muscle that ‘unlocks’ knee prior to locomotion
ROLL AND SLIDE - KNEE FLEXION TO EXTENSION
Aka standing from sitting
Tibia fixed and quads bring femur into ext
Tibia slides in same direction and femur rolls
ROLL AND SLIDE - KNEE EXTENSION TO FLEXION
Sitting down
To flex knee must ‘unlock’- popliteal (rotates tibia)
Tibia is fixed and femur moving
Femur rolls in opposite direction to tibia which slides anteriorly
Interplay between gradual contraction of hamstrings to flex knee and gradual controlled relaxation of quads to allowed controlled descent
Antagonist- needs optimal functioning
Cruciate ligament controls anterior slide of tibia
FEMUR AND PATELLA MAL-TRACKING
Patella Mal-tracking - during flexion/extension movement isn’t smooth on posterior part of the patella (causes erosion)
CAUSES OF PATELLA MAL-TRACKING
- Dysplastic hip
- Laxity of periarticular tissue - quads etc
- Excessive tightening of lateral patella retinaculum
- Coxa varus
- Excessive femoral antiversion - congenital, OA changes in hip
- Large Q-angle
- Genu valgum
- Alteration of foot mechanics
SIGNIFICANCE OF THE TALUS
No muscular attachment, point of contact between distal tibia and fibula as well as calcaneus
Torque converter- causing rotation of leg to be converted to inversion and eversion vectors of foot
Helps adapt foot to react to ground forces
Locking of talus during toe off phase creates stable base for weight bearing snd propulsion
Tibia and fibula movement on talus is a sliding movement which acts in opposite movement to talus which rolls calcaneus
THINGS THAT CAN GO WRONG IN ADULTHOOD
- Parkinson’s- shuffling
- DDH (developmental dysplasia of hip)- limp
- Trendelenburg- ipsilateral weakness of glutes med/min, causing pelvis to drop during mid stance phase (leg off ground)
- Toe walking- cerebral palsy
- Festinating gait (jerky, uneven gait)- basal ganglia
- Foot drop- common peroneal nerve compression, lower motor neuron
- Stamping- loss of sensation, common in Px with Type 1 diabetes, can’t feel ground
CHILDHOOD CONDITIONS THAT CAN LEAD TO ALTERED GAIT IN ADULTHOOD
- DDH
- Slipped capital femoral head - adolescent problem, growth spurts, interrupted blood supple to the femoral head
- Perthe’s (hip)- adolescent
- Sever’s (ankle)- swelling/irritation of growth plate in calcaneum- adolescent
- Osteomyelitis tumour- common in hip
Need to rule out these conditions before deciding they are MSK
HOW IS UNILATERAL STANCE MAINTAINED
Body must be in counter torque of equal weight of head, torso and other leg to stop pelvis dropping
Hip abductors must generate 3xBW to maintain stance
SB toward stance leg reduces need for hip abductor force (produces counter torque)
Loading occurs as result of both ground reaction force and muscular contraction
Primary weight bearing area superior portion of acetabulum- this area accommodates both ground reaction forces and muscular contraction
INTERNAL INFLUENCING FACTORS OF GAIT
- Vertical displacement
- COG
- Single or double leg displacement
- Lateral pelvic tilt
- Ant/post rotation of pelvis
- Pelvic rotation
- Knee flexion
- Physiologic valgus at the knee
- Knee, ankle, foot interactions
- Muscle power
- Energy available
- Feedback
- Femoral angle of inclination
- Q angle
- Patella tracking
- Role of the talus
EXTERNAL INFLUENCING FACTORS OF GAIT
- Gravity
- COG
- Inertia
- Ground reaction force (GRF)
- External sources of force
PATHOLOGICAL INFLUENCING FACTORS OF GAIT
- Osteoarthritis
- Rheumatoid arthritis
- Congenital dysplasia of the hip
