Locomotion Flashcards
How is the unilateral stance maintained
To maintain the unilateral stance, there has to be a counter torque of equal weight of there head, torso and other leg to stop the pelvis from dropping towards the non-stance side. This torque force is created by the abductors.
This force from abductors on the stance side is up to 3x the body weight to ensure that the unilateral stance is maintained.
Side bending towards the non stance side will occur to reduce the stress on there abductor force to create counter torque.
Significance of the femoral angle of inclination
Formed by an axis passing through the femoral head and a longitudinal axis passing through the femoral shaft.
Normal- 125
Angle is larger at birth at about 150 degrees, then it becomes 125 at skeletal maturity.
Significance of the Q angle
Angle formed between the quadriceps muscles and the patella tendon.
Considered clinically as a very important parameter which displays the biomechanics effects of the quadriceps muscle on the knee, and it is also regarded a crucial factor for the proper posture and movement of the knee patella.
– the larger the Q angle, the less more likely there is for knee problems
Regularly used as an assessment parameter during the diagnosis of many knee-related problems, including the anterior knee pain, osteoarthritis, and degenerative knee disorders.
Men- 13 degrees
Women- 18 degrees, due to women having genetically larger pelvis’s. This increased Q angle increases the pressure on the lower body of women.
It’s called a dynamic Q angle as it will change depending on the activity that you are doing, as seen by the photos below.
Can also change if there are arthritic changes in the knee, hip and maybe even ankle, as the femur will try and find a position to place itself with the least pain.
What is locomotion
Movement or the ability to move from one place to another.
Gait
The pattern of movement
Pelvis’s role in locomotion
There is a functional relationship between the opposing pelvic muscles:
– hip flexors will anteriorly rotate pelvis, when hamstrings and abdominal wall are weak
– hamstrings will posteriorly rotate pelvis, when ES group are weak.
The pelvis takes all the weight and diffuses it equally across the whole pelvic ring and then down the 2 legs.
Also takes the forces coming up from the feet through the legs and absorbs it and dissipates it equally around the pelvic girdle so it doesn’t just hit the lumbar spine full on creating bad back problems.
Climbing stairs
Centre of gravity:
– is different depending on whether you are going up or down stairs
- going up stairs- moves the centre of gravity forward as we subconsciously lean forward when walking up the stairs
- going down the stairs- moves centre of gravity backwards
Force coupling in the pelvis:
– occurs round the acetabular socket
– looks at the relationship between the anterior and posterior pelvic musculature
- anterior superior mms, anterior inferior mms, posterior superior mms, posterior inferior mms
- Anterior superior pelvic mms:
– abdominal muscles - anterior inferior pelvic mms
– hip flexors deep and superficial (psoas, iliacus and pectineus deep) and (rectus femoris superficial) - posterior superior pelvic mms
– erector spinae mms
– quadratus lomborum
– latissimus dorsi can influence - posterior inferior pelvis mms:
– hamstrings
– its the push and pull between these muscles that can directly affect the force coupling (rotation) that the hip is going through with the pivot being the acetabular socket.
– so if someone is having problems going up and down stairs or just having problems with their centre of gravity in general, you need to look at these structures that influence the rotation of the pelvis.
Purpose of the patella
It increases the leverage available to Quadraceps’ muscle group:
– provides the maximum amount of torque during 20-60 degrees flexion
– applying a mechanical advantage for the knee and quadriceps
– when the knee is in flexion the patella gets compressed and pushes it back into the patella femoral joint space, so if the patella is not sitting evenly within the knee then this is where friction occurs and erosion of the femoral condyles and the exterior surface of the patella.
3.3 times body weight going upstairs and 7.7 going downstairs:
– always ask patients having trouble climbing stairs if it is worse going up or going down the stairs
Stabilised by the cruciate ligaments
– protective component
– increases stability- helps maintain proper tracking and alignment of the knee
Role of the talus in gait mechanics
Talus acts as a torque converter, causing rotations of the leg to be converted to inversion and eversion vectors in the foot.
Causes the rotations of the leg to be converted to inversion and eversion vectors of the foot.
This helps adaptation of the foot to ground reaction forces.
Locking of the talus during toe off create a stable base for weight bearing and propulsion.
The tibia and fibular movement on the talus is a sliding movement which acts in the opposite movement to the talus which rolls on the calcaneum.
Patella Mal-tracking
Normal tracking:
– where during knee flexion and extension, the patella will move smoothly in a vertical line up and down between the femur and the tibia.
Mal tracking of the patella:
– sometimes the patella can move off course, and affect underlying structures during movement
– can be a cause of anterior knee pain
– can cause erosion to femoral condyles and other articular structures
Why does Mal tracking happen?:
– usually because of the quadriceps group, as distally all 4 heads attach to the patella via the quadriceps tendon, connecting the patella to the tibia.
– when the quadriceps contract, this pulls the patella upwards, meaning the tibia will come forward putting the leg into extension
– due to the hips being wide and the knee being closer together, and due to the quadriceps running from the hip to the knee, this will mean they run at an ‘oblique angle’ meaning a ‘slight wonk’
– meaning overall there will also be a slight lateral pull on the patella as well as straight up
– causing mal tracking
Things that can cause it:
– dysplastic hip
– laxity of periarticular tissue
– excessive tightness of lateral retinaculum
– shortening/tightness of internal rotators and adductors of the hip
– coxa vara
– excessive femoral anteversion
– external tibial torsion
– large q-angle
– genu valium
– weakness of poor control of muscles e.g: VMO
– alterations of foot biomechanics; over-pronation causing excessive tibial and femoral internal rotation beneath the patella
Caused by:
– dysplastic hip
– genu algum
– weakness or poor control of muscles (quads)
– coxa varus
– shortening/tightness of internal rotators and adductors of the hip
– large q-angle
– excessive femoral anteversion
What can go wrong and lead to an alteration in locomotion and gait
Adult life:
– parkinsons- leading to shuffling
– DDH (developmental dysplasia of the hip)
– trendelenberg- ipsilateral weakness of glutes med/min, causing pelvis to ‘drop’ during mid stance phase
– antalgic (painful) gait- pain, disc herniation
– toe walking- cerebral palsy
– festinating gait- problems with the basal ganglia
– foot drop- lower motor neuron lesion, common perineal nerve compression
– circumduction- spastic CNS
– Ataxic gait- cerebellar dysfunction
– stamping- loss of sensation in feet- neuropathic loss, diabetes
Childhood conditions that can lead to an altered gait in adulthood:
– DDH
– slipped capital femoral head
– perches disease
– severs disease
– osteomyelitis tumour
Roll and slide mechanism of the knee
Convex and concave roll and slide:
– helps to maintain the articular surface contact
– helps the maintain the joint congruity throughout the whole range of motion
Why does it roll and slide:
– in order to prevent an undesirable translators movement there has to be some degree of slide, otherwise the bone will lose traction/leverage during the movement.
– also the moving bone may find itself in an undesirable position
femur- convex
tibia is concave
Knee flexion into extension (getting up from sitting):
– tibia is fixed
– quadriceps bring femur into extension
– femur rolls anteriorly, whilst sliding posteriorly
– the ACL and PCL are what control this movement
Knee extension into flexion:
– first knee needs to unlock via the screw home mechanism, which is completed where the popliteus will externally rotate the tibia and produce the first 10-15 degrees of flexion to unlock the knee
– tibia is fixed and the femur is moving
– femur rolls posteriorly and slides anteriorly
– interplay between the quads and the hamstrings, gradual contraction of hamstrings to flex the knee, and the relaxation of the quads helps control it
– ACL and PCL play a roll
Screw home mechanism of the knee
It’s a stabilising mechanism for the tibiofemoral joint during extension
—- when standing it allows the quadriceps to relax and locks out the knee
—- maximises the contact between the femur and the tibia, therefore helping the congruency of the knee and stability
- requires 10 degrees of external rotation during the last 30 degrees of extension
- it is mechanically linked to extension and flexion of the knee and cannot be performed individually
- it maximises overall contact area of the adult knee
- thus, favouring joint congruency and stability
Unlocked by the popliteus, which medially rotates the knee to unlock it before locomotion (also involved with the first 10-15 degrees of flexion)
