PT3 - Knee In Locomotion

Question 1

What are the functions of the knee during locomotion?

Answer 1

• stability for weight baring
• stability + ROM to transmit + amplify motion of hip to lower leg
• stability + ROM to dissipate + transmit movements of foot + ankle to hip

Question 2

What are the functions of the knee?

Answer 2

• stable platform
• mobility
• facilitates gait
• smoothes out uneven ground
• propriception
• shock absorption

Question 3

What are the specialisations of the knee?

Answer 3

• popliteus = initiates internal tibial rotation + PCL support for posterior glide of tibia
• ACL + PCL = control anterior/posterior movements (reinforced by hamstrings + quads)
• quads = deceleration force + powerful extension of knee
• hamstrings = antagonistic control of quads + aids ACL

Question 4

What are the specialisations of the menisci?

Answer 4

• improve congruency of bony surfaces + weight distribution through joint
• balance intra-articular pressure of muscular action => creates a more congruous joint
• lubrication + shock absorption => spreading + gliding
• joint gliding motion of ovoid femoral condyles
• divide femoro-tibial joint into superior menisco-femoral joint => flexion + extension; inferior tibo-meniscal joint => rotation around media meniscus

Question 5

What are the specialisations of the patellofemoral joint?

Answer 5

• non-axial between posterior (femoral) patella and anterior (patella)
• patella = sesamoid bone => protects articular condyles, synovium + neurovascular structures from power of quads
• increase mechanical advantage of quads => movement torque moves away from axis => 30%+ efficacy

Question 6

What are the 6 determinants of gait?

Answer 6

• pelvic rotation
• pelvic tilt
• knee flexion (stance phase)
• foot + knee mechanisms
• lateral displacement of pelvis

Question 7

What are the 3 key functions during locomotion

Answer 7

• dissipation of force from foot to hip
• control mobility and forces transferred from hip to foot
• stability while in single leg stance

Question 8

What are 4 key ligaments of the knees as related to locomotion?

Answer 8

• PCL
• ACL
• LCL
• MCL

Question 9

Describe how foot and ankle function supports healthy knee function during locomotion

Answer 9

• mid-tarsal joint opens, resulting in a mobile foot
• movement from hind foot through subtalar results in torque moving upwards, changing direction from transverse plane to frontal plan in tibia
• allows internal rotation of tibia
• popliteus initiates internal rotation, unlocks the knee, allowing the knee to bend during heel strike
• LCL, MCL, PCL, ACL assist the knee by reinforcing the muscles to keep the knee gliding in ranges of movement that it can tolerate = stability
• meniscus dampens forces from the foot upwards and the body downwards

Question 10

Why is the MCL stronger than the LCL?

Answer 10

• consistent with meniscus
• due to q angle coming in, needs to resist medially during weight bearing (stance phase)
• increase anteversion + q angle = more strain on MCL

Question 11

What is the difference between medial and lateral meniscus?

Answer 11

• medial = c shaped = larger + blends with capsule + more commonly injured + firmly attached
• lateral = d shaped = moveable + less likely to be injured

Question 12

Describe how hip function supports healthy knee function during locomotion

Answer 12

• hip has a congruent surface + multi-axial joint, allowing for greater ranges of motion at the hip. If the hip is not able to move in these greater ranges, then the body will adapt to provide greater ranges elsewhere e.g. in the knee
• hip is a stabilised by multiple ligaments and muscles and has a deep socket. Allowing for transmission + dissolving of forces from the ground up to the head and vice versa. If the hip is not healthy, this shock absorption may be required to occur in the knee by the meniscus.
• the knee does not have as many stabilising structures as the hip (4 ligaments), making it less adapted for greater ranges of movements
• medial + lateral collateral ligaments resist medial and lateral movements, anterior cruciate ligament + posterior cruciate ligaments provide anterior-posterior stability
• MCL is stronger (consistent with meniscus) => q angle => needs to resist medially during weight baring (stance phase)
• increased retained ante-version + increased q angle => more strain on MCL