Biomechanics Of The Knee - L4

Front 1

Hip anteversion vs Femoral anteversion

Back 1

see doc Hip anteversion vs Femoral anteversion in POTH225/images/L4

Front 2

How is anteversion of the hip compensated?

Back 2

Like femoral anteversion see doc Hip ante-version in POTH225/images/L4

Front 3

Knee anatomy

Back 3

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Front 4

Femur's characteristics

Back 4

* Angled from the vertical

* Contains:

1. Condyles (med & lat.) - articulate with TIBIA

2. Patella surface - articulate with PATELA (fibula)

Front 5

Femoral Condyle Differences

Back 5

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Front 6

Tibia plateau Differences

Back 6

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Front 7

Stress = smaller on which Tibia plateau? The consequence of stress reduction?

Back 7

On Medial Tibia plateau (where the area = larger than the lateral one)

Stress = force/area => stress ↓ when area ↑ =>

↑ loading on medial side!

Front 8

Meniscus - def

Back 8

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Front 9

Meniscus - function

Back 9

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Front 10

Axis of movement:

- Medial-lateral rotation

- Flexion-extension

- ADD-ABDuction

Back 10

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Front 11

REVIEW: According to the concave-convex rule - What tibia glide (w.r.t femur) accompanies open kinetic chain knee flexion - anterior or posterior?

(open kinetic chain: tibial-on-femoral rotation)

Back 11

Tibia fixed

Front 12

REVIEW: According to the concave-convex rule - What femur glide (w.r.t femur) accompanies closed kinetic chain knee flexion] - anterior or posterior?

(closed kinetic chain: femoral-on-tibial rotation)

Back 12

Posterior

Front 13

REVIEW: Relative Motion of the Femur and Tibia during Knee Flexion and Extension

Back 13

Flexion: Tib Med rot For rol Fem Lat rot Bac rol

Extension: the contrary

Front 14

OSTEOARTHRITIS (OS) def

Back 14

deterioration of joint tissue (bone,cartilage)

Front 15

Describe Screw home mechanism

Back 15

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Front 16

Joint surface motion - summary

Back 16

Knee flexion - vaRus alignment

-> tibia MEDially rotate w.r.t. femur - tibia deviates MEDially w.r.t. femur

Knee extension - vaLgus alignment

-> tibia LATerally rotate w.r.t. femur - tibia deviates LATerally w.r.t. femur

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Mnemonic:

*fLexion has L already -> with VARUS

*extension doesnt have L -> with vaLgus xP

Front 17

Describe Closed Kinetic Chain- Lever Arm

Back 17

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Front 18

How to compensate weak quadriceps?

Back 18

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Front 19

Valgus-varus stress and ABD-ADDuction

Back 19

Valgus stress = ABDuction

Varus stress = ADDuction

Front 20

Summary of Varus/ Valgus knee and the ligaments affected by the stress (important)

Back 20

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Lat. collat ligamt -> resists varus stress/inversion/adduction (imagine cuz of the stress, we have to go IN

-> lat. collat. ligamt pulls us back)

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Med. collat ligamt -> resists valgus stress/eversion/abduction

(imagine cuz of the stress, we have to go OUT -> med. collat. ligamt pulls us back)

Front 21

Summary of Varus/ Valgus knee and the ligaments affected by the stress (important)

Back 21

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Front 22

The significance of the ACL in terms of non-contact injuries regarding the muscles?

Back 22

muscles = Quadriceps (Q) & Hamstrings (H)

Quadricep overload can lead to ACL tear by creating an excessive shear force anteriorly (pull tibia anteriorly +femur staying put) THUS the hamstrings also play a role in counter balancing this anterior shear force by the quads

Front 23

Closed kinetic chain vs Free weight - Which has the least chain reaction force and when the feet are in which position?

Back 23

in a closed kinetic chain movement

Position: where the feet are planted on the ground, the joint reaction force is the least when the patellar femoral joint is in full extension (0 degrees ROM)

Front 24

moment arm decreasing/ increasing vs motion: flexion/extension

Back 24

*flexion: moment arm decreases

*extension: moment arm increases

Front 25

When is patella pulled the most towards femur?

Back 25

In full knee flexion