Knee Biomechanics Flashcards
What is the size of the posterior tibial slope
9 degrees inferiorly
What is the closed pack position of the knee
Extension
What is the normal range of knee flexion with hip flexion
130-140
What is the normal knee flexion with hip extension
120
What is the only quadriceps muscle to cross the hip
Rectus femoris
How much knee flexion is needed for level surface gait
60-68
How much knee flexion is needed for ascending stairs
80
How much knee flexion is needed for descending stairs
90
How much knee flexion is needed for sit stand sit transfer
90
How much knee flexion is needed to tie a shoe
106
How much knee flexion is needed for full squat to floor
150-160
What is normal range of knee extension
5-10 hyperextension
What is the AAOS normal range for knee flexion
10-0-135
Which meniscal horn tears are more effected while descending stairs
Posterior horns
Which meniscal horn tears are more effected while ascending stairs
Anterior horns
How can your knee flex to 150-160 during a deep squat if the normal range is 135
Due to the super incumbent body weight
Are the femoral condyles concave or convex
Convex
Is the tibial plateau concave or convex
Concave
Which side of the tibial plateau is more concave and which is flat/slightly convex
Lateral is flat/slightly convex
Medial is more concave
What are the arthrokinematics of OKC knee extension
Concave tibial plateau moving on convex femoral condyles
Which way do the mensci translate during OKC knee motions
The same direction of the roll
Which way if the patella drawn during OKC knee extension
Superiorly
What does the patella moving superiorly do to the menisci
Pulls them anteriorl
How does the patella pull the menisci anteriorly
Due to the attachment of the coronary ligaments from patella to the anterior horns of the mensci
Which way are the menisci drawn during OKC knee flexon
Posteriorly
What cause the menisci to be drawn posteriorly during OKC knee flexion
Attachment of the semimebranosus and popliteus to the posterior horns of the menisci
Which menisci do the semimembranosus and popliteus attache to
Semimembranosus: medial meniscus
Popliteus: lateral meniscus
What is the function of the popliteus
Initiate flexion of the knee
What does the popliteus act like
Anconeus
What are the functions of the menisci (3)
- Increases tibial plateau radius of curvature
- Reduces tibiofemoral friction
- Attenuates tibiofemoral compression loads
How much of the menisci are red zone and white zone
Red: 1/3
White: 2/3
Which compartment of the knee has more surface area
Medial compartment
What are the arthrokinematics of CKC knee flexion
Convex femur on concave tibia
What is the roll and slide with CKC knee flexion
Posterior roll and anterior glide
What happens at 15 degrees of knee flexion
Medial compartment posterior roll begins to be accompanied by a small amount of anterior slide
Why is there anterior slide on the medial compartment during knee flexion at 15 degrees
Due to the larger surface area resulting in more ground to cover
How do you name rotation of the knee
Based on the tibia
What type of knee rotation occurs with CKC knee flexion
Internal rotation
What type of knee rotation occurs with CKC knee extension
External rotation
What happens at 25 degrees of CKC knee flexion
Lateral compartment posterior roll begins to be accompanied by anterior glide
What happens at mid ROM CKC knee flexion
Equal amounts of posterior roll and anterior glide in both compartments
What happens at late ROM CKC knee flexion
Greater anterior glide than posterior roll in both compartments
What happens at end ROM CKC knee flexion
All anterior femoral glide in both compartments
When is the angle of inclination of the ACL the greatest
Full knee extension
What is the main function of the ACL
Convert roll into slide
What happens to the inclination of the ACL as knee flexion increases
Decreases
Is the ACL in a better position to create anterior glide of the femur on the tibia in full knee extension or knee flexion and why
Knee flexion due to decreased angle of inclination
What position is the ACL most vulnerable to being torn full knee extension or knee flexion
Knee flexion
What happens to the ACL at end ROM extension
The midsubstance of the ACL comes in contact with the femoral intercondylar shelf
What is another name for the intercondylar shelf
Notch of Grant
What does the contact point with the notch of Grant do to the ACL
Acts as a fulcrum to tension load the ACL
True or False:
Constant rubbing of the ACL on the notch of Grant can lead to an ACL tear
True
Where does the ACL insert on the femur
Medial aspect of lateral femoral condyle
Where does the ACL run
Anteromedial to posterolateral
Do we want ligaments to have small or large angles of inclination
Small angles of inclination
What are the 2 bands of the ACL
- Anteromedial band (AMB)
2. Posterolateral band (PLB)
When is the AMB of the ACL most taut
Greater degrees of flexion
When is the PLB of the ACL most taut
Greater degrees of extension
What is isometricity
Some portion of a ligament is taut in all varying degrees of osteokinematic motion
True or False:
The ACL has isometricity
True
At what amount of knee flexion are both bands of the ACL not particularly tensed
30 degrees
What is the lack of tension at 30 degrees good for
Testing the integrity of the ACL
Why is there great tension in both bands of the ACL during hyperextension of the knee
The ACL is hitting the Notch of Grant
When is the angle of inclination of the PCL the greatest
Full flexion
Where does the PCL insert on the femur
Lateral aspect of medial femoral condyle
Where does the PCL run
Posterolateral to anteromedial
How many bundles does the PCL have
2
Do the bundles of the PCL have different or the same function
Same