Knee Complex Biomechanics & Kinesiology

Question 1

Sagittal plain TF biomechanics

Answer 1

9 degree posterior tibial slope
Run out of room laterally during sliding
Starts transverse plane motion. One goes up the slope one goes down, creates frontal plane angulation

Question 2

TF Joint sagittal plane osteokinematics

Answer 2

Flexion 130-140 with hip flexion
Flexion 120 with hip extension
Extension 5-10 degrees

Question 3

TF requirements for specific activity

Answer 3

Level surface gait 60-68 degrees flexion
Stairs 80 degrees up 90 degrees down
Sit to stand transfers 90 degrees
Tying a shoe 106 degrees
Full squat to floor 150-160 degrees

Question 4

TF OKC Extension sagittal plane arthrokinematics

Answer 4

Convex femoral condyles
Concave tibial plateau
Roll and slide in same direction
Menisci translate anterior due to meniscopatellar ligaments

Question 5

TF OKC Flexion sagittal plane arthrokinematics

Answer 5

Convex femoral condyles
Concave tibial plateau
Roll and slide in same direction
Menisci translate posterior due to semimembranosus and popliteus

Question 6

Function of the menisci

Answer 6

Increase tibial plateau radius of curvature
Reduces TF friction
Attenuates TF compression loads

Question 7

TF CKC Flexion Sagittal Plane Arthrokinematics

Answer 7

Convex on concave
Opposite Gliding from rolling
Initially, predominantly posterior roll followed by anterior slide

Question 8

TF CKC Flexion Early ROM

Answer 8

By 15 degrees flexion in the medial compartment posterior roll begins to have anterior slide
By 25 degrees flexion the lateral compartment roll begins to have anterior slide

Question 9

TF CKC Flexion Mid ROM

Answer 9

Approximately equal magnitude of posterior roll and anterior slide in both compartments

Question 10

TF CKC Flexion End ROM

Answer 10

Essentially all anterior femoral slide in both compartments

Question 11

TF CKC Flexion ACL control

Answer 11

Angle of ACL inclination greatest at full extension
Anterior directed component force will eventually restrain posterior femoral roll
As TF flexion increases, angle of inclination decreases

Question 12

Hyperextension Impact on ACL

Answer 12

End ROM extension brings the midsubstance of the ACL in contact with the femoral intercondylar shelf
Notch of grant acts as a fulcrum to tension load to the ACL

Question 13

ACL Orientation

Answer 13

Anteromedial to posterolateral
Anteromedial band taut in greater degrees of flexion
Posterolateral Band taut in greater degrees of extension

Question 14

Greatest excursion of tibia anteriorly at….

Answer 14

30 degrees of flexion when neither band of ACL is particularly taut

Question 15

TF CKC Flexion PCL Control

Answer 15

Angle of inclination of PCL greatest at full flexion
Posterior directed force will restrain anterior femoral roll
As tibiofemoral extension increases, PCL angle of inclination decreases

Question 16

TF Joint Transverse Plane Osteokinematics

Answer 16

TF Rotation at 90 degrees of flexion
-40 degrees lateral
-30 degrees medial
Axis of rotation is longitudinal axis running medial to medial tibial intercondylar tubercle
Results in greater excursion laterally during rotation

Question 17

Medial rotation of knee checked by

Answer 17

Cruciate ligaments

Question 18

Lateral rotation of knee checked by

Answer 18

Collateral ligaments

Question 19

Transverse Plane Femoral Condyle Asymmetry

Answer 19

LFC lies in sagittal plane: acts as buttress for patella

MFC lies oblique to sagittal plane

Question 20

Screw Home Mechanism

Answer 20

Automatic ER of tibia with terminal 20-30 degrees of knee extension

Question 21

TF Joint Frontal Plane Posture

Answer 21

Anatomic or longitudinal axis of the tibiofemoral joint is 5-10 degrees of valgus
Femoral longitudinal is oblique due to proximal femoral angle of inclination

Question 22

Mechanical Axis of the TF Joint

Answer 22

Weight bearing line from the center of the femoral head to superior talus center
Allows WB in stance of the medial & lateral TF Compartments

Question 23

Increase in valgus results in…

Answer 23

Compression overload to the lateral compartment

Distraction overload to the medial TF Compartment

Question 24

Increase in varus results in…

Answer 24

Compression overload to the medial TF compartment

Distraction overload to the lateral TF compartment

Question 25

Etiology of coupled motion Frontal Plane TF

Answer 25

In ER, Lateral Femoral Condyle climbs up tibial slope
Lengthens the lateral compartment
Medial Femoral Condyle falls down tibial slope
Shortens medial compartment

Question 26

Frontal Plane TF Osteokinematics

Answer 26

Slight valgus with IR

Slight varus with ER

Question 27

Patellar Function

Answer 27

Contributes to quadriceps moment arm
13% at 90 degrees flexion
31% at 0 degrees flexion
No angle without patella therefore no compressive resultant

Question 28

PF compressive force function

Answer 28

Stabilizes patella in trochlea groove
Patella assures some compression in full extension
Patella not in femoral sulcus

Question 29

PFC force ___ with ____ flexion

Answer 29

Increases; Increased

Question 30

Patellar contact areas

Answer 30

Superior at 90
Middle at 45
Inferior at 20
Medial and Lateral at 120

Question 31

Normal length of patellar tendon

Answer 31

Equal to patellar height

Question 32

ITB impact on patellofemoral mechanics

Answer 32

The fascial slip from the ITB to the patella will add a force with a tendency to laterally translate the patella

Question 33

Quadriceps angle

Answer 33

Resultant force has a tendency to laterally translate the patella
13 in males
18 in females

Question 34

Increased Q angle

Answer 34

Laterally displaced tibial tuburcle
-External tibial rotation and torsion
Medially displaced patella
-Internal femoral rotation
-Femoral anteversion
Laterally displaced ASIS

Question 35

When do we sublux

Answer 35

At the greatest Q angle
Least PF compressive forces
Greatest Quad force
Least patellar contact with femoral trochlea

Full extension or hyperextension