knee articulation

Question 1

primary function

Answer 1

functional lengthening and shortening of the lower limb

Question 2

stability function

Answer 2

supports the body during both static and dynamic activities

Question 3

the knee joint is also called

Answer 3

tibiofemoral joint

Question 4

tibiofemoral joint

Answer 4

articulation b/w the condyles of the femur proximally and the tibial plateaus distally

Question 5

what kind of joint is the knee joint

Answer 5

modified hinge joint

2 degrees of freedom

Question 6

motions that the knee joint allows

Answer 6

flexion and extension

ER and IR

ABD and ADD

Question 7

femoral condyles

Answer 7

the distal femur flares into 2 condyles

separated posteriorly by an intercondylar notch or fossa

Question 8

femoral condyles anteriorly

Answer 8

blend to form the concave trochlear groove

articulating surface for the patella

Question 9

what shape are the femoral condyles

Answer 9

biconvex

convex in the frontal and sagittal planes

Question 10

in which direction are the femoral condyles longer

Answer 10

anteroposterior direction > mediolateral direction

Question 11

lateral lip of the lateral femoral condyle

Answer 11

approximately 7 mm more anterior than the medial femoral condyle

gives osseous stability for the patella

Question 12

which femoral condyle is larger and longer

Answer 12

medial femoral condyle

Question 13

despite asymmetry of the femoral condyles

Answer 13

condyles are horizontal d/t angulation of the femoral shaft

Question 14

tibial plateaus

Answer 14

proximal end of the tibia flares into a plateau that has a medial and lateral section

Question 15

what are the tibial plateaus separated by

Answer 15

prominent tibial spine

will articulate w/ femoral intercondylar notch

Question 16

what shape are the tibial plateaus in the frontal plane

Answer 16

concave

Question 17

what shape is the medial tibial plateau in the sagittal plane

Answer 17

concave

the total surface area is larger than that of the lateral tibial plateau

–> accommodates the larger medial femoral condyle

Question 18

lateral tibial plateau shape in the sagittal plane

Answer 18

convex

will create a convex on convex in the sagittal plane –> incongruency that is assisted by the menisci

Question 19

the presence of the fibrocartilaginous menisci on the tibial plateaus creates

Answer 19

trough for the femoral condyles

menisci are concave –> create congruency

Question 20

description of the knee joint

Answer 20

modified hinge joint w/ 2 degrees of freedom

Question 21

motions the knee joint allows

Answer 21

flexion/extension (sagittal plane)

IR and ER (transverse plane)

small amount of automatic ABD and ADD in the frontal plane

Question 22

extension ROM

Answer 22

actively = 0

passively = 5-10 degrees beyond 0 is considered hyperextension

Question 23

what could affect extension ROM

Answer 23

passive insufficiency of hamstrings when the hip is flexed

Question 24

what is hyperextension also called in the knee

Answer 24

genurecurvatum

Question 25

flexion ROM

Answer 25

passively = 0-130 or 140

Question 26

what is flexion limited by

Answer 26

soft tissue approximation also dependent on position of the hip --> passive insufficiency of the rectus femoris when the hip is extended

Question 27

rotation ROM

Answer 27

passive only greatest when knee is flexed to 90 degrees (ligaments are lax) least extension occurs w/ knee in full flexion --> screw home mechanism

Question 28

ER ROM

Answer 28

0-40

Question 29

IR ROM

Answer 29

0-30

Question 30

axis of motion

Answer 30

axis for flexion/extension is through the femoral condyles oblique

Question 31

why is the axis of motion oblique

Answer 31

medial femoral condyle is larger and longer

Question 32

how is the axis oriented

Answer 32

medially and inferiorly relative to the transverse plane allows for accessory motions

Question 33

accessory motion with flexion

Answer 33

ADD

Question 34

accessory motion with extension

Answer 34

ABD

Question 35

concept of "instantaneous axis" of motion

Answer 35

femoral condyles are longer than the tibial plateaus --> femur must glide to maintain contact ---> changes the axis of motion ----> as you flex, the axis moves superiorly and posteriorly

Question 36

angles of the knee

Answer 36

medial tibiofemoral angle Q angle

Question 37

medial tibiofemoral angle

Answer 37

medial angle formed by the femoral and tibial shaft axes

Question 38

why isnt the formal shaft axis included in the medial tibiofemoral angle

Answer 38

since the femoral head over hangs the femoral shaft --> the axis of the femoral shaft doesn't coincide with that of the leg ----> but forms an obtuse angle

Question 39

normal medial tibiofemoral angle

Answer 39

185-190 degrees physiologic valgus (genuvalgum) frontal plane angle

Question 40

when does the medial tibiofemoral angle become pathological

Answer 40

when it is increased of decreased from normal

Question 41

medial tibiofemoral angle is increased

Answer 41

greater than 195 degrees genuvalgum knock knees could be influenced by coxa vera

Question 42

medial tibiofemoral angle is decreased

Answer 42

less than 180 degrees genuvarum bow legs coxavalga could influence this

Question 43

what could genuvalgum/genuvarum cause

Answer 43

can lead to asymmetrical loading of the knee and cause arthritic changes --> wear out one compartment of the knee

Question 44

q angle

Answer 44

angle formed by the intersection of a line drawn from the ASIS to the mid-patella and a line drawn from mid-patella to the tibial tubercle

Question 45

what is the q angle intended to represent

Answer 45

the force vector of the quadriceps femoris muscle

Question 46

normal q angle

Answer 46

15 degrees may be greater in women and less in men

Question 47

when is the q angle considered abnormal

Answer 47

greater than 20 degrees will lead to changes in patellar tracking