knee

Question 1

2 joints of the knee

Answer 1

tibiofemoral patellofemoral

Question 2

movements of the knee joint

Answer 2

flexion-extension rotation (during flexion only)

Question 3

why is there no rotation of the knee during extension

Answer 3

because the ligaments of the knee are tight and wont allow rotation

Question 4

what is the close packed position of the knee

Answer 4

extension (most stable)

Question 5

3 support structures of the knee

Answer 5

cruciate ligaments collateral ligaments menisci

Question 6

explain the shape of the articular surfaces of the femur

Answer 6

medial condyle is longer than lateral lateral condyle is wider than medial

Question 7

what is the function of the notch in the intracondylar space of the femur

Answer 7

where the anterior cruciate ligament lies

Question 8

explain the movement of the femur on the tibia during extension

Answer 8

the femur orates medially on the fixed tibia during the last 15-20 degrees of extension around tight ACL (passive screw-home mechanism)

Question 9

explain the movement of the femur on the tibia during flexion

Answer 9

femur rotates laterally on the fixed tibia - requires active contraction of popliteus muscle

Question 10

what are the structures that are enclosed in the knee joint capsule

Answer 10

• menisci - cruciate ligaments (intracapsular but extrasynovial) - synovial membrane - synovidal fluid

Question 11

what are the anterior reinforcements of the capsule of the knee

Answer 11

the patellar tendon and retinacular fibres

Question 12

what are the lateral reinforcements of the capsule of the knee

Answer 12

popliteus muscle biceps femoris muscle iliotibial tract

Question 13

what is the medial reinforcement of the capsule of the knee

Answer 13

pes anserinus tendons

Question 14

what is the posterior reinforcement of the capsule of the knee

Answer 14

oblique popliteal ligament

Question 15

what are the muscle insertions of the pes anserinus tendons reinforcing the knee joint capsule

Answer 15

sartorius gracilis bursa semiTendinosus “Say Grace Before Tea”

Question 16

explain the deficiencies in the knee joint capsule

Answer 16

2 deficiencies: - above patella for suprapatellar bursa - posteriorly for popliteus tendon and semimembranousus bursa

Question 17

attachments of the ACL

Answer 17

from the anterior part of the tibia to the lateral condyle of the femur

Question 18

attachments of the PCL

Answer 18

from the posterior tibia up to the medial condyle of the femur

Question 19

functions of the ACL

Answer 19

(passively rotates lateral condyle in medial direction) - stops the tibia from being displaced anteriorly from the femur or the femur being displaced posteriorly from the tibia - assists internal rotation of the femur - contributes to locking in extension

Question 20

function of the PCL

Answer 20

stops the femur from sliding forwards off the tibial plateau during extension and stops posterior displacement of the tibia during flexion

Question 21

how does ACL injury occur

Answer 21

when rotation occurs laterally (opposite direction) during extension on a weight bearing leg

Question 22

how does PCL injury occur

Answer 22

• fall on flexed knee - bumper bar impact

Question 23

function of medial collateral ligament

Answer 23

• resists abduction forces of the knee and lateral rotation of the tiba - limits anterior displacement of the tibia when ACL damaged

Question 24

why is it that when the medial collateral ligament is damaged you often get damage to the medial meniscus

Answer 24

because the medial collateral ligament deep fibres attach to the medial meniscus

Question 25

how does MCL injury occur

Answer 25

usually with a rotational injury with a force in a lateral direction

Question 26

function of lateral collateral ligament

Answer 26

resists adduction forces (movement medially of the tiba in respect to the femur)

Question 27

why is the LCL not as often damaged compared to the MCL

Answer 27

because it is separated from the joint by the tendon of popliteus

Question 28

function of the menisci of the knee joint

Answer 28

• shock absorb - weight distribution

Question 29

why is the medial meniscus more commonly injured compared to the lateral

Answer 29

• attachment to MCL - longer - horns are further apart - less mobile

Question 30

what is the normal alignment of the patellofemoral joint maintained by

Answer 30

• vastus medialis muscle (active) - medial patellar retinaculum (passive) - raised lip on lateral femoral condyle (passive)

Question 31

how does dislocation of the patella occur

Answer 31

patella pulled laterally by the strong quadriceps muscle

Question 32

how does chondromalacia patella predispose to subluxation/dislocation of the patella

Answer 32

because there is a mechanical problem of tracking of the patella in the femoral groove due to degeneration of cartilage