Knee Mechanics

Question 1

Functions of menisci

Answer 1

• Distribute force
• Shock absorber
• Provide nutrients

Question 2

How the menisci move

Answer 2

Posteriorly with flexion of the knee. Medial 5mm, lateral 11 mm.

Question 3

Facilitates movement of the meniscus

Answer 3

Popliteus and semimembranosus

Question 4

Male Q angle

Answer 4

10-13

Question 5

Female Q angle

Answer 5

15-17

Question 6

Line from patella to head of femur

Answer 6

Mechanical axes (Mikulicz line)

Question 7

Line along neck of femur

Answer 7

Anatomic axes

Question 8

Angle difference between mechanical and anatomical axes

Answer 8

6 degrees

Question 9

Knee flexion for gait

Answer 9

60-70

Question 10

Knee flexion for stairs

Answer 10

80

Question 11

Knee flexion for sitting and standing

Answer 11

90+

Question 12

Vascularization of the menisci

Answer 12

Receeds once one becomes weight bearing

Question 13

Types of knee alignment with medial compression

Answer 13

Genu varum

Question 14

Types of knee alignment with lateral compression

Answer 14

Valgus

Question 15

Arthrokinematics of flexion

Answer 15

Femur rolls posteriorly, glides anteriorly

Question 16

Internal/external rotation of the knee in 90 flexion

Answer 16

10 internal, 25 external

Question 17

Screw home open chain

Answer 17

Tibia externally rotates

Question 18

Screw home closed chain

Answer 18

femur internally rotates

Question 19

Part of patella only in contact with femur past 120 flexion

Answer 19

odd facet (medial, upper 45)

Question 20

As flexion increases, contact of the patella moves….

Answer 20

Superior (20 at bottom of patella, 90 at top)

Question 21

Goals of treatment in patellar fractures

Answer 21

• Functional extensor mechanism
• Articular congruity
• Full, painless ROM of the knee

Question 22

Which condyle requires more force to fracture

Answer 22

Medial

Question 23

Term for when a tibial fracture goes up to the plateua

Answer 23

Intra-articular

Question 24

Stages of OA

Answer 24

• Collagen gets disrupted, becomes exposed.
• Chondrocytes overreact and activate macrophages, and enzymes that lead to fissures
• Collagen degrades
• Osteocytes get activated as subchondral bone gets destroyed, osteophytes form and sclerotic bone thickening occurs

Question 25

Main pathologies noticed in OA

Answer 25

• Osteophytes
• Joint narrowing
• Subchondral sclerosis
• Lesions

Question 26

Pain in OA is caused by

Answer 26

Chemical mediators

Question 27

Ligaments limiting anterior tibial translation

Answer 27

ACL

Question 28

Ligaments limiting posterior tibial translation

Answer 28

PCL and posterior meniscofemoral ligament

Question 29

Ligaments providing lateral knee stability

Answer 29

LCL, ACL, PCL, ITB

Question 30

Ligaments providing medial knee stability

Answer 30

MCL, ACL, PCL

Question 31

Dynamic stabilizers, limit anterior tibial translation

Answer 31

• H/S

- Soleus in WB

Question 32

Dynamic stabilizers, limit posterior tibial translation

Answer 32

• Quads
• Popliteus
• Gastrocs

Question 33

Dynamic medial knee stabilizers

Answer 33

• Sartoroius
• Gracilis
• Semtendin/membranosus
  Medial head of gastroc

Question 34

Dynamic lateral knee stabilizers

Answer 34

• Bicep fem

- Lat gastroc

Question 35

Function of bursa

Answer 35

Decrease friction between structures during movement (bone, muscle, ligament, tendon, or skin)

Question 36

Bursa on front of knee cap

Answer 36

Prepatellar

Question 37

Can be compressed with popilteal artery enlargement/aneurysym

Answer 37

Tibial nerve, foot drop + no inversion