Lecture: Clinical Anatomy of the Knee

Question 1

palpable surfaces of the knee and leg

Answer 1

• patella
• lateral and medial condyles of knee
• tibia
• medial malleolus of tibia
• lateral malleolus of fibula
• calcaneus (heel of foot)

Question 2

What is the importance of the tibial tuberosity

Answer 2

attachment point for the patella ligament

Question 3

Why are the shallowly concave condyles of the tibia a reason for the increased vulnerability of the knee joint

Answer 3

reduce stability

Question 4

What does the fibula articulate with

Answer 4

two primary points of the tibia and the lateral aspect of the femur above it.
The fibula is enmeshed in the connective tissue of the knee but provides a moderately small architectural contribution to the joint. It does provide points of connection for some knee musculature.

Question 5

What does the patellar articulate with

Answer 5

intercondylar notch of femur

Question 6

patella function

Answer 6

elevates the quadriceps muscles from the center of knee rotating, increasing the efficiency and provides it with leverage for extending the leg.

Question 7

What are the repercussions of a patella-ectomy?

Answer 7

Removal of the patella compromises extension (but is performed)

Question 8

Describe the two knee articulations

Answer 8

The tibiofemoral joint: medial and lateral condyles of the distal femur articulate with the medial and lateral condyles of the proximal tibia.The patellofemoral joint: the anterior distal femur articulates with the patella.

Question 9

Knee
* joint type
* movements permitted

Answer 9

• modfied hinge
• flexion (~130-140 degrees) and extension (0- -10 degrees) ; internal and external rotation

Question 10

Describe the Q angle

• list normal values

Answer 10

The quadriceps (Q) angle can be described as the angle formed by the bisection of two lines, one line drawn from the ASIS to the center of the patella, and the other line drawn from the center of the patella to the tibial tubercle.

As the force of the quadriceps muscle contraction is transmitted through the tibial tubercle, at an angle to the
quadriceps muscle pull, the patella experiences a laterally directed force.
This force is resisted dynamically by the vastus medialis muscle, which is attached more distally to the patella than the vastus lateralis. The angle is a measure of the tendency of the patella to move laterally when the quadriceps muscles are contracted.

Various normal values for the Q-angle have been reported. The most frequent ranges cited are 8–14 degrees for males
and 15–17 degrees for females. The discrepancy between males and females allegedly results from the wider pelvis of
the female, although this has yet to be proven.

Question 11

Genu varum vs genu valgum

Answer 11

genu varum (bow legged): decreased Q angle

genu valgum (knock knee): increased Q angle

Question 12

valgus vs varus

Answer 12

valgus: distal bone displaced lateral
varus: distal bone displaced medially

Question 13

Describe intrinsic and extrinsic factors that can contribute to abnormal patellar tracking

Answer 13

intrinsic
* weak vastus medialis
* bowstring force on the patella
* tight iliotibial band or lateral retinaculum
* hypertrophy of the vastus lateralis

all cause laterally tracking of patella

extrinsic
* weak external rotators or abductors of the hip
* pronation of foot
–> larger q angle, knock knee genu valgum

Question 14

Describe the structures damaged during medial impact of the knee

Answer 14

lateral meniscus
LCL

Question 15

Describe the structures damaged during lateral impact of the knee

Answer 15

• unhappy triad; ACL MCL meniscus

Question 16

Describe the unhappy triad

Answer 16

• ACL, medial meniscus, MCL

Question 17

meniscus function

Answer 17

• shock absorber
• deepen articular surface of tibia to increase stability

Question 18

Why is the medial meniscus usually damaged with the MCL?

Answer 18

they’re attached to eachother