11. Osteology of the distal femur, patella, tibia and fibula

Question 1

Why does the shaft of the femur descend with a slight medial angulation?

Answer 1

This brings the knees closer to the body’s centre of gravity, hence increasing the stability of the body.

Question 2

What is located on the posterior surface of the femoral shaft?

Answer 2

Linea aspera - roughened ridge of bone

Question 3

What does the linea aspera become proximally?

Answer 3

The medial border of the linea aspera becomes the pectineal line proximally

The lateral border becomes the gluteal tuberosity for insertion of the gluteus maximus

Question 4

What does the linea aspera become distally?

Answer 4

• Distally, the linea aspera widens and forms the floor of the popliteal fossa
• the medial and lateral borders form the medial and lateral supracondylar lines.
• The medial supracondylarline ends at the adductor tubercle, where the adductor magnus muscle inserts. • • • The lateral supracondylar line ends at the lateral femoral condyle.

Question 5

What is the distal femur characterised by?

Answer 5

The medial and lateral condyles

Question 6

What forms the knee joint?

Answer 6

The medial and lateral condyles articulate with the tibia and patella to form the knee joint

Question 7

Why is the medial femoral condyle larger than the lateral femoral condyle?

Answer 7

It bears more weight in the standing position because the centre of mass of the body passes medial to the knee joint

Question 8

Where is the trochlear (patellofemoral) groove located?

Answer 8

Lies on the anterior surface of the distal femur articulates with the patella

Question 9

What does the lateral femoral condyle help to prevent?

Answer 9

• The more prominent lateral femoral condyle helps prevent lateral displacement of the patella during patellar tracking.
• People with a flatter lateral femoral condyle (a natural anatomical variant) are more likely to experience patellar instability

Question 10

What do the inferior and posterior surfaces of the femoral condyles articulate with?

Answer 10

The meniscus of the knee and the tibia

Question 11

What are the epicondyles?

Answer 11

The medial and lateral epicondyles are bony elevations above the non-articular areas of the condyles

Question 12

Which epicondyle is larger?

Answer 12

medial epicondyle is larger

Question 13

Where do The medial and lateral collateral ligaments of the knee originate from?

Answer 13

The medial and lateral collateral ligaments of the knee originate from their respective epicondyles

Question 14

Where do the ligaments of the knee attach?

Answer 14

• The anterior cruciate ligament (ACL) attaches to the medial aspect of the lateral femoral condyle
• the posterior cruciate ligament (PCL) to the lateral aspect of the medial femoral condyle

Question 15

What is the intercondylar fossa?

Answer 15

A depression found on the posterior surface of the femur between the two condyles

Question 16

Where is the patella located?

Answer 16

• at the anterior aspect of the knee joint
• within the trochlear (patellofemoral) groove
• its superior aspect is attached to the quadriceps tendon
• its inferior aspect is attached to the patellar ligament

Question 17

Describe the shape of the patella bone

Answer 17

• triangular shaped
• has anterior and posterior surfaces
• the apex is inferior and connected to the tibial tuberosity by the patella ligament
• the base forms the superior aspect of the bone and provides the insertion area for the quadriceps tendon

Question 18

How is the posterior surface of the patella marked?

Answer 18

• articulates with the femur
• marked by two facets:
> medial which articulates with the medial femoral condyle
> lateral that articulates with the lateral femoral condyle

Question 19

What are the functions of the patella?

Answer 19

• By enabling the quadriceps muscle to directly cross the anterior aspect of the knee and by acting as a fulcrum, the patella enhances the leverage that the quadriceps tendon can exert on the femur, increasing the mechanical efficiency of the muscle by 33-50%.
• Protection. It protects the anterior aspect of the knee joint from physical trauma.
• It reduces the frictional forces between the quadriceps and the femoral condyles during extension of the leg.

Question 20

What is the proximal tibia aided by?

Answer 20

It is widened by the tibial medial and lateral condyles which aid in weight bearing

Question 21

Where does the proximal and distal ends of the tibia articulate?

Answer 21

It has expansions at its proximal and distal ends where it articulates at the knee and ankle joints respectively

Question 22

What is the tibial plateau?

Answer 22

A flat surface formed by the tibial condyles that articulates with the femoral condyles to form the major articulation of the knee joint

Question 23

Where does the head of the fibula articulate with the proximal tibia?

Answer 23

at the proximal tibiofibular joint. It does not form part of the knee joint.

Question 24

Where is the intercondylar area located?

Answer 24

The intercondylar area is located between the tibial condyles

Question 25

Where is the intercondylar eminence located?

Answer 25

In the centre of the intercondylar area located between the tibial condyles

Question 26

What is the importance of the intercondylar eminence and intercondylar area?

Answer 26

• On either side of the intercondylar eminence are the medial and lateral intercondylar tubercles.
• The intercondylar eminence is the main site of attachment for the anterior cruciate ligament and the menisci of the knee joint.
• The posterior cruciate ligament attaches to the posterior edge of the intercondylar area

Question 27

What do the intercondylar tubercles of the tibia articulate with?

Answer 27

The intercondylar tubercles of the tibia articulate with the intercondylar fossa of the femur.

Question 28

What is the shape of the tibial shaft?

Answer 28

• prism

- three borders: anterior, posterior and lateral

Question 29

Describe the anterior border of the tibial shaft?

Answer 29

palpable subcutaneously down anterior surface of leg. It’s proximal aspect is marked by the tibial tuberosity, the insertion point for the patellar ligament

Question 30

Describe the posterior border of the tibial shaft?

Answer 30

marked by a ridge of bone called the soleal line, which is the site of origin for part of the soleus muscle. The soleal line extends inferomedially to eventually blend with the medial edge of the tibia

Question 31

Describe the lateral border of the tibial shaft?

Answer 31

`also known as the interosseous border. This gives attachment to the interosseous membrane that binds the tibia and the fibula together.

Question 32

What is the distal tibia aided by?

Answer 32

Widens to assist with weight bearing

Question 33

What is the medial malleolus?

Answer 33

• A bony projection continuing inferiorly on the medial aspect of the tibia.
• Articulates with the tarsal bones to form part of the ankle joint

Question 34

What is found lateral to the medial malleolus?

Answer 34

The fibular notch, where the fibula is bound to the tibia to form the inferior tibiofibular joint

Question 35

Where is the fibula located?

Answer 35

lateral side of lower leg

Question 36

What is the function of the fibula?

Answer 36

Act as an attachment for muscles

Question 37

What are the main articulations of the fibula?

Answer 37

1) proximal tibiofibular joint - articulates with the lateral condyle of the tibia
2) distal tibiofibular joint - articulates with the fibular notch of the tibia
3) ankle joint - articulates with the talus bone of the foot

Question 38

How does the fibula articulate with the tibia proximally?

Answer 38

At the proximal end, the fibula has an enlarged head, which contains a facet for articulation with the lateral condyle of the tibia

Question 39

Where is the common peroneal (/ fibular) nerve most commonly injured?

Answer 39

It winds around the posterior and lateral surface of the neck of the fibula near the knee - therefore vulnerable to damage in a proximal fibular fracture

Question 40

What is the lateral malleolus?

Answer 40

Where the fibula continues inferiorly and distally. The lateral malleolus of the fibula is more prominent than the medial malleolus of the tibia and can be palpated at the ankle on the lateral side of the leg

Question 41

Which lip of the trochleR groove is more prominent and why?

Answer 41

Lateral lip of trochlear groove is more prominent – resists patellar dislocation