MSK Bones of the lower limb

Question 1

What are the bony structures of the proximal femur and what are their functions?

Answer 1

The head: has a depression for attachment of ligament, articulates with acetabulum of the pelvis

The neck

Greater trochanter: originates from anterior shaft, site of attachment for abductor and lateral rotators of the leg

Less trochanter: site of attachment for posts major and iliacus muscles

Intertrochanteric line: anterior ridge connecting the trochanters, where the iliofemoral ligament attaches. After it passes the lesser trochanter it is the pectineal line

Intertrochanteric crest: posterior ridge connecting 2 trochnaters, there is the quadrate tubercle where the quadrates femoris attaches

Question 2

What are the types of proximal femur fracture?

Answer 2

Intracapsular fracture:
Most common in elderly women - result of minor trip
Occurs within the joint capsule, can damage medial femoral circumflex artery causing avascular necrosis of femoral head
Distal fragment pulled upwards so shorter leg with toes pointing laterally

Extracapsular fracture:
More common in young and middle aged
Blood supply to head of femur remains intact
Leg is shortened and laterally rotated

Question 3

What is the linea aspera?

Answer 3

Roughened bone on the posterior humeral shaft
Proximally the medial border becomes the pectineal line, the lateral border becomes the gluteal tuberosity (glut max attaches)

Distally the line aspera forms floor of popliteal fossa, medial and lateral borders form medial and lateral supracondylar lines
The medial supracondylar line stops at the adductor tubercle where the adductor magnus attaches

Question 4

What are the cause and consequence of fractures to the femoral shaft?

Answer 4

Relatively uncommon and require a lot of force so usually a result of trauma e.g. vehicular accident.

A spiral fragment results in shortening of the leg due to the fragments overriding each other.

Because the injury results from high force there is often soft tissue damage. Very important to establish if femoral artery compromised.

Question 5

What are the bony structures of the distal femur and what are their functions?

Answer 5

Medial and lateral condyles: rounded areas that articulate with the tibia and patella

Medial and lateral epicondyles: attachment of some muscles and collateral ligaments of knee joint

Intercondylar fossa: Depression found on posterior surface containing 2 facets for attachment of knee ligaments

• facet for attachment of posterior cruciate ligament found on medial wall of intercondylar fossa
• facet for attachment of anterior cruciate ligament found on lateral wall of intercondylar fossa

Question 6

What type of bone is the patella?

What is the patella attached to?

Answer 6

Largest sesamoid bone in the body, sits within the quadriceps tendon
Superiorly to quadriceps tendon
Inferiorly to patellar ligament

Question 7

What are facets on the posterior surface of the patella?

Answer 7

Medial facet - articulates with medial condyle of femur

Lateral facet - articulates with lateral condyle of femur

Question 8

What are the functions of the patellar?

Answer 8

Enhances leverage that the quadriceps tendon can exert on the femur - increasing efficiency of muscle

Protects anterior knee joint from trauma

Question 9

What are the causes and consequences of patellar dislocations?

Answer 9

Caused by high force impact on patellar or forceful sudden twisting of the knee e.g. football, rugby, ice hockey
Most dislocations occur laterally

Question 10

What are the causes and consequences of patellar fractures?

Answer 10

Usually result from direct trauma
Most common in males (20-25yrs)
If the patella fractures into fragments they will usually separate

Question 11

What are the bony landmarks of the proximal fibula?

Answer 11

An enlarged head which has a facet for articulation with lateral condyle of the tibia.
On posterior lateral surface of neck the common fibular nerve can be found

Question 12

What are the bony landmarks of the distal fibula?

Answer 12

There is the lateral malleolus (more prominent than medial melleolus) can be palpated at lateral ankle

Question 13

What are the common fractures to the fibula?

Answer 13

The lateral malleolus is prone to fracture
Two causes:
- forced external rotation of the ankle, the force of the talus against the bone causes a spiral fracture
- eversion (foot twisted outwards - less common) the tales presses against the lateral malleolus causing a transverse fracture

Question 14

What are the bony landmarks of the proximal tibia?

Answer 14

The medial and lateral condyles form a flat surface called the tibial plateau - this articulates with the femoral condyles to form the knee joint.

Between the condyles there are 2 intercondylar tubercles and a roughened area that make up the intercondylar eminance. This is the attachment site for the menisci of the knee and the intercondylar tubercles fit into the intercondylar fossa of the femur.

On the anterior surface is the tibial tuberosity which is that attachment of the patella ligament

Question 15

What are the bony landmarks of the tibial shaft?

Answer 15

Anterior border - tibial tuberosity
Posterior surface - soleal line where the soleus muscle originates
Lateral border - interosseus border, attaches to interosseous membrane that binds tibia and fibula

Question 16

What are the bony landmarks of the distal tibia?

Answer 16

Medial malleolus that articulates with tarsal bones
On the posterior there is a groove where the tibialis posterior muscle attaches
The fibular notch is where the fibula articulates

Question 17

What are the common tibia fractures?

Answer 17

Tibia fractures are common - proximal end most vulnerable
The medial malleolus can also fracture if the ankle is listed inwards, as the tarsal bone is forced against the medial malleolus
Fragment displacement is minimal

Question 18

What are the tarsal bones in the proximal group and what are their articulations?

Answer 18

Talus - most superior of the tarsals
Articulates with tibia and fibula
Articulates at the subtalar joint with calcaneous
Articulates at the talonavicular joint with the navicular

Calcaneous - makes up the heel, and has an calcaneal tuberosity which the achilles tendon attaches
Articulates at the subtalar joint with tarsal
Artculates at the calcaneocuboid joint with the cuboid

Question 19

What are the tarsal bones in the intermediate group and what are their articulations?

Answer 19

Only the navicular
Articulates at the talonavicular joint with the talus
Articulates with cuboid and 3 cuneiforms

On the plantar side there is a tuberosity for the attachment of the tibialis posterior tendon

Question 20

What are the tarsal bones in the distal group and what are their articulations?

Answer 20

Cuboid - most lateral bone in distal row
Articulates with calcaneous and 2 metatarsals

3 Cuneiforms (lateral, intermediate, medial)
Wedge shape
Articulate with navicular and metatarsals
They help form the transverse arch across the foot

Question 21

How many phalanges are in the toes?

Answer 21

3 in all toes except big toe which only has 2

Question 22

What are the common fractures to the talus?

Answer 22

Neck fractures: Caused by excessive dorsiflexion
Neck of talus pushed against tibia, blood supply may be disturbed leading to avascular necrosis

Body fractures: caused by jumping from a heart

Question 23

What are the causes and consequences of fractures to the calcaneus?

Answer 23

Often fractured in a crush type injury eg falling on heel from a height
The bone can break into several pieces (comminuted fracture) and appears shorter and wider on xray

After treatment the sub-talar joint may become arthritic

Question 24

What is the general structure of the metatarsals?

Answer 24

Distal head, proximal base and shaft

Question 25

What are the articulations of the metacarpals?

Answer 25

Proximally - tarsometatarsal joint (cuneiforms/cuboid)
Laterally - intermetatarsal joints between metatarsals
Distally - metatarsophalangeal joint

Question 26

What are the causes of fractures to the metatarsals?

Answer 26

Most common is a direct blow e.g. a heavy object dropped onto the foot

Repeated stress to the bone such as in athletes can cause a stress fracture (incomplete fracture).

Excessive inversion of the foot can cause a fracture. If the inversion is forceful the fibularis brevus muscle can avulse (tear off) base of metacarpal 5