Bones - Tibia (shin)

Question 1

What does the tibia articulate with?

Other facts?

Answer 1

Proximally - the knee

Distally - the ankle

The second largest bone in the body.

Question 2

Proximal tibia

Bony landmarks?

Articulations?

Answer 2

1) Medial and lateral condyles - the condyles form a flat surface, known as the tibial plateau - articulates with the femoral condyles to form the key articulations of the knee.
2) Intercondyle eminence - located between the medial and lateral intercondylar tubercles of the tibia. This is the main area of attachment for the ligaments and menisci of the knee.
3) Intercondylar tubercles of the tibia - articulate with the interconylar fossa of the femur.

Question 3

Shaft of the tibia

Bony landmarks?

Answer 3

Prism shaped - there are three borders and surfaces; anterior, posterior and lateral. For brevity, only the clinical landmarks are shown:

1) Anterior border - palpable border known as the shin. The tibial tuberosity is located proximally - this is the attachment site for the patella (connect by the patella tendon).
2) Posterior surface - marked proximally by a ridge of bone, known as the soleal line that extends inferomedially, and then blends with the medial border. There is usually a artery nutrient that runs proximal to this line.
3) Lateral border (interroseous border) - gives attachment to the interroseous membrane that binds the tibia and fibula together.

Question 4

Clinical relevance: interosseous access?

Answer 4

A form of vascular access used in the emergency setting. Allows administration of fluids, blood products, and medications directly into the bone marrow.

IO is typically used when intravenous access is not available. There are two main sites where IO takes place:

1) Anteromedial surface, 2-3cm below tibial tuberosity.
2) Proximal to the medial malleolus.

Complications of IO - osteomyelitis, iatrogenic, and compartment syndrome. IO infusions should be stopped when IV access has been achieved.

Question 5

Distal tibia?

Bony landmarks?

Answer 5

The distal tibia is widened to assist in weight-bearing.

Fractures of the tibia are relatively common. There are two main types:

1) High energy trauma - occurs predominantly in the younger population.
2) Low energy trauma or insufficiency fractures - occurs predominantly in the elderly.

Fractures most commonly occur at the shaft of the tibia. They are typically associated with fibula fractures.

Fractures of the proximal tibia are known as tibial plateua fractures - condyles may be broken and damage of the menisci and ligaments are not uncommon.

Fractures are classified using the Schatzker classification, and if very displaced will need operative management.

It is important to monitor for compartment syndrome in the pre- and post-operative phases.

At the ankle, the medial malleolus can be fractured. This is caused by the ankle twisting inwards (over-inversion). The talus of the foot is forced against the medial malleolus, causing a spiral fracture. Rarely occurs in isolation - lateral malleolus may be fractured too. Produces an unstable fracture - may need operative care.