pelvis and lower limb trauma

Question 1

which nerve root and arterial systems are at risk with pelvic injury?

Answer 1

Branches of the internal iliac arterial system and the pre‐sacral venous plexus are prone to injury with risk of serious hypovolaemia.

Nerve roots and branches of the lumbosacral plexus are prone to injury.

Question 2

what are the three patterns of pelvic injury?

Answer 2

A lateral compression fracture occurs with a side impact (eg RTA) where one half of the pelvis (hemipelvis) is displaced medially. Fractures through the pubic rami or ischium are accompanied by a sacral compression fracture or SI joint disruption.

A vertical shear fracture occurs due to axial force on one hemipelvis (eg fall from height, rapid deceleration) where the affected hemipelvis is displaced superiorly. The sacral nerve roots and lumbosacral plexus are at high risk of injury and major haemorrhage may occur. The leg on the affected side will appear shorter.

An anteroposterior compression injury may result in wide disruption of the pubic symphysis the pelvis opening up like the pages of a book – the so‐called open book pelvic fracture. Substantial bleeding from torn vessels occurs and as the pelvic volume increases exponentially with the degree of displacement, with widely displaced injuries the pelvis can contain several litres of blood (ie the entire circulating volume) before tamponade and clotting will occur.

Question 3

Management of anteroposterior compression fracture

Answer 3

With open book pelvic fractures it is critical to promptly reduced the displacement and minimizing the pelvic volume to allow tamponade of bleeding to occur. Application of a tied sheet or a special pelvic binder around the outside of the pelvis will hold the reduction temporarily and allow clotting of the vessels. An external fixator will provide more secure initial stabilization.

Question 4

What exam is mandatory to assess sacral nerve root function?

Answer 4

A PR exam is mandatory to assess sacral nerve root function and to look for the presence of blood. The presence of blood indicates a rectal tear rendering the injury an open fracture and carries a higher risk of mortality.

Question 5

low energy pubic fractures in elderly management?

Answer 5

Low energy pubic rami fractures in the elderly tend to be minimally displaced lateral compression injuries (with sacral fracture or SI joint disruption posteriorly) and settle with conservative management over time.

Question 6

which artery is more likely to be damaged in femoral neck fracture?

Answer 6

Medial circumflex artery

Question 7

What management is typically used for hip fractures?

Answer 7

Surgery as non-operative required bed rest which is not suitable

Question 8

what are the risks of intracapsular hip fracutre due to disrupted arterial supply?

Answer 8

Avascular necrosis of the femoral head and non‐union of the fracture.

Question 9

due to the risks with intracapsular hip fracture, how are they usually treated?

Answer 9

these fractures are more reliably treated with a replacement femoral head which can either be a hemi‐arthroplasty (replacing the femoral head alone) or total hip replacement (replacing the acetabulum as well as the femoral head).

Question 10

when is THR compared to hemi-arthroplasty normally used in intracapsular hip fracutre?

Answer 10

Total hip replacement has a higher risk of dislocation (particularly in the cognitively impaired) but can give better function and is reserved for the higher functioning hip fracture patient with hemi‐ arthroplasty generally preferred for the those with restricted mobility and the cognitively impaired patient.

Question 11

How are extracapsular hip fracture usually treated?

Answer 11

Extracapsular hip fractures should not cause avascular necrosis and have a high union rate. These fractures can, therefore, be fixed with internal fixation keeping the patient’s own natural hip joint.

Question 12

describe types of internal fixation for extracapsular hip fracture?

Answer 12

Such fixation can include compression or dynamic hip screw. This fixation consists of a large screw, inserted into the femoral head across the fracture line, and a plate which has a barrel which engages with the lateral end of the screw and is fixed to the femoral shaft. As the patient weight bears, the screw is allowed to slide in the barrel of the plate, which results in compression at the fracture site which promotes fracture healing. The fracture usually heals in a shortened position.

Question 13

what is the risk of displaced femoral shaft fractures?

Answer 13

substantial blood loss of up to 1.5L can occur. Fat from the medullary canal can enter the damaged venous system resulting in fat embolism with confusion, hypoxia and risk of ARDS.

Question 14

Initial management of femur fracture?

Answer 14

Initial management after initial resuscitation includes optimizing analgesia with a femoral nerve block and application of a Thomas splint which stabilizes the fracture minimizing further blood loss and fat embolism.

Question 15

definitive management of femoral shaft fracturs?

Answer 15

Definitive management is usually closed reduction and stabilization with an intramedullary nail however minimally invasive plate fixation with minimal disruption to the fracture site blood supply can also be used.

Question 16

what is particular about childrens bones in fractures?

Answer 16

Children’s bones are more elastic and pliable and tend to buckle or partially fracture or splinter with some degree of continuity of some “fibres” of bone (like breaking a green stick from a tree) rather than break completely. Hence the terms “buckle fracture” and “greenstick fracture”.

The periosteum (which serves to increase the width/circumference of growing long bones) is much thicker and tends to remain intact which can help stability and can assist reduction if required.

Children’s fractures heal more quickly than adults due to the ticker periosteum which is a rich source of osteoblasts. Children have much greater potential to remodel as they grow with bone being formed along the line of stress and children can correct angulation up to 10° per year of growth remaining in that bone.

Question 17

how are children’s bone fractures usually managed?

Answer 17

For these reasons children’s fractures tend to be surgically stabilized less frequently and greater degrees of displacement or angulation can be accepted. If the fracture position is unaccepatable, manipulation and casting may be all that is required accepting a degree of residual angulation or displacement. Furthermore, if surgical stabilization is required for more unstable injuries, less invasive temporary pins, wires and flexible rods tend to be used with plates and screws reserved for very unstable periarticular injuries or where a fracture is associated with a dislocation and loss of position may result in redislocation (eg Monteggia and Galeazzi injuries of the forearm).

Once a child has reached puberty (around 12‐14), fractures tend to be treated as an adult’s fracture would as the remodeling potential is less.

Fractures around the physis (growth plate) also have the potential to disturb growth which could result in a shortened limb or an angular deformity if one side of the physis is affected by growth arrest.