Pelvis and Lower Limb Trauma

Question 1

Explain the polo mint theory

Answer 1

It applies to the pelvic ring

(the pelvic ring is formed by the sacrum, ilium, ischium & pubic bones)

If the pelvic ring is disrupted in one place, there is invariably a further disruption elsewhere in the ring

Question 2

What are the 3 main patterns of injury that occur in the pelvis?

Answer 2

1. A lateral compression fracture
2. A vertical shear fracture
3. An anteroposterior compression injury

Question 3

Discuss lateral compression fractures of the pelvic ring

Answer 3

• occurs with a side impact
• one half of the pelvis is displaced medially
• fractures through the pubic rami or ischium are accompanied by a sacral compression fracture or SI joint disruption

Question 4

Discuss vertical shear fractures of the pelvic ring

Answer 4

• occurs due to axial force on one hemipelvis where the affected hemipelvis is displaced superiorly
• sacral nerve roots and lumbosacral plexus are at high risk of injury and major haemorrhage may occur
• the leg on the affeced side will appear shorter

Question 5

Discuss anteroposterior compression injury

Answer 5

• may result in wide disruption of the pubic symphysis, the pelvis opening up like the pages of a book: “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 injury the pelvis can contain several litres of blood (i.e. the entire circulating volume) before tamponade and clotting will occur

Question 6

We know that pelvic injuries are usually high energy and so involve other systems. What systems might this include?

Answer 6

Bladder and urethral injuries (blood at the urethral meatus) may also occur and urinary catheterisation may risk further injury!

Urological assessment and intervention may be required.

Question 7

What exam MUST you do to a patient presenting with a pelvic fracture?

Answer 7

A PR exam is mandatory to assess sacral nerve root function and to look for the presence of blood.

Question 8

Why is it important to do a PR exam in someone presenting with a pelvis injury?

Answer 8

Blood on a PR exam would indicate a rectal tear rendering the injury an open fracture and carries a higher risk of mortality.

Question 9

An elderly patient presents with a low energy pubic rami fracture. What type of fracture is it likely to be?

Answer 9

Tends to be minimally displaced lateral compression injuries (with sacral fracture or SI joint disruption posteriorly) and settle with conservative management over time.

Question 10

A car driver’s knees collide with the dashboard in a RTA. What injury might they have?

Answer 10

Posterior wall fractures of the acetabulum may be associated with a hip dislocation.

In these cases, the posterior wall of the acetabulum is fractured as the head of the femur is pushed out the back of the joint.

Question 11

What imaging investigation is most appropriate for suspected acetabulum fractures?

Answer 11

CT Scan

The pattern of the fracture can be difficult to determine on plain X-Rays (oblique views may help) and CT scans help to determine the pattern of the fracture and are essential for surgical planning.

Question 12

Non-operative management of hip fracture is just as risky as operative management

T/F

Answer 12

Yes

Almost all hip fractures undergo surgery within the first 24 hours unless time is required for medical optimisation

Question 13

Describe the arterial supply of the femoral head

Answer 13

comes from a ring anastomosis of the circumflex femoral arteries at the insertion of the hip capsule at the base of the femoral neck

The medial and lateral circumflex femoral arteries are branches of the profunda femoral artery

Arteries from the ring anastomosis travel up the femoral neck and into the femoral head

Question 14

For which patients are hemi-arthroplasties more appropriate than a total hip replacement?

Answer 14

those with restricted mobility and the cognitively impaired

Question 15

Extra-capsular hip fractures are more associated with AVN than intra-capsular hip fractures

T/F

Answer 15

FALSE

Extracapsular hip fractures should not cause AVN and have a high union rate

Question 16

What is the typical surgical management of an extra-capsular hip fracture?

Answer 16

Internal fixation, keeping the patient’s own natural hip joint. Either:

• compression
• dynamic hip screw

Question 17

Which patient and MoI is most common in subtrochanteric hip fractures?

Answer 17

Usually occur in elderly patient with osteoporosis & fall onto the side

Question 18

If a femoral shaft fracture hasn’t occurred as a high energy injury, what risk factors might the patient have that contributed to this injury?

Answer 18

• osteoporosis
• metastatic disease
• Paget’s disease
• paradoxically long term bisphosphonate use for osteoporosis

Question 19

(in terms of stablisation) what are the roles of the medial and lateral collateral ligaments?

Answer 19

resist valgus and varus stresses respectively

Question 20

(in terms of stablisation) what are the roles of ACL and PCL?

Answer 20

stabilise the tibia in the sagittal and rotational planes

Question 21

What position is usually adopted by those with a distal femoral fracture?

Answer 21

Flexed position due to the pull of the gastrocnemii muscles

Question 22

Is a knee dislocation a surgical emergency?

Answer 22

A knee dislocation is a surgical emergency with a high incidence of vascular injury (intimal tears, vascular occlusion, complete transection), nerve injury and compartment syndrome

Question 23

What way does the patella usually dislocate?

Answer 23

Laterally

due either to a direct blow or a contraction of the quadriceps with a rotational force with the patella not engaged in the trochlea

Question 24

What are tibial plataeu fractures?

Answer 24

They are intra-articular fractures with either:

• a split in the bone,
• a depression of the articular surface
• or a combination of both.

Question 25

A patient presents with a valgus stress injury to the knee. Waht do you think has happened?

Answer 25

(there may be)

a lateral plataeu fracture with a failure of the MCL and possibly ACL with increasing force

Question 26

A patient sustained a direct blow from a car bumper as they were using the zebra crossing.

What injury might they have sustained?

Answer 26

Proximal fibular fracture and injury to the common peroneal nerve with foot-drop

Question 27

A patient presents with a varus injury.

What do you think may have happened?

Answer 27

Medial plateau fracture (less common than lateral i think?) with potential for LCL rupture and stretch injury to the common peroneal nerve

Question 28

Which fractures are the commonest cause of compartment syndrome after trauma?

Answer 28

Tibial shaft fractuers

(esp. anterior compartment of the leg)

Question 29

What is a “pilon” fracture?

Answer 29

Intra-articular fractures of the distal tibia are termed “pilon” fractures.

They generally require ORIF to ensure a congruent articular surface.

Question 30

What movements are most ankle injuries caused by?

Answer 30

An inversion injury

and/or rotational force on a planted foot

Question 31

How might a sprain of ankle ligaments present?

And which ligaments are likely to be sprained?

Answer 31

• pain
• bruising
• mild to moderate tenderness over involed ligaments

Sprains of the lateral ankle ligaments (anterior & posterior talofibular ligaments and calcaneofibular ligament) are commonplace

Question 32

What criteria is used to identify suspected ankle fracture and give guidance as to which ankle injuries require an X-Ray?

Answer 32

the Ottawa criteria

Question 33

What merits an X-Ray with a suspected ankle fracture?

Answer 33

Bony tenderness of the distal tibia or fibula

or inability to weight bear for four steps