Ch. 26 Multiple Extremity Injuries After Motorcycle Accident

Question 1

Consequence of humeral mid-shaft fracture?

Answer 1

Stretch or entrapment of radial nerve

The radial nerve descends down the medial aspect of the humerus until a third of the way down, where it dives more posteriorly. At this level, the radial nerve runs in the spiral groove and remains in contact with the posterior surface of the humerus.

The radial nerve gives off the branches that innervate the triceps in the axilla proximal to the lesion so triceps fxn remains intact. Pts will experience distal loss of fxn:

wristdrop (weakness in extension),

loss of MP joint extension,

and sensory loss over dorsum of the hand

**finger extension at DIP joints still possible since innervated by ulnar nerve (interossei and ulnar two lumbricals) and median nerve (radial two lumbricals)

Question 2

How does Fat Embolism Syndrome present? and what is the presumed pathophysiology?

Answer 2

• Occurs in up to 15% of polytrauma pts, particularly in association with long bone fractures like the femur
• Embolization of fat and marrow from fracture (or from surgical intramedullary rodding) into bloodstream
• Typically presents between 24-72 hrs following trauma
• Classic triad:
  
  • respiratory symptoms, (first)
    
    • ​hypoxemia, dyspnea, tachypnea
    • CXR –> ARDS
  • neurological changes,
    
    • ​Confusion, drowsiness
    • Severe –> seizure, paralysis
  • reddish-brown petechial rash
    
    • ​results from extravasation of erythrocytes 2/2 occlusion of dermal capillaries by fat emboli

Question 3

What is a dangerous sequela for a tibia fracture (or forearm fracture)?

What else to watch out for?

Answer 3

Compartment syndrome.

6 Ps:

pain out of proportion to injury with gentle passive stretch of involved muscles

pressure (swollen and tense compartments)

paresthesia

pulselessness

poikilothermia

paralysis

**SURGICAL EMERGENCY**

Also watch out for rhabdomyolysis and subsequent kidney failure in pts with crush injuries

Question 4

What concomitant fracture is important to consider in all femur fractures?

Answer 4

A concomitant femoral neck fracture

A missed femoral neck fracture may lead to AVN if not treated (largely irreversible –> end-stage dysfunction of the hip joint)

Question 5

What are Seddon’s Three Basic Categories of Nerve Injury?

Answer 5

Question 6

How fast does an injured axon regenerate?

Answer 6

Approximately 1 mm per day, though factors like age and nutritional status may affect the rate

Question 7

Does Wallerian degeneration occur with neurapraxia?

Answer 7

Not with neuropraxia. Yes with axonotmesis and neurotmesis.

Question 8

What are the three layers of the nerve sheath?

Answer 8

Endoneurium, perineurium, epineurium

Question 9

What are the classic nerve injuries associated with UE & LE fractures?

Answer 9

Question 10

What is a floating knee?

Answer 10

When an ipsilateral femur and tibia fracture are present

A floating knee tends to flail or float beween bony disconnections above and below the injury

Question 11

Which pts with open fractures should be given abx coverage?

Answer 11

All open fractures are by definition contaminated and should receive abx.

Grade I and II open fractures are mainly at risk for gram-positive infections –> 1st gen cephalosporin

Grade III fractures are at higher risk of infection –> aminoglycoside + cephalosporin

Question 12

What abx are indicated for open fractures in farm accidents or soil-contaminated wounds?

What else should be considered for wounds contaminated with dirt and soil?

Answer 12

Penicillin or its equivalent is added to cover anaerobes, esp. C. perfringens.

Gas gangrene has led to many amputations in the past

TIG or TT administration depending on vaccine hx and level of contamination

Wounds at highest risk for C. tetani infection include those containing foreign bodies and/or necrotic tissue

Question 13

What are the principles of surgical mgmt of an open fracture? What is the optimal timing?

Answer 13

Taken to OR as soon as possible for surgical irrigation and debridement, typically within 6 hrs of injury (Grade IIIC injuries are a surgical E)

All devitalized skin, tissue, and bone should be excised

Question 14

What single type of orthopedic fracture is at greatest risk for hemorrhagic shock?

Answer 14

Pelvic fractures

Some are benign and cause minimal blood loss, while some are highly unstable and may require 10-15 units of blood transfusion or its equivalent due to high pelvic volume into which blood may accumulate

Question 15

Is there an important consideration for a femur fracture in a nonambulatory child?

Answer 15

Yes, child abuse.

In some cases, these children are found to have fragile bones as in OI.

Question 16

What is the mgmt for Fat Embolism Syndrome?

Answer 16

Supportive care including ventilatory support with high PEEP and early stabilization of the fractures

Corticosteroids have been reported to be beneficial in some patients, but there is not sufficient evidence to recommend corticosteroids in every pt

Question 17

What is the most important factor to prevent fat embolism syndrome before it occurs in a polytrauma patient?

Answer 17

early stabilization of long bone fractures within the first 24 hrs