Ch. 43 Pedestrian Struck by Motor Vehicle

Question 1

What is the most common presentation of popliteal artery injury?

Answer 1

Thrombosis with acute distal limb ischemia

Question 2

Common skeletal and associated arterial injuries:

1. Shoulder girdle dislocation*
2. Clavicle fracture*
3. Supracondylar fracture*
4. Pelvic fracture*
5. Hip dislocation*
6. Knee dislocation*
7. Tibial plateau fracture*

Answer 2

1. Shoulder girdle dislocation: axillary a.
   
   1. ​Posterior dislocations (rare): seizures/electrocution –> axillary n.
   2. Anterior dislocations: –> axillary a.
2. Clavicle fracture: subclavian a.
   
   1. ​Patients may have associated pneumothorax and/or hemothorax
3. Supracondylar fracture: brachial a.
   
   1. ​Occurs more commonly in children; may result in Volkmann’s contracture if left untreated
4. Pelvic fracture: Branches of internal iliac a. (superior gluteal and internal pudendal)
   
   1. ​Both posterior and anterior fractures can result in HEMORRHAGIC SHOCK
5. Hip dislocation: Femoral a.
   
   1. ​Posterior dislocations –> inc. risk of sciatic n. injury
   2. Anterior dislocations –> femoral a. injury
   3. RISK OF AVASCULAR NECROSIS if combined with femoral head fracture
6. Knee dislocation: Popliteal a.
   
   1. ​Usually posterior dislocation
7. Tibial plateau fracture: Popliteal a.
   
   1. ​Usually medial injuries

Question 3

In the absence of hard signs of vascular injury, what noninvasive bedside test provides objective evidence of a vascular injury?

If this noninvasive imaging is abnormal, what additional vascular imaging study is recommended?

Answer 3

ABI compares systolic BP of lower extremities with upper extremities via Doppler –> normal is between 1.0 and 1.2

An ABI of <0.90 is highly sensitive/specific for arterial injury following both blunt and penetrating injuries

If ABI is <0.9, additional vascular imaging is recommended:

Contrast arteriography

CTA*** (test of choice)

Duplex U/S

Question 4

What is the management of knee dislocation?

Answer 4

1. Primary survery (ABCDEs)
2. Secondary survery (detailed head-to-toe exam)
3. Immediate reduction indicated in an ischemic limb
4. Check neurovascular status
   
   1. If still no pulse, start IV heparin and check ABI
   2. If ABI <0.9, obtain CTA
   3. If CTA confirms arterial injury, take pt to OR
   4. Repair injured artery with reverse saphenous vein from contralateral leg

Question 5

If a conduit is needed to replace the injured artery, where is it taken from?

Answer 5

Autogenous vein grafts (greater saphenous vein is harvested from uninjured leg)

Question 6

What if there is a combined orthopedic and vascular injury, which is repaired first?

Answer 6

This depends on the severity of the ischemia to the limb.

Prolonged initial repair of an orthopedic injury may lead to irreversible muscle ischemia.

Alternatively, secondary repair of the orthopedic injury, with required manipulation and stretching of the limb, risks disruption of the arterial repair.

INSERTION OF INTRAVASCULAR SHUNT PRIOR TO ORTHOPEDIC STABILIZATION allows for expeditious temporary restoration of blood flow. Following orthopedic fixation, definitive vascular repair may then be undertaken.

Question 7

Why does Heparin help follow trauma?

Contraindications?

Answer 7

Reduces rates of amputation by preventing microvascular thrombosis in the setting of low-flow arterial circulation

Contraindications: active hemorrhage, intracranial injury, coagulopathy