41/42: External Fixation Rings - Smith

Question 1

acute trauma indications for ring ex fix

Answer 1

• Tibial articular fractures (pilon, plateau)
• Tibial articular fractures with diaphyseal extension
• High energy diaphyseal fractures of tibia
• Calcaneal fractures
• Ankle fractures
• Also limb reconstruction (correction of post-traumatic, acquired and congenital deformities that are multiplanar)

Question 2

*****

stability is created by …

rigidity is created by …

Answer 2

• Stability created with tensioned wires inserted into bone
• Rigidity created with half pins screwed into bone

Question 3

what is a hybrid fixator?

Answer 3

combination of unilateral and circular fixators

Stability created with tensioned wired attached to circular frame

Rigidity created with half pins attached to circular frame and unilateral frame

*****

Question 4

describe properties of transosseous wires

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Answer 4

• Transosseous wires are placed under tension and undergo a self-stiffening effect
• Increased stability in the bone-fixator interface
• Optimal stabilizing position is 90 degrees to each other
  
  • Smaller angles maybe used, but have to increase wires

Question 5

transosseous wire care

Answer 5

• daily cleaning with alcohol or peroxide
• betadine avoided
• antibiotic ointment applied

Question 6

dynamization

*****

Answer 6

• removal of circular fixator
• release some of tension from the wires over time
• allows the bone to strengthen with an increase in WB force
• decreases potential for fx
• short leg cast with partial WB if dynamization is not possible

Question 7

minor complications for ex fix

Answer 7

• edema
• pin tract irritation
• pin tract infection (dif from irritation with cultures)
• fractured transosseous wires
• pain secondary to positioning of the wires

Question 8

why is edema a complication for ex fix?

Answer 8

• ex fix does not allow postop wound compression
• can lead to hematoma, compartment syndrome, serous and hemorrhagic fluid around wires

Question 9

major complications ex fix

Answer 9

• nonunion
• osteomyelitis
• neurovascualr injury
• joint subluxation
• fracture

Question 10

factors contribution to nonunion

Answer 10

• poor fixation construction (not enough wires to produce stiffness)
• distraction too quickly
• infection, smoking

Question 11

prevent joint subluxation

Answer 11

fixation distal to distracted joints

Question 12

technique to decrease neurovascular injury

Answer 12

damage occurs by twisting structures around wire during drilling

• decrease by drilling wire through cortices and ushing through skin