40: External Fixation Rails - Smith

Question 1

purpose external fixation

Answer 1

• anchor multiple osseous fragments or segments together through the use of wires, pins and rods

Question 2

advantages of external fixation over internal fixation

Answer 2

• Decreased soft tissue dissection
• Immobilization of multiple regions of the affected limb with compression or distraction at different sites
• Allow debridement or grafting around fixation
• Immediate mobilization (circular or hybrid)
• Allows for immediate weightbearing
• Post-op adjustment

Question 3

principles of external skeletal fixation

Answer 3

• Avoid and respect all vital anatomic structures in the area
• Allow access to the injured area for later fixation, bone grafting, debridement and soft tissue reconstruction
• Meet the mechanical demand of both the patient and the injury

Question 4

where are safe zones/corridors?

Answer 4

• medial and anterior surface of tibia
• avoid tarsal tunnel and dorsal structures on foot
• corridors exist for safe wire insertion

Question 5

straight bar is only capable of…

Answer 5

distraction or compression

Question 6

indications for unilateral fixators

Answer 6

• Primary fusion of joints
• Lengthening of bone (callus distraction)
• Osteomyelitis
• Joint distraction
• Comminuted fractures
• Bone defect
• Escessive shortening trauma
• Soft tissue defects
• Osteoporotic bone

Question 7

foot and ankle indications for external fixation

Answer 7

• transverse plane deformities
• brachymetatarsia
• fractures
• hallux limitus
• joint fusion

Question 8

define a jones fracture

Answer 8

• fx that occurs at 5th met proximal diaphyseal/metaphyseal junction
• assoc w/ delayed healing due to tenuous vascualr supply at this region

Question 9

define hallux limitus

Answer 9

• condition involving the 1st met-phalangeal jt in which there is limited motion and jt jamming
• ex fix distraction can increase jt motion (arthrodiastasis)

Question 10

benefits and drawbacks of arthrodiastasis

Answer 10

benefits

• Allows for immediate weight bearing
• Allows for early range of motion
• Preserves cartilage
• Minimally Invasive procedure
• Does not eliminate any further treatment options

drawbacks

• Pin tract infection and importance of compliance
• Limited results for severe cartilaginous pathology
• Little research has been published

Question 11

what is brachymetatarsia?

Answer 11

congenital shortening or trauma shortening of the metatarsal due to premature fusion of metatarsal physis

Question 12

osteotomy v. corticotomy

Answer 12

corticotomy = circumferential drill holes around cortex, preserving the endosteum

osteotomy = technically easier requiring less dissection

Question 13

where on bone anatmoy should osteotomy be done? (level of osteotomy)

Answer 13

diaphyseal

• less metabolically active bone
• easier technique

metaphyseal

• difficult technique
• greater diameter, increased osteogenic potential and greater amount of soft tissue coverage

Question 14

latency period before callous distraction begins?

rate of distraction?

Answer 14

• 5 days - 2 weeks
• 0.25 mm every 6 hrs (1 mm/day) until radiographic findings are sufficient
• rule of thumb 1:1 ratio lengthen: ossify

Question 15

complications of arthrodesis with ex fix

Answer 15

• Loss of joint motion (minimized if lengthened <10% of the initial length)
• Subluxation/dislocation
• Delayed union or nonunion
• Malalignment
• Chronic edema
• Neurovascular compromise
• Pin site irritation/infection

Question 16

comminuted fx of distal tibia

Answer 16

pilon fracture