Principles of ESF Application Flashcards
When applying an ESF - What diameter should be pre-drilled?
Predrilling with a drill of diameter 0.1 mm less than the pin core diameter
What speed are pins inserted?
A slow (<140 rpm) power drill
What MUST be used during drilling?
Saline cooling
What interface is an important concept in application of an ESF?
Pin-bone interface
What is the consequence of excessive stress at the pin-bone interface?
Bone resorption; resulting in premature pin loosening
What factors does stress at the pin-bone interface depend on? (4)
Degree of load sharing between the bone and the frame
Number and size of fixation pins
Pin design
Spacing and angle of the pins in relation to the fracture site.
The stiffness of the overall construct depends on some factors. Have a look at the sentences below and select the correct ones.
A) Increasing pin number (up to four pins per bone fragment) doesn’t change the frame stiffness.
B) Increasing pin number (up to four pins per bone fragment) increases frame stiffness.
C) Pin stiffness is related to the radius to the fourth power, and thus a small increase in diameter markedly increases stiffness.
D) Pin stiffness is related to the radius to the fourth power, and thus a small increase in diameter markedly decreases stiffness.
B) Increasing pin number (up to four pins per bone fragment) increases frame stiffness.
C) Pin stiffness is related to the radius to the fourth power, and thus a small increase in diameter markedly increases stiffness.
What are “safe corridors”
They are considered longitudinal regions overlying bone that do not contain important neurovascular or musculotendinous structures.
What are “hazardous corridors”
are those containing musculotendinous units but no important neurovascular structures
How should the patient be position for ESF placement if the fracture is on the proximal femur?
Lateral
How should the patient be position for ESF placement if the fracture is on the crus?
Dorsal
How should the patient be position for ESF placement if the fracture is on the distal humerus?
Dorsal
How should the patient be position for ESF placement if the fracture is on the femur including distal femur?
Dorsal
How should the patient be position for ESF placement if the fracture is on the antebrachium?
Dorsal
How should the patient be position for ESF placement if the fracture is on the Proximal humerus?
Lateral
What are the advantages to suspending the affected limb? (4)
Avoid large muscle masses/vessels/nerves
Aids in fracture reduction and limb alignment
Facilitates limb preparation
Allows 360° access to the limb, facilitating pin placement.
When choosing pin location:
A) Soft tissue area?
B) What size incisions created through intact skin?
C) Soft tissue positioning?
A) minimal
B) Small (approx 1cm)
C) Ensure current anatomical position
When choosing pin location:
A) With open/contaminated wounds?
B) How to prevent soft tissue damage during drilling/placement?
C) Which “areas” should be used where poss?
A) NOT to be used
B) Tissue protectors
C) Safe corridors
Pins can, if required, be placed within the surgical incision, what are needed to allow wound apposition without tension?
Perpendicular incisions