Internal Fixation Flashcards
Which type of bone are staples designed for, cortical or cancellous?
cancellous
should plate fixation lie on the compression side or tension side?
tension
what is the fixation device of choice for a fracture with soft tissue loss?
external fixation
why is the proximal cortex overdrilled when using lag technique?
to prevent distraction of the osteotomy and allow for compression
what is the difference in pitch between cortical and cancellous screws?
cortical- 1,25mm
cancellous- 1.75 mm (needs larger area to grab onto softer bone)
the ilizarov bone lengthening osteotomy requires how long of a period of compression before callous distraction begins?
3 weeks
what is the maximum documented amount of callous distraction that can be achieved in one day with Ilizarov bone lengthening tecnique?
1mm
why is countersinking important?
- reduces screw head prominence
- also increases the surface area btwn the cortex and screw head, which serves to prevent stress risers
which method of fixation would be most advantageous in opening wedge osteotomies?
staples bc they maintain the size of the osteotomy when bone graft is being resorbed
what is the most inherently stable fracture pattern?
transverse
what is the complication of not overdrilling the proximal fragment in standard AO fixation?
causes distraction rather than compression
how many threads of the screw should extend beyond the far cortex?
two
regarding screw anatomy, what is the undersurface of the screw head called ?
“land”
pneumatic surgical instruments use what type of gas?
nitrogen
