- Discussion:
- screw should be placed in the central 1/3 of the femoral head between
5-12 mm from subchondral bone;
- consider short barrel dynamic hip screw side plate when screw < 80 mm
or shorter is inserted to maximize sliding capacity;
- whether compression screw should be left in place is controversial,
however, one should leave compression screw in place if short
barrel plate is used, to prevetn disengagement of assembly;
- there is increase in failure rate if tip of nail is > 12 mm from femoral head
subchondral articular surface.
- others argue that for best fixation, the nail should be advanced
within 0.5 cm of the articular surface of the femoral head;
- Technical Considerations:
- w/ 135 deg plate, typically a 95 mm screw is required;
- determine correct length of lag screw w/ direct measuring gauge;
- this measurement allows for 5 mm of compression
- if more compression is desired, use a shorter screw;
- screw 5 mm shorter permits 10 mm of compression;
- if a shorter screw is used (for better compression) then compression screw must
be left in place, so that scew barrel assembly does not become disengaged;
- if screw sliding brings threads in contact w/ plate barrel, additional impaction will
not occur & device becomes biomechanical equivalent of a rigid nail-plate;
- use short-barrel dynamic hip screw sideplate when screw 80 mm or shorter is
inserted to maximize available sliding capacity;
Subchondral screw fixation for femoral neck frx
