- Discussion:
- device that is placed at
lower angle has less force working parallel
to sliding axis & more force working perpendicular to sliding axis.
- this perpendicular force acts to jam or bend the device, thereby
preventing impaction.
- device that is placed at
lower angle may be used effectively
in
Stable Frx because controlled collapse is not important
for impaction of the fracture and early weight-bearing;
-
130 deg plate
- bent w/ loading, resulting in jamming of nail in 2/6 of cases with
unstable fractures;
- as compared to higher angled plates, 130 deg plates showed highest tensile forces;
- conclusion is that, in most cases 135 or 140 deg plate should be used;
-
135 deg plate:
- 135 deg plates are indicated for most patients - for anatomic reduction;
- easier to insert in desired central position of femoral head;
- insertion point is in metaphyseal bone, which produces less of stress riser
effect than diaphyseal insertion point required for 150 deg devices;
- nail entry site is directly opposite
lesser trochanter;
-
140 deg plates:
- have lowest plate tensile forces;
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A biomechanical analysis of the sliding hip screw: the question of plate angle.
