The Detrimental Screw Hole

Posted by on Aug 25, 2016 | Comments Off on The Detrimental Screw Hole

A screw hole in the bone concentrates the stress in torsion. There is a 70% decrease in energy storage capacity. In other words, a much smaller amount of torsion can cause a fracture through this stress concentrator. If the screw is removed it takes 11 months for the hole to fill in. If the screw is left in place, the stress riser will be present for four years.

Application the fractures that occur when the retrograde standard nail ends at the high stress area of the femur. This is 6 cm below the lesser trochanter. The screw holes that are used to place the interlocking screws may result in fracture through these holes. SIGN accordingly suggest using the fin nail for retrograde stabilization of the femur.

xray-243949 High Stress Area from Technique manual

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