Review Question - QID 1075

Figure A shows an intertrochanteric fracture treated with a cephalomedullary device. A starting point slightly anterior to the piriformis fossa (starting point for standard antegrade femoral nail) has the benefit of improved placement of screws through the nail and into the femoral head. This is due to the fact that the hip is anteverted and the femoral neck arises from the anterior portion of the proximal femur. Therefore, by moving the nail anterior, that will increase the distance between the head screw and the posterior cortex of the neck and lead to a “straight” shot into the center of the femoral head.

Johnson et al investigated the effect of starting hole position, fracture component length, reamed diameter, and nail type on the potential for femoral bursting and fracture instability. They found the most significant factor in the proximal femoral component was found to be the position of the starting hole. They found excessive anterior displacement greater than 6 mm from the neutral axis of the medullary canal consistently caused high hoop stresses at the level of the fracture, which can increase the possibility of iatrogenic fracture. Posterior starting points increase the risk of possible distal femur anterior cortex impingement/fracture.

Ostrum et al showed that lateral starting points should be avoided in order to avoid varus reduction when using a trochanteric antegrade nail in subtrochanteric fractures. They recommended a slightly medial starting point.