[Locked nail plate: a new treatment for unstable pertrochanteric fractures].

Purpose Of The Study: This work is the outcome of a preliminary study on pertrochanteric fractures which showed that impaction with simple nail plates (SNP) was lead by hypercorrection in valgus demineralization and malposition of the nail in the femoral neck. To improve anchoring of the nail in the cervico-cephalic part, the authors propose to use a locked nail-plate (LNP), an innovative device based on the addition to the normal nail plate, of a screw securing neck and nail.

Mechanical Study: Mechanical flexion and compression tests carried out on 8 pairs of femurs of fresh cadavers showed comparable rigidity for the two mounting, SNP and LNP. The difference became apparent at an equivalent load through a perforation in the SNP across the femoral head and by separation of the head from the LNP without any perforation.

Clinical Study: 56 patients operated on between June 1994 and June 1996 were included 30 cases could be followed. There was only one complication: one dismantling of the plate from the diaphysis. The other 29 cases consolidated within an average of 8 weeks without any complications. Locking of the nail was effective and there was never cutting out the head by the nail nor any impaction in the focus of the fracture site. This was despite the fact that, in 12 cases there was advanced demineralization, in 8 cases hypercorrection in valgus, and in 13 cases of misalignment of the nail in the neck, all three of these being recognized as causes of articular deterioration.

Discussion: Pertrochanteric fractures currently represent a serious public health problem for which costs are definitely going to grow in the near future. We need a method for solid osteosynthesis simple and relatively inexpensive, but which also avoids the common mechanical complications. The LNP seems to correct SNP problems. This modification represents an improvement and should be used for any unstable pertrochanteric fracture.