The sliding plate has appeared to be a reliable answer for trochanteric fractures. However, impaction allowed by the material may, have an adverse effect (medialisation, shortening, jutting out of the lag screw). The aim of our study was to measure the sliding of the screw in order to assess the impaction in various types of fracture, according to the Ender classification.
Hundred trochanteric fractures have been treated between 1991 and 1993. Eighty four have been analyzed with a follow-up of three months after surgery. The average age was 80.1 years with a 4.2 sex ratio (16 males). One hundred and thirty five degrees free sliding plates were employed for fracture fixation. Full weight bearing was allowed in 78.6 per cent of patients. According to Ender classification, 35 per cent of fractures were type 1, 4 or 5. This was the first group. The second group consisted of types 2 and 3 and the third group of types 6, 7 and 8. The results were assessed on AP and lateral X-rays. The ratio between screw thread length (constant) and screw outside the barrel length, was used to measure impaction on AP view. Osteoporosis was evaluated according to Singh.
Despite two screw protrusions out of the femoral head and two failures of the plate, we have observed a healing rate of 100 per cent after three months. Sliding averaged 6.2 mm in group 1, 10.5 mm in group 2 and 16.4 mm in groupe 3. Weight bearing had a low influence on the amount of sliding.
Group 1 consists of fractures (types 1, 4 and 5) which are two parts fractures considered as stable. Group 2 corresponds to types 2 and 3 considered as intermediate fractures with relative stability. In group 3 (types 6, 7 and 8) we have observed major fracture instability. Osteoporosis does not seem to be the major factor regarding screw sliding.
The sliding plate is reliable. However, complex fractures healed in a wrong position which is definitely not acceptable, especially for young patients. Therefore, we advise to avoid the use of sliding plate in case of Ender type 6, 7 and 8.