Proximal femoral nails effective at managing trochanteric femoral fractures

Lag screws were inserted close to the subchondral bone, resulting in 90% being placed at the optimal site.

Proximal femoral nails appear useful for treating trochanteric femoral fractures, according to a study by researchers in Japan.

"In our study, although the lateral slide in seven of the 45 patients with A2 fractures was over 10 mm, cut-out of lag screws did not occur regardless of the extent of slide. Therefore, free sliding of a PFN (proximal femoral nail) may provide better impaction for unstable A2 fractures," the study authors wrote.

Also, "The presence of an additional anti-rotational screw, and the free sliding mechanism of the lag screw may increase rotational stability of cervico-cephalic fragments and decrease overload on the femoral head," they added.

Toru Morihara, MD, and colleagues at Kyoto Prefectural University of Medicine in Japan, reviewed outcomes for 87 consecutive patients treated with a proximal femoral nail for trochanteric femoral fractures. They published their results in the Journal of Orthopaedic Surgery.

Patients averaged 85 years of age. Of the 87 cases, 45 patients had fractures classified as type A2, 36 had type A1 fractures and six had type A3 fractures, based on the AO classification system, according to the study.

In all cases, proximal femoral nail fixation was achieved using an intramedullary nail measuring 10 mm to 11 mm in diameter, a lag screw measuring 90 mm to 105 mm in length and a hip pin measuring 10 mm to 15 mm shorter than the lag screw.

"The lag screw was inserted near the subchondral femoral head. The intramedullary nail was interlocked distally with one or two screws," the authors wrote.

Patients were permitted to begin mobilization 2 days after surgery, and weight-bearing walking was started as tolerated 3 to 4 days postop, according to the study.

"In AP radiographs, 100% of lag screws appeared to be placed in the inferior part of the femoral head. In lateral radiographs, 90% of lag screws appeared to be placed centrally, 8% anteriorly, and 2% posteriorly," the authors reported.

"The optimal position - inferior on AP view and central on lateral view - was achieved in 78 of 87 (90%) patients," they noted.

"In our study, the lag screw was inserted close to the subchondral bone, and the hip pin superior to the femoral head. This resulted in 90% of the lag screws being inserted at the optimal site (inferior to the center of the femoral head) and to an optimal depth, thereby achieving rigid fixation," they wrote.

Overall, the lag screws had an average lateral slide of 3.7 mm. Specifically, lateral slide averaged 2.7 mm for A1 fractures, 4.4 mm for A2 fractures and 4.8 mm for A3 fractures, according to the study.

At 2 years follow-up, mean mobility scores of all fracture types had decreased, although not significantly. Mean scores for social functioning also increased; however, it was not significant.

For more information:
Morihara T, Arai Y, Tokugawa S, et al. Proximal femoral nail for treatment of trochanteric femoral fractures. J Orthop Surg (Hong Kong). 2007;15:273-277.