The unreamed AO femoral intramedullary nail, advantages and disadvantages of a new modular interlocking system. A prospective study of 67 cases.

Compared with the Reamed Femoral Nail (RFN), the Unreamed Femoral Nail (UFN) has some theoretical advantages. It can also be used for subtrochanteric fractures and ipsilateral fractures of the femoral neck, there is less iatrogenic damage to the vascularisation of the bone, the risk of fat embolism syndrome and ARDS is reduced and the operation is a less time consuming procedure, associated with less blood loss. From April 1995 to July 1996, 66 patients with 67 fractures have been treated with the UFN: 16 patients with metastatic disease, 18 patients with a subtrochanteric fracture, 32 patients with 33 diaphyseal fractures. In 6 cases however, previous reaming was necessary. The spiral blade (SB) was used 35 times. Four patients died within six months after the operation. Fat embolism syndrome or ARDS were never observed. Five mechanical complications were observed in four patients. In one patient with a metastatic fracture, we noted a breakage of the SB twice. Migration of the SB was observed three times needing reintervention twice. Delayed union needing renailing with a reamed nail was observed twice. The reoperation rate for all patients treated with an UFN-SB was 9%. For diaphyseal fractures, the rate of delayed-union was 6%. This complication was only observed in open fractures. We concluded that the UFN is a safe and less severe procedure than the reamed nail in multiply injured patients. For subtrochanteric fractures, the UFN-SB is a useful implant, but not superior to other methods of treatment. As a definitive treatment for a femoral fracture primarily stabilized with an external fixator, we strongly suggest to carry on using a reamed nail.