Introduction: The interlocking retrograde ostheosynthesis was developed by Drs. Green, Selingson and Henry to address the whole spectrum of fractures localised to distal femur. The primary indications were in supracondylar fractures type A (AO), than in supra and inter-condylarfractures type C (AO). Secondary indications may be in periprosthetic fractures, non-union, fractures of femoral shaft, which cannot be nailed with antegrade technique (politrauma, ipsilateral femoral neck fracture or obese patient)

Methods: In our department between 2001–2004, 24 distal femoral fractures were nailed with retrograde technique; 16 type A (AO), 8 type C (AO) and 1 peri-prostetique fractures 5 cm. distal to femoral stem. We have used a retro nail which allows us proximal interlocking with 2 screws and distal interlocking with screws or bolts if it is comminution or ostheoporosis. The fractures reduction was achived with traction on the fracture table or by manual manipulation. The insertion of the nail was percutaneous through a 5 cm incision centered on the patellar tendon those the blood loss was minimized. If there was an intercondylar fracture extension first we have reduced this and fixed with 2 percutaneos screws and then we have nailed the fracture. We have measured the whole blood loss, operating time, union period and knee ROM at 6 months. Also we have analysed the whole distal femoral alignment and the articular surface reduction.

Results: We have achieved union in all fractures, 17 were anatomic (varus/valgus< 5°), 5 malunion with valgus more than 5° and 2 mallunion with hiperextension. The malunion in hiperextension was obtained in eldery patients with important ostheoporosis and cominution. The operating time was on average 75 min. The average blood loss was 250 ml, the ROM at 6 months was 125 ° (70°–140°). During recovery period we have started early ROM with partial weight bearing which shortened the recovery time.

Discussion & conclusions: We believe that retrograde ostheosinthesis is a good method of treatment for distal femoral fractures but a proper selection of fractures must be done. The percutaneous technique is less invasive for these fractures, which are very difficult to treat, and in long-term results they alter the knee biomechanics. The reduction of the articular surface is essential and this must be done every time, if this is not possible using the retro nail we must change the implant and use one which allows to achieve this. Though the biomechanical advantages of retro nail, the small amount of blood loss and the sort operating time at the end of learning curve makes retro nail an implant of first choice in the treatment of distal femoral fractures.