The use of interfragmentary positional screw in minimally invasive plate osteosynthesis for simple distal femur fractures in elderly patients: A retrospective, single-centre pilot study

Introduction Minimally invasive plate osteosynthesis (MIPO) using locking plates has been used in distal femur fractures, but various problems, such as nonunion, malalignment, and implant failure, have been reported. Simple fractures sometimes have poorer outcomes than complex fractures. We studied elderly patients with simple fracture patterns who underwent open reduction followed by placement of a single positional screw to hold the reduced interfragmentary gap, and compared these cases with patients who underwent surgery using conventional MIPO techniques. Patients and methods A retrospective analysis was conducted on 80 cases of patients with distal femur fractures and simple fracture patterns (33-A1, A2, and C1). The mean age was 74 (60–90) years, and the mean follow-up period was 14 (12–25) months. Group A included 40 patients who underwent conventional MIPO technique while Group B included 40 patients who had surgery using positional screws. Interfragmentary gaps in Group B were reduced using percutaneous reduction clamps, and cortical screws were inserted to sustain the reduction. Then, locking plates were inserted using conventional MIPO techniques. Results Bony union was achieved in all 80 cases, mean initial callus formation was observed in 11 weeks (8–13 weeks), and radiological union was observed in 27 weeks (15–54 weeks). Time to initial callus formation was not different, but radiologic union was achieved in 30 weeks (18–54 weeks) for Group A and 25 weeks (15–41 weeks) for Group B (p = 0.006). No differences were seen in clinical function at 1 year (p = 0.580). Five cases of malalignment occurred in Group A (p = 0.021). The rate of union during the 1-year period was significantly higher in group B than in group A (p = 0.002). Conclusions In a distal femur fracture with a simple fracture pattern, using positional screws to sustain the reduced interfragmentary gap may achieve a more rapid union by reducing fracture gap. Though functional differences were not seen in follow-ups, patients can be expected to return to their normal lives earlier as union is achieved in a shorter time. Performing MIPO using positional screws to sustain the reduced interfragmentary gap after fracture reduction will be helpful in the treatment of simple femoral fracture.