Avoidance of Malreduction of Proximal Femoral Shaft Fractures With the Use of a Minimally Invasive Nail Insertion Technique (MINIT)

Objectives: To determine our rate of malalignment in proximal femoral shaft fractures treated with intramedullary (IM) nails, with and without the use of a minimally invasive nail insertion technique (MINIT). Design: Retrospective study. Setting: Level 1 trauma center. Methods: Between July 1, 2003, and June 31, 2005, 100 consecutive proximal femoral shaft fractures (97 patients) were treated with IM nails. The average age of the 56 men and 41 women was 43.5 years (range, 17 to 96 years). There were 92 closed fractures and 8 open fractures. Fractures were classified according to the Russell-Taylor classification (69 type 1A, 11 type 1B, 3 type 2A, 17 type 2B). All patients underwent antegrade IM nailing using a fracture table in the supine (83) or lateral (17) position. A total of 72 entry portals were trochanteric, and 28 were piriformis. Seventy-seven percent of the femurs were opened with MINIT, a technique that uses a percutaneous cannulated channel reamer over a guide pin as opposed to the standard method of Kuntscher, which employs a femoral awl. Nails were locked proximally using standard locking in 37 fractures, and recon mode in 63. Fracture reduction was examined on immediate postoperative films to determine angulation in the coronal and sagittal planes. Criteria for acceptable reduction were less than 5 degrees angulation in any plane. In addition, surgical position, entry portal, mechanism of injury, Russell-Taylor classification, OTA classification, open or closed fracture, open or closed reduction, and type of implant used were analyzed for significance. Results: The frequency of malalignment was 10% for the entire group of patients. Malalignment occurred in 26% of fractures treated without the use of the MINIT and in 5.2% when the MINIT was used (P < 0.01). There was no statistically significant difference between the different Russell-Taylor fracture types, although there was a trend towards more malalignment in type 2A and 2B fractures (P = 0.06). None of the other factors studied had a statistically significant effect on malalignment. A whole-model test of the factors that were surgeon-controlled (use of the MINIT, surgical position, open or closed reduction, type of implant used, and entry portal) found that only use of the MINIT had a statistically significant effect on malalignment (P < 0.01). Conclusions: The results indicate that use of the minimally invasive nail insertion technique (MINIT) significantly decreases the occurrence of malalignment in proximal femoral shaft fractures.