Contributing factors affecting initial bony healing in interlocking nailings for femoral shaft fractures

Abstract

The objective of this study was to evaluate bony healing and predict factors affecting bony healing of femoral fractures treated with interlocking nailing (ILN) in static or dynamic conditions, and in reamed or unreamed procedures. Seventy-four femoral fractures (69 patients) were initially stabilized with ILNs in static condition. Among these fractures, ten static ILNs were dynamized after approximately 6 (median 6.4, range 1–13) months because of poor fracture healing. Reamed ILNs were performed for 55 fractures and unreamed ILNs for 19 fractures. Clinical and roentgenograhic processes were analyzed with emphasis on whether or not ILNs were dynamized. To evaluate any significant contributing factors affecting the nonunion of femoral shaft fractures treated with ILNs, logistic regression analysis was done. The union rates of static ILNs and dynamized ILNs were 92% (59/64) and 70% (7/10) respectively, but there was no significant difference between them. Five nonunions were seen in reamed ILNs and three in unreamed ILNs. The predictive logistic regression equation for nonunion was as follows: Log 1-p/p=1.05 −1.20 × AO/ASIF fracture grade in the femur −3.07 × existence of multiskeletal trauma in lower extremity + 0.06 × age −1.11 × smoking history −0.3 × existence of polytrauma −0.626 × the severity of soft tissue injury (p=0.002; each variable in the above equation was arranged according to the significant order). Among the variables, AO fracture grade (type C) in the femur and existence of multiskeletal trauma in lower extremity were significantly related to nonunion. Static ILN in most femoral shaft fractures does not inhibit the process of fracture healing. The following associated skeletal lesions were our concerns for nonunion and broken nail in static or dynamic ILNs: (1) C-type femoral fracture; and (2) existence of multiskeletal trauma, such as double lesions in the ipsilateral femur, floating knee injury, and bilateral femoral fractures.