The Effect of Dynamization on Slowing the Healing of Femur Shaft Fractures after Interlocking Nailing

The aim of this retrospective study was to investigate the effect of dynamizing a static interlocking nail to promote femoral fracture healing and the adverse effect of dynamization.Twenty-eight static femoral interlocking nails were dynamized after 4 months (median, 6 months; range, 4-12 months) because of poor fracture healing. The clinical and roentgenographic healing processes were recorded. Significant complications were treated and analyzed.Twenty-four patients were followed for at least one year (median, 32 months; range, 13-49 months). Fourteen patients (58%) achieved a solid union with a union period of 5.2 +/- 2.0 months after dynamization. Twenty-one percent of patients (5 of 24) had more than 2 cm of femoral shortening; all occurred in cases of nonunion (p < 0.01, Fisher's exact test). All 10 cases of nonunion were treated with cancellous bone grafting with or without lengthening and achieved satisfactory outcomes.Dynamization is a method that can be tried to improve fracture healing in femoral fractures that show delayed healing after interlocking nailing. In my experience, however, not all cases achieve union after dynamization. Patients must be examined regularly after dynamization to avoid significant shortening.