Overdistraction of the fracture eases reduction in delayed femoral nailing: results of intraoperative force measurements.

BACKGROUND: (Initial) primary external fixation of femoral shaft fractures followed by secondary intramedullary nailing is a concept of damage control orthopedics. We hypothesized that external fixation with overdistraction of the fracture might reduce reduction forces and shorten reduction time during the secondary nailing.
METHODS: An experimental study on seven patients with eight fractures of the femoral shaft was conducted. Intraoperative reduction forces were determined in all patients using a load cell. The amount of distraction was measured on the latest radiographs before nailing. The reduction time was recorded as an indirect indicator of the intricacy of reposition. Reduction forces and reduction times were compared between those fractures fixed with shortening (Group A) and those fixed in distraction (Group B).
RESULTS: Three femurs showed some shortening and five femurs showed some distraction within the fracture. The maximum measured distraction force along the shaft axis was 396 N. On average the maximal force was 336 N (+/- 51.9 N) in Group A and 200 N (+/- 43.1 N) in Group B. This difference is statistically significant (p = 0.007). The average reduction time was 28.3 minutes (+/- 21.8 minutes) in Group A and 5.8 minutes (+/- 4.0 minutes) in Group B. This difference shows a trend toward significance (p = 0.056).
CONCLUSION: Fracture shortening leads to higher restraining forces and consequently prolonged reduction time in delayed nailing. Overdistraction should be performed as soon as possible under careful soft-tissue monitoring.