Factors affecting the results of distal femoral fractures treated by retrograde intramedullary nailing.

OBJECTIVE: To assess the factors that affect the outcome of distal femoral fractures treated by retrograde intramedullary nailing.

METHODS: Between November 1999 and June 2006, 30 patients with 31 distal femoral fractures (15 males and 15 females, 1 bilateral) were treated by retrograde nailing. Their ages ranged from 44 to 82 years old (average, 67.2 years old). The causes of injury were slipping downs in 17 patients, traffic accidents in 11, and falling from height in 2. The average interval from injury to operation was 1.8 days. There were 14 cases of A1 fracture, 7 cases of A2, 8 cases of A3, and 2 cases of C1 according to AO/OTA classifications. The mean distance between the most distal line of the fracture and the intercondylar notch was 7.2 cm (range, 0-12 cm). Closed retrograde nailing was done without reaming, and bone grafts were not done.

RESULTS: The operation time averaged 76 minutes (range, 45-110 minutes). All patients were followed up for 19-69 months, and the mean follow-up duration was 27 months. Twenty-eight of 31 fractures united on the average of 14.7 weeks (range, 12-22 weeks). Complications occurred in 7 cases. There were 3 nonunions in AO-A3 fractures which were treated by changing implants or bone graft. Two patients suffered screw loosening of distal locking, that were re-fixed. Two patients showed limited knee motion of less than 90 degrees flexion. There were no cases of deep infection, malunion over 10 degrees of angulation or 1 cm of shortening. A satisfactory outcome (excellent and good results) was achieved in 26 of 31 cases (84%), according to Schatzker and Lambert's criteria. Poor results and complications were related to fractures of comminution and located within 5 cm from the intercondylar notch (Pearson Chi-square test, P = 0.03). Other possible factors including age, kinds of nails used, associated injury, and numbers of distal locking screws were not related to the outcome and complication (Pearson Chi-square test, P > 0.05).

CONCLUSION: Retrograde nailing may be a useful option for distal femoral fractures, but attention should be paid to comminuted fractures or fractures close to the knee joint.