Our purpose is to use radiographs to compare callus formation with two types of intramedullary nailing for femoral shaft fractures: reamed interlocking (IL) and Ender nails.

Femoral shaft type A fractures according to AO classification were studied.

From 1991 to 1995, 27 patients with 27 fractures were treated with reamed IL nailing and 79 patients with 81 fractures were treated with Ender nailing. IL group included with an average of 22 (range, 16–28) years, and the Ender group included with an average of 28 (range, 15–72) years.

Patients had been followed for an average of 1.8 (range, 1–2.8) years after surgery. In all cases of IL group, the femoral canal was reamed. For type A3 fractures, an interlocking screw was inserted only at the distal site. For type A1 and A2 fractures, both proximal and distal locking screws were placed. In the Ender nailing cases, 3 to 5 Ender nails were inserted from medial or lateral side of the supracondylar or intertrochanteric regions of the femur as was dictated by the fracture site. All of these fractures were reduced by a closed technique. The measurement of postoperative callus area was calculated from the maximum cross-sectional area on the anteroposterior and lateral radiographs.

Fracture healing was successful in all patients. On the radiograph, the callus for the IL group appeared at a mean of 3.9 weeks after surgery, and at a mean of 2.8 weeks for the Ender group. In the IL and Ender groups, fracture healing was noted at a mean of 3.4 and 2.0 months, respectively. The mean area of callus formation in the IL and Ender nailing was 439.5mm2 and 699.4 mm2, respectively. To compare the two groups by using a Mann-Whitney U test, the significant differences were seen in the callus appearance period (p< 0.05) and in the callus area (p< 0.01).

Dynamization at the fracture site is reported to increase external callus formation.

Our results indicate that the elasticity of the fixation obtained with Ender nailing promotes callus formation.