Review Question - QID 4393

Figure A illustrates a comminuted distal femur fracture. AP fluoroscopic imaging with the leg in 30 degrees of internal rotation is important to prevent intercondylar screw prominence.

Hardware irritation is a common post-operative complication of distal femoral plate fixation. Two common sites of pain are laterally where the iliotibial band is in contact with the plate, and medially where intercondylar screws may penetrate the cortex if they are of inappropriate length. Iliotibial irritation most commonly presents with activities requiring knee flexion and extension. It is important to remember that the lateral metaphysis of the distal femur is angulated 10 degrees from the sagittal plane, and the medial metaphysis is angulated 25 degrees from the sagittal plane. Therefore, if a straight AP view is obtained, a distal screw can appear to be inside the bone even if it is too long. In order to assess the exact length of the screw, one must obtain an AP view with 30° internal rotation of the lower extremity.

Gwathmey et al discuss distal femoral fractures in their review article. They state that the goal of surgical management is to promote early knee motion while restoring the articular surface, maintaining limb length and alignment, and preserving the soft-tissue envelope with a durable fixation that allows functional recovery during bone healing. They describe a variety of surgical exposures, techniques, and implants developed to treat these injuries, including intramedullary nailing, screw fixation, and periarticular locked plating, possibly augmented with bone fillers.

Illustration A demonstrates the sagittal plane angulation of the medial and lateral cortex of the distal femur. Illustration B shows a knee in external rotation, with the intercondylar screw appearing to be of appropriate length. Illustration C shows the knee in internal rotation, which indicates that the screw is penetrating the medial cortex.