Robot-assisted fracture reduction: a preliminary study in the femur shaft.

Reduction in femoral shaft fractures can be difficult to achieve with minimally invasive techniques. Malalignment and high intra-operative radiation exposure can result. The hypothesis was that robot-assisted fracture reduction could improve the quality of reduction while reducing the amount of radiation exposure. A robot system was developed that allows fracture manipulation with a joystick as input device. The system provides the surgeon with haptic and metric feedback. Fifteen synthetic femurs were broken and reduced by simulated open (group A) and closed techniques (group B). These techniques were compared with the robot-assisted reduction with (group C) and without (group D) haptic and metric information. An image intensifier was simulated with two orthogonal cameras. All reduction techniques showed minor malalignment. In group C, the alignment was: procurvatum/recurvatum 0.6 degrees (0-2.0 degrees); varus/valgus 0.8 degrees (0-3.0 degrees); and axial rotation 0.8 degrees (0-3.1 degrees). A significant difference was seen between the groups (two-way ANOVA, p < 0.001). Axial rotation was significantly lower in group C than in group B (1.9 degrees; p < 0.001). The residual varus and valgus deviation was higher in group C compared with group A (0.4 degrees, p = 0.03). The median number of simulated radiographs was significantly less in group C (35) compared with group D (72; p < 0.001) and group B (49; p = 0.01). Robot-assisted fracture reduction of the femur provides high precision in alignment while reducing the amount of intraoperative imaging. Further research in this field is worthwhile.