Telemanipulated Long Bone Fracture Reduction

Fractures of the human thigh bone, the femur, are commonly caused by high-energy injury mechanisms, like traffic accidents, predominantly in young males or by low-energy mechanisms, like falling, in elderly females (Martinet et al., 2000; Zlowodzki et al., 2006). With approximately 37 per 100,000 persons per year this is an extremely frequently encountered injury (Arneson et al., 1988; Zlowodzki et al., 2006). In 1999 334,410 patients with fractures of the lower extremities have been counted in Germany1. 144,659 of which had fractures of the thigh bone. After subtracting fractures in the proximal (hip side) femur, 25,695 patients remain with fractures in the femoral shaft (the middle, diaphyseal) region to which this work is dedicated. Today, the treatment of choice for femur shaft fractures preferred by many surgeons is the minimal invasive technique of intramedullary nailing, which has been established as a standard technique for a definite stabilizing treatment in diaphyseal fractures of the lower extremities (Kempf et al., 1985; Krettek et al., 1996; Krettek, 2001; Winquist et al., 1984). The complete process of intramedullary nailing is shown as a sketch in figure 1. The process starts with the opening of the medullary cavity. A small soft tissue cut of about 5 cm has to be placed at the proximal end of the femur. In extension of the femoral shaft, the bone's cavity has to be opened. This is achieved with a surgical drill. Now the intramedullary nail is inserted into the bone's medullary cavity until it reaches the fracture region. Subsequently the two major bone fragments are aligned accordingly to their correct anatomical position. For this the distal (knee side) fracture segment is moved by the surgeon by means of a socalled Schanz' screw, whereas the proximal fracture segment is hold in its position by means of a second Schanz' screw. According to (Ruedi & Murphy, 2000), this form of manipulation is called “joystick” reduction. When the fracture segments are finally aligned correctly, the intramedullary nail is further inserted. Finally the nail is locked with the bone by means of lateral screws. During the final insertion and the locking of the nail, the correct retention, which means maintaining the correct segment positions, has to be ensured. The whole process is supervised by means of X-ray imaging. A detailed description of this surgical procedure can be found in (Ruedi & Murphy, 2000).