Robotic-assisted internal fixation of hip fractures: a fluoroscopy-based intraoperative registration technique

The internal fixation of proximal femoral (hip) fractures is the most frequently performed orthopaedic surgery procedure. When using a sliding compression hip screw, a commonly used fixation device, accurate positioning of the device within the femoral neck-head is achieved by initially drilling a pilot hole. A cannulated component of the hip screw is then inserted over the guide wire (surgical drill bit), which is used to drill the pilot hole. However, in practice, this fluoroscopically controlled drilling process is severely complicated by a depth perception problem and, as such, a surgeon can require several attempts to achieve a satisfactory guide wire placement. A prototype robotic-assisted orthopaedic surgery system has therefore been developed, with a view to achieving accurate right-first-time guide wire insertions. This paper describes the non-invasive digital X-ray photogrammetry-based registration technique which supports the proposed robotic-assisted drilling scenario. Results from preliminary laboratory (in vitro) trials employing this registration technique indicate that the cumulative error associated with the entire X-ray guided robotic system is within acceptable limits for the guide wire insertion process

Robotic-assisted internal fixation of femoral fractures

Closed surgical techniques for the internal fixation of femoral fractures require orthopaedic surgeons to work in close proximity to X-rays. In addition to the occupational health risk this imposes, inexperienced surgeons often encounter great difficulty in achieving optimal positioning of fracture repair fixtures. A vision-guided robotic system has been proposed as a possible solution to these problems and an initial investigation involving two exemplar orthopaedic procedures has been undertaken. Robotic surgery assistance imposes rigorous safety-related design constraints, since the orthopaedic robot must operate in close proximity to the patient and operating staff. The design and implementation of a purpose-built robotic system for orthopaedic surgery assistance is described in this paper

Intraoperative registration for robotic-assisted orthopaedic surgery : a digital X-ray photogrammetry based technique

Changes in orthopaedic practice have led to an increased reliance upon fluoroscopic image-guidance during fracture fixation (osteosynthesis) procedures. The resulting complexity of surgical techniques, and concerns over X-ray radiation exposure levels to orthopaedic surgeons, has prompted an investigation of robotic-assisted orthopaedic surgery, with a view to improving the precision, repeatability and radiation safety of existing fluoroscopically-guided bone drilling procedures. A prerequisite for such an application is to establish the patient's location with respect to the robotic manipulator. Owing to the inherent nature of osteosynthesis procedures, this intraoperative registration process can only be performed by quantifying the existing fluoroscopic examination process. A digital X-ray photogrammetry based registration technique, which uses a radiolucent robot-mounted X-ray calibration frame, has therefore been investigated. When this calibration frame is simultaneously imaged with the patient, discrete registration markers, corresponding to radiopaque fiducials embedded in the frame, are superimposed into the standard intraoperative X-ray images. Digitising these images, using a PC-based frame grabber card, has allowed semi-automatic image analysis routines to be implemented. Applying correction-calibration software, which provides on-line compensation for image distortion effects, then allows the imaged part of the patient's skeleton to be located, with respect to the calibration frame's coordinate system, thus establishing intraoperative registration. In vitro laboratory-based trials of this registration technique indicate that reconstruction errors are in the sub-millimetre range. As such, this new approach represents a low cost non-invasive registration option, which fully adheres to "operating room compatibility" criteria, and is applicable to a wide range of osteosynthesis procedures. Significantly, by extending the technique to include quantification of the trajectory plarming process, it has also been possible to demonstrate major improvements over existing surgical techniques