Each year, thousands of femoral and tibial internal fracture repairs are performed by orthopedic surgeons in the United States. Internal fixation of long bones using intramedullary nails (IMN) has decreased incidence of non-union, allowed shorter hospitalization time, and earlier weight bearing for the patient compared to other fixation methods. Orthopedic surgeons have expressed that one of the most difficult parts of this intramedullary nailing of long bones, is locating and drilling the interlocking screw holes. IMN interlocking requires the surgeon to locate the holes in the nail, center the drill, and advance the bit through the bone to meet them. Many novel procedures and devices have been developed to assist the surgeon in distal locking of intramedullary nails, but have some disadvantages. These can include the need for extensive x-ray exposure, expensive x-ray equipment, high power consumption, active electronics in vivo, soft tissue damage, which all lead to inaccurate screw placement. For these reasons, a new prototype device for locating and drilling IMN distal interlocking holes has been developed. This prototype device uses magnetic sensors to locate a permanent magnet placed at a know distance from the IMN interlocking hole. A drill sleeve may be attached to the targeting sensors so that when they are aligned with the target magnet, the drill sleeve is aligned with the axis of the interlocking hole to be drilled. This new prototype device has significant advantages over existing devices, including the following. It has no active or passive electronics in vivo, no x-ray imaging is needed for targeting, while allowing real time feedback of alignment. It is a percutaneous technique, which can be adapted for use with existing IMN's. The new prototype also has low power requirements allowing battery operation, a single target magnet with unique axisymmetric field and novel magnet orientation, and adjustable sensitivity. Additionally, the new device allows visual, audible, or tactile positioning feedback. This prototype magnetic targeting device can improve orthopedic surgeons' ability to target and drill distal IMN interlocking screw holes. This device may allow shorter surgery, decreased x-ray exposure, and fewer complications for the surgeon and patient. / Master of Science

Background and Objectives: Freehand distal interlocking of intramedullary nails is technically demanding and prone to handling issues. It requires precise placement of a screw through the nail under fluoroscopy guidance and can result in a time consuming and radiation expensive procedure. Dedicated training could help overcome these problems. The aim of this study was to assess construct and face validity of new Digitally Enhanced Hands-On Surgical Training (DEHST) concept and device for training of distal interlocking of intramedullary nails. Materials and Methods: Twenty-nine novices and twenty-four expert surgeons performed interlocking on a DEHST device. Construct validity was evaluated by comparing captured performance metrics—number of X-rays, nail hole roundness, drill tip position and drill hole accuracy—between experts and novices. Face validity was evaluated with a questionnaire concerning training potential and quality of simulated reality using a 7-point Likert scale. Results: Face validity: mean realism of the training device was rated 6.3 (range 4–7). Training potential and need for distal interlocking training were both rated with a mean of 6.5 (range 5–7), with no significant differences between experts and novices, p 0.234. All participants (100%) stated that the device is useful for procedural training of distal nail interlocking, 96% wanted to have it at their institution and 98% would recommend it to colleagues. Construct validity: total number of X-rays was significantly higher for novices (20.9 6.4 versus 15.5 5.3, p = 0.003). Success rate (ratio of hit and miss attempts) was significantly higher for experts (novices hit: n = 15; 55.6%; experts hit: n = 19; 83%, p = 0.040). Conclusion: The evaluated training device for distal interlocking of intramedullary nails yielded high scores in terms of training capability and realism. Furthermore, construct validity was proven by reliably discriminating between experts and novices. Participants indicate high further training potential as the device may be easily adapted to other surgical tasks.