Grant: Collaborative Health Research Projects (NSERC partnered)

Of the more than 300,000 wrist fractures that occur in North America each year, 90% include fracture of the scaphoid, a cashew-shaped small bone. The conventional treatment comprises immobilizing the wrist in a cast for several weeks, until union is detectable on X-ray images. Complications, including malunion or nonunion (that if untreated cause progressive wrist arthritis) are common, and lead to surgical treatment involving placing a screw in the central one-third of the bone. Since the scaphoid is locally as narrow as 6 mm, the surgical intervention is challenging, may result in damage to cartilage or the surrounding small bones, and demands strict accuracy with error tolerance of less than 2 mm. There is currently no efficient intra-operative means for accurate screw placement, short of surgical exposure that inevitably causes scarring and devascularization, and may dislodge previously non-displaced bone fragments. Less invasive techniques involve liberal usage of X-ray fluoroscopy, which often provides suboptimal images whilst exposing patient and surgical team to significant doses of ionizing radiation. Hence, there is an acute need for a minimally invasive, nonionizing navigation technique for visualizing the relative location of wrist anatomy and the screw for accurate fracture reduction. Ultrasound guidance is highly promising for this problem, as it is non-ionizing and real-time.