Implementation and performance evaluation of a drilling assistive device for distal locking of intramedullary nails.

Intramedullary nailing is a common treatment for long bone fractures. The nail might deform during implantation because of the shape of medullary cavity. Thus, surgeons take many X-ray images to position distal locking holes and check the drilling process. In this study, we developed a positioning algorithm with a passive or active (robot arm) assistive device for promptly positioning of distal locking holes and stably drilling guidance and support. Using the passive device, the surgeon could manually align the positioning probe with locking hole within 60 seconds based on 20 test cases. In 36 test cases, the active device aligned the positioning probe with locking hole automatically with average errors of 2.2 mm in position and 3.19° in direction. The passive device provides a reliable and low-cost solution for distal locking of intramedullary nails, while the active device is easy and friendly to use.