Precise Robot-Assisted Guide Positioning for Distal Locking of
Intramedullary Nails

Ziv Yaniv and Leo Joskowicz

School of Computer Science and Engineering, The Hebrew University of
Jerusalem, Jerusalem 91904 Israel.

This paper presents a novel image-guided robot-based system to assist
orthopedic surgeons in performing distal locking of long bone
intramedullary nails.  The system consists of a bone-mounted miniature
robot fitted with a drill guide that provides rigid mechanical guidance for
hand-held drilling of the distal screws' pilot holes. The robot is
automatically positioned so that the drill guide and nail distal locking
axes coincide, using a single fluoroscopic X-ray image.  Since the robot is
rigidly attached to the intramedullary nail or bone, no leg immobilization
or real-time tracking is required. We describe the system and protocol and
present a method for accurate and robust drill guide and nail hole
localization and registration.  The in-vitro system accuracy experiments
for fronto-parallel viewing show a mean angular error of 1.3 degrees (std =
0.4 degrees) between the computed drill guide axes and the actual locking
holes axes, and a mean 3.0mm error (std = 1.1mm) in the entry and exit
drill point, which is adequate for successfully locking the nail.

Published in: IEEE Transactions on Medical Imaging, Vol 24(5), 2005, pp
624--635.