Automated Manufacture of Spinal Instrumentation

Current scoliosis corrective surgeries may include the use of multiple instrumentation devices including screws, wires, nuts, and rods. The instrumentation in most cases is implemented in its native form. However, the instrumentation rods must be contoured to a desired shape prior to fixation to the spine. The contouring of the instrumentation rod is currently performed manually and may require significant time for completion. This results in an increase of operation time and reduced accuracy of the instrumentation rod. The feasibility of automating the contouring process was studied to determine if the time required to contour a rod could be reduced and if the accuracy of the rod could be improved.

This study built upon a previous effort to construct a prototype that would automate the manufacture of spinal instrumentation rods. The Spinal Instrumentation Bending Prototype (SIBP) focused on ease of use, time of manufacture, and accuracy. In order to complete the manufacturing process, the current SIBP uses a set of three dimensional control points that represent the desired contour of the rod. These control points are translated into manufacturing inputs that control the SIBP. The control application for the SIBP contains local and global feedback routines that correct for any manufacturing errors. A comparative study was made between the SIBP and an experienced orthopedic surgeon to determine the level of bending accuracy improvement.