Active markers in operative motion analysis

Surgical correction of spinal deformities is a complex mechanical process that may involve the insertion of screws, hooks, and curved rods. Visualizing the correction of the spine during the surgical procedure is difficult because the size of the incision and exposure of the spine are minimized to reduce trauma and scarring to the patient. The issue of visualization is compounded by the three-dimensional (3-D) nature of typical deformities and the applied instrumentation further obscuring the view of the spine. The amount of correction on the spine relies on a subjective feeling from the orthopedic surgeons. To provide an objective measurement of correction, an innovative marker system has been developed to track the position of the spine in real time. For this system, the errors in a patient-less operating room during a simulated surgical correction procedure in 3-D translation and rotation measurements were found to be 60plusmn4 mum and 0.05plusmn0.23deg, respectively. This system will potentially help orthopedic surgeons deliver better treatment to patients and assess immediate treatment effects in real time