1. Introduction

Each year, around 1.3 million cases of spine surgery are performed in the United States alone, 53 % of which could be categorized as spinal fusion surgeries (McWilliams 2011; Solomon 2010), necessitating the insertion of screw implants into small bones in the spinal vertebrae, called pedicles (see Figs. 1.1 and 1.3). Pedicle screw placement is a complex 3-D navigation problem that involves risk to the patient. Of major concern is the fact that improperly inserted screws could place the surrounding vital structures at risk. This could lead to lawsuits for hospitals and the financial burden of revision surgeries for healthcare. Statistics show a 6.8 % readmission rate within 30 days of this procedure in USA hospitals (Weiss et al. 2013).