Learning curve of computer-assisted navigation system in spine surgery

<正> Background Spine surgery using computer-assisted navigation (CAN) has been proven to result in low screwmisplacement rates,low incidence of radiation exposure and excellent operative field viewing versus the conventionalintraoperative image intensifier (Clll).However,as we know,few previous studies have described the learning curve ofCAN in spine surgery.Methods We performed two consecutive case cohort studies on pedicel screw accuracy and operative time of twospine surgeons with different experience backgrounds,A and B,in one institution during the same period.Lumbar pedicelscrew cortical perforation rate and operative time of the same kind of operation using CAN were analyzed and comparedusing Clll for the two surgeons at initial,6 months and 12 months of CAN usage.Results CAN spine surgery had an overall lower cortical perforation rate and less mean operative time compared withClll for both surgeon A and B cohorts when total cases of four years were included.It missed being statistically significant,with 3.3% versus 4.7% (P=0.191) and 125.7 versus 132.3 minutes (P=0.428) for surgeon A and 3.6% versus 6.4%(P=0.058),and 183.2 versus 213.2 minutes (P=0.070) for surgeon B.In an attempt to demonstrate the learning curve,the cases after 6 months of the CAN system in each surgeon's cohort were compared.The perforation rate decreased by2.4% (P=0.039) and 4.3% (P=0.003) and the operative time was reduced by 31.8 minutes (P=0.002) and 14.4 minutes(P=0.026) for the CAN groups of surgeons A and B,respectively.When only the cases performed after 12 months usingthe CAN system were considered,the perforation rate decreased by 3.9% (P=0.006) and 5.6% (P <0.001) and theoperative time was reduced by 20.9 minutes (P <0.001) and 40.3 minutes (P <0.001) for the CAN groups of surgeon Aand B,respectively.Conclusions In the long run,CAN spine surgery decreased the lumbar screw cortical perforation rate and operativetime.The learning curve showed a sharp drop after 6 months of using CAN that plateaued after 12 months;which wasdemonstrated by both perforation rate and operative time data.Careful analysis of the data showed CAN is especiallyuseful for less experienced surgeon to reduce perforation rate and intraoperative time,although further comparativestudies are anticipated.