148. Sacroiliac joint fusion navigation: how accurate is pin placement?

Abstract

BACKGROUND CONTEXT Percutaneous pin placement is used in a variety of orthopedic surgery settings. These include, but are not limited to, external fixator placement, fracture fixation, and reference frame application for navigation. Although pin placement typically is uncomplicated, it can become more difficult with the need for obliquely angled pins and the potential for the pin to slip off the bone. For spine and pelvic cases with intraoperative navigation, often a standard reference frame is placed using a percutaneous pin. The goal is for this pin to be placed into the posterior ilium, which is an oblique surface. Proper placement of this pin helps to ensure the correct placement of the sacroiliac joint (SIJ) fusion implants. To date, there is no literature specifically examining the accuracy of pin placement. PURPOSE The purpose of our study was to evaluate the occurrence of ideal percutaneous pin placement into the iliac wing during navigated SIJ fusion surgery. STUDY DESIGN/SETTING IRB approved retrospective chart review study completed at an academic medical institution. PATIENT SAMPLE Patients who underwent navigated SIJ fusion by the senior author between 10/2013 and 1/2020. OUTCOME MEASURES Pin placement accuracy graded in concordance with a scheme developed and tested by the authors. METHODS Following IRB approval, we reviewed the charts and intraoperative CT imaging of patients who underwent navigated SIJ fusion by the senior author between 10/2013 and 1/2020. A pin placement grading scheme was developed initially and tested. The definition of ‘ideal’ placement was a concept developed by the authors. A modification was made and found to be acceptable to attending surgeons. This was then used for two rounds of grading. Six attending surgeons completed two rounds of pin placement grading. RESULTS Of the 95 eligible patients, 54.7% had ‘ideal’ pin placement. There were no observed complications from pin placement. There was no relationship between BMI and ideal placement. Male patients were 3.6 times more likely to have ideal placement than females. Additionally, patients undergoing right-sided fusion were 2.9 times more likely to have ideal placement than those with left-sided fusion. Interobserver reliability was rated as 0.48 and 0.47 in the first and second rounds defined as ‘moderate agreement.’ The measured intraobserver reliability ranged from 0.62 to 0.74 defined as ‘substantial agreement.’ Conclusions This study shows that even in the hands of an experienced surgeon, nonideal pin placement occurs 45.3% of the time. However, engagement of the lateral or medial cortex may make the pin more rigid. Though pin placement does not meet our preconceived ‘ideal’, it is only rarely a true ‘miss’ where it is placed into the sacrum. Male patients and patients undergoing right-sided fusion were more likely to have ‘ideal’ pin placement. When placing percutaneous pins, regardless of the location, it is important to be aware of factors that can decrease the accuracy of pin placement. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.