# Obturator inlet and iliac oblique fluoroscopic views allow for placement of longer iliac screws

## TL;DR

A new fluoroscopic technique allows for longer and safer iliac screw placement during spinal fusion surgeries compared to traditional methods.

## Contribution

The OIIO fluoroscopic technique enables longer screw placement without increased risk of cortical breaches.

## Key findings

- OIIO group had significantly longer screws (97.95 mm) compared to freehand (78.68 mm) and CT navigation (85.27 mm).
- OIIO had no cortical breaches, similar to CT navigation and lower than freehand.
- OIIO technique showed no increased revision rates, indicating comparable safety.

## Abstract

Achieving strong distal fixation in posterior spinal fusion (PSF) surgeries sometimes necessitates iliac screw placement. However, traditional methods such as freehand and CT navigation techniques face limitations concerning screw length, accuracy, ergonomic challenges, surgical time, and drill deflection. Fluoroscopic iliac screw guidance using the obturator inlet and iliac oblique (OIIO) views may mitigate some of these drawbacks.

This retrospective comparative study was conducted at a university-affiliated tertiary care hospital and Level 1 trauma center, reviewing cases from January 2020 to December 2022. A total of 119 patients who underwent posterior spinal fusion with pelvic fixation were included and categorized into 3 groups: OIIO (n = 20), freehand (n = 46), and CT navigation-assisted (n = 53). Screw length, diameter, and cortical breach rates were assessed using intraoperative and postoperative imaging. Statistical analyses were performed using 1-way ANOVA and Fisher’s Exact test (p < .05).

Screw lengths were 97.95 ± 6.95 mm, 78.68 ± 5.17 mm, and 85.27 ± 7.01 mm in the OIIO, freehand, and navigation groups, respectively (p < .0001). Despite the longer screws, the OIIO group had no cortical breaches, compared to 0.58% in the freehand group and 0% in the CT navigation group (p = .5683). No significant differences were observed in iliac screw revision rates across groups (p = .6175), suggesting the OIIO technique is not inferior to freehand and navigation-assisted methods regarding safety and screw length.

The OIIO technique allows for favorable screw sizes compared to freehand and navigation-assisted methods without increasing cortical breach risk. This technique provides a safe and ergonomic alternative, particularly in settings where advanced navigation technology is unavailable.