# Percutaneous Reduction and Fixation for Traumatic Thoracolumbar Vertebral Fracture Using a Monoaxial Screw System

## TL;DR

This study shows that using a monoaxial screw system for spine surgery in thoracolumbar fractures is minimally invasive and effective, with good recovery outcomes.

## Contribution

The study introduces the use of a monoaxial screw system for percutaneous fixation of thoracolumbar vertebral fractures.

## Key findings

- No surgical complications occurred, and implant failure was not observed in any patients.
- Significant improvement in spinal kyphosis angle and wedge deformity was seen immediately after surgery.
- Improvements in spinal parameters were maintained after implant removal, despite some loss of correction.

## Abstract

Background and aim: The development of percutaneous pedicle screws (PPSs) has led to the development of minimally invasive spine stabilization (MISt) procedures, which has decreased the invasiveness of spine surgery. Conventionally, PPSs were available as polyaxial screws only, making it technically challenging to perform percutaneous repair of thoracolumbar vertebral fractures with implants. This study aimed to evaluate percutaneous posterior fixation for thoracolumbar vertebral fractures using a monoaxial screw system and determine imaging and clinical outcomes until after implant removal.

Methods: We retrospectively reviewed 20 patients who underwent posterior fixation using the S4 Spinal Fracture Reduction Instrumentation (FRI) system with percutaneous vertebroplasty for traumatic thoracolumbar vertebral fractures. Follow-up continued until after implant removal. AO classification was type A3 in 19 patients and type B2 in one. Implants were removed after confirmation of bone healing. The mean follow-up period was 753 days. We evaluated intraoperative blood loss, operative time, neurological status, and radiological parameters, including local kyphosis angle, wedge deformity rate, and spinal canal stenosis rate.

Results: No surgical complications (e.g., worsening paralysis or infection) occurred. No patients had implant failure or required blood transfusion during surgery, reoperation, or routine painkiller use at the final follow-up. The mean spinal kyphosis angle was 12.6° preoperatively, 1.9° immediately postoperatively, 6.5° before implant removal, and 7.9° after implant removal, showing significant improvement between the preoperative and immediate postoperative periods. However, there was a significant loss of correction after implant removal compared with immediate postoperatively (mean 6°). Kyphosis angle tended to decrease from the preoperative period to after implant removal, albeit not significantly. The mean wedge deformity rate and spinal canal stenosis rate showed significant improvement immediately postoperatively. These improvements were maintained after implant removal.

Conclusions: Posterior fixation using the monoaxial PPS with the S4 Spinal FRI system is minimally invasive and is considered a useful surgical technique for thoracolumbar vertebral fractures.