# Assessing vertebral bone density changes with phantomless QCT after posterior open reduction and internal fixation

## TL;DR

This study uses a new CT method to track changes in bone density after spinal surgery, finding significant decreases in bone mineral density that persist over time.

## Contribution

The study introduces a novel phantom-less quantitative CT system for measuring vertebral bone density changes after spinal surgery.

## Key findings

- Postoperative bone mineral density was significantly lower than preoperative values in all measured segments.
- BMD loss in the anterior region of the caudal adjacent vertebra was greater than in the posterior region.
- There was no significant difference in BMD loss between short-term and longer-term follow-up groups.

## Abstract

This study was to investigate vertebral body bone mineral density (BMD) changes using a novel automatic phantom-less quantitative CT (PL-QCT) system in short and relatively long-term periods after posterior open reduction and internal fixation. 109 patients (77 men [70.6%]; median age, 48 [IQR 37, 55]) who underwent posterior open reduction and internal fixation for thoracolumbar fractures were enrolled into the study. The median follow-up duration was 441 days (IQR 377–553). Based on the median follow-up time, patients were divided into Group 1 (378 days [IQR 350–412]) and Group 2 (553 days [IQR 493–706]). Bone mineral density (BMD) was measured for the injured vertebrae, the upper and lowest instrumented vertebra, as well as the cranial and caudal adjacent vertebrae preoperatively and postoperatively. The postoperative BMD in all segments was significantly lower compared to the preoperative values (P < 0.05). There was no difference in BMD loss between Group1 and Group2 (P > 0.05). The BMD loss in the anterior region of the caudal adjacent vertebra was greater than that in the posterior region (− 13.0 mg/cm³ [IQR − 26.8, − 6.8] vs. − 12.0 mg/cm³ [IQR − 20.8, − 3.1], P = 0.006). Early monitoring and intervention for bone loss following surgery, particularly focusing on the anterior region of the adjacent vertebrae, could potentially aid in improving clinical outcomes with more follow-up studies.

The online version contains supplementary material available at 10.1038/s41598-025-01739-z.