Image by crystal light/Shutterstock

Researchers at University of Tsukuba investigated the mechanism by which posterior spinal fixation, a technique that fixes the infected vertebrae by sandwiching them between normal vertebrae, suppresses infection in pyogenic spondylodiscitis using animal models. Results suggested that increasing the stability of the bones suppresses the activity of osteoclasts, prevents bone destruction, and allows the infection to be controlled without treating the infected site directly.

Tsukuba, Japan—Pyogenic spondylodiscitis is a disease caused by bacterial infections of the spine and intervertebral discs. Disease progression can lead to lower back pain, numbness, and paralysis of the lower limbs. However, because intervertebral discs have little blood flow and it is difficult for antibiotics to reach them, treatment is difficult, so early detection and thorough treatment are crucial. In the past, treatment was based on antibiotic use and rest, but recently, surgery has become more common. Posterior fixation, in which the normal spine is fixed with pedicle screws and rods to stabilize the infected site, is a treatment method that suppresses infection. However, the mechanism by which infection is suppressed without direct treatment of the infected site is not well understood.

In this study, researchers created a new animal model, the pyogenic spondylodiscitis-posterior fixation model rat, and investigated the mechanism by which posterior fixation suppresses infection. This model mimics infection and surgery in the human body. Infection is reproduced by injecting bacteria into the intervertebral discs of the rat's tail, and screws are inserted into the tailbone to fix the infected intervertebral discs. Results confirmed that fixing the infected site prevents the tailbone from being destroyed and weakens the activity of the osteoclasts, suggesting that posterior fixation increases bone stability and suppresses the activity of osteoclasts, thereby preventing bone destruction and helping to control infection.

The research team previously investigated the effectiveness, safety, and timing of posterior fixation surgery for pyogenic spondylodiscitis in clinical research. This study supports the effectiveness of posterior fixation surgery from a basic mechanism, and these findings are expected to lead to the development of improved treatment methods.

###
This study was supported by TEIJIN Nakashima Medical (2022-A19, 2023-A11)　(Paid directly to the institution).

Original Paper

Title of original paper:

Posterior fixation without debridement for pyogenic spondylodiscitis can promote infection control: Initial evaluation of a pyogenic spondylodiscitis posterior fixation rat model

Journal:

European Spine Journal

DOI:

10.1007/s00586-025-08750-y

Correspondence

Assistant Professor FUNAYAMA Toru
Institute of Medicine, University of Tsukuba>

GAMADA Hisanori
Doctoral Program in Medical Sciences, Degree Programs in Comprehensive Human Sciences, Graduate School of Comprehensive Human Sciences

Related Link

Institute of Medicine

Doctoral Program in Medical Sciences, Graduate School of Comprehensive Human Sciences