Pain and functional improvement effects of methylene blue injection on the soft tissue around fusion site after traumatic thoracolumbar fixation: A double-blind, randomized placebo-controlled study.

Objective: Fractures of the thoracolumbar spine can cause pain, long-term reductions in quality of life (QOL), and neural deficits. The aim of this study was to investigate the effects of methylene blue (MB) on preventing postoperative pain and improving QOL in patients with throracolumbar fractures undergoing posterior pedicle screw fixation.

Methods: Fifty patients underwent standard posterior pedicular screw fixation for stabilization of the thoracolumbar fractures: 25 received 1ml of MB solution at a concentration of 0.5% and 25 received normal saline on the soft tissue around fusion site. Primary outcomes were the control of pain, evaluated at 48h, 2 and 6 months after surgery with the use of a visual analog scale (VAS), and the improvement of QOL, assessed 2 and 6 months postoperatively by means of Oswestry Disability Index (ODI) questionnaire.

Results: The mean VAS scores for pain were significantly lower in the MB group compared with the control group at 2 months (1.30±0.45 vs. 2.60±1.19, P<0.001) and 6 months (1.17±0.37 vs. 1.60±0.87; P=0.028) after treatment. At 2 months after the surgery, the mean ODI score was significantly lower in the MB-treated patients than the control group (20.4±10.92 vs. 34.8±15.11; P=0.001). The ODI score in the MB-treated patients was better than the control group at 6 months after the surgery (12.2±11.66 vs. 20.8±11.14; P=0.016).

Conclusion: A single dose of MB on the soft tissue around fusion site shows promising results in terms of safety, reduction of postoperative pain, and functional results when compared with placebo 6 months after surgery.