Background: Lumbar facet joint syndrome (LFJS) has been suggested to be a main source of low back pain. Methylene blue (MB), an inhibitor of nitric oxide synthesis with potential analgesic and anti-inflammatory properties, has been widely applied for a variety of pain-related diseases. However, no studies have been conducted on the treatment of LFJS patients using MB.
Objectives: The purpose of this study was to evaluate the therapeutic effects of intra-articular injection of MB on LFJS patients.
Study design: A prospective, randomized, controlled clinical trial.
Setting: Department of pain, Shanghai East Hospital.
Methods: A total of 120 eligible patients with LFJS were randomly divided into an MB group and a control group. Numeric Rating Scale (NRS), Oswestry Disability Index (ODI), Pittsburgh Sleep Quality Index (PSQI), Patient Health Questionnaire-9 (PHQ-9) were used to evaluate the pre-operation and post-operation states of the patients, and adverse events were recorded. The patients participating in this study were followed up for a period of 6 months.
Results: A total of 104 patients were followed up for the entire 6 months period. The control group included 51 patients, and the MB group included 53 patients. In both groups, the NRS scores, ODI scores, PHQ-9 scores, and PSQI scores decreased at different time points after treatment, compared to baseline. Moreover, the NRS scores were significantly lower than that of the control group at 3 months and 6 months after operation (P < 0.05). The ODI, PSQI, and PHQ-9 scores of the MB group were also respective significantly lower than that of the control group at 3 months and 6 months after operation (P < 0.05). As for the clinical efficacy, the total effective treatment rate of the MB group was significantly higher than that of the control group at 6 months after the procedure (P < 0.05). On the first day after operation, the incidence of hyperglycemia in patients with diabetes in the MB group was significantly lower than that of the control group (P < 0.05).
Limitations: Firstly, the patients enrolled were recruited from a single center, and the sample size was small. Secondly, the patients were only followed-up for a period of 6 months after treatment. Thirdly, double blinding was not used in the design of this research study.
Conclusion: Ultrasound-guided intra-articular MB injection is a safe and effective therapy for patients with LFJS. Intra-articular injection with MB can significantly reduce pain intensity, improve patient lumbar function, pain-related depression and sleep quality, increase total effective rate with no severe adverse side effects.
Keywords: intra-articular injection; methylene blue; ultrasound guidance; Facet joint syndrome.