The therapeutic effect of intra-articular facet joint injection with normal saline as a comparator for chronic low back pain: a systematic review and meta-analysis

BackgroundIntra-articular facet joint injection (FJI) has been increasingly used as a treatment for chronic low back pain (LBP). Choice of the substance has been based on clinical experience with unclear evidence on marginal effectiveness of active substance over normal saline as a placebo control. This systematic review investigates the comparative effectiveness between normal saline and active substances on patient-reported outcomes (PROs). MethodsSystematic search was conducted in five databases: PubMed, Embase, Scopus, Web of Science, and CENTRAL for randomized controlled trials and observational studies of evaluating the PROs of FJI comparing active injected substances with normal saline as placebo in chronic LBP patients in the English language without publication date restriction. Quality assessment was performed using ROB2 and ROBINS-I. The meta-analysis was done using a random-effects model. Mean difference with 95% CIs of efficacy outcomes including pain, numbness, disability, quality of life were measured. ResultsOf 2,467 potential studies, three were included in the systematic review and meta-analysis (247 patients). Compared to other active substances, normal saline provided similar therapeutic effects on pain outcome within one hour (MD 2.43, 95% CI -11.61 to 16.50), at 1-1.5 months follow up (MD -0.63, 95% CI -7.97 to 6.72), and at 3 to 6 months (MD 1.90, 95% CI -16.03 to 19.83) as well as the quality of life at one and six months follow-up. ConclusionsThe short-term and long-term clinical improvements of intra-articular FJI using normal saline are comparable to the other active substances in LBP patients. PROSPEROregistration number CRD42020216426