Facet-joint injections for non-specific low back pain: a feasibility RCT.

BACKGROUND: Pain of lumbar facet-joint origin is a common cause of low back pain in adults and may lead to chronic pain and disability, with associated health and socioeconomic implications. The socioeconomic burden includes an inability to return to work resulting in loss of productivity in addition to direct and indirect health-care utilisation costs. Lumbar facet-joints are paired synovial joints between the superior and inferior articular processes of consecutive lumbar vertebrae and between the fifth lumbar vertebra and the sacrum. Facet-joint pain is defined as pain that arises from any structure that is part of the facet-joints, including the fibrous capsule, synovial membrane, hyaline cartilage and bone. This pain may be treated by intra-articular injections with local anaesthetic and steroid, although this treatment is not standardised. At present, there is no definitive research to support the use of targeted lumbar facet-joint injections to manage this pain. Because of the lack of high-quality, robust clinical evidence, the National Institute for Health and Care Excellence (NICE) guidelines on the management of chronic low back pain [NICE. Low Back Pain in Adults: Early Management . Clinical guideline (CG88). London: NICE; 2009] did not recommend the use of spinal injections despite their perceived potential to reduce pain intensity and improve rehabilitation, with NICE calling for further research to be undertaken. The updated guidelines [NICE. Low Back Pain and Sciatica in Over 16s: Assessment and Management . NICE guideline (NG59). London: NICE; 2016] again do not recommend the use of spinal injections.

OBJECTIVES: To assess the feasibility of carrying out a definitive study to evaluate the clinical effectiveness and cost-effectiveness of lumbar facet-joint injections compared with a sham procedure in patients with non-specific low back pain of > 3 months' duration.

DESIGN: Blinded parallel two-arm pilot randomised controlled trial.

SETTING: Initially planned as a multicentre study involving three NHS trusts in the UK, recruitment took place in the pain and spinal orthopaedic clinics at Barts Health NHS Trust only.

PARTICIPANTS: Adult patients referred by their GP to the specialist clinics with non-specific low back pain of at least 3 months' duration despite NICE-recommended best non-invasive care (education and one of a physical exercise programme, acupuncture or manual therapy). Patients who had already received lumbar facet-joint injections or who had had previous back surgery were excluded.

INTERVENTIONS: Participants who had a positive result following a diagnostic test (single medial branch nerve blocks) were randomised and blinded to receive either intra-articular lumbar facet-joint injections with steroids (intervention group) or a sham procedure (control group). All participants were invited to attend a group-based combined physical and psychological (CPP) programme.

MAIN OUTCOME MEASURES: In addition to the primary outcome of feasibility, questionnaires were used to assess a range of pain-related (including the Brief Pain Inventory and Short-Form McGill Pain Questionnaire version 2) and disability-related (including the EuroQol-5 Dimensions five-level version and Oswestry Low Back Pain Questionnaire) issues. Health-care utilisation and cost data were also assessed. The questionnaire visits took place at baseline and at 6 weeks, 3 months and 6 months post randomisation. The outcome assessors were blinded to the allocation groups.

RESULTS: Of 628 participants screened for eligibility, nine were randomised to receive the study intervention (intervention group, n  = 5; sham group, n  = 4), six completed the CPP programme and eight completed the study.

LIMITATIONS: Failure to achieve our expected recruitment targets led to early closure of the study by the funder.

CONCLUSIONS: Because of the small number of participants recruited to the study, we were unable to draw any conclusions about the clinical effectiveness or cost-effectiveness of intra-articular lumbar facet-joint injections in the management of non-specific low back pain. Although we did not achieve the target recruitment rate from the pain clinics, we demonstrated our ability to develop a robust study protocol and deliver the intended interventions safely to all nine randomised participants, thus addressing many of the feasibility objectives.

FUTURE WORK: Stronger collaborations with primary care may improve the recruitment of patients earlier in their pain trajectory who are suitable for inclusion in a future trial.

TRIAL REGISTRATION: EudraCT 2014-003187-20 and Current Controlled Trials ISRCTN12191542.

FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment ; Vol. 21, No. 74. See the NIHR Journals Library website for further project information.