Intraarticular Facet Injections for Low Back Pain:
Design Considerations, Consensus Methodology
to Develop the Protocol for a Randomized
Controlled Trial
Authors: Ellard David R 
Published: February 2021

Background: Since the publication of guidelines by the UK National Institute for Health and Care
Excellence (NICE) and the American Pain Society guidelines for low back pain in 2009 there have
been deep divisions in the pain treatment community about the use of therapeutic intraarticular
facet joint injections. While evidence for the effectiveness or not of intraarticular facet joint injections
remains sparse, uncertainty will remain. The Warwick feasibility study, along with a concurrent study
with a different design led by another group, aims to provide a stable platform from which the
effectiveness and cost effectiveness of intraarticular facet joint injections added to normal care could
be evaluated in randomized controlled trials (RCTs).
Objectives: To reach consensus on key design considerations for the Warwick facet feasibility
study from which the study protocol and working manuals will be developed.
Study Design: A consensus conference involving expert professionals and lay members.
Methods: Preliminary work identified 5 key design considerations for deliberation at our consensus
conference. Three concerned patient assessment and treatment: diagnosis of possible facet joint pain,
interaarticular facet joint injection technique, and best usual care. Two concerned trial analysis: a
priori sub-groups and minimally important difference and are reported elsewhere. We did systematic
evidence reviews of the design considerations and summarized the evidence. Our design questions
and evidence summaries were distributed to all delegates. This formed the basis for discussions on
the day. Clinical experts in all aspects of facet joint injection from across the UK along with lay people
were invited via relevant organizations. Nominal group technique was used in 15 facilitated initial
small group discussions. Further discussion and ranking was undertaken in plenary. All small group and
plenary results were recorded and checked and verified post conference. Where necessary participants
were contacted via email to resolve outstanding issues.
Results: Fifty-two delegates attended the conference with lay people and all relevant professions
represented. Consensus was reached on the details of how to assess patients for facet joint pain,
undertake the injections, and deliver usual care. Where post conference checking of results revealed
errors in calculating ranking results on the day, consensus was reached by email consultation. All but
3 delegates agreed to be associated with the outcome.
Limitations: Allocating one day for discussing a wide range of topics imposed time pressure on
discussion and calculation of the numerous rankings.
Conclusions: Through the use of an evidence-based, systematic, inclusive, and transparent process
we have established consensus from expert health professionals in the UK, with lay input, on the
clinical assessment of suspected facet joint pain, interaarticular injection for facet joint pain, and
best usual care for use in a feasibility study for a proposed pragmatic clinical trial of interaarticular
facet joint injections. This provides a strong basis for a clinical trial that will be acceptable to the pain
treatment community.
Key words: Low back pain, interaarticular facet joint injections, best usual care, consensus,
nominal group technique