Facet joint injections for people with persistent non-specific low back pain (Facet Injection Study): a feasibility study for a randomised controlled trial oleh David R Ellard, Martin Underwood, Felix Achana, James HL Antrobus, Shyam Balasubramanian, Sally Brown, Melinda Cairns, James Griffin, Frances Griffiths, Kirstie Haywood, Charles Hutchinson, Ranjit Lall, Stavros Petrou, Nigel Stallard, Colin Tysall, David A Walsh, Harbinder Sandhu