The value of provocative facet blocking as a predictor of success in lumbar spine fusion.

Studies attempting to correlate facet blocking with successful relief of pain after fusion have reached unfavorable results. These studies, however, did so in a retrospective fashion, and facet blocking was not the sole criterion by which surgical candidates were chosen. The current study is the first to use facet blocking in a prospective fashion and as the definitive criterion by which patients were chosen. Ninety-one patients with chronic low back pain who responded to bracing underwent 197 facet blocks. Twenty-eight patients who had > 70% relief of their pain for >6 h on three separate occasions were surgical candidates and underwent fusion along with two others with mechanical abnormalities but negative blocks. Pre- and postoperative Prolo (Prolo DJ, Oklund SA, Butcher M: Toward uniformity in evaluating results of lumbar spine operations. A paradigm applied to posterior lumbar interbody fusions. Spine 11:601-606, 1986) outcome scores were assigned and the patients underwent self-assessment. Twenty-three of 30 patients had successful fusion. Nineteen of 23 described 90% relief, 3 patients had 50-90% partial relief, and 1 failed by self-assessment. A preoperative mean Prolo score of 3.95 (range 2-7) improved to 7.7 (range 3-10) with fusion. Provocative facet blocking can be used to successfully predict outcome in patients undergoing arthrodesis for chronic low back pain.