Low Back Pain: Prediction of Short-term Outcome of Facet Joint Injection with Bone Scintigraphy

Abstract

To prospectively evaluate use of bone scintigraphy with single photon emission computed tomography (SPECT) for identification of patients with low back pain who would benefit from facet joint injections. The protocol was reviewed and approved by the institutional review board. All patients provided informed consent. Forty-seven patients (23 men and 24 women) with low back pain, who were scheduled for facet joint injections, were prospectively enrolled and randomized into groups A and B (mean ages, 43.3 and 44.2 years, respectively) with a group A-group B ratio of 2:1. Group A patients underwent bone scintigraphy with SPECT prior to injection. Group A patients with bone scans positive for facet joint abnormalities received injections at the levels where abnormalities were identified on the scan (group A1). Group A patients with negative scans (group A2) received injections at the levels that were decided as in group B. Group B patients received injections at the levels indicated by the referring physician and did not undergo bone scintigraphy. All patients completed a pain and function questionnaire before injection and at 1, 3, and 6 months afterward. The change in the American Academy of Orthopaedic Surgeons pain scores after 1, 3, and 6 months compared with baseline scores was analyzed with analysis of variance and post hoc Bonferroni multiple-comparison tests between groups. Cost analysis was performed. The change in the pain score at 1 month was significantly higher (P < .004) in group A1 than it was in the other two groups. In group A1, 13 of 15 patients had improvement in pain score of greater than 1 standard deviation at 1 month, whereas improvement occurred in only two of 16 patients in group A2 and five of 16 patients in group B. In patients with positive scans, the number of facets treated with injection was decreased from 60, which was the number originally indicated by the referring physician, to 27. The Medicare cost was reduced from $2191 per patient to $1865 with the use of SPECT. Bone scintigraphy with SPECT can help identify patients with low back pain who would benefit from facet joint injections.