Therapeutic efficacy of facet joint blocks.

OBJECTIVE

The objective of our study was to investigate outcome predictors of short- and medium-term therapeutic efficacy of facet joint blocks.

MATERIALS AND METHODS

Forty-two patients with chronic lower back pain who were undergoing facet joint blocks at one (n = 29) or two (n = 13) levels were analyzed. All patients underwent MRI or CT of the lumbar spine within 5 months before the facet joint blocks. The facet joint blocks were performed under fluoroscopic guidance. A small amount (< 0.3 mL) of iodinated contrast agent, 0.5 mL of local anesthetics and 0.5 mL of steroids, were injected. The initial pain response was prospectively assessed using a visual analogue scale. Additional data, including short-term effect (> 1 week) and medium-term effect (> 3 months), were collected by a structured telephone interview. CT and MRI were reviewed with regard to the extent of facet joint abnormalities. Multiple logistic regression analyses were conducted to identify outcome predictor for efficacy of facet joint blocks.

RESULTS

A positive immediate effect was seen in 31 patients (74%). A positive medium-term effect was found in 14 patients (33%). Pain alleviated by motion (p = 0.035) and the absence of joint-blocking sensation (p = 0.042) predicted pain relief. However, the extent of facet joint osteoarthritis on MRI and CT was not a significant predictor for outcome (p = 0.57-0.95).

CONCLUSION

Facet joint blocks appear to have a beneficial medium-term effect in one third of patients with chronic lower back pain and may therefore be a reasonable adjunct to nonoperative treatment. However, outcome appears to depend on clinical, not on morphologic, imaging findings.