STUDY DESIGN

A retrospective review.

OBJECTIVE

The aim of this study was to study the effectiveness of percutaneous radiofrequency neurotomy of facet joints by monitoring compound muscle action potentials (CMAPs) of the multifidus muscle group as an objective index of treatment efficacy.

SUMMARY OF BACKGROUND

Percutaneous radiofrequency neurotomy of the medial branches of the dorsal rami of the lumbar nerves is a widely accepted treatment for chronic lumbar intervertebral joint pain. However, its success rate has varied in different studies because an objective method for evaluating the facet joint denervation is lacking.

METHODS

Fifty-five patients (age range, 19-76 y; mean age, 55 y) with low back pain persisting for ≥3 months, in whom facet block and/or block of the medial branch of the dorsal ramus were only temporarily effective, were included. The Japanese Orthopaedic Association (JOA) scoring system for back pain was used for clinical assessment. JOA scores were measured before treatment and 1 week, 3 months, 6 months, and 12 months afterward. The improvement rate was calculated with ≥40% improvement rate defined as successful, and the success rate was subsequently evaluated.

RESULTS

The patient success rate was 75% (41/55) at 1 week, 71% (39/55) at 3 months, 60% (33/55) at 6 months, and 51% (28/55) at 12 months after treatment. Two cases had minor postoperative complications, which were localized burning pain lasting <1 week at the site of electrode insertion.

CONCLUSIONS

Our results suggest that percutaneous radiofrequency facet joint denervation with CMAPs monitoring is a safe, long-lasting, and effective treatment for chronic facet joint pain. CMAP monitoring may be useful as an objective index for facet denervation.