Radiofrequency Neurotomy Does Not Cause Fatty Degeneration of the Lumbar Paraspinal Musculature in Patients with Chronic Lumbar Pain-A Retrospective 3D-Computer-Assisted MRI Analysis Using iSix Software.

OBJECTIVE: The present study aimed (1) to analyze the relative paraspinal autochthonous intramuscular fat volume before and after radiofrequency neurotomy (RFN) and (2) to compare it to the contralateral non-treated side.

DESIGN: Retrospective cohort study.

SETTING: Inselspital, University Hospital Bern, University of Bern.

SUBJECTS: Twenty patients (59.60 ± 8.49 years; 55% female) with chronic low back pain, treated with RFN (L2/3-L5/S1) due to symptomatic facet joint syndrome (FCS) between 2008 and 2017 were included.

METHODS: All patients received a magnetic resonance imaging (MRI) of the lumbar spine before and at a minimum of 6 months after RFN. The absolute (cm3) and relative (%) paraspinal muscle and fat volume was analyzed three-dimensionally on standard T2-MRI sequences using a newly developed software (iSix, Osiris plugin). Both sides were examined and allocated as treated or non-treated side.

RESULTS: A total of 31 treated and 9 non-treated sides (Level L2/3-L5/S1) were examined. There were no differences in the relative paraspinal intramuscular fat volume before and at a median of 1.4 [0.9 - 2.6] years after RFN (P = .726). We found no differences in the relative fat volume between the treated and non-treated side before (P = .481) and after (P = .578) RFN.

CONCLUSIONS: Our study shows that there are no differences in the paraspinal muscle/fat distribution after RFN. RFN of the medial branches for FCS does not seem to cause fatty degeneration of the lumbar paraspinal muscles as a sign of iatrogenic muscle denervation.