Classification of paravertebral muscle trophism and its correlation with thoraco-lumbar fascia thickening in patients with chronic low back pain

Objective: The aim of this work is to demonstrate how the chronicity of low back pain can modify the trophism of the paraspinal muscles, by performing an ultrasound and MRI evaluation of the paraspinal muscles in the lumbar spine and correlating it to the time of onset of low back pain. Materials and Methods: An ultrasound evaluation was carried out in the lumbar area with a 5–17 MHz linear probe of the paraspinal muscles of the lumbar region, compared with the MRI of the lumbar spine, in patients presented to our attention for chronic low back pain (> 6 months), from January 2021 to January 2023. In each patient, two series of images were analyzed, in the coronal and sagittal planes. Results: Between January 2021 and January 2023, a total of 79 patients were retrospectively evaluated by ultrasound for chronic low back pain. The patients, including 46 men and 33 women, had an average age of 51.6 years (min 24–max 74). In the evaluation of the profile of the paravertebral muscles, 22 patients (27.8%) showed hypotrophy of the paravertebral muscles with a concave profile, while the measurement of the thickness of the fascia showed an average thickness of 2.19 mm with a range between 1, 3 and 3.2 mm and an interquartile range of 1.7–2.65 mm. 77.2% of patients with a concave profile showed a thickness of the FTL > 2.5 mm, and an average duration of symptoms of approximately 15.3 months, to demonstrate a correlation between muscle hypotrophy, thickness of the FTL and duration of onset of symptoms. Conclusion: In the evaluation of chronic low back pain carried out with MRI and ultrasound, the paravertebral musculature profile and the thickness of the thoracolumbar fascia are two instrumental data which, associated with the proposed classification and correlated to the clinical picture, allow to determine the chronicity of the pathological picture.