An Ultrasound investigation of the Thoracolumbar Fascia of people with and without lower back pain in prone and standing positions

Introduction

The prevalence of lower back pain is a global issue that is predicted by the World Health Organisation to increase to over 800 million cases in the next 30 years. At any one time, 1 in 5 people in the UK will have lower back pain, and 10% will have chronic lower back pain. Changes to the morphology of the thoracolumbar fascia (TLF) have been identified as a possible cause of lower back pain in adults. In recent years, ultrasound imaging (US) has been shown to be a reliable and valid method to study the TLF. The aim of this study was to measure the TLF in a prone position compared to a standing position, in people with LBP, using US. Outcome measures were thickness and echogenicity.

Methodology

26 adult participants were recruited, 13 with chronic LBP, 13 without LBP. Mean age was 52.42 (SD 18.59), 38% of participants were male. Age, gender and activity levels were matched between both groups. Pain intensity, frequency and disability were measured with standard questionnaires. US acquisition (Esaote, MyLab25Gold, Rimini, Italy) was made on one visit. US in both prone and standing positions were acquired 2cm medial and 2 cm lateral of the intervertebral disc space between Lumbar vertebrae 2 and 3. Participants laid on a treatment couch for the prone measurements. The standing position was standardised on an isokinetic dynamometer (HUMAC NORM, CSMi, Stoughton, MA, USA). The thickness and echogenicity were analysed in Matlab (version R2020b, The Mathworks, Natick, MA, USA) using a customised greyscale script. Data was analysed using Pearson's product movement correlation, matched pairs T-tests and non-parametric tests.

Results

There was no significant difference in the thickness of the TLF between the prone and standing position in the whole cohort, nor between the LBP group and control groups. The echogenicity for the whole cohort was significantly brighter in prone compared to standing (p=0.04). There was a strong linear relationship and strong positive correlation between the Oswestry disability score and thickness of the TLF in both the prone (r= 0.92) and standing position (r= 0.62), The thoracolumbar fascia was significantly more disorganised in the standing position (p= 0.04).

Conclusion

To our knowledge, this is the first time a comparison between prone and standing positions of TLF ultrasound images has been conducted. Interestingly, no difference was found in thickness of the TLF in prone or standing. This is significant for future TLF research, particularly for participants who may have been previously excluded because of an inability to lie in a prone position. The significant decrease in echogenicity in a standing position, may be due to changes in force transmission in the TLF, this warrants further investigation. The novel nature of using US in a prone and a standing position is a promising finding and contributes to the development of use of US research methodologies into the TLF of people with LBP.