Quantifying Thoracolumbar Fascia Deformation to Discriminate Acute Low Back Pain Patients and Healthy Individuals Using Ultrasound

Objective: To examine the reliability and discriminative validity (patients vs. healthy individuals) of an ultrasound (US) measurement method for the quantification of thoracolumbar fascia deformation (TLFD). Design: Cross-sectional study with US assesment and rater blinding.Setting: Manual therapy clinic, university laboratory.Participants: aLBP patients (n = 16) and healthy individuals (n = 15).Interventions: Participants performed a standardized trunk extension task. US measurements of TLFD were carried out independendly by two raters by imaging the TLF in the starting and ending positions of the movement.Main Outcome Measures: Intrarater and interrater reliability were calculated using intraclass correlation coefficients (ICCs) and minimal dedectable changes (MDC) were calculated. Receiver operating characteristic (ROC) curve analysis was used to determine the cut-off for TLFD to discriminate the study groups. Kappa statistics were performed to assess rater agreement in discrimination.Results: Intrarater ICC was .92 with an MDC of 5.54 mm and the interrater ICC was .78 with an MDC of 8.70 mm (all p < .001). The cut-off for TLFD was 6 mm with a sensitivity of 100% and a specificity of 93.75%. The raters agreed with a κ of 0.74 (p < .001).Conclusion: Reliability of the US method for assessing TLFD is moderate to excellent, and the ability to discriminate aLBP patients from healthy individuals is moderate. The method could be used to capture an additional parameter in morphological aLBP screenings.