Methodological consistency and measurement reliability of transversus abdominis real time ultrasound imaging in chronic low back pain populations: a systematic review

Abstract

Bac kgr o und:Real tim e ultrasound im aging (RTUI) is used to m easure transversus abdom inis (TrA) thickness in low back pain (LBP ) populations. However, individuals with chronic low back pain (C LBP ) pose specific im aging challenges, such as older age and higher body m ass index, com pared to asym ptom atic populations or acute and sub-acute LBP groups. These challenges potentially increase m easurem ent error and m ay require different im aging m ethods. O bje c t ive s :This review describes the m ethodologies and reported reliability for RTUI m easurem ent of TrA specific to C LBP populations. Me t ho ds :A system atic database search of Medline, C INAHL, P EDro, the full C ochrane library, Scopus, and Inform it identified 20 studies that used RTUI to m easure TrA of C LBP participants. Two independent raters appraised the quality of the studies using the Q ualSyst and the Q AREL critical appraisal tools. Re s ult s :Methodological quality varied from low to high. Methods for patient and transducer positioning and m uscle m easurem ent were inconsistent between studies. Eight articles cited reliability results from past studies of non-C LBP populations. O nly two studies reported reliability in C LBP populations specifically and found higher Intraclass C orrelation C oefficients for thickness m easures at rest (0.63-0.97), com pared to thickness change over tim e or contraction ratios (0.28-0.80). Co nc lus io ns :Inconsistency of m ethodology, variable m ethodological quality, and lim ited and variable reliability reporting was highlighted in this review. This LBP subgroup poses challenges for RTUI, therefore future research should include standarized m ethods for im age acquisition. This will im prove the quality of study m ethods, reliability of TrA m easurem ent, and im prove the applicability and com paribility of research evidence available to clinicians. Ke ywo r ds Transversus abdom inis ReliabilityReal tim e ultrasound Back pain Int roduct ionReal tim e ultrasound im aging (RTUI) is used in research and clinical practice to m easure various m usculoskeletal structures. [1][2][3] In the last 20 years, a plethora of studies have m easured transversus abdom inis (TrA). 4-8 Through its attachm ent to the linear alba and thoracolum bar fascia, TrA provides spinal stability via m ultiple m echanism s, including feed-forward activation. 9 Hence it has been investigated in sports perform ance, and in relation to low back pain (LBP ). 10Several studies agree that TrA m orphology and function is altered in patients with low back pain. [11][12][13][14] When com pared to healthy populations, both delayed anticipatory activation and reduced m uscle thickness has been reported in individuals who had experienced at least one previous episode of LBP , but were asym ptom atic at the tim e of RTUI. 12 In part, this provides insight into the progression from acute to recurrent low back pain and then chronic pain via central sensitization. This system atic review identifies the current evidence for m easurem ent m...

Intra-rater reliability of transversus abdominis measurement by a novice examiner: Comparison of “freehand” to “probe force device” method of real-time ultrasound imaging

“…However, there is no external means of controlling probe-patient pressure, inclination (side to side tilt), and roll (forward and backward tilt) using this method, leading to variability in these probe parameters. This constitutes a potential source of TrA measurement error, [16][17][18] and theoretically reduces the reliability of US TrA measurement by clinicians and researchers, because a clinical measurement must be reliable if it is to be useful. 16 Costa et al 16 and Whittle et al 18 suggested that reliability of TrA measurement using US in both healthy and LBP groups has been suboptimal due to poor study designs and a lack of standardization of imaging procedures.…”

“…This constitutes a potential source of TrA measurement error, [16][17][18] and theoretically reduces the reliability of US TrA measurement by clinicians and researchers, because a clinical measurement must be reliable if it is to be useful. 16 Costa et al 16 and Whittle et al 18 suggested that reliability of TrA measurement using US in both healthy and LBP groups has been suboptimal due to poor study designs and a lack of standardization of imaging procedures. Measurement of TrA-C has demonstrated the lowest reliability when compared to resting thickness of the transverse abdominis (RTrA) and contracted thickness of the transverse abdominis (CTrA), and only a few studies have reported reliability of TrA-C, despite its clinical importance.…”

“…Measurement of TrA-C has demonstrated the lowest reliability when compared to resting thickness of the transverse abdominis (RTrA) and contracted thickness of the transverse abdominis (CTrA), and only a few studies have reported reliability of TrA-C, despite its clinical importance. 16,18 Experienced examiners using FH US have shown greater reliability compared to novice examiners using FH US to measure muscle thickness 19 ; Ferreira et al 17 found that errors made by novice examiners were greater during the process of data acquisition rather than image analysis. Specifically, novice examiners may demonstrate increased variability in the pressure applied through the probe.…”

Measurement of transversus abdominis activation in chronic low back pain patients using a novel standardized real-time ultrasound imaging method

“…Some studies have demonstrated TrA-C anomalies, 4 TrA morphological changes 5 and the efficacy of some therapeutic interventions to improve TrA-C. 6 Notwithstanding, US TrA-C measurement in CLBP populations has been characterized by widely variable and generally suboptimal intra-observer reliability. 7 Only two prior studies have reported intra-observer TrA-C measurement reliability in CLBP. 3,8 Reliability was suboptimal (intra-class correlation coefficient (ICC) ¼ 0.32-0.72).…”

“…3,8 Reliability was suboptimal (intra-class correlation coefficient (ICC) ¼ 0.32-0.72). 7 Such variability has been considered solely dependent upon the failed application of rigorous application protocols, 9 yet a consensus regarding such protocols is currently lacking and is problematic given that US is a 'freehand' procedure. 7 Methodological deficiencies inherent with 'freehand' US are uncontrolled probe force (amount of pressure applied to the patients skin), inclination (side-to-side tilt of the probe perpendicular to the plane of the probe) and roll (forward and backward movement parallel to the scan plane of the probe).…”