Chronic low back pain: diagnostic classification, physical assessment and ultrasound imaging

Optimal physiotherapy examination and the resulting classifications provided for chronic low back pain (CLBP) patients should involve the application of evidence-based methods. An ideal examination and classification process will be valid and reliable, with demonstrated improvement in patient outcomes to evidence its overall worth. To this end, valid examination processes for diagnostic classification, and established reliability of physical assessment and clinical measurement, are required. This thesis aimed to develop an evidence-based physiotherapy examination algorithm to classify CLBP, to establish reliable methods for clinical measurement of lumbar spine range of motion, and to trial a novel standardised real-time ultrasound imaging method to measure the transversus abdominis in CLBP. A physiotherapy CLBP examination algorithm (MK-C), with reliable methods of clinical measurement, were applied in a series of studies. Studies were conducted in a CLBP population to determine classification characteristics, and diagnostic agreement between a physiotherapist and available reference standards. Additionally, standardised and reliable real-time ultrasound imaging methods were applied to investigate the function of the transversus abdominis following pain abolition in CLBP. Literature reviews identified evidence-based components for inclusion in the MK-C. Two systematic reviews appraised CLBP studies by using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses methods. The first appraised validity or diagnostic accuracy of physiotherapy low back pain classification systems, individual examination tests or test clusters (N = 5). Clustered clinical tests for radiculopathy, discogenic pain and facet joint syndrome had been validated in CLBP. The second review appraised reliability of physiotherapy low back pain classification systems (N = 3). High risk of bias and variable inter-rater reliability (k = .32 to .96) were identified. There was no evidence to suggest that any existing physiotherapy low back pain classification system had demonstrated high reliability or reference standard validity as a standalone method of examination in a CLBP population. Intra-examiner reliability of lumbar spine range of motion and joint range of motion associated with lumbar neuro-dynamic tests was reported in a blinded test– retest study of asymptomatic participants (N = 19) with demographics that simulated CLBP patients (age > 50 years; body mass index > 24). High intra-examiner measurement reliability (ICC = .68–.99) was established using standard tape measure and goniometry protocols. This supported the suitability of these measurements in CLBP examination. The MK-C was applied to classify CLBP and report characteristics within and between classification categories by using a cross-sectional study design (N = 150). Reported characteristics were age, gender, body mass index (BMI), pain intensity scored on a visual analogue scale, pain duration (months), disability scored on the Oswestry Disability Index and Roland–Morris disability questionnaire, and pain somatisation rated using the Modified Somatic Pain Perceptions Questionnaire. Results supported utility of the MK-C for CLBP examination, with 94% of participants classified at first attendance. Facet joint syndrome was most frequently classified. All classification categories demonstrated 'distressed' levels of pain somatisation (score > 13). Age, disability and pain somatisation were distinguishing CLBP characteristics. A second blinded cross-sectional study (N = 92) reported level of CLBP diagnostic agreement between a physiotherapist using the MK-C and available reference standards, which included a CLBP medical specialist's diagnosis based on clinical examination and magnetic resonance imaging, and the outcome of a diagnostic spinal anaesthetic injection when clinically indicated. Observed examiner agreement was 51%, with 'Fair' after-chance agreement (k = .22, CI [1.57, −1.13]). Chi-square analysis of subjects who received a diagnostic spinal anaesthetic injection (N = 50) identified that combined examiner diagnosis was truly positive in 46% of cases. A blinded intra-examiner reliability study applied standardised probe force, inclination and roll using a 'force probe device' during transversus abdominis real-time ultrasound imaging in CLBP (N = 17). High measurement reliability was reported for resting transversus abdominis (ICC = .98, CI [0.93, 0.99]), contracted transversus abdominis (ICC = .99, CI [0.97, 0.99]) and transversus abdominis activation (ICC = .93, CI [0.82, 0.97]). This was superior to previous reliability reported using 'free-hand' real-time ultrasound imaging. A pre–post intervention study (N = 47) used the same ultrasound imaging methods to measure transversus abdominis activation before and following pain relief from a diagnostic spinal anaesthetic injection (>75% pre–post reduction on a visual analogue scale). Transversus abdominis activation was calculated as a rest to contracted thickness change from paired images (N = 324). Results indicated that pain relief did not immediately result in a statistically (p 20%) significant improvement in transversus abdominis activation. Thus, as an isolated intervention, pain relief appears insufficient, supporting the need for transversus abdominis retraining following CLBP relief. Clinical contributions: • This study has provided a unique contribution to knowledge on diagnostic classification, physical assessment and real-time ultrasound imaging in CLBP. • New knowledge has been presented about physiotherapy CLBP diagnostic classification characteristics and agreement using an MK-C examination algorithm, and transversus abdominis function using standardised real-time ultrasound imaging methods. This will assist treatment focus and CLBP resource planning. • Intra-rater reliability of established physical assessment measurements has been confirmed for lumbar spine range of movement in CLBP to guide clinical measurement during physiotherapy examination. • Characteristics of CLBP and between diagnostic classification categories have been reported, which provide knowledge to guide clinical reasoning. • MK-C 'Fair' diagnostic agreement, although not optimal, provides clinicians with new knowledge on the value of the MK-C, which can be considered an evidence-based architype examination algorithm suitable to classify CLBP. • Pain abolition in isolation does not enhance transversus abdominis activation, suggesting that routine physiotherapist-guided transversus abdominis retraining immediately following pain abolition interventions may be indicated. Future research should determine if this approach improves patient outcomes. Research implications: • A critical need for research specific to physiotherapy examination and classification in CLBP has been highlighted. • Research evidence related to physiotherapy examination of CLBP has been provided, which can be used as a comparator for future studies. • Improved and reliable methods of real-time ultrasound imaging for transversus abdominis measurement using a 'force probe device' have been demonstrated, which can be used to improve measurement accuracy in future studies. • Research evidence about the complex relationship between pain abolition and transversus abdominis function in CLBP has been provided, which was previously subject to hypothetical assumption.