Poor lumbar spine coordination in acute low back pain predicts persistent long-term pain and disability.

PURPOSE: Sitting balance on an unstable surface requires coordinated out-of-phase lumbar spine and provides sufficient challenge to expose quality of spine control. We investigated whether the quality of spine coordination to maintain balance in acute low back pain (LBP) predicts recovery at 6 months. METHODS: Participants in an acute LBP episode (n = 94) underwent assessment of sitting balance on an unstable surface. Seat, hip and spine (lower lumbar, lumbar, upper lumbar, thoracic) angular motion and force plate data were recorded. Coordination between the seat and hip/spine segments to maintain balance was quantified in the frequency domain to evaluate coordination (coherence) and relative timing (phase angle: in-phase [segments move together]; out-of-phase [segments move opposite]). Center of pressure (CoP) and upper thorax motion assessed overall balance performance. Hip and spine coordination with the seat were compared between those who did not recover (increased/unchanged pain/disability), partially recovered (reduced pain/disability) or recovered (no pain and disability) at 6 months. RESULTS: In both planes, coherence between the seat and lower lumbar spine was lower (and in-phase-unhelpful for balance) at baseline in those who did not recover than those who recovered. Coherence between the seat and hip was higher in partially recovered in both planes, suggesting compensation by the hip. LBP groups had equal overall balance performance (CoP, upper thorax motion), but non-recovery groups used a less optimal strategy that might have consequences for long-term spine health. CONCLUSION: These longitudinal data revealed that individuals with compromised contribution of the lumbar spine to the balance during unstable sitting during acute LBP are less likely to recover.

An evaluation of the behavioural inhibition system and behavioural activation system (BIS-BAS) model of pain in athletes.

This study examined coping and pain responses using a behavioural inhibition (BIS) - behavioural activation (BAS) framework in 489 student athletes (M(age) = 20, SD = 4; 69% female). Two samples of athletes (226 pain-free athletes and 232 athletes with current pain) completed surveys assessing BIS- and BAS-related cognitions, emotions, and behaviours. Distinct groupings of BAS-related variables were identified in both samples, evidenced by significant positive correlations within BAS-related variables (positive affect, pain openness, approach thoughts and behaviours). Most BIS-related variables (depression, anxiety, harm beliefs, pain catastrophizing and avoidance behaviours) were also correlated in the sample of athletes with pain; however, this was not observed in pain-free athletes. In athletes with pain, BIS-related variables were significantly associated with pain variables, with this association stronger than that found for BAS-related variables. Regression analyses highlighted the pivotal role of pain catastrophizing as a predictor of pain unpleasantness and intensity. Findings shed light on the factors shaping athletes' coping, pain perception and decisions as to whether to pause or push through. Future investigations to explore these dynamics in more depth may aid in the development of targeted interventions that enhance athletes' ability to cope and to manage pain more effectively.

Evidence for increased tone or overactivity of pelvic floor muscles in pelvic health conditions: a systematic review.

OBJECTIVE: Pelvic floor muscle tone, which includes active and passive components, is argued to be increased in many pelvic health conditions, including those involving pain. This study systematically reviewed evidence for increased pelvic floor muscle tone in pelvic health conditions. DATA SOURCES: Electronic databases (PubMed, CINAHL, and Embase) were searched up to May 31, 2021. The search strategy included variants of pelvic and/or floor, muscle, and tone using keywords and Medical Subject Headings (MeSH) terms. STUDY ELIGIBILITY CRITERIA: Studies were included if they investigated increased tone of the pelvic floor muscle and reported measures of active or mechanical properties of the pelvic floor muscle in humans with any pelvic health condition, including pain, bowel, urogenital, or sexual dysfunctions. Studies of any design were included, except systematic and narrative reviews. Reference lists of studies, reviews, and book chapters were searched for additional studies. METHODS: Data were extracted using a standardized form, including measurement tool and outcome measure. Risk of bias was analyzed using a modified ROBINS-I (Risk of Bias In Non-randomized Studies - of Interventions) tool, and a score was allocated to determine whether the study provided "convincing" interpretation (comparison with condition-free control group, valid measure, no application issues). RESULTS: In total, 151 studies were included, reporting 8 different tools (electromyography, dynamometry, manometry, digital palpation, defecography, ultrasound, magnetic resonance imaging, other). The most common pelvic health condition was pelvic pain (n=16 conditions), followed by bowel and urogenital conditions. Most studies (57%) were cross-sectional. A healthy control group was infrequently included for comparison (27%). Unvalidated methods or methods applied in a manner that precluded convincing interpretation were common (94%). Of the 15 measurement tools that provided convincing evidence, 10 demonstrated greater tone in a pelvic health condition (all pain) compared with controls, and 5 showed no difference. CONCLUSION: Despite the large literature, few studies provide convincing evidence for increased tone/overactivity of pelvic floor muscles in pelvic health conditions. Interpretation is hampered by design and measurement issues. Terminology was often inaccurate. Few studies investigate male, transgender, and pediatric groups.

Adaptability of the load sharing between the longissimus and components of the multifidus muscle during isometric trunk extension in healthy individuals.

PURPOSE: Redundancy of the musculoskeletal system implies multiple strategies are theoretically available to coordinate back extensor muscles. This study investigated whether coordination between back muscles during a tightly constrained isometric trunk extension task varies within and between individuals, and whether this changes following brief exposure to activation feedback of a muscle. METHODS: Nine healthy participants performed three blocks of two repetitions of ramped isometric trunk extension in side-lying against resistance from 0-30% of maximum voluntary contraction over 30 s (force feedback). Between blocks, participants repeated contractions with visual feedback of electromyography (EMG) from either superficial (SM) or deep multifidus (DM), in two conditions; 'After SM' and 'After DM'. Intramuscular EMG was recorded from SM, DM, and longissimus (LG) simultaneously with shear wave elastography (SWE) from SM or DM. RESULTS: In the 'Natural' condition (force feedback only), group data showed incremental increases in EMG with force, with minor changes in distribution of activation between muscles as force increased. SM was the most active muscle during the 'Natural' condition, but with DM most active in some participants. Individual data showed that coordination between muscles differed substantially between repetitions and individuals. Brief exposure to EMG feedback altered coordination. SWE showed individual variation, but findings differed from EMG. CONCLUSION: This study revealed substantial variation in coordination between back extensor muscles within and between participants, and after exposure to feedback, in a tightly constrained task. Shear modulus revealed similar variation, but with an inconsistent relationship to EMG. These data highlight highly flexible control of back muscles.

Can training of a skilled pelvic movement change corticomotor control of back muscles? Comparison of single and paired-pulse transcranial magnetic stimulation.

Evidence suggests excitability of the motor cortex (M1) changes in response to motor skill learning of the upper limb. Few studies have examined immediate changes in corticospinal excitability and intra-cortical mechanisms following motor learning in the lower back. Further, it is unknown which transcranial magnetic stimulation (TMS) paradigms are likely to reveal changes in cortical function in this region. This study aimed to (1) compare corticospinal excitability and intra-cortical mechanisms in the lower back region of M1 before and after a single session of lumbopelvic tilt motor learning task in healthy people and (2) compare these measures between two TMS coils and two methods of recruitment curve (RC) acquisition. Twenty-eight young participants (23.6 ± 4.6 years) completed a lumbopelvic tilting task involving three 5-min blocks. Single-pulse (RC from 70% to 150% of active motor threshold) and paired-pulse TMS measures (ICF, SICF and SICI) were undertaken before (using 2 coils: figure-of-8 and double cone) and after (using double cone coil only) training. RCs were also acquired using a traditional and rapid method. A significant increase in corticospinal excitability was found after training as measured by RC intensities, but this was not related to the RC slope. No significant differences were found for paired-pulse measures after training. Finally, there was good agreement between RC parameters when measured with the two different TMS coils or different acquisition methods (traditional vs. rapid). Changes in corticospinal excitability after a single session of lumbopelvic motor learning task are seen, but these changes are not explained by changes in intra-cortical mechanisms.

Effects of different modalities of afferent stimuli of the lumbo-sacral area on control of lumbar paravertebral muscles.

Somatosensory feedback to the central nervous system is essential to plan, perform and refine spine motor control. However, the influence of somatosensory afferent input from the trunk on the motor output to trunk muscles has received little attention. The objective was to compare the effects of distinct modalities of afferent stimulation on the net motoneuron and corticomotor excitability of paravertebral muscles. Fourteen individuals were recruited. Modulation of corticospinal excitability (motor-evoked potential [MEP]) of paravertebral muscles was measured when afferent stimuli (cutaneous noxious and non-noxious, muscle contraction) were delivered to the trunk at 10 intervals prior to transcranial magnetic stimulation. Each peripheral stimulation was applied alone, and subsequent electromyography (EMG) modulation was measured to control for net motoneuron excitability. MEP modulation and MEP/EMG ratio were used as measures of corticospinal excitability with and without control of net motoneuron excitability, respectively. MEP and EMG modulation were smaller after evoked muscle contraction than after cutaneous noxious and non-noxious stimuli. MEP/EMG ratio was not different between stimulation types. Both MEP and EMG amplitudes were reduced after evoked muscle contraction, but not when expressed as MEP/EMG ratio. Noxious and non-noxious stimulation had limited impact on all variables. Distinct modalities of peripheral afferent stimulation of the lumbo-sacral area differently modulated responses of paravertebral muscles, but without an influence on corticospinal excitability with control of net motoneuron excitability. Muscle stimulation reduced paravertebral activity and was best explained by spinal mechanisms. The impact of afferent stimulation on back muscles differs from the effects reported for limb muscles.

Distinct displacement of the superficial and deep fascial layers of the iliotibial band during a weight shift task in runners: An exploratory study.

Motion of the fascial layers of the iliotibial band (ITB), as a reinforcement of the deep fascia lata, is likely to be relevant for its function and mechanical behaviour. This exploratory study aimed to evaluate the ITB fascial layers displacement during a weight shift task. Thirteen pain-free runners performed a 6-second standing weight shift task. B-mode ultrasound imaging using an automated fascicle tracking algorithm was used to measure proximal and distal displacement of superficial and deep ITB layers at the middle region. To study the potential contributors to individual variation of fascial motion, we recorded the activity of five hip/thigh muscles with electromyography (EMG), thigh/pelvis/trunk position with accelerometers, and centre of pressure with a force plate. Linear regressions estimated the relationship between displacement of fascial layers and hip/trunk angles. Independent t-tests or Fisher's exact tests compared EMG and movement-related parameters between participants who demonstrated motion of the fascia in the proximal and distal directions. Thickness of the ITB and the loose connective tissue between its layers were calculated. Proximal displacement was observed in six (-4.1 ± 1.9 mm [superficial]) and two (-6.2 ± 2.0 mm [deep]) participants. Distal displacement was observed for seven participants for each layer (3.1 ± 1.1 mm [superficial]; 3.6 ± 1.3 mm [deep]). Four participants did not show displacement of the deep layer. Trunk lateral flexion and gluteus medius muscle activity were determinants of proximal motion of the superficial layer. Loose connective tissue was thinner in participants without displacement of the deep layer. Displacement of the ITB fascial layers varies between individuals. Variation related to differences in joint movements and muscle activity. This study highlights the complex interaction between fascia and movement.

The influence of prostatectomy and body position on location and displacement of pelvic landmarks with pelvic floor muscle contraction.

AIMS: To compare pelvic floor muscle (PFM) anatomy and function (i) between pre- and post-prostatectomy in standing, and (ii) between sitting and standing postprostatectomy. METHODS: Thirty-two men scheduled to undergo a prostatectomy volunteered to participate. Transperineal ultrasound imaging was used to visualize five anatomical pelvic landmarks that have been validated to reflex anatomy and activity of PFMs (pubic symphysis, anorectal junction [ARJ], mid-urethra [MU], bulb of penis [BP], and urethrovesical junction [UVJ]). Both before and after prostatectomy, participants performed three submaximal PFM contractions in sitting and/or standing positions while ultrasound data were recorded. RESULTS: Postprostatectomy the UVJ location was more caudal and dorsal, the ARJ (puborectalis) vector was longer, the BP was more ventral than preprostatectomy, and these landmarks moved less ventrally with contraction. After prostatectomy, the MU, BP, and ARJ were more ventral in standing than sitting. The UVJ was more caudal and elevated more with contraction in standing than sitting after prostatectomy. CONCLUSION: These data demonstrate differences in the anatomy and mechanics of PFMs post- versus pre-prostatectomy, and between sitting and standing positions postprostatectomy. Findings are consistent with surgical changes to the bladder and urethral anatomy. Reduced passive support for the urethra and bladder are likely to may contribute to differences between standing and sitting postprostatectomy.

The relationship between pre- and postprostatectomy measures of pelvic floor muscle function and development of early incontinence after surgery.

AIMS: The aim of this study is to investigate (i) whether pelvic floor muscle (PFM) shortening can be enhanced by provision of training focused on striated urethral sphincter (SUS) with feedback before prostatectomy, (ii) whether PFM shortening during voluntary efforts and coughing before and after prostatectomy differs between men who do and do not report symptoms of urinary incontinence 1 month after prostatectomy, and (iii) the relationship between severity of incontinence after prostatectomy and features of pelvic floor function (muscle shortening) and urethral length before and after prostatectomy. METHODS: Sixty men referred for preoperative PFM training before radical prostatectomy participated. The International Continence Society Male Short Form questionnaire was used to quantify continence status. Transperineal ultrasound (US) imaging was used to record pelvic displacements related to activation of striated urethral sphincter, bulbocavernosus (BC) and puborectalis muscles during cough, "natural" voluntary contraction following pamphlet instruction, and trained voluntary contraction after formal physiotherapist instruction including US feedback. RESULTS: Pelvic floor displacements following training differed between continent and incontinent men; continent participants demonstrated increased SUS shortening after training (compared with "natural"), but no difference was observed between trained and "natural" contractions for incontinent participants. Motion at ano-rectal junction during cough was reduced following surgery, but voluntary and involuntary activation of SUS or BC was not consistently affected by surgery. CONCLUSIONS: Participants' capacity to improve function of the SUS with training appears related to postprostatectomy continence outcome.

Validation of shear wave elastography as a noninvasive measure of pelvic floor muscle stiffness.

OBJECTIVES: To investigate the validity of shear wave elastography (SWE) as a measure of stiffness of the puborectalis muscle by examining: (1) the relationship between puborectalis muscle stiffness and pelvic floor muscle (PFM) activation at different intensities; and (2) the relationship between puborectalis stiffness and pelvic floor morphometry during contractions at different intensities. METHODS: Fifteen healthy asymptomatic women performed 6-s isometric PFM contractions at different intensities (0, 10%, 20%, 30%, 50%, 75%, and 100% of maximal voluntary contraction) guided by intravaginal electromyography (EMG). Stiffness of the puborectalis muscle was measured using SWE by calculating the average shear modulus in regions of interest that contained puborectalis muscle fibers parallel to the transducer. Pelvic floor morphometry was assessed in the mid-sagittal plane using transperineal B-mode ultrasound imaging. Shear modulus, EMG (root mean square amplitude) and pelvic floor morphometry parameters were normalized to the value recorded during maximal voluntary contraction. To assess the relationship between stiffness and pelvic floor activation/morphometry, coefficient of determination (r2 ) was calculated for each participant and a group average was computed. RESULTS: Shear modulus and EMG were highly correlated (average r2 ; left 0.90 ± 0.08, right 0.87 ± 0.15). Shear modulus also strongly correlated with bladder neck position (x-axis horizontal coordinates relative to the pubic symphysis), anorectal rectal angle and position, levator plate angle, and antero-posterior diameter of the levator hiatus (average r2 : range 0.62-0.78). CONCLUSIONS: These findings support the validity of SWE to assess puborectalis muscle stiffness in females. Stiffness measures were strongly associated with PFM EMG and pelvic floor morphometry and may be used to indirectly assess the level of activation of the puborectalis muscle without the use of more invasive techniques. By overcoming limitations of current assessment tools, this promising noninvasive and real-time technique could enable important breakthrough in the pathophysiology and management of pelvic floor disorders.

Muscle spindles of the multifidus muscle undergo structural change after intervertebral disc degeneration.

PURPOSE: Proprioceptive deficits are common in low back pain. The multifidus muscle undergoes substantial structural change after back injury, but whether muscle spindles are affected is unclear. This study investigated whether muscle spindles of the multifidus muscle are changed by intervertebral disc (IVD) degeneration in a large animal model. METHODS: IVD degeneration was induced by partial thickness annulus fibrosus lesion to the L3-4 IVD in nine sheep. Multifidus muscle tissue at L4 was harvested at six months after lesion, and from six age-/sex-matched naïve control animals. Muscle spindles were identified in Van Gieson's-stained sections by morphology. The number, location and cross-sectional area (CSA) of spindles, the number, type and CSA of intrafusal fibers, and thickness of the spindle capsule were measured. Immunofluorescence assays examined Collagen I and III expression. RESULTS: Multifidus muscle spindles were located centrally in the muscle and generally near connective tissue. There were no differences in the number or location of muscle spindles after IVD degeneration and only changes in the CSA of nuclear chain fibers. The thickness of connective tissue surrounding the muscle spindle was increased as was the expression of Collagen I and III. CONCLUSION: Changes to the connective tissue and collagen expression of the muscle spindle capsule are likely to impact their mechanical properties. Changes in capsule stiffness may impact the transmission of length change to muscle spindles and thus transduction of sensory information. This change in muscle spindle structure may explain some of the proprioceptive deficits identified with low back pain.

The Flares of Low back pain with Activity Research Study (FLAReS): study protocol for a case-crossover study nested within a cohort study.

BACKGROUND: Although it is generally accepted that physical activity and flares of low back pain (LBP) are related, evidence for the directionality of this association is mixed. The Flares of Low back pain with Activity Research Study (FLAReS) takes a novel approach to distinguish the short-term effects of specific physical activities on LBP flares from the cumulative effects of such activities, by conducting a longitudinal case-crossover study nested within a cohort study. The first aim is to estimate the short-term effects (≤ 24 h) of specific physical activities on LBP flares among Veterans in primary care in the Veterans Affairs healthcare system. The second aim is to estimate the cumulative effects of specific activities on LBP-related functional limitations at 1-year follow-up. METHODS: Up to 550 adults of working age (18-65 years) seen for LBP in primary care complete up to 36 "Scheduled" surveys over 1-year follow-up, and also complete unscheduled "Flare Window" surveys after the onset of new flares. Each survey asks about current flares and other factors associated with LBP. Surveys also inquire about activity exposures over the 24 h, and 2 h, prior to the time of survey completion (during non-flare periods) or prior to the time of flare onset (during flares). Other questions evaluate the number, intensity, duration, and/or other characteristics of activity exposures. Other exposures include factors related to mood, lifestyle, exercise, concurrent treatments, and injuries. Some participants wear actigraphy devices for weeks 1-4 of the study. The first aim will examine associations between 10 specific activity categories and participant-reported flares over 1-year follow-up. The second aim will examine associations between the frequency of exposure to 10 activity categories over weeks 1-4 of follow-up and long-term functional limitations at 12 months. All analyses will use a biopsychosocial framework accounting for potential confounders and effect modifiers. DISCUSSION: FLAReS will provide empirically derived estimates of both the short-term and cumulative effects of specific physical activities for Veterans with LBP, helping to better understand the role of physical activities in those with LBP. TRIAL REGISTRATION: ClinicalTrials.gov NCT04828330 , registered April 2, 2021.

Physiotherapists Both Reproduce and Resist Biomedical Dominance when Working With People With Low Back Pain: A Qualitative Study Towards New Praxis.

Despite recommendations to incorporate physical and psychosocial factors when providing care for people with back pain, research suggests that physiotherapists continue to focus on biological aspects. This study investigated how interpersonal and institutional norms influence this continued enactment of the biological aspects of management. We used theoretically-driven analysis, drawing from Foucauldian notions of power, to analyse 28 ethnographic observations of consultations and seven group discussions with physiotherapists. Analysis suggested that physiotherapy training established expectations of what a physiotherapist 'should' focus on, and institutional circumstances strongly drew the attention of physiotherapists towards biological aspects. Resistance to these forces was possible when, for example, physiotherapists reflected upon their practice, used silences and pauses during consultations, and actively collaborated with patients. These circumstances facilitated use of non-biomedical management approaches. Findings may assist physiotherapists to rework the enduring normative focus on biomedical aspects of care when providing care for patients with back pain.

Coordination of hip and spine to maintain equilibrium in unstable sitting revealed by spectral analysis.

Unstable sitting paradigms have been used to assess the trunk's contribution to postural control. The coordination of spine or hip with an unstable seat that underpin postural control during this task remain unclear. This study aimed to address this issue using analysis in the frequency domain. Seventy-two healthy pain-free participants maintained balance while sitting on a seat fixed to a hemisphere. Angular motion of seat, spinal regions (lower lumber, lumbar, upper lumbar, and thoracic), and hip was recorded with a three-dimensional (3-D) motion capture system. Coordination between spinal regions and hip with the seat was quantified using cross-spectral analyses. In the sagittal plane, amplitude spectrum of hip and lumbar segments were higher than other segments, coherence between these segments and the seat was high, and their motion was generally opposite in direction to the seat. In the frontal plane, amplitude spectrum of lower lumbar and lumbar segments, but not the hip, were higher than other segments, and coherently moved in the opposite direction to the seat. Segments closest to the seat made a direction-specific and greater contribution to maintenance of equilibrium than upper body segments, which were more limited during unstable sitting. Although eye closure and higher body mass index involved larger amplitude of center of pressure movement, rather than inferring poor control, this was associated with enhanced coordination between segments and seat. Understanding how hip/spine segments are coordinated with the seat is important to interpret postural strategies used to maintain equilibrium and to interpret observations for other populations (e.g., back pain).NEW & NOTEWORTHY This is the first multidirectional spectral analysis of how the hip and spine coordinate during unstable sitting and how different factors impact this coordination. Seat movement was coherently counteracted (out-of-phase) by angular motion of the hip and lower lumbar spine in the sagittal plane and by the lumbar spine in the frontal plane. Although higher BMI and balancing with eyes closed increased movement amplitude, this did not compromise coordination between segments to control balance, instead, coherence increased.

Characterisation of motor cortex organisation in patients with different presentations of persistent low back pain.

Persistence of low back pain is thought to be associated with different underlying pain mechanisms, including ongoing nociceptive input and central sensitisation. We hypothesised that primary motor cortex (M1) representations of back muscles (a measure of motor system adaptation) would differ between pain mechanisms, with more consistent observations in individuals presumed to have an ongoing contribution of nociceptive input consistently related to movement/posture. We tested 28 participants with low back pain sub-grouped by the presumed underlying pain mechanisms: nociceptive pain, nociplastic pain and a mixed group with features consistent with both. Transcranial magnetic stimulation was used to study M1 organisation of back muscles. M1 maps of multifidus (deep and superficial) and longissimus erector spinae were recorded with fine-wire electromyography and thoracic erector spinae with surface electromyography. The nociplastic pain group had greater variability in M1 map location (centre of gravity) than other groups (p < .01), which may suggest less consistency, and perhaps relevance, of motor cortex adaptation for that group. The mixed group had greater overlap of M1 representations between deep/superficial muscles than nociceptive pain (deep multifidus/longissimus: p = .001, deep multifidus/thoracic erector spinae: p = .008) and nociplastic pain (deep multifidus/longissimus: p = .02, deep multifidus/thoracic erector spinae: p = .02) groups. This study provides preliminary evidence of differences in M1 organisation in subgroups of low back pain classified by likely underlying pain mechanisms. Despite the sample size, differences in cortical re-organisation between subgroups were detected. Differences in M1 organisation in subgroups of low back pain supports tailoring of treatment based on pain mechanism and motor adaptation.

The repeatability of measurements of male pelvic floor anatomy and function made from transperineal ultrasound images of healthy men and those before and after prostatectomy.

AIMS: To investigate the inter- and intratester repeatability of measurement of the location and displacement of five pelvic landmarks related to pelvic floor muscles with transperineal ultrasound (TPUS) imaging recorded from healthy men and men before and after prostatectomy. METHODS: TPUS images were selected from four different participant groups: healthy men, men awaiting prostatectomy, men 2 weeks after prostatectomy, and men 12 months after prostatectomy. On two separate occasions, two assessors with different levels of experience performed analysis of location and displacement of five pelvic landmarks in images made at rest and during voluntary contraction. A two-way mixed effects, single measurement, absolute agreement intraclass correlation coefficient (ICC) was used to investigate the repeatability. RESULTS: Intertester reliability of all locations at rest for all groups was excellent (ICCs > 0.8) except for the craniocaudal coordinate of the ventral urethrovesical junction for men 2 weeks postprostatectomy and the anorectal junction for men with a cancerous prostate. Intertester reliability of the measurement of landmark displacement was acceptable (>0.5) for the dorsoventral axis of motion but not for the craniocaudal axis of motion for all landmarks across all groups. The more experienced assessor was consistently more repeatable. More deeply placed landmarks were more often excluded from analysis and had poorer reliability. CONCLUSIONS: Analysis of TPUS images across clinical groups is repeatable for both location and displacement of pelvic landmarks related to pelvic floor muscles when measures are made twice. Analysis experience, landmark depth and optimization of ultrasound settings appear to be important factors in reliability.

Exploring Why People with Back Pain Use the Pain Management Strategies They Do: Is Research Looking in the Wrong Places?

OBJECTIVE: Low back pain (LBP) is a significant issue with considerable impact on people's lives and economies. A plethora of research has investigated interventions to manage LBP. However, despite considerable knowledge translation efforts, individuals with the condition frequently use management strategies considered to be "ineffective." To address this concern, our aim was to explore why people with LBP choose the management strategies they do. METHODS: We used a predominantly inductive, descriptive qualitative design. We interviewed 20 Australian adults who have or have had LBP to investigate the management strategies they have used and why. Data were analyzed thematically. RESULTS: Analysis identified three interrelated themes that highlight that participants chose management strategies, at least in part, because they: 1) reduce symptoms in the very short term (e.g., immediately, a few hours); 2) have effects beyond the condition (e.g., low cost, lack of negative side effects, convenience, social effects); and 3) are pleasurable. DISCUSSION: These outcomes suggest that people with LBP are likely to have nuanced reasons for choosing the management strategies they use, and this can contrast with the outcomes tested in empirical studies. Our findings suggest that researchers may need to broaden or rethink which outcomes they measure and how, including by meaningfully engaging consumers in research design. Furthermore, clinicians could better explore their patients' reasons for using the strategies they do before suggesting they discard existing strategies or offering new ones.

Paraspinal muscle imaging measurements for common spinal disorders: review and consensus-based recommendations from the ISSLS degenerative spinal phenotypes group.

PURPOSE: Paraspinal muscle imaging is of growing interest related to improved phenotyping, prognosis, and treatment of common spinal disorders. We reviewed issues related to paraspinal muscle imaging measurement that contribute to inconsistent findings between studies and impede understanding. METHODS: Three key contributors to inconsistencies among studies of paraspinal muscle imaging measurements were reviewed: failure to consider possible mechanisms underlying changes in paraspinal muscles, lack of control of confounding factors, and variations in spinal muscle imaging modalities and measurement protocols. Recommendations are provided to address these issues to improve the quality and coherence of future research. RESULTS: Possible pathophysiological responses of paraspinal muscle to various common spinal disorders in acute or chronic phases are often overlooked, yet have important implications for the timing, distribution, and nature of changes in paraspinal muscle. These considerations, as well as adjustment for possible confounding factors, such as sex, age, and physical activity must be considered when planning and interpreting paraspinal muscle measurements in studies of spinal conditions. Adoption of standardised imaging measurement protocols for paraspinal muscle morphology and composition, considering the strengths and limitations of various imaging modalities, is critically important to interpretation and synthesis of research. CONCLUSION: Study designs that consider physiological and pathophysiological responses of muscle, adjust for possible confounding factors, and use common, standardised measures are needed to advance knowledge of the determinants of variations or changes in paraspinal muscle and their influence on spinal health.

Fat infiltration in the multifidus muscle is related to inflammatory cytokine expression in the muscle and epidural adipose tissue in individuals undergoing surgery for intervertebral disc herniation.

PURPOSE: Recent animal studies have discovered dysregulation of local inflammatory activity as a novel mechanism to explain fat and connective tissue accumulation in the multifidus muscle in association with intervertebral disc (IVD) degeneration/injury. This study aimed to test whether similar mechanisms are active in humans by investigation of whether expression of inflammatory genes in the multifidus muscle differed between individuals with low and high levels of intra-muscular fat in the muscle. The secondary aims were to compare inflammatory gene expression in the intra-muscular, subcutaneous and epidural fat between groups. METHODS: Muscle and fat were procured from 24 individuals undergoing spine surgery for IVD herniation. Gene expression was quantified using qPCR assays. Participants were allocated to high- and low-fat infiltration groups based on clinical assessment of multifidus fat using Kjaer grading of MRI. RESULTS: TNF expression in the multifidus muscle was greater in participants with high rather than low levels of fat infiltration. This group also had greater expression of leptin, but lower arginase-1 (marker of anti-inflammatory M2 macrophages) in intra-muscular and subcutaneous adipose tissue, and greater expression of TNF, adiponectin and nitric oxide synthase 2 (marker of pro-inflammatory M1 macrophages) in epidural fat. CONCLUSION: The results support the hypothesis that IVD degeneration is associated with dysregulation of the inflammatory state of the local multifidus muscle, which provides initial evidence for translation of some, but not all, observations from recent animal studies to humans. Discovery of inflammatory dysregulation in epidural adipose tissue has potential for broad impact on tissue health and LBP symptoms.

ISSLS PRIZE IN CLINICAL SCIENCE 2021: What are the risk factors for low back pain flares and does this depend on how flare is defined?

PURPOSE: Although risk factors for new low back pain (LBP) episodes and acute-to-chronic transition have been identified, risk factors for flares of LBP remain largely unknown. This case-crossover study aimed to identify: (1) risk factors LBP flares and (2) whether risk factors differed when flare is defined by pain increase (pain-defined flare: PDF) or identified by participants according to a broader flare definition that considered emotions and coping (self-reported flare: SRF). METHODS: One hundred and twenty-six participants with LBP for > 3 months were included. Candidate risk factors and flares (PDF/SRF) were assessed daily using a smartphone application for 28 days. Data on exposure to risk factors one, two and three days preceding PDF/SRF were compared to control periods. Conditional logistic regression estimated associations between risk factors and PDF/SRF. RESULTS: Odds of PDF and SRF were increased by poor sleep quality and morning pain. Good sleep quality reduced odds of flare. Odds for increased pain (PDF), but not SRF, were increased after days with higher afternoon and evening pain, fatigue, fear of physical activity and leisure physical activity. CONCLUSION: LBP flare has been largely ignored but is more reflective of the LBP experience than conventional definitions of acute, sub-acute and chronic LBP. This study highlights risk factors for flare and that these differ depending on whether flare is defined by pain alone (PDF) or a broad multidimensional definition (SRF). Potential targets to reduce the intensity/frequency of LBP flares are identified, with strong indication for the potential role of sleep intervention to mitigate LBP flare risk.