Uneven intervertebral motion sharing is related to disc degeneration and is greater in patients with chronic, non-specific low back pain. An in-vivo, cross-sectional cohort comparison of intervertebral dynamics using quantitative fluoroscopy.

Purpose: Evidence of intervertebral mechanical markers in chronic, non-specific low back pain (CNSLBP) is lacking. This research used dynamic fluoroscopic studies to compare intervertebral angular motion sharing inequality and variability (MSI and MSV) during continuous lumbar motion in CNSLBP patients and controls. Passive recumbent and active standing protocols were used and the relationships of these variables to age and disc degeneration were assessed. Methods: Twenty patients with CNSLBP and 20 matched controls received quantitative fluoroscopic lumbar spine examinations using a standardised protocol for data collection and image analysis. Composite disc degeneration (CDD) scores comprising the sum of Kellgren and Lawrence grades from L2-S1 were obtained. Indices of intervertebral motion sharing inequality (MSI) and variability (MSV) were derived and expressed in units of proportion of lumbar range of motion from outward and return motion sequences during lying, (passive) and standing (active) lumbar bending and compared between patients and controls. Relationships between MSI, MSV, age and CDD were assessed by linear correlation. Results: MSI was significantly greater in the patients throughout the intervertebral motion sequences of recumbent flexion (0.29 vs 0.22, p= 0.02) and when flexion, extension, left and right motion were combined to give a composite measure (1.40 vs 0.92, p=0.04). MSI correlated substantially with age (R=0.85, p=0.004) and CDD (R=0.70, p=0.03) in lying passive investigations in patients and not in controls. There were also substantial correlations between MSV and age (R=0.77, p=0.01) and CDD (R=0.85, p=0.004) in standing flexion in patients and not in controls. Conclusion: Greater inequality and variability of motion sharing was found in patients with CNSLBP than in controls, confirming previous studies and suggesting a biomechanical marker for the disorder at intervertebral level. The relationship between disc degeneration and MSI was augmented in patients, but not in controls during passive motion and similarly for MSV during active motion, suggesting links between in vivo disc mechanics and pain generation

Individualised assessment of aberrant intervertebral mechanics

Individualised assessment of aberrant intervertebral mechanics Alan Breen Introduction: Much of low back pain is considered to be the result of soft tissue stresses in the spine [1]. However, Individualised biomechanical assessment is problematical due to the spine’s inaccessibility to non-invasive physical measurement. This has led to concern about an over-reliance on psycho-social management for people with chronic non-specific spinal pain [2]. Cadaveric experiments have explored the subtle biomechanics of disco-ligamentous sub-failure and muscle overuse caused by added physical demands [3]. There have also been attempts to accurately represent the biomechanics of the spine with mechanical models [4]. These efforts have recognised the need to access kinetic and kinematic information from the mid-range of motion rather than just at its ends. In the 1980s, the merging of fluoroscopy and image processing to overcome this problem was achieved [5]. Between then and now, systems have been improved and some consensus has been reached about how they might be operated [6]. Methods: A series of studies has been conducted into the biomechanics of the lumbar and cervical spines using this this technology, now known as ‘Quantitative Fluoroscopy’ (QF). These investigated its 2-D measurement properties in terms of conventional intervertebral kinematics, such as maximum RoM, translation and finite centre of rotation. Later, new variables were introduced, namely ‘Initial Attainment Rate (a measure of laxity in the mid-range), ‘Motion Sharing Inequality’ (MSI) throughout the range, representing intersegmental co-ordination and ‘Motion Sharing Variability’ (MSV) representing spinal control.[7] Initial sEMG studies examined the relationship to back muscle activation and QF-informed finite element (FE) loading models were generated. Results: These studies have found that most of these measurement parameters have good observer repeatability and most good intra-subject reliability, although not necessarily agreement. Laxity and MSI have so far been the best biomarkers for chronic, non-specific low back pain and its relationship to disc degeneration [7]. The FE studies have demonstrated the feasibility of more closely representing subject-specific tissue loading with such models [8] and contemporaneous sEMG studies have found relationships to spine control (MSV). Only one outcome study has so far been conducted (in the cervical spine), which found no relationship between IV-RoM change and disability score change over a treatment period [9]. Conclusion: Despite these encouraging findings, there is a great deal more work to do to establish the clinical utility of these technologies, not least in the field of spinal surgery, where ‘adjacent segment disease’ is usually attributed to aberrant motion patterns consequent to surgical procedures. The weight bearing condition has barely been explored for the lower back, but individualised FE load modelling seems a real possibility. References [1] Borenstein D (2013) Nature review. Rheumatology,9:643-653. [2] Deane JA & McGregor AH (2016) BMJ Open,2017:e011075. [3] Panjabi MM (1992) Journal of Spinal Disorders,5:390-397. [4] Bassini T et al. (2017) Journal of Biomechanics,58:89-96. [5] Breen AC, Allen, R., Morris, A. (1988) Clinical Biomechanics,3:5-10.[6] Breen AC et al. (2012) Advances in Orthopaedics,1-10. [7] Breen AC, Breen, Ax.C. (2017) European Spine Journal,doi:10.1007/s00586-017-5155-y: [8] Zanjani-Pour S, Meakin, J,R,, Breen, Ax., Breen A. (accepted) Journal of Biomehcanics, [9] Branney J & Breen AC (2014) Chiropractic & Manual Therapies,22:24

Aberrant intervertebral motion in patients with treatment‑resistant nonspecific low back pain: a retrospective cohort study and control comparison

Purpose Intervertebral kinematic assessments have been used to investigate mechanical causes when back pain is resistant to treatment, and recent studies have identified intervertebral motion markers that discriminate patients from controls. However, such patients are a heterogeneous group, some of whom have structural disruption, but the effects of this on intervertebral kinematics are unknown.Methods Thirty-seven patients with treatment-resistant back pain referred for quantitative fluoroscopy were matched to an equal number of pain-free controls for age and sex. All received passive recumbent flexion assessments for intervertebral motion sharing inequality (MSI), variability (MSV), laxity and translation. Comparisons were made between patient sub-groups, between patients and controls and against normative levels from a separate group of controls.Results Eleven patients had had surgical or interventional procedures, and ten had spondylolisthesis or pars defects. Sixteen had no disruption. Patients had significantly higher median MSI values (0.30) than controls (0.27, p = 0.010), but not MSV (patients 0.08 vs controls 0.08, p = 0.791). Patients who received invasive procedures had higher median MSI values (0.37) than those with bony defects (0.30, p = 0.018) or no disruption (0.28, p = 0.0007). Laxity and translation above reference limits were not more prevalent in patients.Conclusion Patients with treatment-resistant nonspecific back pain have greater MSI values than controls, especially if the former have received spinal surgery. However, excessive laxity, translation and MSV are not more prevalent in these patients. Thus, MSI should be investigated as a pain mechanism and for its possible value as a prognostic factor and/or target for treatment in larger patient populations

Exploring joint hypermobility syndrome, developmental coordination disorder and pain

INTRODUCTION Floppy, clumsy, hypermobile children are increasingly referred to occupational and physical therapy under the label of dyspraxia. Motor impairments associated with the umbrella diagnosis of developmental coordination disorder (DCD) have been reported as persisting into adolescence and adulthood and subsequently affecting functional abilities (Cousins and Smyth 2003). Within this heterogeneous condition the underlying mechanisms causing the motor difficulties remains unclear. Ayers (1985) hypothesised that some individuals might have somatosensory processing issues contributing to their poor motor planning and coordination difficulties. Similarities in functional difficulties have been noted in children with a diagnosis of DCD and joint hypermobility syndrome (JHS) (Kirby and Davies 2006). There is limited understanding of the relationship between the two conditions. JHS is a multisystemic inherited connective tissue disorder, in which hypermobile joints, pain, clumsiness, poor proprioception and dislocations are familiar features (Grahame and Hakim 2006; Adib et al 2005). It has been suggested that adults with JHS show poor movement patterns which contribute to biomechanical dysfunction and continuing pain (Clark et al 2009). Pain and disability reported in adults with JHS often leads to anxiety, depression, work incapacity and social isolation (Grahame and Hakim 2006). The purpose of this study was to explore the association between adults with JHS and DCD and long term pain. METHODOLOGY/ METHODS A mixed methods design influenced by a pragmatic paradigm was utilised. Subjects: 90 patients with JHS (18-65 years) recruited from a hypermobility clinic were compared, using a questionnaire, with 113 healthy volunteers (18-65 years) with no pain recruited from a university. Analysis: Quantitative data were described and examined by regression, odds ratios were calculated. Qualitative data was analysed thematically FINDINGS The percentage of subjects who reported DCD in patients with JHS and healthy volunteers were 56% and 19% respectively. A significant association between patients with JHS and DCD was noted, chi square = 30.11, p < .001. Patients with JHS were 6 times [95% CI 2.9 – 10.3] more likely to report DCD than healthy volunteers. Pain was a significant feature with an average of 9.8 pain sites reported (out of a total of 17). Open ended questions revealed many patients recalling pain starting in early childhood and adolescence. DISCUSSION These results suggest a significant association between patients with JHS and DCD and the reporting of long term pain. Early recognition and understanding of the needs of children with DCD who present with somatosensory impairment, pain modulation and JHS is therefore essential. Sensory integration therapy as part of a comprehensive early intervention program has the potential to mitigate long term problems. A multidisciplinary approach which involves health professionals and teachers is also recommended. CONCLUSION This research may be considered an early step in the identification of an association of DCD and JHS. Further studies are required to explore somatosensory processing issues experienced by those with DCD and JHS as this might be an important underlying mechanism

Dynamic interactions between lumbar intervertebral motion segments during forward bending and return

Continuous dynamic multi-segmental studies of lumbar motion have added depth to our understanding of the biomechanics of back pain, but few have attempted to continuously measure the proportions of motion accepted by individual levels. This study attempted to compare the motion contributions of adjacent lumbar levels during an active weight bearing flexion and return protocol in chronic, non-specific low back pain (CNSLBP) patients and controls using quantitative fluoroscopy (QF). Eight CNSLBP patients received QF during guided standing lumbar flexion. Dynamic motion sharing of segments from L2 to S1 were calculated and analysed for interactions between levels. Eight asymptomatic controls were then matched to the 8 patients for age and sex and their motion sharing patterns compared. Share of intersegmental motion was found to be consistently highest at L2-L3 and L3- L4 and lowest at L5-S1 throughout the motion in both groups, with the exception of maximum flexion where L4-L5 received the greatest share. Change in motion sharing occurred throughout the flexion and return motion paths in both participant groups but tended to vary more at L4-L5 in patients (p<0.05). In patients, L5-S1 provided less angular range (p<0.05) and contributed less at maximum bend (p<0.05), while L3-L4, on average over the bending sequence, provided a greater share of motion (p<0.05). Intervertebral motion sharing inequality is therefore a normal feature during lumbar flexion. However, in patients, inequality was more pronounced, and variability of motion share at some levels increased. These effects may result from differences in muscular contraction or in the mechanical properties of the disc

A reference database of standardised continuous lumbar intervertebral motion analysis for conducting patient-specific comparisons.

Introduction: To understand spinal disorders in terms of their biomechanical effects on symptoms and evaluate treatment effects, biomechanical variables must be repeatable over an acceptable follow-up period in a symptomatically stable population. In previous work using quantitative fluoroscopy (QF), where both the motion task (lumbar flexion) and the analysis were highly standardised, some intervertebral motion sharing characteristics in the lumbar spine were found to be significantly different in NSLBP patients and asymptomatic controls (1). Control measurements were also stable over 6 weeks, making measures suitable for use in outcome and prognostic studies (2). Previous studies have found it advantageous to study the outward and return paths of lumbar flexion separately in order to appreciate the differences in dynamic loading models during bending and lifting tasks (3). Against such normative data, individual patient studies using the same protocols can be compared. The aim of this study was to establish a database of reference values for key dynamic lumbar motion variables during controlled outward and return bending using standardised QF recording and analysis protocols. These could serve as reference information for both the construction of mathematical models and for comparison with patient-specific kinematics. Methods: Low dose continuous fluoroscopic image sequences, recorded at 15 fps, were acquired from 131 asymptomatic participants during active, weight-bearing lumbar flexion and return motion. This used a bending protocol guided by an upright motion frame (Fig 1). This standardised the bending range and velocity and minimized accessory movements. Continuous intervertebral rotations in the sagittal plane were extracted for each level (L2-S1) in each frame and transformed into contributions proportional to the total L2-S1 angle. Mean and ± 95% confidence intervals across all participants were calculated for each 1% increment of L2–S1 motion. Data were separated to distinguish the flexion and return-to-neutral portions of the bending task. Statistically significant differences between each level’s contribution to motion were detected by the absence of overlap in the ±CI95 bands and checked using statistical parametric mapping. Results: Full data sets were extracted from 127 participants, (48.8% female, mean age 38.6 years, range: 21-70). The proportion of the motion performed by each level at full flexion was similar to previous studies (4). However, there were significant differences in the contributions to bending during motion, both between and within levels, which change as participants progress through the tasks (Figures 2a and b). Across the study population, each intervertebral level also had its own characteristic motion signature, with significant differences (p<0.05) between each level’s contribution. These were sustained throughout the motion. In the individual back pain patient example (Fig 2c), L2-3 initially accepted a higher proportion of the outward motion than that of the controls (Fig 2a), and considerably less at L4-5, although both showed return to near-normal sharing levels by completion of the bend. On the return motion (Fig 2d), it is L4-5 that initially accepts a higher proportion in this patient, and L3-4 considerably less, although by the time the upright position has been reached and all but L4-5’s share of the motion resemble the normative values (Fig 2b). Figure 1. Upright motion controller Figure 2. Proportional contributions to motion from L2-S1 with 95% CIs in 127 healthy controls in a) flexion, b) return and comparison with a patient with chronic, non-specific low back pain c) and d). Controls (n=127) Outward Return Figure 2a Figure 2b Patient (n=1) Figure 2c Figure 2d Discussion: In the controls (Fig 2a and b), despite differences in gender, BMI, age, anatomy, co-ordination and strength, all levels exhibited consistent motion contributions. This was attributed to the use of the guided motion apparatus (Fig 1) making the database also suitable for comparison with both cross-sectional and longitudinal data from individuals and with groups of patients with low back pain in research and clinical studies. The patient (Fig 2c), exhibits much more initial flexion at L3-4 than the controls during forward bending, while L4-5’s motion is initially paradoxical. On return, L4-5 initially accepts much more of the motion and L2-3 much less (Fig 2d). These differences are likely to be related to a combination of loading, motor control and tissue material characteristics. They may also be suitable for modelling dynamic segmental loading in clinical and occupational settings. References 1. Breen A, et al. Eur Spine J. 27:145-153, 2017 2. Breen A, et al. Eur Spine J. 28:450–460 2019. 3. Aiyangar A, et al. J Biomech. 48:3709-3715, 2015. 4. Widmer, J., et al. A of Biomed. Eng., 47:1491-1522, 2019

Investigator analytic repeatability of two new intervertebral motion biomarkers for chronic, nonspecific low back pain in a cohort of healthy controls

Background: Understanding the mechanisms underlying chronic, nonspecific low back pain (CNSLBP) is essential to advance personalized care and identify the most appropriate intervention. Recently, two intervertebral motion biomarkers termed “Motion Sharing Inequality” (MSI) and “Motion Sharing Variability” (MSV) have been identified for CNSLBP using quantitative fluoroscopy (QF). The aim of this study was to conduct intra- and inter-investigator analytic repeatability studies to determine the extent to which investigator error affects their measurement in clinical studies.  Methods: A cross-sectional cohort study was conducted using the image sequences of 30 healthy controls who received QF screening during passive recumbent flexion motion. Two independent investigators analysed the image sequences for MSI and MSV from October to November 2018. Intra and inter- investigator repeatability studies were performed using intraclass correlations (ICC), standard errors of measurement (SEM) and minimal differences (MD). Results: Intra-investigator ICCs were 0.90 (0.81,0.95) (SEM 0.029) and 0.78 (0.59,0.89) (SEM 0.020) for MSI and MSV, respectively. Inter-investigator ICCs 0.93 (0.86,0.97) (SEM 0.024) and 0.55 (0.24,0.75) (SEM 0.024). SEMs for MSI and MSV were approximately 10% and 30% of their group means respectively. The MDs for MSI for intra- and inter-investigator repeatability were 0.079 and 0.067, respectively and for MSV 0.055 and 0.067. Conclusions: MSI demonstrated substantial intra- and inter-investigator repeatability, suggesting that investigator input has a minimal influence on its measurement. MSV demonstrated moderate intra-investigator reliability and fair inter-investigator repeatability. Confirmation in patients with CNSLBP is now required