Prevalence of diffuse idiopathic skeletal hyperostosis (DISH) and early-phase DISH across the lifespan of an American population.

OBJECTIVES: DISH is a common musculoskeletal disorder; however, the imaging features and disease continuum from early to advanced stages is poorly understood. The purpose of this study was to evaluate the prevalence of DISH and early-phase DISH in an American population and to assess the extent and pattern of ectopic mineralization across the thoracic spine. METHODS: Data were retrieved in collaboration with the Rochester Epidemiology Project. We conducted a retrospective image evaluation of a sample of individuals over 19 years of age with CT of the thoracic spine from a Northern US catchment area. Stratified random sampling by age and sex was used to populate the study. We examined the prevalence and extent of ectopic mineralization along the thoracic spine using previously established criteria. RESULTS: A total of 1536 unique images (766 female and 770 male individuals) including 16 710 motion segments were evaluated for imaging features of the continuum of DISH. Collectively, 40.5% of all motion segments evaluated displayed evidence of ectopic mineralization in the thoracic spine. The prevalence of early-phase DISH was 13.2% (10.4% of female and 15.8% of male individuals). The prevalence of established DISH was 14.2% (7.4% of female and 20.9% of male individuals). Remarkable heterogeneity was detected in individuals within each disease classification, based on the extent of the thoracic spine affected and degree of mineralization. CONCLUSIONS: The continuum of imaging features associated with DISH is detected in more than one in four adults and both sexes in an American population.

Lumbar foraminal stenosis was associated with back pain and leg pain: epidemiological evidence from a population-based cohort.

OBJECTIVES: To determine the characteristics of lumbar foraminal stenosis (LFS) on magnetic resonance (MR) images and their association with back pain and radiating leg pain in a population-based sample of Chinese subjects. METHODS: This study was an extension of the Hangzhou Lumbar Spine Study, a cross-sectional study focusing on back pain and lumbar spine MR imaging findings. Questionnaire data, including demographics, lifestyle, occupational exposures, back pain and radiating leg pain were included. On lumbar spine MR images, disc degeneration was assessed using Pfirrmann grade and Modic changes were evaluated. Using Lee's scale, the L3-S1 intervertebral foramina were evaluated, with grade 2-3 representing substantial LFS and grade 0-1 no LFS. Characteristics of LFS were noted, and associations of LFS with back pain and radiating leg pain were examined. RESULTS: Among the 644 study subjects, 141 (21.9%) had at least one LFS, and its occurrence was associated with greater age (OR = 1.93 for each 10 years, p < 0.001). Substantial LFS was associated with the presence of back pain (OR = 1.92, p = 0.001) and the intensity of the worst back pain (Coef = 8.30, p < 0.001) over the past 12 months, and disabling back pain during their lifetime (OR = 2.25, p < 0.001). Substantial LFS was also associated with leg pain (OR = 14.27, p < 0.001), with a sensitivity of 75.7% for the presence of radiating leg pain and a specificity of 81.4%. CONCLUSION: Substantial LFS on MR images was a common age-related degenerative phenotype in adults, and appears to be an independent risk factor for back pain and leg pain.

Depression as a prognostic factor for lumbar spinal stenosis outcomes: a systematic review.

PURPOSE: Lumbar spinal stenosis (LSS) is associated with increased levels of psychological distress, including depression; however, the prognostic value of depression remains unclear. The purpose of this systematic review was to synthesize the evidence on the prognostic value of depression for a range of outcomes in patients with LSS. METHODS: Inclusion criteria were prospective cohort studies that investigated depression in patients diagnosed with LSS. Searches were conducted in 7 databases. Critical appraisal, data extraction, and judgement of cumulative evidence were conducted independently by two reviewers. A meta-analysis was not conducted due to a lack of unique cohorts for each outcome, varying follow-up times, and differences in measurements for both prognostic factors and outcomes. RESULTS: Twenty-three articles were included. There was evidence for an association between preoperative depression and postoperative disability and symptom severity outcomes for patients with LSS. Odds ratios ranged from 1.15 to 2.94 for postoperative disability and 1.16-1.20 for symptom severity at various follow-up times. Using GRADE, evidence supporting depression as a prognostic factor for these LSS outcomes was deemed to be of moderate quality. Similarly strong evidence suggested depressive symptoms are of no prognostic value for postoperative walking capacity. CONCLUSION: Depression appears to have small to moderate prognostic value for LSS outcomes, with the strongest evidence for postoperative disability and symptom severity. The prognostic value of depression for LSS outcomes should be further explored using standardized measures in additional cohorts, including patients managing their condition conservatively, who have been neglected in related research.

Consensus on a standardised treatment pathway algorithm for lumbar spinal stenosis: an international Delphi study.

BACKGROUND: Lumbar spinal stenosis (LSS) is a common degenerative spinal condition in older adults associated with disability, diminished quality of life, and substantial healthcare costs. Individual symptoms and needs vary. With sparse and sometimes inconsistent evidence to guide clinical decision-making, variable clinical care may lead to unsatisfactory patient outcomes and inefficient use of healthcare resources. METHODS: A three-phase modified Delphi study comprising four consensus rounds was conducted on behalf of the International Taskforce for the Diagnosis and Management of LSS to develop a treatment algorithm based on multi-professional international expert consensus. Participants with expertise in the assessment and management of people with LSS were invited using an international distribution process used for two previous Delphi studies led by the Taskforce. Separate treatment pathways for patients with different symptom types and severity were developed and incorporated into a proposed treatment algorithm through consensus rounds 1 to 3. Agreement with the proposed algorithm was evaluated in the final consensus round. RESULTS: The final algorithm combines stratified and stepped approaches. When indicated, immediate investigation and surgery is advocated. Otherwise, a stepped approach is suggested when self-directed care is unsatisfactory. This starts with tailored rehabilitation, then more complex multidisciplinary care, investigations and surgery options if needed. Treatment options in each step depend on clinical phenotype and symptom severity. Treatment response guides pathway entrance and exit points. Of 397 study participants, 86% rated their agreement ≥ 4 for the proposed algorithm on a 0-6 scale, of which 22% completely agreed. Only 7% disagreed. Over 70% of participants felt that the algorithm would be useful for clinicians in public healthcare (both primary care and specialist settings) and in private healthcare settings, and that a simplified version would help patients in shared decision-making. CONCLUSIONS: International and multi-professional agreement was achieved for a proposed LSS treatment algorithm developed through expert consensus. The algorithm advocates different pathway options depending on clinical indications. It is not intended as a treatment protocol and will require evaluation against current care for clinical and cost-effectiveness. It may, however, serve as a clinical guide until evidence is sufficient to inform a fully stratified care model.

Traumatic vertebra and endplate fractures promote adjacent disc degeneration: evidence from a clinical MR follow-up study.

OBJECTIVES: The integrity of endplate is important for maintaining the health of adjacent disc and trabeculae. Yet, pathological impacts of traumatic vertebra and endplate fractures were less studied using clinical approaches. This study aims to investigate their effects on the development of adjacent disc degeneration, segmental kyphosis, Modic changes (MCs), and high-intensity zones (HIZs). MATERIALS AND METHODS: Magnetic resonance (MR) images of patients with acute traumatic vertebral compression fractures (T11-L5) were studied. On MR images, endplate fractures were evaluated as present or absent. Disc signal, height, bulging area, sagittal Cobb angle, MCs, and HIZs were measured on baseline and follow-up MR images to study the changes of the disc in relation to vertebra fractures and endplate fractures. RESULTS: Ninety-seven patients were followed up for 15.4 ± 14.0 months. There were 123 fractured vertebrae, including 79 (64.2%) with endplate fractures and 44 (35.8%) without. Both the adjacent and control discs decreased in signal and height over time (p < 0.001), and the disc adjacent to vertebral fractures had greater signal and height loss than the control disc (p < 0.05). In the presence of endplate fractures, the adjacent discs had greater signal decrease in follow-up (p < 0.05), as compared to those without endplate fractures. Sagittal Cobb angle significantly increased in segments with endplate fractures (p < 0.05). Vertebra fractures were associated with new occurrence of MCs in the fractured vertebra (p < 0.001) but not HIZs in the adjacent disc. CONCLUSIONS: Traumatic vertebral fractures were associated with accelerated adjacent disc degeneration, which appears to be further promoted by concomitant endplate fractures. Endplate fractures were associated with progression of segmental kyphosis.

Innervation of the Human Intervertebral Disc: A Scoping Review.

OBJECTIVE: Back pain is an elusive symptom complicated by a variety of possible causes, precipitating and maintaining factors, and consequences. Notably, the underlying pathology remains unknown in a significant number of cases. Changes to the intervertebral disc (IVD) have been associated with back pain, leading many to postulate that the IVD may be a direct source of pain, typically referred to as discogenic back pain. Yet despite decades of research into the neuroanatomy of the IVD, there is a lack of consensus in the literature as to the distribution and function of neural elements within the tissue. The current scoping review provides a comprehensive systematic overview of studies that document the topography, morphology, and immunoreactivity of neural elements within the IVD in humans. METHOD: Articles were retrieved from six separate databases in a three-step systematic search and were independently evaluated by two reviewers. RESULTS: Three categories of neural elements were described within the IVD: perivascular nerves, sensory nerves independent of blood vessels, and mechanoreceptors. Nerves were consistently localized within the outer layers of the annulus fibrosus. Neural ingrowth into the inner annulus fibrosus and nucleus pulposus was found to occur only in degenerative and disease states. CONCLUSION: While the pattern of innervation within the IVD is clear, the specific topographic arrangement and function of neural elements in the context of back pain remains unclear.

The association between vertebral endplate structural defects and back pain: a systematic review and meta-analysis.

PURPOSE: To clarify the current state of knowledge on the association of endplate structural defects and back pain. METHODS: Five databases were searched for studies reporting on the association between endplate structural defects and back pain. Covidence and comprehensive meta-analysis software were used for article screening and selection and pooling of extracted data. Overall quality of evidence was assessed using GRADE. RESULTS: Twenty-six studies comprised of 11,027 subjects met inclusion criteria. The presence of moderate heterogeneity (I2 = 73%; p = 0.001) prevented the pooling of estimates across all studies. However, it was possible to pool studies of specific endplate defect phenotypes, such as erosion (OR: 2.69; 95% CI: 1.35-5.50) and sclerosis (OR: 1.97; 95% CI: 1.50-2.58), which yielded significant associations with back pain. Schmorl's nodes were also associated with most individual back pain phenotypes (OR: 1.53-1326, I2 = 0-7.5%) and back pain overall (OR: 1.63, 95% CI: 1.37-1.94, I2 = 26%) in general population samples. The pooling of data from all studies of specific back pain phenotypes, such as frequent back pain (OR: 2.83; 95% CI: 1.77-4.52) and back pain incidence (OR: 1.65; 95% CI: 1.30-2.10), each yielded significant association with endplate structural defects and was supported by low heterogeneity (I2 = < 7.5.%). CONCLUSION: Overall, there is moderate quality evidence of an association between back pain and endplate structural defects, which is most evident for erosion, sclerosis and Schmorl's nodes. Going forward, research on specific endplate defect phenotypes and back pain case definitions using strong study designs will be important in clarifying the extent of associations and underlying mechanisms. The study was prospectively registered in Prospero (CRD42020170835) on 02/24/2020.

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.

Vertebral endplate defects: nomenclature, classification and measurement methods: a scoping review.

PURPOSE: To summarize the scope of nomenclature and measurement methods used to document endplate defects in the health sciences literature. METHODS: The scoping review followed the York framework and was reported according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews. The databases of PubMed, Scopus, Embase and CINAHL were searched using key terms. Screening and selection were conducted by two independent reviewers. A standardized, pilot-tested form was used for extracting data, which were analyzed descriptively. RESULTS: The review included 211 studies, originating from 29 countries, with the USA (18.8%) and China (12.26%) as leading contributors. Thirty-four different terms for structural endplate defects were reported, but were never defined in most studies (65%). Of the 34 different terms used, some appeared to represent the same phenomenon, while the same terms were occasionally defined differently between studies. Schmorl's nodes were most commonly investigated (n = 99 studies) and defined similarly across studies, with the main difference relating to whether the indentation (node) was required to have a sclerotic margin. There were also similarities in definitions for endplate sclerosis. However, there was great variability in the definitions of other terms, such as lesions, irregularities, abnormalities, erosions and changes. CONCLUSION: With the possible exception of Schmorl's nodes, we lack a common language for effectively communicating structural endplate findings. This review provides a foundation and impetus for standardizing terminology and core measures to improve communication and synthesis of the growing body of endplate research to advance related knowledge. These slides can be retrieved under Electronic Supplementary Material (paragraph). Then process the ppt slide as graphical image.

What Motivates Engagement in Work and Other Valued Social Roles Despite Persistent Back Pain?

Purpose The prognosis of persistent back pain is variable, with some individuals adjusting poorly and others continuing to actively engage in work and other valued social roles. The aim of this study was to better understand why some individuals, despite persistent back pain, continue to actively engage in work and other valued social roles. Methods Individuals with persistent back pain, who were participating in their regular duties as a full-time employee, homemaker, student or any combination of these, were recruited from a multidisciplinary pain centre and orthopedic physical therapy clinics in Alberta, Canada. A qualitative study was conducted using semi-structured interviews of 15 participants and a thematic analysis to analyze the data. Results There were two motivators identified for participating in the work role: (1) participation formed part of the participant's self-schema (a cognitive framework that includes one's beliefs about oneself) and (2) participation made it possible to achieve a valued outcome. Conclusions Further understanding of important motivators for maintaining engagement in work and other valued social roles despite persistent back pain can help inform the development of more successful disability and pain management programs.

Measuring and reporting of vertebral endplate bone marrow lesions as seen on MRI (Modic changes): recommendations from the ISSLS Degenerative Spinal Phenotypes Group.

PURPOSE: The positive association between low back pain and MRI evidence of vertebral endplate bone marrow lesions, often called Modic changes (MC), offers the exciting prospect of diagnosing a specific phenotype of chronic low back pain (LBP). However, imprecision in the reporting of MC has introduced substantial challenges, as variations in both imaging equipment and scanning parameters can impact conspicuity of MC. This review discusses key methodological factors that impact MC classification and recommends guidelines for more consistent MC reporting that will allow for better integration of research into this LBP phenotype. METHODS: Non-systematic literature review. RESULTS: The high diagnostic specificity of MC classification for a painful level contributes to the significant association observed between MC and LBP, whereas low and variable sensitivity underlies the between- and within-study variability in observed associations. Poor sensitivity may be owing to the presence of other pain generators, to the limited MRI resolution, and to the imperfect reliability of MC classification, which lowers diagnostic sensitivity and thus influences the association between MC and LBP. Importantly, magnetic field strength and pulse sequence parameters also impact detection of MC. Advances in pulse sequences may improve reliability and prove valuable for quantifying lesion severity. CONCLUSIONS: Comparison of MC data between studies can be problematic. Various methodological factors impact detection and classification of MC, and the lack of reporting guidelines hinders interpretation and comparison of findings. Thus, it is critical to adopt imaging and reporting standards that codify acceptable methodological criteria. These slides can be retrieved under Electronic Supplementary Material.

The association between occupational loading and spine degeneration on imaging - a systematic review and meta-analysis.

BACKGROUND: There are inconsistencies in findings regarding the relationship of occupational loading with spinal degeneration or structural damage. Thus, a systematic review was conducted to determine the current state of knowledge on the association of occupational loading and spine degeneration on imaging. METHODS: We performed electronic searches on MEDLINE, CINAHL and EMBASE. We included cross-sectional, case control and cohort studies evaluating occupational loading as the exposure and lumbar spine structural findings on imaging as the outcomes. When possible, results were pooled. RESULTS: Seventeen studies were included in the review. Ten studies evaluated the association of occupational loading with disc degeneration (signal intensity), four of which were pooled into a meta-analysis. Of the 10 studies, only two did not identify a relationship between occupation loading and disc degeneration. A meta-analysis including four of the studies demonstrated an association between higher loading and degeneration for all spinal levels, with odds ratios between 1.6 and 3.3. Seven studies evaluated disc height narrowing and seven evaluate disc bulge, with six and five identifying an association of loading and with imaging findings respectively. Three studies evaluated modic changes and one identified and association with occupational load. CONCLUSIONS: There was moderate evidence suggesting a modest association between occupational loading and disc degeneration (signal intensity), and low-quality evidence of an association between occupational loading and disc narrowing and bulging.

Population-averaged MRI atlases for automated image processing and assessments of lumbar paraspinal muscles.

PURPOSE: Growing evidence suggests an association between lumbar paraspinal muscle degeneration and low back pain (LBP). Currently, time-consuming and laborious manual segmentations of paraspinal muscles are commonly performed on magnetic resonance imaging (MRI) axial scans. Automated image analysis algorithms can mitigate these drawbacks, but they often require individual MRIs to be aligned to a standard "reference" atlas. Such atlases are well established in automated neuroimaging analysis. Our aim was to create atlases of similar nature for automated paraspinal muscle measurements. METHODS: Lumbosacral T2-weighted MRIs were acquired from 117 patients who experienced LBP, stratified by gender and age group (30-39, 40-49, and 50-59 years old). Axial MRI slices of the L4-L5 and L5-S1 levels at mid-disc were obtained and aligned using group-wise linear and nonlinear image registration to produce a set of unbiased population-averaged atlases for lumbar paraspinal muscles. RESULTS: The resulting atlases represent the averaged morphology and MRI intensity features of the corresponding cohorts. Differences in paraspinal muscle shapes and fat infiltration levels with respect to gender and age can be visually identified from the population-averaged data from both linear and nonlinear registrations. CONCLUSION: We constructed a set of population-averaged atlases for developing automated algorithms to help analyze paraspinal muscle morphometry from axial MRI scans. Such an advancement could greatly benefit the fields of paraspinal muscle and LBP research. These slides can be retrieved under Electronic Supplementary Material.

Association between paraspinal muscle morphology, clinical symptoms and functional status in patients with lumbar spinal stenosis.

PURPOSE: Lumbar spinal stenosis (LSS) is a disabling condition associated with narrowing of the spinal canal or vertebral foramina. Paraspinal muscle atrophy and fatty infiltration have been reported in patients with chronic LBP and disc herniation. However, very few imaging studies have examined paraspinal muscle morphology and composition in patients with LSS. The purpose of this study was to investigate the association of paraspinal muscle size, composition and asymmetry with functional status in patients with LSS. METHODS: Thirty-six patients diagnosed with LSS at L4-L5 with neurogenic claudication were included. Paraspinal muscle measurements were obtained from axial T2-weighted MR images, bilaterally, at the level of the superior and inferior vertebral endplates of L5. Muscle measurements of interest included: total cross-sectional area (CSA), functional CSA (FCSA), the ratio of FCSA to CSA (FCSA/CSA) as an indicator of muscle composition, and relative % asymmetry in muscle CSA. The association between muscle parameters and other patient characteristics with function as indicated from Oswestry Disability Index (ODI) scores and pain interference status was investigated. RESULTS: Greater multifidus muscle fatty infiltration (e.g., lower FCSA/CSA) and lower psoas relative CSA were associated with lower function (higher ODI and pain interference scores) in univariable and multivariable analyses. There was no association between the different muscle parameters and stenosis severity or back or leg pain duration or severity. CONCLUSIONS: Our findings suggest an association of multifidus muscle fatty infiltration and psoas muscle size with functional status in patients diagnosed with LSS. Future prospective studies are needed to evaluate whether such muscle parameters are associated with prognosis and functional recovery following surgical treatment.

ISSLS PRIZE IN BIOENGINEERING SCIENCE 2017: Automation of reading of radiological features from magnetic resonance images (MRIs) of the lumbar spine without human intervention is comparable with an expert radiologist.

STUDY DESIGN: Investigation of the automation of radiological features from magnetic resonance images (MRIs) of the lumbar spine. OBJECTIVE: To automate the process of grading lumbar intervertebral discs and vertebral bodies from MRIs. MR imaging is the most common imaging technique used in investigating low back pain (LBP). Various features of degradation, based on MRIs, are commonly recorded and graded, e.g., Modic change and Pfirrmann grading of intervertebral discs. Consistent scoring and grading is important for developing robust clinical systems and research. Automation facilitates this consistency and reduces the time of radiological analysis considerably and hence the expense. METHODS: 12,018 intervertebral discs, from 2009 patients, were graded by a radiologist and were then used to train: (1) a system to detect and label vertebrae and discs in a given scan, and (2) a convolutional neural network (CNN) model that predicts several radiological gradings. The performance of the model, in terms of class average accuracy, was compared with the intra-observer class average accuracy of the radiologist. RESULTS: The detection system achieved 95.6% accuracy in terms of disc detection and labeling. The model is able to produce predictions of multiple pathological gradings that consistently matched those of the radiologist. The model identifies 'Evidence Hotspots' that are the voxels that most contribute to the degradation scores. CONCLUSIONS: Automation of radiological grading is now on par with human performance. The system can be beneficial in aiding clinical diagnoses in terms of objectivity of gradings and the speed of analysis. It can also draw the attention of a radiologist to regions of degradation. This objectivity and speed is an important stepping stone in the investigation of the relationship between MRIs and clinical diagnoses of back pain in large cohorts. LEVEL OF EVIDENCE: Level 3.

Long-term evaluation of a Canadian back pain mass media campaign.

PURPOSE: This paper evaluates the long-term impact of a Canadian mass media campaign on general public beliefs about staying active when experiencing low back pain (LBP). METHODS: Changes in beliefs about staying active during an episode of LBP were studied using telephone and web-based surveys. Logistic regression analysis was used to investigate changes in beliefs over time and the effect of exposure to campaign messaging. RESULTS: The percentage of survey respondents agreeing that they should stay active through LBP increased annually from 58.9 to ~72.0%. Respondents reporting exposure to campaign messaging were statistically significantly more likely to agree with staying active than respondents who did not report exposure to campaign messaging (adjusted OR, 95% CI = 1.96, 1.73-2.21). CONCLUSION: The mass media campaign had continued impact on public LBP beliefs over the course of 7 years. Improvements over time were associated with exposure to campaign messaging.

Paraspinal muscle asymmetry and fat infiltration in patients with symptomatic disc herniation.

PURPOSE: To investigate asymmetry in size and composition of the multifidus and erector spinae in patients with posterolateral disc herniation and concordant radicular symptoms, and determine whether symptom duration is associated with degree of asymmetry. METHODS: Thirty-three patients diagnosed with posterolateral disc herniation at L4-L5 verified on imaging and concordant leg pain were included. Multifidus and erector spinae cross-sectional area (CSA), functional cross-sectional area (FCSA, fat-free area), signal intensity and ratio of FCSA to total CSA were measured bilaterally from T 2-weighted axial magnetic resonance imaging (MRI) at L3-L4, L4-L5, L5-S1 and S1 levels. RESULTS: No side-to-side differences in multifidus CSA, FCSA, and ratio of FCSA/CSA reached statistical significance at any spinal level. The multifidus signal intensity at L5-S1 was significantly greater (more fatty infiltration) on the side of the disc herniation. The erector spinae FCSA (lean muscle mass) at L5-S1 was found to be significantly smaller on the side of the herniation and the ratio of FCSA/CSA was smaller (more fatty infiltration) on the side of the herniation at L4-L5 and L5-S1. The degree of muscle asymmetry was not associated with symptoms duration. CONCLUSIONS: There was no significant asymmetry of the multifidus at spinal level above, same or level below the disc herniation. Instead, variations in muscle composition were observed, with greater fat infiltration on the side and at spinal levels adjacent to the disc herniation. Muscle asymmetry was not correlated with symptom duration.

Are performance-based functional assessments superior to semistructured interviews for enhancing return-to-work outcomes?

OBJECTIVE: To examine whether use of functional capacity evaluation (FCE) leads to better outcomes for injured workers. DESIGN: Cluster randomized controlled trial conducted with analysis at level of claimant. SETTING: Rehabilitation facility. PARTICIPANTS: Participants included claimants (N=203); of these, 103 were tested with FCE. Data were collected on all claimants undergoing RTW assessment at the facility for musculoskeletal conditions. Participants were predominantly employed (59%) men (73%) with chronic musculoskeletal conditions (median duration, 496d). INTERVENTIONS: FCEs are commonly used to identify work abilities and inform return-to-work (RTW) decisions. Therefore, FCE results have important consequences. Clinicians who were trained and experienced in performing FCEs were randomized into 2 groups. One group included 14 clinicians who were trained to conduct a semistructured functional interview; the other group (control group) continued to use standard FCE procedures. MAIN OUTCOME MEASURES: Outcomes included RTW recommendations after assessment, functional work level at time of assessment and 1, 3, and 6 months after assessment, and compensation outcomes. Analysis included Mann-Whitney U, chi-square, and t tests. RESULTS: All outcomes were similar between groups, and no statistically or clinically significant differences were observed. Mean differences between groups on functional work levels at assessment and follow-up ranged from 0.1 to 0.3 out of 4 (3%-8% difference, P>.05). CONCLUSIONS: Performance-based FCEs did not appear to enhance RTW outcomes beyond information gained from semistructured functional interviewing. Use of functional interviewing has the potential to improve efficiency of RTW assessment without compromising clinical, RTW, or compensation outcomes.

Genetics of disc-related disorders: current findings and lessons from other complex diseases.

Disc-related disorders are highly genetic conditions with heritability estimates of up to 75 % and yet, few genomic locations have been moderately associated with the disorders. Candidate gene studies have shown possible disease associations on loci and genes of 1p21.1 (COL11A1), 6q27 (THBS2), 9q22.31 (ASPN), 10p12.31 (SKT), 20q11.2 (GDF5) and 20q13.12 (MMP9). More recently, in 2012, the first genome-wide association study revealed variants on loci and genes of 3p26.2, 6p21.32 (HLA region) and 6q26 (PARK2) that associate with disc-related disorders. In many other complex diseases, large meta-analyses of hundreds of thousands of study subjects and loci have revealed remarkable pathways. As methodology is evolving rapidly, we have already stepped into the era of routinely sequencing all bases in all human exons and we are approaching the era of sequencing the entire genome of study subjects with common diseases. The past decade has taught us that the common variants seen throughout populations seem to have low effects in many common diseases, explain relatively little of the overall heritability of the diseases and demand thousands of study subjects to identify associations. It seems that familial rare variants play an important role in many common diseases leading us back to valuing studies with large families and isolated populations. Moreover, careful characterization of environmental conditions are needed to explore and determine gene-environment interactions as genes that increase disease risk in one context may not do so under another context.

Disc degeneration-related clinical phenotypes.

The phenotype, or observable trait of interest, is at the core of studies identifying associated genetic variants and their functional pathways, as well as diagnostics. Yet, despite remarkable technological developments in genotyping and progress in genetic research, relatively little attention has been paid to the equally important issue of phenotype. This is especially true for disc degeneration-related disorders, and the concept of degenerative disc disease, in particular, where there is little consensus or uniformity of definition. Greater attention and rigour are clearly needed in the development of disc degeneration-related clinical phenotypes if we are to see more rapid advancements in knowledge of this area. When selecting phenotypes, a basic decision is whether to focus directly on the complex clinical phenotype (e.g. the clinical syndrome of spinal stenosis), which is ultimately of interest, or an intermediate phenotype (e.g. dural sac cross-sectional area). While both have advantages, it cannot be assumed that associated gene variants will be similarly relevant to both. Among other considerations are factors influencing phenotype identification, comorbidities that are often present, and measurement issues. Genodisc, the European research consortium project on disc-related clinical pathologies has adopted a strategy that will allow for the careful characterisation and examination of both the complex clinical phenotypes of interest and their components.