Biomechanical Phenotyping of Chronic Low Back Pain: Protocol for BACPAC.

OBJECTIVE: Biomechanics represents the common final output through which all biopsychosocial constructs of back pain must pass, making it a rich target for phenotyping. To exploit this feature, several sites within the NIH Back Pain Consortium (BACPAC) have developed biomechanics measurement and phenotyping tools. The overall aims of this article were to: 1) provide a narrative review of biomechanics as a phenotyping tool; 2) describe the diverse array of tools and outcome measures that exist within BACPAC; and 3) highlight how leveraging these technologies with the other data collected within BACPAC could elucidate the relationship between biomechanics and other metrics used to characterize low back pain (LBP). METHODS: The narrative review highlights how biomechanical outcomes can discriminate between those with and without LBP, as well as among levels of severity of LBP. It also addresses how biomechanical outcomes track with functional improvements in LBP. Additionally, we present the clinical use case for biomechanical outcome measures that can be met via emerging technologies. RESULTS: To answer the need for measuring biomechanical performance, our "Results" section describes the spectrum of technologies that have been developed and are being used within BACPAC. CONCLUSION AND FUTURE DIRECTIONS: The outcome measures collected by these technologies will be an integral part of longitudinal and cross-sectional studies conducted in BACPAC. Linking these measures with other biopsychosocial data collected within BACPAC increases our potential to use biomechanics as a tool for understanding the mechanisms of LBP, phenotyping unique LBP subgroups, and matching these individuals with an appropriate treatment paradigm.

Gait Variability to Phenotype Common Orthopedic Gait Impairments Using Wearable Sensors.

Mobility impairments are a common symptom of age-related degenerative diseases. Gait features can discriminate those with mobility disorders from healthy individuals, yet phenotyping specific pathologies remains challenging. This study aims to identify if gait parameters derived from two foot-mounted inertial measurement units (IMU) during the 6 min walk test (6MWT) can phenotype mobility impairment from different pathologies (Lumbar spinal stenosis (LSS)-neurogenic diseases, and knee osteoarthritis (KOA)-structural joint disease). Bilateral foot-mounted IMU data during the 6MWT were collected from patients with LSS and KOA and matched healthy controls (N = 30, 10 for each group). Eleven gait parameters representing four domains (pace, rhythm, asymmetry, variability) were derived for each minute of the 6MWT. In the entire 6MWT, gait parameters in all four domains distinguished between controls and both disease groups; however, the disease groups demonstrated no statistical differences, with a trend toward higher stride length variability in the LSS group (p = 0.057). Additional minute-by-minute comparisons identified stride length variability as a statistically significant marker between disease groups during the middle portion of 6WMT (3rd min: p ≤ 0.05; 4th min: p = 0.06). These findings demonstrate that gait variability measures are a potential biomarker to phenotype mobility impairment from different pathologies. Increased gait variability indicates loss of gait rhythmicity, a common feature in neurologic impairment of locomotor control, thus reflecting the underlying mechanism for the gait impairment in LSS. Findings from this work also identify the middle portion of the 6MWT as a potential window to detect subtle gait differences between individuals with different origins of gait impairment.

Motor Learning in People with Multiple Sclerosis: A Systematic Review and Meta-analysis.

OBJECTIVE: To systematically review and quantitatively synthesize the existing evidence of motor learning in persons with multiple sclerosis (PwMS). DATA SOURCES: PubMed, Cumulative Index to Nursing and Allied Health Literature, and Web of Science were searched using the following terms: multiple sclerosis, task learning, motor learning, skill learning, performance learning. STUDY SELECTION: Studies had to include PwMS with a main outcome being motor learning, be published in peer-reviewed journals, and be written in English. The search yielded 68 results, and the inclusion criteria were met by 17 studies. DATA EXTRACTION: Basic descriptors of each study, study protocol, and motor learning measures were extracted. The Grading of Recommendations Assessment, Development, and Evaluation approach revealed the quality of evidence was low with a high risk of bias. Meta-analysis was conducted to determine the difference in implicit and explicit learning in PwMS and controls without multiple sclerosis. DATA SYNTHESIS: Studies scored on average 15.9 of 18 for quality assessment. PwMS were able to learn functional mobility and upper limb manipulation motor skills as indicated by short-term acquisition, transfer, and retention. Implicit learning conditions from the meta-analysis showed that PwMS were able to learn at a similar rate to controls without multiple sclerosis (P<.001), yet explicit learning conditions did not display a significant rate of learning (P=.133). CONCLUSIONS: While this review indicated that PwMS are capable of motor learning, several knowledge gaps still exist. Future research should focus on using higher-quality evidence to understand motor learning in PwMS and translate the findings to rehabilitation and activities of daily living.

The Validity of a Mixed Reality-Based Automated Functional Mobility Assessment.

Functional mobility assessments (i.e., Timed Up and Go) are commonly used clinical tools for mobility and fall risk screening in older adults. In this work, we proposed a new Mixed Reality (MR)-based assessment that utilized a Microsoft HoloLensTM headset to automatically lead and track the performance of functional mobility tests, and subsequently evaluated its validity in comparison with reference inertial sensors. Twenty-two healthy adults (10 older and 12 young adults) participated in this study. An automated functional mobility assessment app was developed, based on the HoloLens platform. The mobility performance was recorded with the headset built-in sensor and reference inertial sensor (Opal, APDM) taped on the headset and lower back. The results indicate that the vertical kinematic measurements by HoloLens were in good agreement with the reference sensor (Normalized RMSE ~ 10%, except for cases where the inertial sensor drift correction was not viable). Additionally, the HoloLens-based test completion time was in perfect agreement with the clinical standard stopwatch measure. Overall, our preliminary investigation indicates that it is possible to use an MR headset to automatically guide users (without severe mobility deficit) to complete common mobility tests, and this approach has the potential to provide an objective and efficient sensor-based mobility assessment that does not require any direct research/clinical oversight.

Novel sensing technology in fall risk assessment in older adults: a systematic review.

BACKGROUND: Falls are a major health problem for older adults with significant physical and psychological consequences. A first step of successful fall prevention is to identify those at risk of falling. Recent advancement in sensing technology offers the possibility of objective, low-cost and easy-to-implement fall risk assessment. The objective of this systematic review is to assess the current state of sensing technology on providing objective fall risk assessment in older adults. METHODS: A systematic review was conducted in accordance to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement (PRISMA). RESULTS: Twenty-two studies out of 855 articles were systematically identified and included in this review. Pertinent methodological features (sensing technique, assessment activities, outcome variables, and fall discrimination/prediction models) were extracted from each article. Four major sensing technologies (inertial sensors, video/depth camera, pressure sensing platform and laser sensing) were reported to provide accurate fall risk diagnostic in older adults. Steady state walking, static/dynamic balance, and functional mobility were used as the assessment activity. A diverse range of diagnostic accuracy across studies (47.9% - 100%) were reported, due to variation in measured kinematic/kinetic parameters and modelling techniques. CONCLUSIONS: A wide range of sensor technologies have been utilized in fall risk assessment in older adults. Overall, these devices have the potential to provide an accurate, inexpensive, and easy-to-implement fall risk assessment. However, the variation in measured parameters, assessment tools, sensor sites, movement tasks, and modelling techniques, precludes a firm conclusion on their ability to predict future falls. Future work is needed to determine a clinical meaningful and easy to interpret fall risk diagnosis utilizing sensing technology. Additionally, the gap between functional evaluation and user experience to technology should be addressed.

Cognition is associated with gait variability in individuals with multiple sclerosis.

Fluctuations in gait, or gait variability, are closely related to cognitive function in various clinical populations. However, there are limited data on this relationship in multiple sclerosis (MS) patients. This investigation determined whether cognitive function as measured by processing speed is associated with gait variability in individuals with MS. This secondary analysis included 191 individuals with MS who underwent gait assessment and cognitive assessment. Cognitive processing speed was index by symbol digit modalities test (SDMT). Gait variability was indexed by step length and step time coefficient of variation (CV). Hierarchical linear regressions were performed to examine whether SDMT scores would predict step length and step time CV. After adjusting for age, gender, and disability, we found that SDMT was a significant predictor of step time CV (p < 0.001) and step length CV (p = 0.03). Overall, slower cognitive processing speed was significantly associated with greater gait variability. It is speculated that neural damage in MS patients impairs both cognitive processing speed and gait control. This study provides further evidence that motor and cognitive functions are interrelated.

Probing attention prioritization during dual-task step initiation: a novel method.

The present study investigated the attention allocation during reactive stepping using a continuous finger-tapping task. Ten healthy young subjects were recruited to participate in this study. Subjects were required to perform a rapid voluntary step with either left or right leg after hearing an auditory tone while tapping their right index finger on a handhold numeric keypad. Step initiation conditions included simple and choice reaction forward stepping with three variants of continuous tapping task that were: (1) single task--no concurrent finger-tapping task; (2) dual task easy--one-button tapping task; (3) dual task hard--four-button tapping task. Types of anticipatory postural adjustment (APA) were determined by the center of pressure trajectory. Reaction time, APA duration, and stepping latency were compared between APA types and various dual-task conditions. Wavelet analysis was performed on the stimulus-locked finger-tapping data to determine the frequency change of tapping speed related to reactive stepping. Results showed that postural performance was negatively affected only by the high-attention-demanding cognitive task. Significant reduction of finger-tapping speed post-stimulus presentation was observed across all test conditions, indicating attention shift during the execution of a step. In addition, the DTH condition induced early postural prioritization in choice reaction stepping when different motor programs needed to be planned and executed. Error APA also triggered larger deterioration of tapping performance compared to correct APA, indicating the perceived error and the remedial action require additional attentional resources.

Maternal immune activation increases seizure susceptibility in juvenile rat offspring.

Epidemiological data suggest a relationship between maternal infection and a high incidence of childhood epilepsy in offspring. However, there is little experimental evidence that links maternal infection with later seizure susceptibility in juvenile offspring. Here, we asked whether maternal immune challenge during pregnancy can alter seizure susceptibility and seizure-associated brain damage in adolescence. Pregnant Sprague-Dawley rats were treated with lipopolysaccharide (LPS) or normal saline (NS) on gestational days 15 and 16. At postnatal day 21, seizure susceptibility to kainic acid (KA) was evaluated in male offspring. Four groups were studied, including normal control (NS-NS), prenatal infection (LPS-NS), juvenile seizure (NS-KA), and "two-hit" (LPS-KA) groups. Our results demonstrated that maternal LPS exposure caused long-term reactive astrogliosis and increased seizure susceptibility in juvenile rat offspring. Compared to the juvenile seizure group, animals in the "two-hit" group showed exaggerated astrogliosis, followed by worsened spatial learning ability in adulthood. In addition, prenatal immune challenge alone led to spatial learning impairment in offspring but had no effect on anxiety. These data suggest that prenatal immune challenge causes a long-term increase in juvenile seizure susceptibility and exacerbates seizure-induced brain injury, possibly by priming astroglia.

Pentraxin 3 as a novel early biomarker for the prediction of Henoch-Schönlein purpura nephritis in children.

UNLABELLED: We investigated the potential role of pentraxin 3 (PTX3) in Henoch-Schönlein purpura (HSP), a common multisystemic vasculitis affecting children, as a predictor of Henoch-Schönlein purpura nephritis (HSPN). A total of 108 cases consisting of 34 children with HSP, 37 children with HSPN, and 37 healthy control children were enrolled in this prospective study from March 2010 to February 2013. Blood and urine samples were collected to measure plasma PTX3, C-reactive protein (CRP), serum creatinine, blood urea nitrogen (BUN), urine microalbumin (MALB), and ß2-microglobulin (ß2-MG). Median plasma PTX3 concentrations were significantly higher in children with HSPN and HSP than in control subjects before treatment (6.99, 4.18-9.78 ng/ml; 3.19, 1.13-4.27 ng/ml; 1.24, 0.87-2.08 ng/ml, respectively; all p < 0.05). Median plasma PTX3 concentrations were also significantly higher in children with HSPN than in children with HSP before treatment (6.99, 4.18-9.78 vs. 3.19, 1.13-4.27 ng/ml; p < 0.05). After treatment, median plasma PTX3 concentrations significantly decreased in children with HSP (from 3.19, 1.13-4.27 to 1.08, 0.65-2.19 ng/ml; p < 0.05) and HSPN (from 6.99, 4.18-9.78 to 1.29, 1.01-2.26 ng/ml; p < 0.05). Plasma PTX3 concentration was positively correlated with CRP (rho = 0.532, p = 0.001), MALB (rho = 0.606, p < 0.001), ß2-MG (rho = 0.490, p = 0.002), and 24-h urinary protein quantity (rho = 0.650, p < 0.001) in children with HSPN. Considering vasculitis, we found that PTX3 could be used as a more efficient potential predictor of HSPN than CRP as indicated by the area under the receiver operating characteristic (ROC) curve (AUCROC) of PTX3 (AUCROC = 0.837; p < 0.001) and CRP (AUCROC = 0.514; p = 0.845). The threshold PTX3 concentration with optimal sensitivity and specificity was 4.30 ng/ml (sensitivity 73.0 %, specificity 79.6 %). CONCLUSION: PTX3 seems to have an important role in multisystemic vasculitis of HSP, may be involved in the development of HSPN, and used as an early biomarker to predict HSPN.

[Etiology of anti-N-methyl-D-aspartate receptor encephalitis].

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a type of newly recognized autoimmune encephalitis which is commonly seen in children, but its precise etiology is still uncertain. To reveal the etiology of anti-NMDAR encephalitis is very necessary for understanding its pathology, and for starting immune-related therapy as early as possible to improve its prognosis. In the initial literature, tumor, especially teratoma is more related with the anti-NMDAR encephalitis. In recent research, its etiology is related to infection and heredity. This article reviews the recognition and variation of the etiology of anti-NMDAR encephalitis.

Improvement of hypoxia-ischemia-induced white matter injury in immature rat brain by ethyl pyruvate.

Ethyl pyruvate (EP) has been reported to be neuroprotective in several models of brain injury, yet its influence on periventricular leukomalacia still remains elusive. Here we investigated whether repeated administration of EP could protect against white matter injury after hypoxia-ischemia (HI) (right common carotid artery ligation and 6 % O2 for 60 min) in post-natal 3 day rat pups. EP was injected (50 mg/kg, intraperitoneally) 10 min, 1 and 24 h after HI insult. Treatment with EP significantly reduced HI-induced ventricular enlargement, loss of developing oligodendrocytes, and hypomyelination. We further demonstrated a marked inhibitory effect of EP on inflammatory responses, as indicated by the decreased number of activated microglia and astrocytes and the reduced release of proinflammatory cytokines. Moreover, EP down-regulated the expression of cleaved caspase-3 and Bax, and up-regulated Bcl-2 expression after HI exposure. In conclusion, our results demonstrated that EP was able to provide potent protection on white matter injury through blocking the cerebral inflammatory responses and modulating the apoptotic death program of oligodendrocytes, indicating a potential neuroprotective agent in neonatal brain injury.

Neonatal immune challenge exacerbates seizure-induced hippocampus-dependent memory impairment in adult rats.

Our aim was to examine whether neonatal lipopolysaccharide (LPS) exposure is associated with changes in microglia and whether these alternations could influence later seizure-induced neurobehavioral outcomes. Male pups were first injected intraperitoneally with either LPS or saline on postnatal day 3 (P3) and postnatal day 5 (P5). Immunohistochemical analysis showed that LPS-treated animals exhibited increased microglia activation that persisted into adolescence. At P45, seizures were induced in rats by intraperitoneal injection of kainic acid (KA). Rats treated with LPS neonatally showed significantly greater proinflammatory responses and performed significantly worse in the Y-maze, Morris water maze, and inhibitory avoidance tasks after KA insult. Treatment with minocycline at the time of neonatal LPS exposure to block LPS-induced microglia alternation attenuated the exaggerated neuroinflammatory responses and alleviated memory impairment associated with the KA insult. Our findings suggest that neonatal immune activation can predispose the brain to exacerbated behavioral deficits following seizures in adulthood, possibly by priming microglia.

Intermediate observers based robust fault estimation for multi-agent systems under communication constraints via switching scheme.

This paper addresses the problem of robust fault estimation for multi-agent systems (MASs) under communication constraints. Taking into account the possible data packet loss (DPL) in the information interaction of each subsystem, MASs are remodelled as switching systems by introducing a variable sampling strategy. Then, using the local information among agents, a novel intermediate observer design method based on switching scheme is proposed to estimate faults of MASs. Combining Lyapunov's criterion and linear matrix inequality, sufficient conditions for the intermediate observer to be exponentially stable and have H∞ performance against bounded disturbances and the DPL are given. Finally, some simulations are provided to verify the effectiveness of the proposed method.

Pyruvate administered to newborn rats with insulin-induced hypoglycemic brain injury reduces neuronal death and cognitive impairment.

Based on previous studies, we had made a try to administer sodium pyruvate to newborn Wistar rats suffering repetitive and profound hypoglycemia, which can induce brain injury. Fluoro-Jade B was used to marked degenerative neurons 1 day after the third hypoglycemic insult, and Morris water navigation task was performed to assess cognitive function when the rats were 6 weeks old. We found that administration of sodium pyruvate to those rats whose hypoglycemia was terminated by dextrose can reduce neurodegeneration induced by hypoglycemia and improve the cognitive function. Supplementing sodium pyruvate with glucose to terminate severe neonatal hypoglycemia is an effective intervention.

Objective features of sedentary time and light activity differentiate people with low back pain from healthy controls: a pilot study.

BACKGROUND CONTEXT: Physical inactivity has been described as both a cause and a consequence of low back pain (LBP) largely based on self-reported measures of daily activity. A better understanding of the connections between routine physical activity and LBP may improve LBP interventions. PURPOSE: In this study, we aim to objectively characterize the free-living physical activity of people with low back pain in comparison to healthy controls using accelerometers, and we aim to derive a set of LBP-specific physical activity minutes thresholds that may be used as targets for future physical activity interventions. STUDY DESIGN: Cross-sectional. PATIENT SAMPLE: A total of 22 low back pain patients and 155 controls. OUTCOME MEASURES: Accelerometry derived physical activity measures. METHODS: Twenty-two people with LBP were compared to 155 age and gender-matched healthy controls. All subjects wore an ActiGraph accelerometer on the right hip for 7 consecutive days. Accelerometry-based physical activity features (count-per-minute CPM) were derived using Freedson's intervals and physical performance intervals. A random forest machine learning classifier was trained to classify LBP status using a leave-one-out cross-validation procedure. An interpretation algorithm, the SHapley Additive exPlanations (SHAP) algorithm was subsequently applied to assess the feature importance and to establish LBP-specific physical activity thresholds. RESULTS: The LBP group reported mild to moderate disability (average ODI=18.5). The random forest classifier identified a set of 8 features (digital biomarkers) that achieved 88.1% accuracy for distinguishing LBP from controls. All of the top distinguishing features were related to differences in the sedentary and light activity ranges (<800 CPM), whereas moderate to vigorous physical activity was not discriminative. In addition, we identified and ranked physical activity thresholds that are associated with LBP prediction that can be used in future studies of physical activity interventions for LBP. CONCLUSIONS: We describe a set of physical activity features from accelerometry data associated with LBP. All of the discriminating features were derived from the sedentary and light activity range. We also identified specific activity intensity minutes thresholds that distinguished LBP subjects from healthy controls. Future examination on the digital markers and thresholds identified through this work can be used to improve physical activity interventions for LBP treatment and prevention by allowing the development of LBP-specific physical activity guidelines.

The effect of Lactobacillus johnsonii Ncc533 (La1) on the balance of Th1/Th2 cells in BALB/c mice.

PURPOSE: To determine the effect of Lactobacillus johnsonii Ncc533 (La1) on Th1/Th2 balance, the production of IL-4 and IFN-γ by splenocytes was evaluated following its administration to mice from newborn to adult. Changes in IL-4 and IFN-γ expression and serum levels of OVA-specific-IgE were then investigated in an asthma model. METHODS: Using flow cytometry (FCM) and ELISA, the percentage of IL-4 and IFN-γ expressing splenocytes and serum levels of OVA-specific-IgE were measured in different groups of mice. RESULTS: The percentages of IL-4 and IFN-γ expressing splenocytes in the offspring and in the adults of the La1-treated group were not significantly different when compared with the water-treated group. In the asthma model, the percentages of IL-4 expressing cells and the serum levels of OVA-specific-IgE in the La1-treated and water-treated group were significantly increased compared with those in the control group. The percentage of IFN-γ expressing cells was significantly lower in the La1-treated and water-treated groups. The percentage of IL-4 expressing cells and the serum levels of OVA-specific-IgE in the La1-treated group were significantly lower compared with those in the water-treated group, whereas the percentage of IFN-γ expressing cells was significantly higher. CONCLUSION: Administration of La1 had no effect on the immune system from the neonate to the adult in the normal mice. It did, however, significantly alter the percentages of IL-4 or IFN-γ expressing CD4+ T lymphocytes in the asthma model, suggesting that administration of La1 might regulate the immune response.

Examining the Association Between Self-Reported Estimates of Function and Objective Measures of Gait and Physical Capacity in Lumbar Stenosis.

OBJECTIVE: To evaluate the association of self-reported physical function with subjective and objective measures as well as temporospatial gait features in lumbar spinal stenosis (LSS). DESIGN: Cross-sectional pilot study. SETTING: Outpatient multispecialty clinic. PARTICIPANTS: Participants with LSS and matched controls without LSS (n=10 per group; N=20). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Self-reported physical function (36-Item Short Form Health Survey [SF-36] physical functioning domain), Oswestry Disability Index, Swiss Spinal Stenosis Questionnaire, the Neurogenic Claudication Outcome Score, and inertia measurement unit (IMU)-derived temporospatial gait features. RESULTS: Higher self-reported physical function scores (SF-36 physical functioning) correlated with lower disability ratings, neurogenic claudication, and symptom severity ratings in patients with LSS (P<.05). Compared with controls without LSS, patients with LSS have lower scores on physical capacity measures (median total distance traveled on 6-minute walk test: controls 505 m vs LSS 316 m; median total distance traveled on self-paced walking test: controls 718 m vs LSS 174 m). Observed differences in IMU-derived gait features, physical capacity measures, disability ratings, and neurogenic claudication scores between populations with and without LSS were statistically significant. CONCLUSIONS: Further evaluation of the association of IMU-derived temporospatial gait with self-reported physical function, pain related-disability, neurogenic claudication, and spinal stenosis symptom severity score in LSS would help clarify their role in tracking LSS outcomes.

Protective effects of naloxone in two-hit seizure model.

PURPOSE: Early life status epilepticus (SE) could enhance the vulnerability of the immature brain to a second SE in adulthood (two-hit seizure model). Naloxone has been proved to possess inflammation inhibitory effects in nervous system. This study was designed to evaluate the dose-dependent protective effects of naloxone in kainic acid (KA)-induced two-hit seizure model. METHODS: After KA-induced SE at postnatal day 15 (P15), Sprague-Dawley rats were infused with either saline or different doses (1.92, 3.84, 5.76, and 7.68 mg/kg) of naloxone continuously for 12 h. De novo synthesis of cytokines (interleukin-1 beta [IL-1 beta], S100B) was assessed by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) at 12 h after P15 SE. Glial activation states were analyzed by western blotting of glial markers (glial fibrillary acidic protein [GFAP], S100B, Iba1) both at 12 h after P15 SE and at P45. After a second SE at P45, cognitive deteriorations were evaluated by Morris water tests and neuron injuries were evaluated by TdT-mediated dUTP nick end labeling (TUNEL) assays. RESULTS: Naloxone reduced IL-1 beta synthesis and microglial activation most potently at a dose of 3.84 mg/kg. Attenuation of S100B synthesis and astrocyte activation were achieved most dramatically by naloxone at a dose of 5.76 mg/kg, which is equal to the most powerful dose in ameliorating cognitive injuries and neuron apoptosis after second SE. CONCLUSIONS: Naloxone treatment immediately after early life SE could dose-dependently reduce cytokine production, glial activation, and further lower the vulnerability of immature brains to a second hit in adulthood.

Variability among methods and timing of pain assessment tools for tracking improvement of lumbar stenosis patients after surgery.

BACKGROUND CONTEXT: Many different pain and functional outcomes are used to determine progress after surgical intervention for lumbar spinal stenosis (LSS); it is unknown how these different outcomes correlate, or whether timing of pain measurement is important. PURPOSE: The goal was to determine whether method and timing of pain measurement is important in the context of LSS surgical outcomes. STUDY DESIGN/SETTING: Cohort study. PATIENT SAMPLE: LSS patients (N=21). OUTCOME MEASURES: Self-report measures. METHODS: Each patient completed the 36-item Short Form, Oswestry Disability Index, and Swiss Spinal Stenosis Questionnaire 1 week presurgery and 6 months postsurgery. Objective function was measured using the Self-Paced Walking Test (SPWT). Low back and leg pain were assessed by visual analogue scale both immediately before the SPWT (prewalking pain) and at the symptom-limited endpoint (provoked pain). Pain was also assessed before and after surgery using the pain subscales of 36-item Short Form pain, Oswestry Disability Index, and Swiss Spinal Stenosis Questionnaire. RESULTS: Patients averaged 65.3 years of age with 15 being female. After surgery, all outcome measures improved significantly. Postwalking pain (provoked pain) demonstrating a strong relationship with objectively measured function (SPWT). Pain (visual analogue scale prewalk and postwalk) showed little correlation with reported changes in disability, general health or physical function. CONCLUSIONS: Our results suggest that for patients with LSS, the context of the pain measurement matters, and it is important to measure pain after walking (provoked pain). Results also suggest that when examining the relationship between pain and function, objective measures of function are preferable (eg, a walking test). Finally, given the lack of association between measures of pain, it is important to understand that each pain measure is addressing a different pain construct. Therefore, when conducting outcomes studies, it is imperative to compare the exact same pain measures across time points.

Gait features for discriminating between mobility-limiting musculoskeletal disorders: Lumbar spinal stenosis and knee osteoarthritis.

BACKGROUND: Functional ambulation limitations are features of lumbar spinal stenosis (LSS) and knee osteoarthritis (OA). With numerous validated walking assessment protocols and a vast number of spatiotemporal gait parameters available from sensor-based assessment, there is a critical need for selection of appropriate test protocols and variables for research and clinical applications. RESEARCH QUESTION: In patients with knee OA and LSS, what are the best sensor-derived gait parameters and the most suitable clinical walking test to discriminate between these patient populations and controls? METHODS: We collected foot-mounted inertial measurement unit (IMU) data during three walking tests (fast-paced walk test-FPWT, 6-min walk test- 6MWT, self-paced walk test - SPWT) for subjects with LSS, knee OA and matched controls (N = 10 for each group). Spatiotemporal gait characteristics were extracted and pairwise compared (Omega partial squared - ωp2) between patients and controls. RESULTS: We found that normal paced walking tests (6MWT, SPWT) are better suited for distinguishing gait characteristics between patients and controls. Among the sensor-based gait parameters, stance and double support phase timing were identified as the best gait characteristics for the OA population discrimination, whereas foot flat ratio, gait speed, stride length and cadence were identified as the best gait characteristics for the LSS population discrimination. SIGNIFICANCE: These findings provide guidance on the selection of sensor-derived gait parameters and clinical walking tests to detect alterations in mobility for people with LSS and knee OA.