Patients with Axial Spondyloarthritis Show an Altered Flexion/Relaxation Phenomenon

Axial spondyloarthritis (axSpA) is a chronic rheumatic disease characterized by the presence of inflammatory back pain. In patients with chronic low back pain, the lumbar flexion relaxation phenomenon measured by surface electromyography (sEMG) differs from that in healthy individuals. However, sEMG activity in axSpA patients has not been studied. The purpose of this study was to analyze the flexion relaxation phenomenon in axSpA patients. A study evaluating 39 axSpA patients and 35 healthy controls was conducted. sEMG activity at the erector spinae muscles was measured during lumbar full flexion movements. sEMG activity was compared between axSpA patients and the controls, as well as between active (BASDAI ≥ 4) and non-active (BASDAI 0.8 for 1/FRR) and criterion validity. ROC analysis showed good discriminant validity for axSpA patients (AUC = 0.835) vs. the control group using 1/FRR. An abnormal flexion/relaxation phenomenon exists in axSpA patients compared with controls. sEMG could be an additional objective tool in the evaluation of patient function and disease activity status

Paravertebral Muscle Mechanical Properties in Patients with Axial Spondyloarthritis or Low Back Pain: A Case-Control Study

Different musculoskeletal disorders are a source of pain in the spinal region; most of them can be divided into mechanical, such as low back pain (LBP), or inflammatory origins, as is the case of axial spondyloarthritis (axSpA). Nevertheless, insufficient information is available about the muscle negative consequences of these conditions. Thus, the objective of this study was to identify whether mechanical muscle properties (MMPs) of cervical and lumbar muscles are different between patients with axSpA, subacute LBP (sLBP), and healthy controls. Furthermore, we aimed identify whether MMPs were related to sociodemographic and clinical variables in various study groups. The MMPs, sociodemographic, and clinical variables were obtained in 43 patients with axSpA, 43 subjects with sLBP, and 43 healthy controls. One-way ANOVAs and ROC curves were applied to identify whether the MMPs could differentiate between the study groups. Intra-group Pearson r coefficients to test the associations between MMPs and the rest of the variables were calculated. The results showed that axSpA subjects have a higher tone and stiffness and a lower relaxation and creep than sLBP and healthy ones (p 0.8). However, no MMP could differentiate between sLBP and healthy subjects. Each group had a different pattern of bivariate correlations between MMPs and sociodemographic and clinical data, with a worse state and progression of the axSpA group associated with a higher tone and stiffness in both spinal regions. This study supports that MMPs are different and show different patterns of correlations depending on the type of spinal pain

Measuring Spinal Mobility Using an Inertial Measurement Unit System: A Validation Study in Axial Spondyloarthritis

Portable inertial measurement units (IMUs) are beginning to be used in human motion analysis. These devices can be useful for the evaluation of spinal mobility in individuals with axial spondyloarthritis (axSpA). The objectives of this study were to assess (a) concurrent criterion validity in individuals with axSpA by comparing spinal mobility measured by an IMU sensor-based system vs. optical motion capture as the reference standard; (b) discriminant validity comparing mobility with healthy volunteers; (c) construct validity by comparing mobility results with relevant outcome measures. A total of 70 participants with axSpA and 20 healthy controls were included. Individuals with axSpA completed function and activity questionnaires, and their mobility was measured using conventional metrology for axSpA, an optical motion capture system, and an IMU sensor-based system. The UCOASMI, a metrology index based on measures obtained by motion capture, and the IUCOASMI, the same index using IMU measures, were also calculated. Descriptive and inferential analyses were conducted to show the relationships between outcome measures. There was excellent agreement (ICC > 0.90) between both systems and a significant correlation between the IUCOASMI and conventional metrology (r = 0.91), activity (r = 0.40), function (r = 0.62), quality of life (r = 0.55) and structural change (r = 0.76). This study demonstrates the validity of an IMU system to evaluate spinal mobility in axSpA. These systems are more feasible than optical motion capture systems, and they could be useful in clinical practice

Biomechanical evaluation of lumbar musculature in patients with axial spondyloarthritis and juvenile spondyloarthritis

En la EspAx, la presencia de dolor lumbar inflamatorio es un síntoma clave para su diagnóstico. Sin embargo, la aplicación de criterios clínicos que pueden no estar bien definidos en las primeras etapas puede dificultar la identificación de este tipo de dolor. Estudios recientes nos dicen que en la evolución de esta patología, además de un componente inflamatorio, también hay indicios de actividad muscular patológica (estrés biomecánico) que podrían ser la causa / efecto de la inflamación y el daño estructural. La hipótesis principal de la tesis fue: "El uso del análisis biomecánico aplicado a la región lumbar, basado en varias tecnologías (análisis cinemático, electromiografía y miotonometría) nos permitirá descubrir características del dolor lumbar inflamatorio, sirviendo para mejorar la evaluación funcional y una ayuda para el diagnóstico precoz de patologías reumáticas como la espondiloartritis”. La investigación se ha centrado en varias áreas grandes relacionadas con el análisis biomecánico en el área lumbar / cervical en pacientes con dolor lumbar inflamatorio, que permiten caracterizar las propiedades biomecánicas, conocer mejor las patologías, qué efecto producen en el paciente y cómo diagnosticar, clasificar y evaluar al paciente. 1. FORMULA BASDAS Hemos definido una nueva fórmula para calcular el ASDAS ingresando solo el BASDAI y el CRP. Los valores de actividad de la enfermedad obtenidos por esta nueva fórmula arrojan resultados muy similares a los de la fórmula ASDAS original (ligeramente diferente del índice original). Llamamos a esta fórmula BASDAS. Esta fórmula nos permite reutilizar nuestros datos antiguos y proporciona un método simple para evaluar la actividad de la enfermedad. 2. ELECTROMIOGRAFIA La actividad muscular del área lumbar y cervical se ve afectada en presencia de dolor. El efecto de la no relajación de la musculatura en la flexión completa (ausencia del fenómeno de flexión por relajación -FFR), se ha demostrado en numerosos estudios en dolor inespecífico, no en EspAx. Hemos desarrollado un protocolo de evaluación del FFR que se ha aplicado a pacientes y sujetos sanos encontrando que, en el caso de la EspAx, este tono también se altera (no hay relajación). 3. EVALUACIÓN DE LA MOVILIDAD El dolor reduce la movilidad de la columna vertebral del paciente. En el caso del dolor lumbar inflamatorio, esta reducción se debe a la inflamación y al daño estructural que aparece a nivel radiográfico. Para la evaluación de la movilidad axial es importante contar con herramientas fiables y precisas, en este sentido hemos llevado a cabo investigaciones sobre: la utilidad de los sensores inerciales para la metrología de pacientes con EspAx, la relación entre la movilidad lumbar y toraco-lumbar evaluada con sensores inerciales. Además de lo anterior, también analizamos el ritmo lumbo-pélvico en pacientes con dolor lumbar inflamatorio, mecánico y en sujetos sanos. En el caso del dolor lumbar inflamatorio, también es importante conocer la influencia del daño estructural y la inflamación en la movilidad. En todos nuestros estudios se destaca que la postura y la movilidad en pacientes con EspAx se alteran con respecto a pacientes con dolor lumbar y sujetos sanos. Durante estos 3 años, las experiencias mencionadas anteriormente nos han permitido evaluar nuestro propio sistema de sensores inerciales, llamado iUCOTrack. 4. MIOTONOMETRÍA Otra área de investigación es la evaluación del tono muscular en reposo en el área lumbar y cervical. Varios estudios muestran que ciertas patologías alteran el tono muscular (aumento de la rigidez). En nuestro caso, a través del dispositivo MyotonPro©, hemos descubierto que en el caso de EspAx este efecto también ocurre.In axial spondyloarthritis (AxSpA), the presence of inflammatory low back pain is a key symptom for its diagnosis. Identifying a pain as inflammatory, however, is not easy, which is hindered by the application of clinical criteria that may not be well defined in the early stages. Recent studies tell us that in the evolution of these pathologies, in addition to an inflammatory component, there are also indications of pathological muscular activity (biomechanical stress) that could be the cause / effect of inflammation and structural damage. The main hypothesis of the thesis was: “The use of biomechanical analysis applied to the lumbar region, based on several technologies (kinematic analysis, electromyography and myotonometry) will allow us to discover features of inflammatory back pain, serving as for improving functional assessment being and an aid for the early diagnosis of rheumatic pathologies such as spondyloarthritis”. The research has focused on several large areas related to biomechanical analysis in the lumbar / cervical area in patients with inflammatory low back pain, which allow characterizing the biomechanical properties, to know better the pathologies, what effect they produce in the patient and how to diagnose, classify and evaluate the patient. BASDAS FORMULA We have defined a new formula to calculate the ASDAS by inputting only the BASDAI and CRP. The disease activity value obtained by this new formula yield results very similar to those of the original ASDAS formula being slightly different from the original index. We call this formula the BASDAS. This formula allows us to reuse our old data and provides a simple method of assessing disease activity. ELECTROMIOGRAPHY The muscular activity of the lumbar and cervical area is affected in the presence of pain. The effect of a non-relaxation of the musculature in complete flexion (absence of relaxation flexion phenomenon -FFR), has been shown in numerous studies in nonspecific pain, not in AxSpA. We have developed an FFR evaluation protocol that has been applied to patients and healthy subjects. We have found that, in the case of AxSpA, this tone is also altered (there is no relaxation). MOBILITY ASSESMENT The pain reduces the mobility of the patient's spine. In the case of inflammatory low back pain, this reduction is due to inflammation and structural damage that appears at the radiographic level. For its evaluation it is important to have reliable and precise tools for measuring the mobility of the column. In this sense we have carried out research on: usefulness of inertial sensors for the metrology of patients with AxSpA, relationship between lumbar and thoracolumbar mobility evaluated with inertial sensors. In addition to the above, we also analyzed the lumbo-pelvic rhythm in patients with inflammatory, mechanical low back pain and in healthy subjects. In the case of inflammatory low back pain, it is also important to know the influence of structural damage and inflammation in mobility. In all our studies it is highlighted that posture and mobility in patients with AxSpA is altered with respect to patients with low back pain and healthy subjects. During these 3 years, the experiences mentioned above have allowed us to evaluate our own inertial sensor system, called iUCOTrack. MYOTONOMETRY Another area of research is the evaluation of resting muscle tone in the lumbar and cervical area. Various studies show that certain pathologies alter muscle tone (increased stiffness). In our case, through the MyotonPro device, we have discovered that in the case of AxSpA this effect also occurs

Patients with Axial Spondyloarthritis Show an Altered Flexion/Relaxation Phenomenon

Axial spondyloarthritis (axSpA) is a chronic rheumatic disease characterized by the presence of inflammatory back pain. In patients with chronic low back pain, the lumbar flexion relaxation phenomenon measured by surface electromyography (sEMG) differs from that in healthy individuals. However, sEMG activity in axSpA patients has not been studied. The purpose of this study was to analyze the flexion relaxation phenomenon in axSpA patients. A study evaluating 39 axSpA patients and 35 healthy controls was conducted. sEMG activity at the erector spinae muscles was measured during lumbar full flexion movements. sEMG activity was compared between axSpA patients and the controls, as well as between active (BASDAI ≥ 4) and non-active (BASDAI 0.8 for 1/FRR) and criterion validity. ROC analysis showed good discriminant validity for axSpA patients (AUC = 0.835) vs. the control group using 1/FRR. An abnormal flexion/relaxation phenomenon exists in axSpA patients compared with controls. sEMG could be an additional objective tool in the evaluation of patient function and disease activity status.This research has been funded by Health Innovation Projects of Junta de Andalucía (PIN-0079–2016) and Research Promotion Program (2016) of the University of Córdoba.Ye

Mechanical Properties of Lumbar and Cervical Paravertebral Muscles in Patients with Axial Spondyloarthritis: A Case-Control Study

Background: Axial spondyloarthritis (axSpA) affects spinal muscles, due to inflammation and structural damage. The mechanical properties of the muscles, such as tone or stiffness, could be altered in axSpA. The aim of this work is to analyze the mechanical properties of cervical and lumbar spine muscles in axSpA patients and their relationship with metrology measures, function, disease activity, structural damage and quality of life. Methods: axSpA patients and age/gender/BMI matched healthy controls were recruited. The muscle mechanical properties (MMPs), such as tone or frequency, stiffness, decrement (linear elastic properties), relaxation and creep (viscoelastic properties), of cervical (semispinalis capitis) and lumbar (erector spinae) muscles were bilaterally measured at rest using myotonometry. Additionally, conventional metrology, BASMI (metrology index), BASDAI (disease activity index), mSASSS (radiological structural damage index) and SF-12 (health-related quality of life questionnaire) were used in the axSpA group. Between-groups comparison, intra-group correlations and multivariable regression analyses were performed to achieve the study aims. Results: Thirty-four axSpA patients (mean age: 46.21 ± 8.53 y) and 34 healthy volunteers (mean age: 43.97 ± 8.49 y) were recruited. Both in cervical and lumbar spine, linear elastic parameters were significantly higher in axSpA patients in comparison with controls, while viscoelastic parameters were significantly lower. Lumbar muscle frequency, stiffness, relaxation, creep and cervical muscle elasticity were fair to strongly correlated (|0.346| < r < |0.774|) with age, functional status, activity of disease, structural damage and quality of life in axSpA patients. Furthermore, moderate to good fitted multivariate models (0.328 < R2 < 0.697) were obtained combining age, conventional metrology, activity of the disease and function for the estimation of cervical and lumbar MMPs. Conclusion: Mechanical properties of spinal muscles of axSpA patients differ from controls. Lumbar and cervical muscles exhibit greater linear elastic properties and lower viscoelastic properties, which are related with age, clinical and psychophysiological features of axSpA