Physical activity based on daily steps in patients with chronic musculoskeletal pain: evolution and associated factors.

BACKGROUND: People with chronic musculoskeletal pain (CMSP) often have low physical activity. Various factors can influence the activity level. The aim of this study was to monitor physical activity, assessed by the number of steps per day, over time in people with CMSP and identify factors that could be associated with this activity feature. METHODS: This prospective study involved people undergoing rehabilitation following an orthopedic trauma that had led to CMSP. At entry, participants completed self-reported questionnaires assessing pain, anxiety, depression, catastrophyzing, kinesiophobia, and behavioural activity patterns (avoidance, pacing and overdoing). They also underwent functional tests, assessing walking endurance and physical fitness. To determine daily step counts, participants wore an accelerometer for 1 week during rehabilitation and 3 months post-rehabilitation. The number of steps per day was compared among three time points: weekend of rehabilitation (an estimate of pre-rehabilitation activity; T1), weekdays of rehabilitation (T2), and post-rehabilitation (T3). Linear regression models were used to analyze the association between daily steps at T2 and at T3 and self-reported and performance-based parameters. RESULTS: Data from 145 participants were analyzed. The mean number of steps was significantly higher during T2 than T1 and T3 (7323 [3047] vs. 4782 [2689], p < 0.001, Cohen's d = 0.769, and 4757 [2680], p < 0.001, Cohen's d = 0.693), whereas T1 and T3 results were similar (p = 0.92, Cohen's d = 0.008). Correlations of number of steps per day among time points were low (r ≤ 0.4). Multivariable regression models revealed an association between daily steps at T2 and pain interfering with walking, anxiety and overdoing behaviour. Daily steps at T3 were associated with overdoing behaviour and physical fitness. CONCLUSIONS: Despite chronic pain, people in rehabilitation after an orthopedic trauma increased their physical activity if they were given incentives to do so. When these incentives disappeared, most people returned to their previous activity levels. A multimodal follow-up approach could include both therapeutic and environmental incentives to help maintain physical activity in this population.

Resting-state brain activity as a biomarker of chronic pain impairment and a mediator of its association with pain resilience.

Past cross-sectional chronic pain studies have revealed aberrant resting-state brain activity in regions involved in pain processing and affect regulation. However, there is a paucity of longitudinal research examining links of resting-state activity and pain resilience with changes in chronic pain outcomes over time. In this prospective study, we assessed the status of baseline (T1) resting-state brain activity as a biomarker of later impairment from chronic pain and a mediator of the relation between pain resilience and impairment at follow-up. One hundred forty-two adults with chronic musculoskeletal pain completed a T1 assessment comprising a resting-state functional magnetic resonance imaging scan based on regional homogeneity (ReHo) and self-report measures of demographics, pain characteristics, psychological status, pain resilience, pain severity, and pain impairment. Subsequently, pain impairment was reassessed at a 6-month follow-up (T2). Hierarchical multiple regression and mediation analyses assessed relations of T1 ReHo and pain resilience scores with changes in pain impairment. Higher T1 ReHo values in the right caudate nucleus were associated with increased pain impairment at T2, after controlling for all other statistically significant self-report measures. ReHo also partially mediated associations of T1 pain resilience dimensions with T2 pain impairment. T1 right caudate nucleus ReHo emerged as a possible biomarker of later impairment from chronic musculoskeletal pain and a neural mechanism that may help to explain why pain resilience is related to lower levels of later chronic pain impairment. Findings provide empirical foundations for prospective extensions that assess the status of ReHo activity and self-reported pain resilience as markers for later impairment from chronic pain and targets for interventions to reduce impairment. PRACTITIONER POINTS: Resting-state markers of impairment: Higher baseline (T1) regional homogeneity (ReHo) values, localized in the right caudate nucleus, were associated with exacerbations in impairment from chronic musculoskeletal pain at a 6-month follow-up, independent of T1 demographics, pain experiences, and psychological factors. Mediating role of ReHo values: ReHo values in the right caudate nucleus also mediated the relationship between baseline pain resilience levels and later pain impairment among participants. Therapeutic implications: Findings provide empirical foundations for research extensions that evaluate (1) the use of resting-state activity in assessment to identify people at risk for later impairment from pain and (2) changes in resting-state activity as biomarkers for the efficacy of treatments designed to improve resilience and reduce impairment among those in need.

[THE MUSCULAR COMPONENT OF FIBROMYALGIA PATHOPHYSIOLOGY].

INTRODUCTION: Fibromyalgia syndrome (FMS) is a chronic pain syndrome, prevalent in women more than men. The main symptoms are widespread musculoskeletal pain, fatigue, and weakness. To date, the pathophysiological mechanisms are unclear, and there are several pathogenic theories elucidating this condition. In this review, we summarized articles published in the past few years, regarding the effect of musculoskeletal dysfunction on FMS. We focused on the musculoskeletal system and central nervous system (CNS) disarrays.

Association between multisite musculoskeletal pain and disability trajectories among community-dwelling older adults.

BACKGROUND: Pain is linked to disability, but how multisite musculoskeletal pain leads to disability over time is not well elaborated. OBJECTIVE: To examine the associations of multisite musculoskeletal pain with disability among a nationally representative cohort. DESIGN: We used data from the National Health and Aging Trends Study (NHATS) 2015-22. Disability was assessed by basic activities of daily living (ADL) and instrumental activities of daily living (IADL). PARTICIPANTS: A total of 5557 individuals with multisite musculoskeletal pain dwelling in the community were included in this study. METHODS: Group-based trajectory models were applied to identify distinct profiles of disability in ADL and IADL. Design-based logistic regressions were used to examine associations among multisite musculoskeletal pain, disability, and dual trajectory group memberships, adjusted for sociodemographic, health status, behavioral, and mental characteristics. RESULTS: Persons who experienced multisite musculoskeletal pain were at higher risk of disability in ADL and IADL. We identified five heterogeneous disability trajectories and named them based on baseline levels and rates of increase over time. Approximately, 52.42% of older adults with multisite musculoskeletal pain were in trajectories with ADL and IADL declines, and 33.60% experienced a rapid decline. Multisite musculoskeletal pain was associated with elevated relative risk for the adverse disability trajectories, which generally increases with multisite musculoskeletal pain frequency and number of sites. CONCLUSIONS: Persons with multisite musculoskeletal pain had a higher risk of disability. It is essential to adopt effective pain management strategies to maintain the independent living ability of older adults and to realize active aging.

Developing and assessing the measurement properties of an instrument to assess the impact of musculoskeletal pain in children aged 9 to 12-the pediatric musculoskeletal pain impact summary score.

BACKGROUND: Despite the high prevalence of musculoskeletal (MSK) pain in children, there is a lack of instruments to measure the impact of MSK pain on children's activity and participation. OBJECTIVE: To assess the reliability and construct validity of the Pediatric MSK Pain Impact summary score in school children (aged 9 to 12) with MSK pain. METHODS: We used a pragmatic approach in a reflective framework to assess internal consistency, structural validity, convergent validity, and discriminative validity in a sample of 615 children with MSK pain. RESULTS: The confirmatory factor analysis results indicate that the summary score has limited internal consistency and construct validity. The estimated Cronbach's alpha was 0.63, and most goodness of fit indices met the recommended thresholds (SRMR = 0.030; GFI = 0.993, CFI = 0.955, RMSEA 0.073), although they were close to the lower bounds of the thresholds. The convergent validity showed appropriate correlation of the summary score with quality of life (r = -0.33), care-seeking (r = 0.45), and medication intake (r = 0.37). Discriminative validity showed that the instrument can discriminate between the impact of pain on children with frequent and infrequent (2.93; 95% CI: 2.36 - 3.50) MSK pain. CONCLUSION: The Pediatric MSK Pain Impact summary showed limited internal consistency and construct validity; however, it can discriminate between children with frequent and infrequent pain. The results are promising for clinical and research practices as it is a short and convenient tool to be used in school-aged children.

Minimal Clinically Important Change of Movement Pain in Musculoskeletal Pain Conditions.

Movement pain, which is distinct from resting pain, is frequently reported by individuals with musculoskeletal pain. There is growing interest in measuring movement pain as a primary outcome in clinical trials, but no minimally clinically important change (MCIC) has been established, limiting interpretations. We analyzed data from 315 participants who participated in previous clinical trials (65 with chronic Achilles tendinopathy; 250 with fibromyalgia) to establish an MCIC for movement pain. A composite movement pain score was defined as the average pain (Numeric Rating Scale: 0-10) during 2 clinically relevant activities. The change in movement pain was calculated as the change in movement pain from pre-intervention to post-intervention. A Global Scale (GS: 1-7) was completed after the intervention on perceived change in health status. Participants were dichotomized into non-responders (GS ≥4) and responders (GS <3). Receiver operating characteristic curves were calculated to determine threshold values and corresponding sensitivity and specificity. We used the Euclidean method to determine the optimal threshold point of the Receiver operating characteristic curve to determine the MCIC. The MCIC for raw change in movement pain was 1.1 (95% confidence interval [CI]: .9-1.6) with a sensitivity of .83 (95% CI: .75-.92) and specificity of .79 (95% CI: .72-.86). For percent change in movement pain the MCIC was 27% (95% CI: 10-44%) with a sensitivity of .79 (95% CI: .70-.88) and a specificity of .82 (95% CI: .72-.90). Establishing an MCIC for movement pain will improve interpretations in clinical practice and research. PERSPECTIVE: A minimal clinically important change (MCIC) of 1.1- points (95% CI: .9-1.6) for movement pain discriminates between responders and non-responders to rehabilitation. This MCIC provides context for interpreting the meaningfulness of improvement in pain specific to movement tasks.

Through the Lens of Movement-Evoked Pain: A Theoretical Framework of the "Pain-Movement Interface" to Guide Research and Clinical Care for Musculoskeletal Pain Conditions.

Over 120 million Americans report experiencing pain in the past 3 months. Among these individuals, 50 million report chronic pain and 17 million report pain that limits daily life or work activities on most days (ie, high-impact chronic pain). Musculoskeletal pain conditions in particular are a major contributor to global disability, health care costs, and poor quality of life. Movement-evoked pain (MEP) is an important and distinct component of the musculoskeletal pain experience and represents an emerging area of study in pain and rehabilitation fields. This focus article proposes the "Pain-Movement Interface" as a theoretical framework of MEP that highlights the interface between MEP, pain interference, and activity engagement. The goal of the framework is to expand knowledge about MEP by guiding scientific inquiry into MEP-specific pathways to disability, high-risk clinical phenotypes, and underlying individual influences that may serve as treatment targets. This framework reinforces the dynamic nature of MEP within the context of activity engagement, participation in life and social roles, and the broader pain experience. Recommendations for MEP evaluation, encompassing the spectrum from high standardization to high patient specificity, and MEP-targeted treatments are provided. Overall, the proposed framework and recommendations reflect the current state of science in this emerging area of study and are intended to support future efforts to optimize musculoskeletal pain management and enhance patient outcomes. PERSPECTIVE: Movement-evoked pain (MEP) is a distinct component of the musculoskeletal pain experience and emerging research area. This article introduces the "Pain-Movement Interface" as a theoretical framework of MEP, highlighting the interface between MEP, pain interference, and activity engagement. Evaluating and treating MEP could improve rehabilitation approaches and enhance patient outcomes.

Impact of Musculoskeletal Pain on Functioning and Disability in Children with Juvenile Idiopathic Arthritis in Iceland.

AIMS: 1) to map questions of pain from a survey to the International Classification of Functioning, Disability and Health (ICF) 2) to compare the impact of musculoskeletal pain on functioning based on the different components of the ICF in children with juvenile idiopathic arthritis (JIA) and age-matched peers. METHOD: A cross-sectional case-control survey. A total of 28 children with JIA and 36 age-matched children participated. The survey included questions on the child's sex and age, about pain experienced, number of painful body areas, pain frequency and three short forms of Patient-Reported Outcome Measurement Information System (PROMIS) pain questionnaires. Sixteen children with JIA (57%) and 10 peers (28%) reported pain during past seven days. Their responses were used in the description of impact of pain. RESULTS: After the mapping of the questions to ICF, a comparison between the two groups indicated that a higher number of children with JIA described effects of pain on mental function, mobility, general tasks and demands, than their peers. More children with JIA expressed to others that they had pain, non-verbally and verbally. CONCLUSION: The findings provide important information about the impacts of pain on daily life in children with JIA and about their intervention needs.

Pressure Pain Sensitivity and Chronotype: A Population-based Study of Middle-aged Finns.

Evening chronotype individuals experience pain more often than morning chronotypes, but relationships with pain sensitivity have rarely been studied. We examined whether chronotype is associated with pressure pain sensitivity, with special reference to mental health disorders, insomnia, and chronic musculoskeletal (MSK) pain as potential moderating factors. The study sample consisted of members of the Northern Finland Birth Cohort 1966 aged 46. Pressure pain threshold and tolerance were measured via the standardized protocol, categorized as lowest quartile versus others. Chronotype (morning [M; the reference], intermediate [I], and evening [E]) was defined using the Short Morningness-Eveningness questionnaire. Sex-stratified binary logistic regression models were separately adjusted for education, body mass index, long-term diseases (fully adjusted model), and for mental health disorders, insomnia, and chronic MSK pain (a residual confounding analysis). Interaction terms (Chronotype × Mental health/insomnia/chronic MSK pain) were tested. The study had 2,132 males and 2,830 females. The E-type males had 1.5-fold odds of having a low pain threshold (fully adjusted odds ratio [OR] 1.45, 95% confidence interval 1.05-2.00) and pressure pain tolerance (fully adjusted OR 1.47, 1.07-2.02), in comparison to M-types. Having a mental health disorder intensified the association with low pain threshold fourfold (4.06, 1.56-10.6). Being an E-type female was also associated with a low pain threshold, but the association was statistically nonsignificant (fully adjusted OR 1.18, .90-1.53). No statistically significant interactions were found among females. These results emphasize the role of chronotype in pain sensitivity and add an understanding of pain experience in light of innate circadian types. PERSPECTIVE: Male evening chronotypes are more sensitive to pain than morning chronotypes. Diagnosed mental health disorders in particular indicate a low pain threshold for evening chronotype males.

Is musculoskeletal pain associated with increased muscle stiffness? Evidence map and critical appraisal of muscle measurements using shear wave elastography.

INTRODUCTION AND AIMS: Approximately 21% of the world's population suffers from musculoskeletal conditions, often associated with sensations of stiff muscles. Targeted therapy requires knowing whether typically involved muscles are objectively stiffer compared to asymptomatic individuals. Muscle stiffness is quantified using ultrasound shear wave elastography (SWE). Publications on SWE-based comparisons of muscle stiffness between individuals with and without musculoskeletal pain are increasing rapidly. This work reviewed and mapped the existing evidence regarding objectively measured muscle stiffness in musculoskeletal pain conditions and surveyed current methods of applying SWE to measure muscle stiffness. METHODS: A systematic search was conducted in PubMed and CINAHL using the keywords "muscle stiffness", "shear wave elastography", "pain", "asymptomatic controls" and synonyms. The search was supplemented by a hand search using Google Scholar. Included articles were critically appraised with the AXIS tool, supplemented by items related to SWE methods. Results were visually mapped and narratively described. RESULTS: Thirty of 137 identified articles were included. High-quality evidence was missing. The results comprise studies reporting lower stiffness in symptomatic participants, no differences between groups and higher stiffness in symptomatic individuals. Results differed between pain conditions and muscles, and also between studies that examined the same muscle(s) and pathology. The methods of the application of SWE were inconsistent and the reporting was often incomplete. CONCLUSIONS: Existing evidence regarding the objective stiffness of muscles in musculoskeletal pain conditions is conflicting. Methodological differences may explain most of the inconsistencies between findings. Methodological standards for SWE measurements of muscles are urgently required.

Reference intervals and sources of variation of pressure pain threshold for quantitative sensory testing in a Japanese population.

Quantitative sensory testing (QST) is useful when analysing musculoskeletal pain disorders. A handheld algometer is most commonly used for pressure pain threshold (PPT) tests. However, reference intervals for PPTs are not elucidated. We assessed reference intervals of PPTs for QST in 158 healthy adult Japanese with no history of musculoskeletal or neurological problems. A handheld algometer was used to record PPT at five different assessment sites on the body: lumbar paravertebral muscle, musculus gluteus maximus, quadriceps, tibialis anterior muscle, and anterior talofibular ligament. Multiple regression analysis was performed to explore sources of variation of PPT according to sex, age, body mass index, UCLA Activity Level Rating, and Tegner Activity Score. Reference intervals were determined parametrically by Gaussian transformation of PPT values using the two-parameter Box-Cox formula. Results of multiple regression analysis revealed that age was significantly associated with PPT of lumbar paravertebral muscle and musculus gluteus maximus. In females, body mass index showed significant positive correlation with PPT of anterior talofibular ligament, and UCLA Activity Level Rating also showed significant positive association with tibialis anterior muscle and anterior talofibular ligament. Site-specific reference intervals of PPTs for Japanese are of practical relevance in fields of pain research using a handheld algometer.

The Portuguese version of the musculoskeletal pain intensity and interference questionnaire for musicians (MPIIQM-Pt): Translation, cultural adaptation, and multicenter validation study in professional orchestra musicians.

OBJECTIVES: We aim to assess the validity and reliability of the Musculoskeletal Pain Intensity and Interference Questionnaire for Musicians (MPIIQM) and to add to its cross-cultural adaptation process by translating, culturally adapting, and validating the MPIIQM into European Portuguese language in the population of Portuguese musicians. METHODS: A Portuguese version of the MPIIQM (MPIIQM-Pt) was created through a process of forward and back translation, pilot testing, and cultural adaptation by expert panel evaluation. The psychometric evaluation was performed in a validation sample of 134 musicians, at baseline and after 7 days. RESULTS: The high degree of internal consistency and the substantial test-retest reliability coefficients were demonstrated for each subscale (α = 0.896 and ICC = 0.997 for "pain intensity," and α = 0.879 and ICC = 0.999 for "pain interference," respectively). Exploratory factor analysis indicated two-factor structure (pain intensity and interference) that explained 75.5% of the variance. Both convergent and divergent validity are well demonstrated, confirming more than 90% of the previously defined hypotheses regarding correlations with other measures. DISCUSSION: MPIIQM-Pt is the first validated questionnaire to evaluate pain among Portuguese musicians. It showed excellent psychometric properties, both in terms of internal consistency, test-retest reliability, factor analysis, and construct validity. Therefore, it is a valid and reliable tool suitable for both research and clinical practice purposes. MPIIQM-Pt will allow the development of more robust studies on pain among musicians and the improved assessment and monitoring of pain in this population, filling an important gap in this field of Pain Medicine.

Correlations between body postures and musculoskeletal pain in guitar players.

BACKGROUND: The guitar-playing community is the largest group at risk of developing playing related musculoskeletal disorders. A thorough investigation of the relationships between the various risk factors and players' report on musculoskeletal pain using objective and accurate means of assessment has yet to be reported. PURPOSE: (a) to explore the correlations between demographic characteristics, anthropometric measurements, playing habits, and personal habits of guitar player and their complaints of musculoskeletal pain, (b) explore the correlations between the upper body kinematics of guitar players during playing the guitar and their complaints of musculoskeletal pain, and (c) compare the upper body kinematics of guitar players during playing the guitar while sitting versus standing. METHODS: Twenty-five guitar players (27.5±4.6 years old) filled out questionnaires regarding their guitar-playing habits, and the Standardized Nordic Questionnaires for the analysis of musculoskeletal symptoms. Kinematics of their torso and upper limbs were tracked while they played a tune twice, once while sitting and once while standing. RESULTS: We found moderate correlations between the number of painful joints in the last year and factors, such as physical comfort while playing, years of playing, and position during playing. During standing, lower back pain severity correlated with the rotation range of the torso, while during sitting, it moderately correlated with the average radial-ulnar deviation of the right wrist. During sitting, we found higher anterior and right tilt of the torso, combined with greater abduction of the right shoulder, higher flexion in the left shoulder and higher radial deviation in the left wrist. CONCLUSION: Our results point to several risk factors, related both to playing habits but also to playing posture, which should be considered by the guitar players in order to prevent playing-related musculoskeletal disorders.

Associations between pain and physical activity among older adults.

OBJECTIVES: Chronic pain is a significant societal problem and pain complaints are one of the main causes of work absenteeism and emergency room visits. Physical activity has been associated with reduced risk of suffering from musculoskeletal pain complaints, but the exact relationship in an older adult sample is not known. METHODS: Participants self-reported their physical activity level and whether they were often troubled by bone, joint, or muscle pain. Logistic regression analyses revealed the nature of the relationship between musculoskeletal pain and physical activity cross-sectionally and longitudinally over the course of 10 years. Data were taken from the English Longitudinal Study of Ageing, comprising of 5802 individuals residing in England aged 50 or older. RESULTS: Only high levels of physical activity were associated with a reduced risk of suffering from musculoskeletal pain compared to a sedentary lifestyle longitudinally. In addition, having low wealth, being female, and being overweight or obese were found to be risk factors for suffering from musculoskeletal pain. CONCLUSIONS: The development of interventions aimed at alleviating and preventing musculoskeletal pain complaints might benefit from incorporating physical activity programs, weight loss, and aspects addressing wealth inequality to maximise their efficacy.

Are There Distinct Statistical Groupings of Mental Health Factors and Pathophysiology Severity Among People with Hip and Knee Osteoarthritis Presenting for Specialty Care?

BACKGROUND: There is mounting evidence that objective measures of pathophysiology do not correlate well with symptom intensity. A growing line of inquiry identifies statistical combinations (so-called "phenotypes") of various levels of distress and unhelpful thoughts that are associated with distinct levels of symptom intensity and magnitude of incapability. As a next step, it would be helpful to understand how distress and unhelpful thoughts interact with objective measures of pathologic conditions such as the radiologic severity of osteoarthritis. The ability to identify phenotypes of these factors that are associated with distinct levels of illness could contribute to improved personalized musculoskeletal care in a comprehensive, patient-centered model. QUESTIONS/PURPOSES: (1) When measures of mental health are paired with radiologic osteoarthritis severity, are there distinct phenotypes among adult patients with hip and knee osteoarthritis? (2) Is there a difference in the degree of capability and pain self-efficacy among the identified mental health and radiologic phenotypes? (3) When capability (Patient-reported Outcomes Measurement Information System Physical Function [PROMIS PF]) is paired with radiographic osteoarthritis severity, are there distinct phenotypes among patients with hip and knee osteoarthritis? (4) Is there a difference in mental health among patients with the identified capability and radiologic phenotypes? METHODS: We performed a secondary analysis of data from a study of 119 patients who presented for musculoskeletal specialty care for hip or knee osteoarthritis. Sixty-seven percent (80 of 119) of patients were women, with a mean age of 62 ± 10 years. Seventy-six percent (91 of 119) of patients had knee osteoarthritis, and 59% (70 of 119) had an advanced radiographic grade of osteoarthritis (Kellgren-Lawrence grade 3 or higher). This dataset is well-suited for our current experiment because the initial study had broad enrollment criteria, making these data applicable to a diverse population and because patients had sufficient variability in radiographic severity of osteoarthritis. All new and returning patients were screened for eligibility. We do not record the percentage of eligible patients who do not participate in cross-sectional surveys, but the rate is typically high (more than 80%). One hundred forty-eight eligible patients started the questionnaires, and 20% (29 of 148) of patients did not complete at least 60% of the questionnaires and were excluded, leaving 119 patients available for analysis. We measured psychologic distress (Patient Health Questionnaire-2 [PHQ-2] and Generalized Anxiety Disorder-2 questionnaire [GAD-2]), unhelpful thoughts about pain (Pain Catastrophizing Scale-4 [PCS-4]), self-efficacy when in pain (Pain Self-Efficacy Questionnaire-2), and capability (PROMIS PF). One of two arthroplasty fellowship-trained surgeons assigned the Kellgren-Lawrence grade of osteoarthritis based on radiographs in the original study. We used a cluster analysis to generate two sets of phenotypes: (1) measures of mental health (PHQ-2, GAD-2, PCS-4) paired with the Kellgren-Lawrence grade and (2) capability (PROMIS PF) paired with the Kellgren-Lawrence grade. We used one-way ANOVA and Kruskal-Wallis H tests to assess differences in capability and self-efficacy and mental health, respectively. RESULTS: When pairing measures of psychologic distress (PHQ-2 and GAD-2) and unhelpful thoughts (catastrophic thinking) with the grade of radiographic osteoarthritis, six distinct phenotypes arose. These groups differed in terms of capability and pain self-efficacy (for example, mild pathology/low distress versus average pathology/high distress [PROMIS PF, mean ± standard deviation]: 43 ± 6.3 versus 33 ± 4.8; p = 0.003). When pairing the degree of capability (PROMIS PF) with the Kellgren-Lawrence grade, four distinct phenotypes arose. Patients in three of these did not differ in terms of disease severity but had notable variation in the degree of limitations. Patients with these radiologic and capability phenotypes differed in terms of distress and unhelpful thoughts (for example, moderate pathology/low capability versus mild pathology/high capability [PHQ-2, median and interquartile range]: 3 [1 to 5] versus 0 [0 to 0]; p < 0.001). CONCLUSION: Statistical groupings ("phenotypes") that include both measures of pathology and mental health are associated with differences in symptom intensity and magnitude of incapability and have the potential to help musculoskeletal specialists discern mental and social health priorities. Future investigations may test whether illness phenotype-specific comprehensive biopsychosocial treatment strategies are more effective than treatment of pathology alone. LEVEL OF EVIDENCE: Level III, prognostic study.

The effect of elevated muscle pain on neuromuscular fatigue during exercise.

PURPOSE: Muscle pain can impair exercise performance but the mechanisms for this are unknown. This study examined the effects of muscle pain on neuromuscular fatigue during an endurance task. METHODS: On separate visits, twelve participants completed an isometric time-to-task failure (TTF) exercise of the right knee extensors at ~ 20% of maximum force following an intramuscular injection of isotonic saline (CTRL) or hypertonic saline (HYP) into the vastus lateralis. Measures of neuromuscular fatigue were taken before, during and after the TTF using transcranial magnetic stimulation (TMS) and peripheral nerve stimulation. RESULTS: The mean pain intensity was 57 ± 10 in HYP compared to 38 ± 18 in CTRL (P < 0.001). TTF was reduced in HYP (4.36 ± 0.88 min) compared to CTRL (5.20 ± 0.39 min) (P = 0.003). Maximum voluntary force was 12% lower at minute 1 (P = 0.003) and 11% lower at minute 2 in HYP (P = 0.013) compared to CTRL. Voluntary activation was 4% lower at minute 1 in HYP compared to CTRL (P = 0.006) but not at any other time point (all P > 0.05). The TMS silent period was 9% longer at 100 s during the TTF in HYP compared to CTRL (P = 0.026). CONCLUSION: Muscle pain reduces exercise performance through the excacerbation of neuromuscular fatigue that is central in origin. This appears to be from inhibitory feedback from group III/IV nociceptors which acts to reduce central motor output.

Radiographic Severity May Not be Associated with Pain and Function in Glenohumeral Arthritis.

BACKGROUND: Despite the routine use of plain radiographs to stratify the severity of glenohumeral osteoarthritis, little is known about the relationship between radiographic measures and patient-perceived pain and function. QUESTIONS/PURPOSES: (1) What radiographic findings are associated with worse pain and function in patients with glenohumeral osteoarthritis? (2) What demographic factors are associated with worse pain and function in patients with glenohumeral osteoarthritis? METHODS: This retrospective study included patients presenting for an initial office visit for primary glenohumeral osteoarthritis. Patients with other concurrent shoulder pathologic findings, prior surgery, lack of pain and functional scores, recent injection, or inadequate radiographs were excluded. Between January 2017 and January 2019, 3133 patients were eligible based on these inclusion criteria; 59% (1860) had outcome assessments and 48% (893) of those had radiographs. An additional 42% (378) of those with radiographs were excluded because of other shoulder findings, recent injection, prior surgery, or inadequate radiographs, leaving 16% (515 of 3133) who were fully analyzed in this study. A radiographic review included the joint space width, posterior humeral head subluxation, inferior humeral head osteophyte size, cystic change, and head asphericity. Additionally, radiographic arthritis was classified according to the Walch, Samilson-Prieto, and Kellgren-Lawrence classifications by two separate reviewers. Radiographic and demographic criteria as well as the presence of psychologic or mental illness were correlated with VAS Pain (range 1-10; minimal clinically important difference [MCID] 1.6), American Shoulder and Elbow Surgeons (ASES; range 0-100; MCID 13.6), Single Assessment Numeric Evaluation (SANE; range 0-100; MCID 14), and Simple Shoulder Test (SST; range 0-12; MCID 1.5) scores using univariate and multivariable regression analyses. RESULTS: After accounting for age, gender, and psychologic illness in the multivariable analysis, we found that patients with Samilson-Prieto Grade 4 arthrosis had lower VAS Pain scores (ß = -1.9; p = 0.02) than those with Grade 0 or 1 did; however, no clinically important associations were found between Samilson-Prieto Grade 4 and ASES (ß = 7; p = 0.25), SANE (ß = 4; p = 0.63), or SST (ß = 0.5; p = 0.62) scores. No clinically important associations were found between Kellgren-Lawrence Grade 3 and VAS Pain (ß = 1.4; p = 0.10), ASES (ß = -8; p = 0.22), SANE (ß = -13; p = 0.11), or SST scores (ß = 0.4; p = 0.66). Radiographic joint space and posterior subluxation also did not have any clinically important associations with VAS Pain or functional scores. In assessing Walch glenoid type, there was no clinically important association between glenoid type and VAS Pain (F = 3.1; p < 0.01), ASES (F = 1.9; p = 0.15), SANE (F = 0.45; p = 0.66), or SST scores (F = 0.76; p = 0.71). Men had higher SST scores than women did (ß = 2.0; p < 0.01), but there were no clinically important differences in VAS Pain (ß = -0.4; p = 0.04), ASES (ß = 6; p < 0.01), or SANE (ß = 4; p = 0.07) scores. No clinically important association was found between age or the presence of any psychologic illness and VAS Pain or functional scores. CONCLUSION: In patients with glenohumeral arthritis, no consistent clinically important differences in pain or function were discovered with respect to radiographic or demographic factors. Surgeons should understand that the pain levels of patients with glenohumeral arthritis may not parallel radiographic severity. Future studies can build on these findings by examining other non-radiographic or demographic factors that affect pain in patients with shoulder arthritis, such as psychological factors. LEVEL OF EVIDENCE: Level III, prognostic study.

The impact of e-learning during COVID-19 pandemic on students' body aches in Palestine.

Musculoskeletal pain is a major concern in our life due to its negative effects on our ability to perform daily functions. During COVID-19 pandemic, several countries switched their teaching programs into e-learning, where students spend long hour using electronic devices. The use of these devices was associated with several musculoskeletal complains among the students. The aim of this study is to evaluate the different body aches associated with e-learning on university students. The subjects of this study were students from An-Najah University in Palestine. 385 questionnaires were filled using Google forms questionnaire and all the subjects were using e-learning due to COVID-19 pandemic. Our study showed that a large percentage of participants used electronic devices for e-learning during the pandemic. The Duration of these devices use was correlated with duration and degree of pain, and associated with the difficulty in ability to perform several daily activities. Furthermore, most of the students used the sitting position with supine bent forward during the device usage. Thus, the university students that participated in this study had an increase in body aches during the e-learning process, and the aches duration and severity increases if the duration of electronic devices usage increase.

Is adiposity associated with back and lower limb pain? A systematic review.

BACKGROUND: Back and lower limb pain have a major impact on physical function and quality of life. While obesity is a modifiable risk factor for musculoskeletal pain, the role of adiposity is less clear. This systematic review aimed to examine the relationship between both adiposity and its distribution and back and lower limb pain. METHODS: A systematic search of electronic databases was conducted to identify studies that examined the association between anthropometric and/or direct measures of adiposity and site specific musculoskeletal pain. Risk of bias was assessed and a best evidence synthesis was performed. RESULTS: A total of 56 studies were identified which examined 4 pain regions, including the lower back (36 studies), hip (two studies), knee (13 studies) and foot (eight studies). 31(55%) studies were assessed as having low to moderate risk of bias. 17(30%) studies were cohort in design. The best evidence synthesis provided evidence of a relationship between central adiposity and low back and knee pain, but not hip or foot pain. There was also evidence of a longitudinal relationship between adiposity and the presence of back, knee and foot pain, as well as incident and increasing foot pain. CONCLUSIONS: This systematic review provides evidence of an association between both body fat and its central distribution and low back and knee pain, and a longitudinal relationship between adiposity and back, knee and foot pain. These results highlight the potential for targeting adiposity in the development of novel treatments at these sites.