Pain and Dysfunction Reported After Gender-Affirming Surgery: A Scoping Review.

OBJECTIVE: The goal of this scoping review was to determine the types and rates of pain and dysfunction outcomes reported after gender-affirming surgical procedures. In addition, a summary of the involvement of conservative care reported in the literature was produced. METHODS: A research librarian conducted searches through multiple databases from inception to 2021. Abstracts and full texts were reviewed by a team of at least 2 reviewers. Data were extracted from a custom survey and exported for summary. RESULTS: Thirty-one papers discussed masculinizing interventions, and 87 papers discussed feminizing procedures. Most of the studies emphasized surgical outcomes. Of the studies reporting pain or dysfunction, few standardized outcomes were used to collect information from patients. The pain was experienced across body regions after surgery for both feminizing and masculinizing procedures. Vaginal stenosis and incontinence were the most common complications reported. Patients were most often managed by physical therapists for vaginal stenosis or dyspareunia. CONCLUSION: Many published studies do not systematically collect specific or standardized information about pain and dysfunction after gender-affirming surgery. Of those studies that do report these outcomes, few detail the involvement of physical therapists in the recovery after surgery. IMPACT: Pain and urogenital dysfunction, often managed by physical therapists, occur after gender-affirming surgery, suggesting that physical therapists could have a larger role in the recovery of this patient population after surgery. The extent to which interventions used to manage these conditions in cisgender people will be equally effective in transgender people is unknown at this time. Future studies should use recognized measures to characterize patients' experiences with pain and dysfunction after surgery.

Circulating Inflammatory Biomarkers Predict Pain Change Following Exercise-Induced Shoulder Injury: Findings From the Biopsychosocial Influence on Shoulder Pain Preclinical Trial.

Shoulder pain is a highly prevalent musculoskeletal condition that frequently leads to suboptimal clinical outcomes. This study tested the extent to which circulating inflammatory biomarkers are associated with reports of shoulder pain and upper-extremity disability for a high-risk genetic by psychological subgroup (catechol-O-methyltransferase [COMT] variation by pain catastrophizing [PCS]). Pain-free adults meeting high-risk COMT × PCS subgroup criteria completed an exercise-induced muscle injury protocol. Thirteen biomarkers were collected and analyzed from plasma 48 hours after muscle injury. Shoulder pain intensity and disability (Quick-DASH) were reported at 48 and 96 hours to calculate change scores. Using an extreme sampling technique, 88 participants were included in this analysis. After controlling for age, sex, and BMI, there were moderate positive associations between higher c-reactive protein (CRP; ߈ = .62; 95% confidence interval [CI] = -.03, 1.26), interleukin-6 (IL-6; ߈ = 3.13; CI = -.11, 6.38), and interleukin-10 (IL-10; ߈ = 2.51; CI = -.30, 5.32); and greater pain reduction from 48 to 96 hours post exercise muscle injury. Using an exploratory multivariable model to predict pain changes from 48 to 96 hours, we found participants with higher IL-10 were less likely to experience a high increase in pain (߈ = -10.77; CI = -21.25, -2.69). Study findings suggest CRP, IL-6, and IL-10 are related to shoulder pain change for a preclinical high-risk COMT × PCS subgroup. Future studies will translate to clinical shoulder pain and decipher the complex and seemingly pleiotropic interplay between inflammatory biomarkers and shoulder pain change. PERSPECTIVE: In a preclinical high-risk COMT × PCS subgroup, 3 circulating inflammatory biomarkers (CRP, IL-6, and IL-10) were moderately associated with pain improvement following exercise-induced muscle injury.

Characteristics and Outcomes of Patients Receiving Physical Therapy for Low Back Pain with a Nociplastic Pain Presentation: A Secondary Analysis.

Introduction: Individuals with low back pain (LBP) may be classified based on mechanistic descriptors, such as a nociplastic pain presentation (NPP). The purpose of this secondary analysis was to examine the frequency and characteristics of patients with a NPP referred to physical therapy with LBP. Additionally, we characterized patients with LBP meeting the criteria for NPP by demographic, clinical, psychological, and pain sensitivity variables. Finally, we examined short- and long-term clinical outcomes in patients with a NPP compared to those without a NPP. Materials and Methods: Patients referred to physical therapy for LBP completed the Patient Self-report Survey for the Assessment of Fibromyalgia. Participants were categorized as "LBP with NPP" or "LBP without NPP" based on the threshold established in this measure. A rank sum test examined for differences in pain-related psychological factors and pressure-pain threshold between groups. Next, a Friedman test examined if LBP intensity and disability trajectories differed by groups at one and six months after initiation of physical therapy. Results: 22.2% of patients referred to physical therapy for LBP met the criteria for a NPP. Patients with a NPP reported significantly greater disability, pain catastrophizing, depression, anxiety, and somatization compared to individuals without a NPP (p < 0.05). Pressure-pain threshold did not differ between groups (p > 0.05). Individuals with LBP with a NPP demonstrated nonsignificant, small to medium reductions in pain and disability at one and six months. Individuals experiencing LBP without a NPP demonstrated significant reductions in pain and disability in the short- and long term. Conclusion: Patients with LBP with a NPP displayed greater negative pain-related psychological factors but similar pain sensitivity compared to LBP without NPP.

Pain phenotyping and investigation of outcomes in physical therapy: An exploratory study in patients with low back pain.

Phenotypes have been proposed as a method of characterizing subgroups based on biopsychosocial factors to identify responders to analgesic treatments. This study aimed to, first, confirm phenotypes in patients with low back pain receiving physical therapy based on an a priori set of factors used to derive subgroups in other pain populations. Second, an exploratory analysis examined if phenotypes differentiated pain and disability outcomes at four weeks of physical therapy. Fifty-five participants completed psychological questionnaires and pressure pain threshold (PPT). Somatization, anxiety, and depression domains of the Symptom-Checklist-90-Revised, and PPT, were entered into a hierarchical agglomerative cluster analysis with Ward's method to identify phenotypes. Repeated measures ANOVAs assessed pain ratings and disability by phenotype at four weeks. Three clusters emerged: 1) high emotional distress and pain sensitivity (n = 10), 2) low emotional distress (n = 34), 3) low pain sensitivity (n = 11). As an exploratory study, clusters did not differentiate pain ratings or disability after four weeks of physical therapy (p's>0.05). However, trends were observed as magnitude of change for pain varied by phenotype. This supports the characterization of homogenous subgroups based on a protocol conducted in the clinical setting with varying effect sizes noted by phenotype for short-term changes in pain. As an exploratory study, future studies should aim to repeat this trial in a larger sample of patients.

Pain and Disability Following Exercise-Induced Injury in Prognostic and Intervention Studies: The Why May Be More Important Than the How.

OBJECTIVES: In preclinical prognostic studies, the description of expected outcomes during an informed consent process indicates that the extent of pain and disability experienced and recovery time is unknown. In intervention studies, the consent process suggests that pain and disability will definitely occur and a treatment provided. Our objective was to determine whether study design (prognosis or intervention) was associated with the severity of pain intensity and disability reports from a preclinical model. MATERIALS AND METHODS: We pooled pain and disability outcomes from prognostic and intervention studies using an exercise-induced muscle injury model of pain. Pain intensity, disability, and fear of pain were collected by validated self-report measures. Pain and disability data were z-transformed for pooled analyses and compared across the study design. RESULTS: Data from 310 people were included. The primary findings were that self-reported pain intensity and disability were: (1) higher in prognostic studies than in the intervention studies and (2) associated with fear of pain. A secondary finding was that fear of pain was lower in the intervention compared with the prognostic studies. DISCUSSION: Although there are other possible explanations, we speculate that these results could be related to the uncertainty inherent to providing informed consent for a prognostic study. In light of these findings, we recommend that informed consent language be more carefully considered when pain is induced in a controlled manner. Incorporating informed consent language commonly used in prognostic studies could result in higher pain intensity and disability ratings in studies that use preclinical models to test the efficacy of pain interventions.

Biopsychosocial influence on shoulder pain: results from a randomized preclinical trial of exercise-induced muscle injury.

ABSTRACT: Prior cohort studies validated that a subgroup defined by a specific COMT genotype and pain catastrophizing is at increased risk for heightened responses to exercise-induced or surgically induced shoulder pain. In this clinical trial, we used our preclinical model of exercise-induced muscle injury and pain to test the efficacy of interventions matched to characteristics of this high-risk subgroup (ie, personalized medicine approach). Potential participants provided informed consent to be screened for eligibility based on subgroup membership and then, as appropriate, were enrolled into the trial. Participants (n = 261) were randomized to 1 of 4 intervention groups comprised of pharmaceutical (propranolol or placebo) and informational (general education or psychologic intervention) combinations. After muscle injury was induced, participants received randomly assigned treatment and were followed for the primary outcome of shoulder pain intensity recovery over 4 consecutive days. Recovery rates were 56.4% (placebo and psychologic intervention), 55.4% (placebo and general education), 62.9% (propranolol and psychologic intervention), and 56.1% (propranolol and general education). No statistical differences were found between intervention groups in the primary analyses. Additional analyses found no differences between these intervention groups when shoulder pain duration was an outcome, and no differential treatment responses were detected based on sex, race, or level of pain catastrophizing. This trial indicates that these treatments were not efficacious for this high-risk subgroup when shoulder pain was induced by exercise-induced muscle injury. Accordingly, this phenotype should only be used for prognostic purposes until additional trials are completed in clinical populations.

Expectations affect pain sensitivity changes during massage.

BACKGROUND: Pain-inducing massage produces comparable changes in pain sensitivity as a cold pressor task, suggesting shared neurophysiological mechanisms of conditioned pain modulation. Manual therapy and conditioned pain modulation are influenced by positive and negative expectations. Therefore, the purpose of this study was to examine the effects of positive and negative expectations on pain-free and pain-inducing massage. METHODS: 56 healthy participants were randomly assigned to receive a positive or negative expectation instructional set followed by a pain-inducing or a pain-free massage. Pressure pain threshold (PPT) was measured followed by each interval of massage. A repeated measures ANCOVA controlling for post-randomization differences in sex tested for massage x expectation set x PPT interaction effects, as well as two-way interaction effects. RESULTS: A significant three-way interaction effect (p = 0.04) and time x expectation interaction effect was observed for individuals receiving pain inducing massage (p = 0.02). Individuals who received the positive expectation instructional set demonstrated significantly higher PPT at minutes 3 and 4 of massage compared to individuals who received the negative expectation instructional set. CONCLUSIONS: Expectations impact pain sensitivity changes produced during massage. Clinicians planning to provide pain-inducing massage should consider the role of expectations in modulating pain sensitivity changes.

Low Risk for Persistent Back Pain Disability Is Characterized by Lower Pain Sensitivity and Higher Physical Performance.

OBJECTIVE: The STarT Back Tool (SBT) predicts risk for persistent low back pain (LBP)-related disability based on psychological distress levels. Other non-psychological factors associated with LBP, such as pain sensitivity and physical performance, may further characterize SBT-risk subgroups. The purpose of this study was to determine whether a low-risk SBT subgroup demonstrated lower pain sensitivity and/or higher physical performance compared with a medium-/high-risk SBT subgroup. METHODS: In this cross-sectional, secondary analysis, adults with LBP (N = 76) completed SBT and demographics (age, sex, race, chronicity) questionnaires. Participants underwent pain sensitivity (local and remote pressure pain thresholds, temporal summation, conditioned pain modulation) and physical performance (Back Performance Scale, walking speed, obstacle negotiation, Timed "Up & Go" [TUG], TUG Cognitive) testing. Independent samples t tests determined low- versus medium-/high-risk SBT subgroup differences. A follow-up discriminant function analysis was also conducted. RESULTS: The medium-/high-risk subgroup demonstrated a lower proportion of participants with acute pain. The low-risk subgroup demonstrated lower pain sensitivity (higher local pressure pain thresholds and higher conditioned pain modulation) and higher physical performance (superior Back Performance Scale scores, faster walking speeds, faster obstacle approach and crossing speeds, and faster TUG completion). Discriminant function analysis results supported the 2-subgroup classification and indicated strong to moderate relationships with obstacle crossing speed, chronicity, and conditioned pain modulation. CONCLUSION: Lower pain sensitivity and higher physical performance characterized the low-risk SBT subgroup and may represent additional LBP prognostic factors associated with persistent disability. Longitudinal studies are needed to confirm whether these factors can enhance SBT prediction accuracy and further direct treatment priorities. IMPACT: Sensory and physical factors contribute to SBT risk classification, suggesting additional, non-psychological factors are indicative of favorable LBP outcomes. Findings highlight the need for assessment of multiple factors to improve LBP clinical prediction. LAY SUMMARY: People at low risk for back pain disability have less sensitivity to pain and better physical performance. By measuring these factors, physical therapists could guide treatment and improve outcomes for people with back pain.

Functional and Structural Neuroplastic Changes Related to Sensitization Proxies in Patients with Osteoarthritis: A Systematic Review.

OBJECTIVE: Several reports in literature have identified sensitization as a possible basis for the enhanced pain reactions associated with osteoarthritis (OA). The aim of this current systematic review is to summarize functional and structural brain changes associated with surrogate sensitization parameters assessed in patients with OA-related pain. DESIGN: Systematic review. SUBJECTS: Patients with OA related pain. METHODS: A literature search was conducted systematically in MEDLINE, CINAHL, EMBASE databases for human studies up to December 2019. Articles were included if they assessed brain imaging and sensitization parameters (quantitative sensory testing and questionnaires) in adults with OA-related pain. Methodological quality was assessed using the Methodological Index for Non-Randomized Studies (MINORS) score. RESULTS: Five studies reporting on 138 patients were included in this review. The MINORS scale yielded mean scores of 8.5/16 and 12.3/24, for the cohort and case-control studies respectively. Four low-quality studies suggest a greater pain matrix activation associated with clinical measures of sensitization in patients with OA, while another study underlined the presence of structural changes (reduced gray matter volume) in the cortical areas involved in the nociceptive processing possible also related to sensitization. CONCLUSIONS: This review shows conflicting evidence for structural and functional neuroplastic brain changes related to sensitization proxies in patients with OA.

The healthcare buffet: preferences in the clinical decision-making process for patients with musculoskeletal pain.

The preferences a person has for care are associated with outcomes for patients presenting with musculoskeletal pain conditions. These include preferences for differing levels of involvement in the decision-making process, preferences for the provider attributes, and preferences for particular interventions. In this paper, we discuss these various forms of preference, as well as how they influence clinical care within shared decision-making frameworks. We also present a conceptual framing for how patient preferences can be incorporated in clinical decision-making by orthopedic manual physical therapists. Finally, research implications for interpreting findings from clinical studies are discussed.

Physical therapists' attitudes are associated with their confidence in and the frequency with which they engage in prescription opioid medication misuse management practices with their patients. A cross-sectional study.

Background: In the US, prescription opioid medication misuse (POMM) necessitates engagement of physical therapists (PTs). We (1) evaluated the attitudes of (PT) related to their management of patients with POMM and (2) examined the association between these attitudes and PTs confidence in POMM-related management abilities and the frequency with which they engaged in POMM-related management practices. Methods: We conducted a national survey of PTs that included a modified Drug and Drug Problems Perception Questionnaire (DDPPQ). Confidence in POMM-related abilities and the frequency of engaging in POMM-related management practices were measured. Logistic regression evaluated the association between the DDPPQ subscales (role adequacy, role legitimacy, role self-esteem, role support, job satisfaction) and confidence and frequency outcomes. Results: The analysis included 402 respondents. Role adequacy and legitimacy subscales were associated with confidence and frequency outcomes (p<.05), indicating that more favorable role adequacy and legitimacy attitudes are associated with greater odds of having more confidence in POMM-related management abilities and of engaging in more frequent POMM-related management practices. Conclusions: PTs with a greater sense of preparedness to engage in POMM-related management were more likely to report greater confidence in POMM-related management abilities and engage in POMM-related management practices with greater frequency.

The association between advanced orthopedic certification and confidence and engagement in prescription opioid medication misuse management practices: a cross-sectional study.

In the United States, attaining the orthopedic certified specialist (OCS) credential or the orthopedic subspecialty credential of Fellow of the American Academy of Orthopedic Manual Physical Therapists (FAAOMPT), may lead to a higher level of orthopedic practice. It is unknown whether attaining these credentials influences physical therapist confidence in and frequency of engagement in prescription opioid medication misuse (POMM) management practices. A national cross-sectional web-based survey of PTs identified whether respondents had an OCS or FAAOMPT credential. Self-report confidence in POMM-related management practices and the frequency of engaging in these practices were assessed. Logistic regression evaluated association between credential status and confidence in, and frequency of, engagement in POMM-related management practices. The analysis included 402 respondents with a mean age of 41.0 (SD = 11.2) and 203 (50.4%) females. There were 91 (22.6%) PTs with a FAAOMPT credential, 143 (35.6%) with an OCS but with no FAAOMPT credential and 168 (41.8%) had neither credential. Compared to those with an OCS credential, FAAOMPTs reported greater confidence in, and greater frequency of engagement in, POMM-related management practices (p< .05). Compared to those without an OCS or FAAOMPT credential and compared to those with an FAAOMPT credential, those with an OCS did not report greater confidence or greater engagement in any POMM-related management practice (p≥ .05). Obtain the FAAOMPT credential may increase PTs' confidence in some POMM-related management practices. Research is needed to determine why FAAOMPTs report greater confidence and engagement in POMM-related management practices.

Outcomes of Participatory Ergonomics and Self-management in Commercial Clam Farmers with Chronic Low Back Pain: A Feasibility Study.

PURPOSE: Participatory ergonomics engages workers in the development of strategies to reduce workplace-related pain, offering a flexible and practical option to create individualized context-specific strategies. This paper describes the outcomes of a feasibility study using a participatory approach for self-management of low back pain in clam farmers. METHODS: A within-subject time-control design with repeated baseline and post-intervention assessment was used. After refining individual and team-based strategies, stakeholder interviews, and rapid prototyping, workers selected three strategies to use for 8 weeks. Frequency and ease of use for strategies are described. Pre-post paired t-tests were used for analysis of pain-related disability, difficulty and pain with work tasks, pain-related fear, self-efficacy, and coping. Analysis of improvements exceeding published and individual variability was calculated. RESULTS: Participants chose both team and individual strategies, most using strategies 5 days a week >50% of the time. Significant improvements in pain-related disability, pain during specific tasks, pain-related anxiety, and coping were seen after 8 weeks of implementing strategies. No changes in task difficulty, fear, self-efficacy and average resting pain were reported. Pain improvements > MDC95 were reported by 74% with 56-64% > personalized MDC95 for lifting tasks. CONCLUSIONS: Pain-related disability, work activity pain ratings and related pain anxiety and coping improved beyond individual variability in this feasibility study. Multiple strategies allowed workers to choose relevant self-management options. Introduction of work-related changes in the workplace, visual demonstration, review of team videos and reminders were helpful. Further studies of this approach are needed.

A psychophysical study comparing massage to conditioned pain modulation: A single blind randomized controlled trial in healthy participants.

INTRODUCTION: Pain-inducing massage results in greater pain inhibition than pain free massage, suggesting a mechanism dependent on conditioned pain modulation (CPM). The purpose of this study was to test the hypothesis that pain inducing massage produces similar magnitude of reduction in pain sensitivity as a cold pressor task and that baseline conditioned pain modulation efficiency predicts pain inducing massage related hypoalgesia. METHODS: Sixty healthy participants were randomly assigned to receive either pain inducing massage to the neck, cold pressor task to the hand, or pain free massage to the neck. Participants also underwent pre and immediate post-intervention quantitative sensory testing. A repeated measures ANCOVA determined between group differences in pain sensitivity changes. RESULTS: Pain inducing massage used as a conditioning stimulus resulted in comparable experimental pain sensitivity changes as a cold pressor task (p > 0.05). Pain intensity during the intervention demonstrated a weak correlation (r = 0.20, p = 0.12) with changes in pain sensitivity at a remote site. Individuals with an efficient CPM at baseline who received the pain inducing massage displayed greater increases in pressure pain threshold compared to individuals with a less efficient CPM indicating the potential benefit of treatment stratification by mechanism. CONCLUSION: Although pain inducing massage resulted in less self-reported pain than a cold pressor task, both resulted in similar magnitude of the CPM response, suggesting shared underlying mechanisms. Understanding mechanisms of interventions can move us closer to mechanistic based treatments for pain which is consistent with a personalized medicine approach to care.

Associations of Regional and Network Functional Connectivity With Exercise-Induced Low Back Pain.

Musculoskeletal pain is an aversive experience that exists within a variety of conditions and can result in significant impairment for individuals. Gaining greater understanding of the factors related to pain vulnerability and resilience to musculoskeletal pain may help target at-risk individuals for early intervention. This analysis builds on our previous work identifying regions where greater gray matter density was associated with lower pain following standardized, exercise induced musculoskeletal injury. Here we sought to examine the relationship between baseline resting state functional connectivity in a priori regions and networks, and delayed onset muscle soreness (DOMS) pain intensity following a single session of eccentric exercise in healthy adults. Participants completed a baseline functional MRI scan and a high intensity trunk exercise protocol in the erector spinae. Pain intensity ratings were collected 48-hours later. Resting state functional connectivity from four seed regions and 3 networks were separately regressed on pain intensity scores. Results revealed that connectivity between left middle frontal gyrus, the left occipital gyrus and cerebellar network seeds and clusters associated with discriminative, emotional, and cognitive aspects of pain were associated with lower post-DOMS pain. Results suggest resilience to clinically relevant pain is associated with aspects of regional and network neural coherence. Investigations of pain modulatory capacity that integrate multimodal neuroimaging metrics are called for. PERSPECTIVE: Our results provide key support for the role of structural and functional coherence in regional and network connectivity in adaptive pain response and represent an important step in clarifying neural mechanisms of resilience to clinically relevant pain.

Static and Dynamic Pain Sensitivity in Adults With Persistent Low Back Pain: Comparison to Healthy Controls and Associations With Movement-evoked Pain Versus Traditional Clinical Pain Measures.

OBJECTIVES: Despite its impact, individual factors associated with persistent low back pain (LBP) remain poorly understood. This study investigated static and dynamic pain sensitivity in adults with persistent LBP versus pain-free controls; and investigated associations between pain sensitivity and 3 clinical pain measures: recalled, resting, and movement-evoked pain (MEP). MATERIALS AND METHODS: A lifespan sample of 60 adults with persistent LBP and 30 age-matched/sex-matched controls completed 4 laboratory sessions. Static pain sensitivity (pressure pain threshold [PPT], heat pain threshold) and dynamic pain sensitivity (heat pain aftersensations [AS], temporal summation [TS] of second heat pain) were measured. Demographic and clinical factors collected were education, global cognition, and perceived health. Resting and recalled pain were measured via questionnaire, and MEP via the Back Performance Scale. RESULTS: LBP participants demonstrated lower PPT remotely (hand; F1,84=5.34, P=0.024) and locally (low back; F1,84=9.55, P=0.003) and also had higher AS (F1,84=6.01, P=0.016). Neither static nor dynamic pain sensitivity were associated with recalled pain (P>0.05). However, static pain sensitivity (local PPT) explained an additional 9% variance in resting pain, while dynamic pain sensitivity (AS, TS) explained an additional 10% to 12% variance in MEP. DISCUSSION: This study characterized pain sensitivity measures among individuals with persistent LBP and suggests static pain sensitivity plays a larger role in resting pain while dynamic pain sensitivity plays a larger role in MEP. Future studies will confirm these relationships and elucidate the extent to which changes in static or dynamic pain sensitivity predict or mediate clinical pain among adults with persistent LBP.

An Examination of Day-to-Day and Intraindividual Pain Variability in Low Back Pain.

OBJECTIVE: This study aimed to capture day-to-day changes in pain intensity in individuals with low back pain (LBP), which may be indicative of patients' ability to modulate their pain levels. A secondary aim was to explore the presence of latent subgroups characterized by pain level, intraindividual pain variability, and change in pain over a 14-day period. SUBJECTS: Participants were 54 adults with self-reported LBP recruited from outpatient physical therapy clinics and the community. METHODS: Over the course of 14 days, participants completed daily measures of pain intensity, catastrophizing, pain self-efficacy, and negative affect. Change in pain intensity as well as total amount of intraindividual pain variability were also calculated. RESULTS: Daily increases in maladaptive coping and affective responses (i.e., higher catastrophizing, higher negative affect, lower pain self-efficacy) were associated with increases in pain intensity. A hierarchical cluster analysis revealed three subgroups: 1) moderate pain intensity, moderate pain variability, increase in pain over time; 2) low pain intensity, low pain variability, no change in pain over time; and 3) moderate pain intensity, high pain variability, decrease in pain over time. Cluster 2 demonstrated more adaptive coping and affective responses at baseline and during the 14-day period, and clusters 1 and 3 did not differ in their coping or affective responses. CONCLUSIONS: These findings provide support that day-to-day changes in pain, coping, and affective responses are meaningful and provide additional evidence of pain variability as a potential phenotypic characteristic.

Sensory and Psychological Factors Predict Exercise-Induced Shoulder Injury Responses in a High-Risk Phenotype Cohort.

Our prior studies identified a high-risk phenotype (ie, high pain sensitivity variant of the catechol-O-methyltransferase gene (Single Nucleotide Polymorphism [SNP] rs6269) and pain catastrophizing scores) for shoulder pain. The current study identified sensory and psychological predictors of heightened pain responses following exercise-induced shoulder injury. Healthy participants (N = 131) with the SNP rs6269 catechol-O-methyltransferase gene and Pain Catastrophizing Scale scores ≥5 underwent baseline sensory and psychological testing followed by an established shoulder fatigue protocol, to induce muscle injury. Movement-evoked pain, pain intensity, disability, and strength were assessed 24 hours postinjury. Demographic, sensory, and psychological variables were included as predictors in full and parsimonious models for each outcome. The highest variance explained was for the shoulder disability outcome (full model R2 = .20, parsimonious R2 = .13). In parsimonious models, the individual predictors identified were: 1) 1st pulse heat pain sensitivity for isometric shoulder movement-evoked pain and pain intensity; 2) pressure pain threshold for shoulder disability; 3) fear of pain for active shoulder movement-evoked pain and shoulder disability; and 4) depressive symptoms for shoulder strength. Findings indicate specific pain sensitivity and psychological measures may have additional prognostic value for self-reported disability within a high-risk phenotype. These findings should be tested in a clinical cohort for validation. PERSPECTIVE: The current study extends previous work by providing insight regarding how poor shoulder outcomes may develop within a high-risk phenotype. Specifically, 1st pulse heat pain sensitivity and pressure pain threshold were sensory measures, and fear of pain and depressive symptoms were psychological measures, that improved prediction of different shoulder outcomes.

Effects of Neurodynamic Mobilizations on Pain Hypersensitivity in Patients With Hand Osteoarthritis Compared to Robotic Assisted Mobilization: A Randomized Controlled Trial.

OBJECTIVE: To evaluate the effectiveness of the neurodynamic mobilization techniques compared with passive robotic physiologic movement in patients with hand osteoarthritis (OA). METHODS: We conducted a randomized controlled trial. A total of 72 patients (mean ± SD age 71 ± 11 years) with dominant symptomatic hand OA were randomized in 2 groups, and both received 12 treatment sessions over 4 weeks. The experimental group received neurodynamic mobilization of the median, radial, and ulnar nerves, and the control group received robotic-assisted passive movement treatment. Both groups also participated in a program of hand stability exercises. Outcome measures included pain intensity, pressure pain thresholds (PPTs), and strength measurements. Group-by-time effects were compared using mixed-model analyses of variance. RESULTS: After the intervention, the experimental group had statistically significant, higher PPTs than the control group at the thumb carpometacarpal joint by 0.7 kg/cm2 (95% confidence interval [95% CI] 0.6, 0.8), the median nerve by 0.7 kg/cm2 (95% CI 0.6, 0.7), and the radial nerve by 0.5 kg/cm2 (95% CI 0.3, 0.6); however, the difference was not statistically significant at 3 months postintervention. Although mean values in the experimental group were higher than in the control group at all PPT sites at both assessments, these differences were not statistically significant. The experimental group experienced a statistically significant reduction in pain immediately postintervention, but this was not present at the 3-month follow-up. There were no statistically significant differences in pinch or grip strength between groups. CONCLUSION: We found that neurodynamic mobilizations decreased hypersensitivity in patients with hand OA immediately after the intervention; however, differences were no longer present at 3 months. The results suggest that these techniques may have some limited value in the short term but do not have lasting effects.

Empirically derived back pain subgroups differentiated walking performance, pain, and disability.

ABSTRACT: Low back pain (LBP) is a leading cause of disability. However, the processes contributing to disability are not well understood. Therefore, this study (1) empirically derived LBP subgroups and (2) validated these subgroups using walking performance, pain, and disability measures. Seventy adults with LBP underwent testing for a priori determined sensory (temporal summation; conditioned pain modulation), psychological (positive affect/coping; negative coping), and motor (trunk extensor muscle activation during forward bending and walking) measures. A hierarchical cluster analysis determined subgroups that were then validated using walking (walking speed; Timed Up and Go [TUG]; TUG-Cognitive [TUG-Cog]; obstacle negotiation) and clinical (Brief Pain Inventory; Oswestry Disability Index; low back pressure pain threshold) measures. Two subgroups were derived: (1) a "Maladaptive" subgroup (n = 21) characterized by low positive affect/coping, high negative coping, low pain modulation, and atypical trunk extensor activation and (2) an "Adaptive" subgroup (n = 49) characterized by high positive affect/coping, low negative coping, high pain modulation, and typical trunk extensor activation. There were subgroup differences on 7 of 12 validation measures. The Maladaptive subgroup had reduced walking performance (slower self-selected walking speed, TUG completion, and obstacle approach and crossing speed) and worse clinical presentation (higher pain intensity, pain interference, and disability) (moderate to large effect sizes; P's < 0.05). Findings support the construct validity of this multidimensional subgrouping approach. Longitudinal studies are needed to determine whether the Maladaptive subgroup is predictive of poor outcomes, such as pain chronicity or persistent disability.