A Clinical Measure of Trunk Neuromuscular Function Predicts Falling in Older Adults With Chronic Low Back Pain.

BACKGROUND AND PURPOSE: Older adults with low back pain (LBP) are at risk for falling, but condition-specific mechanisms are unknown. Trunk neuromuscular function is critical for maintaining balance during mobility tasks and is often impaired in older adults with LBP. The purpose of this study was to assess whether aberrant lumbopelvic movements (or aberrant movements), a clinical index of trunk neuromuscular function, were associated with increased fall risk among older adults with chronic LBP over a 12-month follow-up period. METHODS: This study analyzed data from a prospective cohort study of 250 community-dwelling older adults with chronic LBP. Participants were screened for 4 aberrant movements during 3 trials of forward flexion from a standing position: instability catch, painful arc, altered lumbopelvic rhythm, and Gower's sign. Aberrant movements were totaled to yield a summary score (ie, 0-4). Prospective falls were monitored via monthly fall calendars for 12 months. A generalized linear model with Poisson distribution and log link function was used to evaluate the association between aberrant movements and prospective fall risk. Age, sex, body mass index, LBP intensity, dynamic balance performance, prior falls, anxiolytic medication usage, and hip osteoarthritis characteristics were included as covariates in the model. RESULTS: Baseline aberrant movements were independently associated with greater fall risk (risk ratio = 1.249, 95% CI = 1.047-1.491, P = .014); each 1-unit increase in aberrant movement score imparted a 24.9% increase in the risk of falling. CONCLUSIONS: Aberrant movements increased the risk of falling among older adults with chronic LBP over a 1-year span.

Examining Psychological Factors as Contributors to Pain, Disability, and Physical Function in Geriatric Chronic Low Back Pain: A Prospective Analysis of the Delaware Spine Studies Cohort.

In younger populations, risk factors from psychologically-focused theoretical models have become accepted as primary drivers behind the persistence of low back pain (LBP), but these risk factors have not been thoroughly assessed in older adult populations (60-85 years). To address this knowledge gap, we sought to examine longitudinal associations between both general and pain-related psychological risk factors and future pain intensity, LBP-related disability, and physical function (gait speed) outcomes in older adults with chronic LBP (n = 250). Questionnaires for general (ie, depressive symptoms) and pain-related psychological risk factors (ie, fear-avoidance beliefs, pain catastrophizing, and kinesiophobia) were collected at baseline. Questionnaire values were entered into principal component analysis to yield a combined psychological component score. LBP intensity (pain thermometers), LBP-related disability (Quebec Back Pain Disability Scale), and gait speed were measured at baseline and 12-month follow-up. Multiple linear regression was used to examine adjusted associations between baseline psychological component scores and each prospective outcome. The baseline psychological component score failed to independently predict 12-month LBP-related disability and gait speed after adjustment for baseline outcomes. Though the psychological component score was associated with 12-month LBP intensity after adjusting for baseline LBP intensity, this association diminished with full adjustment for other baseline characteristics. Cumulatively, general and pain-related psychological risk factors did not independently predict longitudinal pain, disability, and physical function outcomes in this cohort. Compared to younger populations with this condition, general and pain-related psychological risk factors may have less influence on the maintenance of chronic LBP in older adults. PERSPECTIVE: This article failed to establish consistent independent relationships between psychological factors and worse longitudinal pain, disability, and physical function outcomes in older adults with chronic LBP. The findings highlight a need to determine other age-specific biopsychosocial risk factors that may impact the maintenance of chronic pain in this patient population.

Adults with lower-limb amputation: Reduced multifidi muscle activity and extensor muscle endurance is associated with worse physical performance.

Trunk muscles may be an overlooked region of deficits following lower-limb amputation (LLA). This study sought to determine the extent that trunk muscle deficits are associated with physical function following amputation. Sedentary adults with a unilateral transtibial- (n = 25) or transfemoral-level (n = 14) amputation were recruited for this cross-sectional research study. Participants underwent a clinical examination that included ultrasound imaging of the lumbar multifidi muscles, the modified Biering-Sorensen Endurance Test (mBSET), and performance-based measures, that is, the Timed Up and Go (TUG), Berg Balance Scale (BBS), and 10-m Walk Test (10mWT). Associations between trunk muscle metrics and performance were explored with regression modeling, while considering covariates known to impact performance postamputation (p ≤ 0.100). Average ultrasound-obtained, lumbar multifidi activity was 14% and 16% for transfemoral- and transtibial-level amputations, respectively, while extensor endurance was 37.34 and 12.61 s, respectively. For TUG, nonamputated-side multifidi activity and an interaction term (level x non-amputated-side multifidi activity) explained 9.4% and 6.2% of the total variance, respectively. For 10mWT, beyond covariates, non-amputated-side multifidi activity and the interaction term explained 6.1% and 5.8% of the total variance, respectively. For TUG, extensor endurance and an interaction term (level x mBSET) explained 11.9% and 8.3% of the total variance beyond covariates; for BBS and 10mWT, extensor endurance explained 11.2% and 17.2% of the total variance, respectively. Findings highlight deficits in lumbar multifidi activity and extensor muscle endurance among sedentary adults with a LLA; reduced muscle activity and endurance may be important factors to target during rehabilitation to enhance mobility-related outcomes.

Construct validity of movement-evoked pain operational definitions in older adults with chronic low back pain.

OBJECTIVE: Movement-evoked pain (MeP) may predispose the geriatric chronic low back pain (LBP) population to health decline. As there are differing operational definitions for MeP, the question remains as to whether these different definitions have similar associations with health outcomes in older adults with chronic LBP. DESIGN: Cross-sectional analysis of an observational study. SETTING: Clinical research laboratory. SUBJECTS: 226 older adults with chronic LBP. METHODS: This secondary analysis used baseline data from a prospective cohort study (n = 250). LBP intensity was collected before and after the repeated chair rise test, stair climbing test, and 6-minute walk test; MeP change scores (ie, sum of pretest pain subtracted from posttest pain) and aggregated posttest pain (ie, sum of posttest pain) variables were calculated. LBP-related disability and self-efficacy were measured by the Quebec Back Pain Disability Scale (QBPDS) and Low Back Activity Confidence Scale (LOBACS), respectively. Physical function was measured with the Health ABC Performance Battery. Robust regression with HC3 standard errors was used to evaluate adjusted associations between both MeP variables and disability, self-efficacy, and physical function. RESULTS: Greater aggregated posttest MeP was independently associated with worse disability (b = 0.593, t = 2.913, P = .004), self-efficacy (b = -0.870, t = -3.110, P = .002), and physical function (b = -0.017, t = -2.007, P = .039). MeP change scores were not associated with any outcome (all P > .050). CONCLUSIONS: Aggregate posttest MeP was linked to poorer health outcomes in older adults with chronic LBP, but MeP change scores were not. Future studies should consider that the construct validity of MeP paradigms partially depends on the chosen operational definition.

Movement-Evoked Pain Versus Widespread Pain: A Longitudinal Comparison in Older Adults With Chronic Low Back Pain From the Delaware Spine Studies.

It is currently unknown which pain-related factors contribute to long-term disability and poorer perceived health among older adults with chronic low back pain (LBP). This investigation sought to examine the unique influence of movement-evoked pain (MeP) and widespread pain (WP) on longitudinal health outcomes (ie, gait speed, perceived disability, and self-efficacy) in 250 older adults with chronic LBP. MeP was elicited with 3 standardized functional tests, while presence of WP was derived from the McGill Pain Map. Robust regression with HC3 standard errors was used to examine associations between these baseline pain variables and health outcomes at 12-month follow-up. Covariates for these models included age, sex, body mass index, resting and recall LBP intensity, LBP duration, depression, pain catastrophizing, and baseline outcome (eg, baseline gait speed). Greater MeP was independently associated with worse 12-month LBP-related disability (b = .384, t = 2.013, P = .046) and poorer self-efficacy (b = -.562, t = -2.074, P = .039); but not gait speed (P > .05). In contrast, WP and resting and recall LBP intensity were not associated with any prospective health outcome after adjustment (all P > .05). Compared to WP and resting and recall LBP intensity, MeP is most strongly related to longitudinal health outcomes in older adults with chronic LBP. PERSPECTIVE: This article establishes novel independent associations between MeP and worse perceived disability and self-efficacy at 12-months in older adults with chronic LBP. MeP likely has biopsychosocial underpinnings and consequences and may therefore be an important determinant of health outcomes in LBP and other geriatric chronic pain populations.

Body representation among adults with phantom limb pain: Results from a foot identification task.

BACKGROUND: Impaired body representation (i.e. disrupted body awareness or perception) may be a critical, but understudied, factor underlying phantom limb pain (PLP). This cross-sectional study investigated whether adults with lower-limb loss (LLL) and PLP demonstrate impaired body representation as compared to Pain-Free peers with and without LLL. METHODS: Participants (n = 41 adults with PLP, n = 27 Pain-Free peers with LLL, n = 39 Controls with intact limbs) completed an online foot identification task. Participants judged whether randomized images depicted left or right feet (i.e. left-right discrimination) as quickly as possible without limb movement. Using two Generalized Estimating Equations, effects of group, image characteristics (i.e. side, foot type, view, angle) and trial block (i.e. 1-4) were evaluated, with task response time and accuracy as dependent variables (a ≤ 0.050). RESULTS: Adults with PLP demonstrated slower and less accurate performance as compared to Controls with intact limbs (p = 0.018) but performed similarly to Pain-Free peers with LLL (p = 0.394). Significant three-way interactions of group, view and angle indicated between-group differences were greatest for dorsal-view images, but smaller and angle-dependent for plantar-view images. While all groups demonstrated significant response time improvements across blocks, improvements were greatest among adults with PLP, who also reported significant reductions in pain intensity. CONCLUSIONS: Adults with PLP demonstrate body representation impairments as compared to Controls with intact limbs. Body representation impairments, however, may not be unique to PLP, given similar performance between adults with and without PLP following LLL. SIGNIFICANCE: Following lower-limb loss, adults with phantom limb pain (PLP) demonstrate impaired body representation as compared to Controls with intact limbs, evidenced by slower response times and reduced accuracy when completing a task requiring mental rotation. Importantly, 80% of participants with pre-task PLP reported reduced pain intensity during the task, providing compelling evidence for future investigations into whether imagery-based, mind-body interventions have positive effects on PLP.

Aberrant Lumbopelvic Movements Predict Prospective Functional Decline in Older Adults with Chronic Low Back Pain.

OBJECTIVE: To investigate if clinically observable aberrant lumbopelvic movements are associated with physical function at 12-month follow-up in older adults with chronic low back pain (CLBP), both directly and indirectly through baseline physical function. DESIGN: Secondary analysis of a yearlong prospective cohort study. SETTING: Clinical Research Laboratory. PARTICIPANTS: Community-dwelling older adults with CLBP (N=250). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Data from 239 participants were analyzed. Participants were screened at baseline for aberrant lumbopelvic movements during active trunk flexion; total observable aberrant movements were recorded and summed (range 0-4). Latent constructs of physical function were developed from an array of perception-based and performance-based outcome measures at baseline and 12 months, respectively. Structural Equation Modeling was used to assess the direct effect of baseline aberrant movement score on the latent construct of 12-month physical function, and its indirect effect through baseline physical function. RESULTS: Aberrant movements were present in most participants (64.7%) and had a significant negative total effect on 12-month physical function (γ= -0.278, P<.001). Aberrant movement score's direct effect and indirect effect, through baseline functioning, were significantly negatively associated with physical function at 12-months, after adjusting for covariates (γ=-0.068, P=.038; γ= -0.210, P<.001, respectively). CONCLUSIONS: Aberrant lumbopelvic movements are associated with decreased physical function at 12-month follow-up in older adults with CLBP, independent of baseline physical function and covariates. Future studies should evaluate if screening for aberrant movements may inform prognostic and interventional efforts in this patient population.

A Standardized Assessment of Movement-evoked Pain Ratings Is Associated With Functional Outcomes in Older Adults With Chronic Low Back Pain.

OBJECTIVE: Despite high prevalence estimates, chronic low back pain (CLBP) remains poorly understood among older adults. Movement-evoked pain (MeP) is an understudied factor in this population that may importantly contribute to disability. This study investigated whether a novel MeP paradigm contributed to self-reported and performance-based function in older adults with CLBP. MATERIALS AND METHODS: This secondary analysis includes baseline data from 230 older adults with CLBP in the context of a prospective cohort study. The Repeated Chair Rise Test, Six Minute Walk Test, and Stair Climbing Test were used to elicit pain posttest LBP ratings were aggregated to yield the MeP variable. Self-reported and performance-based function were measured by the Late Life Function and Disability Index (LLFDI) scaled function score and Timed Up-and-Go Test (TUG), respectively. Robust regression with HC3 standard errors was used to model adjusted associations between MeP and both functional outcomes; age, sex, body mass index, and pain characteristics (ie, intensity, quality, and duration) were utilized as covariates. RESULTS: MeP was present in 81.3% of participants, with an average rating of 5.09 (SD=5.4). Greater aggregated posttest MeP was associated with decreased LLFDI scores (b=-0.30, t=-2.81, P=0.005) and poorer TUG performance (b=0.081, t=2.35, P=0.020), independent of covariates. LBP intensity, quality and duration were not associated with the LLFDI or TUG, (all P>0.05). DISCUSSION: Aggregated posttest MeP independently contributed to worse self-reported and performance-based function among older adults with CLBP. To understand long-term consequences of MeP, future studies should examine longitudinal associations between MeP and function in this population.

Mechanical Pain Sensitivity in Postamputation Pain.

OBJECTIVES: Postamputation, clinical markers of pain-related peripheral and central nervous system hypersensitivity remain understudied. This study aimed to identify whether adults with postamputation pain demonstrate greater pain sensitivity in primary (ie, amputated region) and secondary (ie, nonamputated region) sites, as compared with pain-free peers and controls with intact limbs. METHODS: Ninety-four participants postunilateral, transtibial amputation (59 with pain, 35 pain-free) and 39 controls underwent pain-pressure threshold (PPT) testing at 10 sites. Pain-pressure thresholds were normalized to sex-specific control data using Z score conversions. Normalized primary-site and secondary-site PPTs were compared between groups using multivariate analysis of variance (P<0.050). RESULTS: Compared with pain-free peers, adults with postamputation pain demonstrated reduced normalized PPTs across primary and secondary sites (mean difference=0.61-0.74, P=0.001 to 0.007). Compared with controls, adults with postamputation pain demonstrated reduced normalized PPTs (mean difference=0.52, P=0.026) only at primary sites. DISCUSSION: Adults with postamputation pain demonstrate greater amputated region pain sensitivity as compared with pain-free peers or controls with intact limbs, indicating peripheral sensitization persists even after limb healing. Secondary-site pain sensitivity was similar between controls and adults with postamputation pain, suggesting central nervous system hypersensitivity may not be ubiquitous with postamputation pain. Studies are needed to investigate mechanisms underlying pain sensitivity differences between adults with and without postamputation pain.

Trunk Muscle Characteristics: Differences Between Sedentary Adults With and Without Unilateral Lower Limb Amputation.

OBJECTIVE: The primary purpose of this study was to compare trunk muscle characteristics between adults with and without unilateral lower limb amputation (LLA) to determine the presence of modifiable trunk muscle deficits (ie, impaired activity, reduced volume, increased intramuscular fat) evaluated by ultrasonography (US) and magnetic resonance imaging (MRI). We hypothesized that compared with adults without LLA (controls), individuals with transfemoral or transtibial LLA would demonstrate reduced multifidi activity, worse multifidi and erector spinae morphology, and greater side-to-side trunk muscle asymmetries. DESIGN: Cross-sectional imaging study. SETTING: Research laboratory and imaging center. PARTICIPANTS: Sedentary adults (n=38 total) with LLA (n=9 transfemoral level; n=14 transtibial level) and controls without LLA (n=15). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: We examined bilateral multifidi activity using US at levels L3/L4-L5/S1. MRI was performed using 3-dimensional quantitative fat-water imaging; bilateral L1-L5 multifidi and erector spinae were manually traced, and muscle volume (normalized to body weight) and percentage intramuscular fat were determined. Between-group and side-to-side differences were evaluated. RESULTS: Compared with adults without LLA, participants with LLA demonstrated reduced sound-side multifidi activity; those with transfemoral LLA had larger amputated-side multifidi volume, whereas those with transtibial LLA had greater sound- and amputated-side erector spinae intramuscular fat (P<.050). With transfemoral LLA, side-to-side differences in erector spinae volume, as well as multifidi and erector spinae intramuscular fat, were found (P<.050). CONCLUSIONS: Impaired trunk muscle activity and increased intramuscular fat may be modifiable targets for intervention after LLA.

Hip osteoarthritis signs and symptoms are associated with increased fall risk among community-dwelling older adults with chronic low back pain: a prospective study.

BACKGROUND: Older adults with concurrent low back and hip pain are predisposed to reductions in physical performance and health-related quality of life. Yet no study to date has assessed whether or not coexisting hip impairments increase fall risk in older adults with chronic low back pain (CLBP). The objective of this study was to determine if hip osteoarthritis (OA) signs and symptoms per American College of Rheumatology (ACR) criteria are associated with fall risk over a 1-year span. METHODS: Falls were prospectively monitored for 1 year via fall calendars. Age, sex, body mass index (BMI), anxiolytic use, balance confidence, LBP-related disability, and prior fall history were identified as covariates. Hip pain, pain with hip internal rotation (IR), hip IR range of motion (ROM) ≥ 15°, and morning stiffness lasting ≤ 60 min were evaluated at baseline and summed to represent hip OA impairment burden. A generalized linear model with a Poisson distribution and log link function assessed the association between ACR criteria and fall risk beyond established covariates. As a secondary analysis, binary logistic regression assessed ACR criteria and the odds of falling two or more times within a year. RESULTS: Data from two-hundred and ten participants were analyzed. Hip OA signs and symptoms were present in 97.1% of the participants, and hip OA impairment burden was significantly greater (p < 0.050) in participants who fell ≥ 2 times compared to single and non-fallers. Higher hip OA impairment burden was associated with significantly increased fall risk (p = 0.001, risk ratio = 1.23, 95% CI 1.09-1.38) and odds of falling multiple times (p < 0.05, odds ratio = 1.41, 95% CI 1.01-1.95) after adjustment for covariates. CONCLUSIONS: Older adults with CLBP and concomitant hip impairments are an at-risk group for falling. Healthcare professionals should employ falls screening and preventive measures to avoid negative sequelae in this vulnerable population.

Vibration Sensitivity Is Associated With Functional Balance After Unilateral Transtibial Amputation.

OBJECTIVES: To evaluate differences in vibration perception thresholds between adults with transtibial amputation and age-matched adults without amputation and to examine associations between vibration perception thresholds and balance performance. We hypothesized that adults with transtibial amputation would demonstrate lower thresholds compared with adults without amputation and that lower thresholds would be associated with better functional balance. DESIGN: Prospective cross-sectional study. SETTING: National conference, clinical practice, and university laboratory. PARTICIPANTS: Adults (N=34) with a nondysvascular, unilateral, transtibial amputation and 43 age-matched controls without amputation. INTERVENTIONS: Participants' vibration perception thresholds were evaluated bilaterally by applying a vibration stimulus to the midpatella and recording their verbal response to conscious perception of stimulus. Functional balance was assessed with the Berg Balance Scale and the Four Square Step Test. MAIN OUTCOME MEASURES: Residual and sound limb (right and left for controls) vibration perception thresholds, Berg Balance Scale, and Four Square Step Test. RESULTS: For participants with transtibial amputation and controls, there were no significant between-group (P=.921) or interlimb (P=.540) differences in vibration perception thresholds. Overall, robust regression models explained 35.1% and 19.3% variance in Berg Balance Scale scores and Four Square Step Test times, respectively. Among adults with transtibial amputation, vibration perception thresholds were negatively associated with Berg Balance Scale scores (P=.009) and positively associated with Four Square Step Test times (P=.048). Among controls, average vibration perception thresholds were not significantly associated with functional balance (P>.050). CONCLUSIONS: Adults with nondysvascular, transtibial-level amputation demonstrated similar vibration detection compared with adults with intact limbs, indicating that vibration detection is preserved in the amputated region postamputation. These findings suggest a unique relationship between vibration perception and functional balance post-transtibial amputation.

Step count accuracy of StepWatch and FitBit One™ among individuals with a unilateral transtibial amputation.

BACKGROUND: Step counts, obtained via activity monitors, provide insight into activity level in the free-living environment. Accuracy assessments of activity monitors are limited among individuals with lower-limb amputations. OBJECTIVES: (1) To evaluate the step count accuracy of both monitors during forward-linear and complex walking and (2) compare monitor step counts in the free-living environment. STUDY DESIGN: Cross-sectional study. METHODS: Adult prosthetic users with a unilateral transtibial amputation were equipped with StepWatch and FitBit One™. Participants completed an in-clinic evaluation to evaluate each monitor's step count accuracy during forward linear and complex walking followed by a 7-day step count evaluation in the free-living environment. RESULTS: Both monitors showed excellent accuracy during forward, linear walking (intraclass correlation coefficients = 0.97-0.99, 95% confidence interval = 0.93-0.99; percentage error = 4.3%-6.2%). During complex walking, percentage errors were higher (13.0%-15.5%), intraclass correlation coefficients were 0.88-0.90, and 95% confidence intervals were 0.69-0.96. In the free-living environment, the absolute percentage difference between monitor counts was 25.4%, but the counts had a nearly perfect linear relationship. CONCLUSION: Both monitors accurately counted steps during forward linear walking. StepWatch appears to be more accurate than FitBit during complex walking but a larger sample size may confirm these findings. FitBit consistently counted fewer steps than StepWatch during free-living walking. Clinical relevance The StepWatch and FitBit are acceptable tools for assessing forward, linear walking for individuals with transtibial amputation. Given the results' consistenty in the free-living enviorment, both tools may ultimiately be able to be used to count steps in the real world, but more research is needed to confirm these findings.

Trunk Muscle Training Augmented With Neuromuscular Electrical Stimulation Appears to Improve Function in Older Adults With Chronic Low Back Pain: A Randomized Preliminary Trial.

OBJECTIVES: To assess the feasibility of a trial to evaluate a trunk muscle training program augmented with neuromuscular electrical stimulation (TMT+NMES) for the rehabilitation of older adults with chronic low back pain (LBP) and to preliminarily investigate whether TMT+NMES could improve physical function and pain compared with a passive control intervention. MATERIALS AND METHODS: We conducted a single-blind, randomized feasibility trial. Patients aged 60 to 85 years were allocated to TMT+NMES (n=31) or a passive control intervention (n=33), consisting of passive treatments, that is, heat, ultrasound, and massage. Outcomes assessed 3- and 6-month postrandomization included Timed Up and Go Test, gait speed, pain, and LBP-related functional limitation. RESULTS: Feasibility was established by acceptable adherence (≥80%) and attrition (<20%) rates for both interventions. Both groups had similar, clinically important reductions in pain of >2 points on a numeric pain rating scale during the course of the trial. But, only the TMT+NMES group had clinically important improvements in both performance-based and self-reported measures of function. In terms of the participants' global rating of functional improvement at 6 months, the TMT+NMES group improved by 73.9% and the passive control group improved by 56.7% compared with baseline. The between-group difference was 17.2% (95% confidence interval, 5.87-28.60) in favor of TMT+NMES. DISCUSSION: It seems that a larger randomized trial investigating the efficacy of TMT+NMES for the purpose of improving physical function in older adults with chronic LBP is warranted.