This study compared a new transient sham TENS that delivers current for 45 seconds to an inactive sham and active TENS to determine the degree of blinding and influence on pain reduction. Pressure pain thresholds (PPT), heat pain thresholds (HPT), and pain intensities to tonic heat and pressure were measured in 69 healthy adults before and after randomization. Allocation investigators and subjects were asked to identify the treatment administered. The transient sham blinded investigators 100% of the time and 40% of subjects compared to the inactive sham that blinded investigators 0% of the time and 21% of subjects. Investigators and subjects were only blinded 7% and 13% of the time, respectively, with active TENS. Neither placebo treatment resulted in significant changes in PPT, HPT, or pain intensities. Subjects using higher active TENS amplitudes (≥17mAs) had significantly higher PPTs and lower pain intensities to tonic pressure than subjects using lower amplitudes (<17mAs). HPTs and pain intensities to tonic heat were not significantly changed. The transient TENS completely blinds investigators to treatment and does not reduce pain, thereby providing a true placebo treatment.

Gluteus medius weakness and gluteal muscle tenderness are common symptoms in people with chronic non-specific LBP. Future investigations should validate these findings with quantitative measures as well as investigate the effect of gluteus medius strengthening in people with LBP.

BackgroundOsteoarthritis of the knee is a major clinical problem affecting a greater proportion of women than men. Women generally report higher pain intensity at rest and greater perceived functional deficits than men. Women also perform worse than men on function measures such as the 6-minute walk and timed up and go tests. Differences in pain sensitivity, pain during function, psychosocial variables, and physical activity levels are unclear. Further the ability of various biopsychosocial variables to explain physical activity, function and pain is unknown.MethodsThis study examined differences in pain, pain sensitivity, function, psychosocial variables, and physical activity between women and men with knee osteoarthritis (N = 208) immediately prior to total knee arthroplasty. We assessed: (1) pain using self-report measures and a numerical rating scale at rest and during functional tasks, (2) pain sensitivity using quantitative sensory measures, (3) function with self-report measures and specific function tasks (timed walk, maximal active flexion and extension), (4) psychosocial measures (depression, anxiety, catastrophizing, and social support), and (5) physical activity using accelerometry. The ability of these mixed variables to explain physical activity, function and pain was assessed using regression analysis.ResultsOur findings showed significant differences on pain intensity, pain sensitivity, and function tasks, but not on psychosocial measures or physical activity. Women had significantly worse pain and more impaired function than men. Their levels of depression, anxiety, pain catastrophizing, social support, and physical activity, however, did not differ significantly. Factors explaining differences in (1) pain during movement (during gait speed test) were pain at rest, knee extension, state anxiety, and pressure pain threshold; (2) function (gait speed test) were sex, age, knee extension, knee flexion opioid medications, pain duration, pain catastrophizing, body mass index (BMI), and heat pain threshold; and (3) physical activity (average metabolic equivalent tasks (METS)/day) were BMI, age, Short-Form 36 (SF-36) Physical Function, Kellgren-Lawrence osteoarthritis grade, depression, and Knee Injury and Osteoarthritis Outcome Score (KOOS) pain subscale.ConclusionsWomen continue to be as physically active as men prior to total knee replacement even though they have significantly more pain, greater pain sensitivity, poorer perceived function, and more impairment on specific functional tasks.

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Multiple assessments are used clinically after total knee arthroplasty (TKA) including self-report, performance tasks, and physical activity levels. It is unclear if these different functional assessments are interchangeable or if they measure different constructs. The objective of this study was to characterize different functional measures before and after TKA. We characterized function before and after TKA using perceived function (KOOS ADL), physical performance (gait speed), and daily activity (steps/day via accelerometry); compared function in people undergoing TKA to age-matched healthy controls; and examined characteristics of those undergoing TKA for potential predictors of postoperative function. Prior to TKA, all three functional assessments were significantly lower for participants than those of healthy controls and each measure remained lower for participants than for controls postoperatively. All three functional assessments developed differently over time postoperatively. Each functional outcome had a unique set of predictors. Perceived function was predicted primarily by anxiety and depression, physical performance was most strongly predicted by age, and daily activity was chiefly predicted by BMI. Pressure pain threshold was a common predictor across all models. Functional limitations exist preoperatively and persist postoperatively across different measures in people undergoing TKA when compared to those measures in healthy controls. Functional outcomes after TKA are different depending on the functional measure utilized, implying that different constructs underlie each measure. Multiple functional measures should be assessed to provide a more comprehensive assessment of function after TKA. Further work should assess the impact of interventions designed to treat modifiable predictors of postoperative TKA function. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2790-2798, 2017.