Severe injuries of lower extremities often lead to chronic pain and reduced walking abilities. We postulated that measuring free-living gait can provide further information about walking ability in complement to clinical evaluations. We sought to validate a method that characterizes free gaits with a wearable sensor. Over one week, 81 healthy controls (HC) and 66 chronic lower limb pain patients (CLLPP) hospitalized for multidisciplinary rehabilitation wore a simple accelerometer (Actigraph). In the acceleration signals, steady 1-min walks detected numbered 7,835 (5,085 in CLLPP and 2,750 in HC). Five gait quality measures were assessed: movement intensity, cadence, stride regularity, and short-term and long-term local dynamic stability. Gait quality variables differed significantly between CLLPP and HC (4%-26%). Intraclass correlation coefficients revealed moderate to high repeatability (0.71-0.91), which suggests that seven days of measurement are sufficient to assess average gait patterns. Regression analyses showed significant association (R = 0.44) between the gait quality variables and a clinical evaluation of walking ability, i.e., the 6-min walk test. Overall, the results show that the method is easy to implement, valid (high concurrent validity), and reliable to assess walking abilities ecologically.

Background The quality of life for millions of people worldwide is affected by chronic pain. In addition to the effect of chronic pain on well-being, chronic pain has also been associated with poor health conditions and increased mortality. Due to its multifactorial origin, the classification of pain types remains challenging. MicroRNAs (miRNA) are small molecules that regulate gene expression. They are released into the bloodstream in a stable manner under normal and pathological conditions and have been described as potential biomarkers. In the present study, we aimed to investigate whether pain may induce an aberrant, specific dysregulation of miRNA expression, depending on the origin of the pain. Methods and findings To do so, we measured the expression changes of 184 circulating miRNAs (c-miRNAs) in the plasma samples of patients with different origins of chronic musculoskeletal pain. After statistical analyses, we identified seven c-miRNA candidates that were differentially expressed depending on the nociceptive or neuropathic origin of the pain. We then developed a two c-miRNA signature (hsa-miR-320a and hsa-miR-98-5p) that was able to correctly classify the pain type of 70% of the patients from the validation set. Conclusions In conclusion, circulating miRNAs are promising biomarkers to identify and characterize the chronic pain type and to further improve its clinical management.

Since the discovery of microRNAs (miRNAs), different approaches have been developed to label, amplify and quantify miRNAs. The TaqMan® technology, provided by Applied Biosystems (ABIs), uses a stem-loop reverse transcription primer system to reverse transcribe the RNA and amplify the cDNA. This method is widely used to identify global differences between the expression of 100s of miRNAs across comparative samples. This technique also allows the quantification of the expression of targeted miRNAs to validate observations determined by whole-genome screening or to analyze few specific miRNAs on a large number of samples. Here, we describe the validation of a method published by ABIs on their web site allowing to reverse transcribe and pre-amplify multiple miRNAs and snoRNAs simultaneously. The validation of this protocol was performed on human muscle and plasma samples. Fast and cost efficient, this method achieves an easy and convenient way to screen a relatively large number of miRNAs in parallel.

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Background Physical therapy and exercising are key components of biopsychosocial rehabilitation for chronic pain. Exercise helps reduce pain and improve physical functions. In addition, a high level of physical activity benefits quality of life and emotional well-being. However, the degree to which hospitalization for extensive rehabilitation effectively increases physical activity has not yet been studied. Therefore, we investigated the physical activity level and the walking behavior of inpatients with musculoskeletal pain. The objectives were 1) to compare physical activity level and walking with or without rehabilitation, 2) to evaluate whether pain site influences physical activity level, and 3) to measure the association between physical activity and pain-related interference with physical functioning. Methods During a rehabilitation stay, 272 inpatients with lower limb, spine, or upper limb pain wore an accelerometer over 1 week. We assessed the daily duration of the practice of moderate physical activity and walking. Weekend days, during which the participants went home (days off), were used as a reference for habitual activities. We also evaluated 93 patients before the hospitalization to validate the use of days off as a baseline. Pain interference was measured with the brief pain inventory questionnaire. Generalized linear mixed models analyzed the association between physical activity and walking levels, and 1) rehabilitation participation, 2) pain sites, and 3) pain interference. Results Weekend days during the stay have similar physical activity level as days measured before the stay (73 min / day at the clinic, versus 70 min / day at home). Rehabilitation days had significantly higher physical activity levels and walking durations than days off (+ 28 min [+ 37%] and + 32 min [+ 74%], respectively). Mixed models revealed 1) a negative association between physical activity and pain interference, and 2) no effect of pain sites. Overall, patients increased their physical activity level independently of reported pain interference. Conclusions Despite their painful condition, the inpatients were able to engage themselves in a higher level of physical activity via increased participation in walking activities. We conclude that walking incentives can be a valid solution to help patients with chronic pain be more physically active. Electronic supplementary material The online version of this article (10.1186/s12891-019-2561-9) contains supplementary material, which is available to authorized users.