No alteration of back muscle oxygenation during isometric exercise in individuals with non-specific low back pain.

The aim of our study was (I) To compare back muscle oxygenation and perfusion as well as Biering-Sorensen muscle endurance (BSME) test holding times between chronic non-specific low back pain (CNSLBP) patients and asymptomatic controls matched for age, body mass index (BMI), sex and physical activity, and (II) to investigate factors associated with BSME holding times. Muscle perfusion (tHb) and oxygenation (SmO2) were measured by near-infrared spectroscopy (NIRS) based oximetry in three back muscles during the BSME. Reliability of tHb and SmO2 was assessed in a separate sample. BSME holding time and SmO2 were compared between patients (n = 45) and controls (n = 45) and factors associated with BSME holding time were assessed using multiple linear regression. Reliability for SmO2 was excellent (ICC = 0.87-0.99). THb showed poor to moderate reliability and was not further used. Groups differed for BSME holding time (P = 0.03), pain intensity (P ≤ 0.0005) and subcutaneous tissue thickness (P = 0.01) but not for NIRS measures. Physical activity and BMI were associated with BSME holding times. Insufficient muscle oxygenation does not seem to be a major factor contributing to CNSLBP. Future investigation should evaluate other determinants of BSME holding times, such as motivation and recruitment of auxiliary muscles.

Translation and validation of the German version of the Young Spine Questionnaire.

BACKGROUND: Back pain in childhood and adolescence increases the risk for back pain in adulthood, but validated assessment tools are scarce. The aim of this study was to validate the Young Spine Questionnaire (YSQ) in a German version (G-YSQ) in children and adolescents. METHODS: Children and adolescents between 10 and 16 years (N = 240, 166 females, mean age = 13.05 ± 1.70 years), recruited in chiropractic practices and schools, completed the G-YSQ (translated according to scientific guidelines) and the KIDSCREEN-10 (assessing health-related quality of life) at three time points. Test-retest reliability was determined calculating intraclass correlation coefficients [ICC(3,1)] using start and two week-data. Construct validity was investigated testing a priori hypotheses. To assess responsiveness, the patients additionally filled in the Patient Global Impression of Change (PGIC) after three months and the area under the curve (AUC) of receiver operating curves was calculated. RESULTS: The ICC(3,1) was 0.88 for pain intensity and pain frequency, indicating good reliability, 0.68 for week prevalence and 0.60 for point prevalence, indicating moderate reliability. Pain intensity, frequency and prevalence differed between patients and controls (p < 0.001) and, except point prevalence, between older (> 12 years) and younger control participants (p < 0.01). Health-related quality of life of participants with severe pain (in one or several spinal regions) was lower (KIDSCREEN-10, total score: F(4,230) = 7.26, p < 0.001; KIDSCREEN-10, self-rated general health: H(4) = 51.94, p < 0.001) than that of participants without pain or with moderate pain in one spinal region. Thus, altogether these findings indicate construct validity of the G-YSQ. The AUC was 0.69 (95 % CI = 0.57-0.82) and 0.67 (95 % CI = 0.54-0.80) for week and point prevalence, respectively, indicating insufficient responsiveness of the G-YSQ. CONCLUSIONS: Apart from the question on point prevalence, construct validity and sufficient test-retest reliability was shown for the G-YSQ. However, its responsiveness needs to be improved, possibly by asking for pain frequency during the last week instead of (dichotomous) week prevalence. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02955342, registered 07/09/2016, https://clinicaltrials.gov/ct2/results?cond=&term=NCT02955342&cntry=CH&state=&city=Zurich&dist= .

Fear-avoidance beliefs are associated with reduced lumbar spine flexion during object lifting in pain-free adults.

ABSTRACT: There is a long-held belief that physical activities such as lifting with a flexed spine is generally harmful for the back and can cause low back pain (LBP), potentially reinforcing fear-avoidance beliefs underlying pain-related fear. In patients with chronic LBP, pain-related fear has been shown to be associated with reduced lumbar range of motion during lifting, suggesting a protective response to pain. However, despite short-term beneficial effects for tissue health, recent evidence suggests that maintaining a protective trunk movement strategy may also pose a risk for (persistent) LBP due to possible pronociceptive consequences of altered spinal motion, potentially leading to increased loading on lumbar tissues. Yet, it is unknown if similar protective movement strategies already exist in pain-free individuals, which would yield potential insights into the role of fear-avoidance beliefs in motor behavior in the absence of pain. Therefore, the aim of this study is to test whether fear-avoidance beliefs influence spinal motion during lifting in a healthy cohort of pain-free adults without a history of chronic pain. The study subjects (N = 57) filled out several pain-related fear questionnaires and were asked to perform a lifting task (5kg-box). High-resolution spinal kinematics were assessed using an optical motion capturing system. Time-sensitive analyses were performed based on statistical parametric mapping. The results demonstrated time-specific and negative relationships between self-report measures of pain-related fear and lumbar spine flexion angles during lifting, indicating potential unfavorable interactions between psychological factors and spinal motion during lifting in pain-free subjects.

A prospective observational study on trajectories and prognostic factors of mid back pain.

BACKGROUND: Although mid back pain (MBP) is a common condition that causes significant disability, it has received little attention in research and knowledge about trajectories and prognosis of MBP is limited. The purpose of this study was to identify trajectories of MBP and baseline risk factors for an unfavorable outcome in MBP patients undergoing chiropractic treatment. METHODS: This prospective-observational study analyzes outcome data of 90 adult MBP patients (mean age = 37.0 ± 14.6 years; 49 females) during one year (at baseline, after 1 week, 1 month, 3, 6 and 12 months) after start of chiropractic treatment. Patients completed an 11-point (0 to 10) numeric pain rating scale (NRS) at baseline and one week, one month, three, six and twelve months after treatment start and the Patient's Global Impression of Change (PGIC) questionnaire at all time points except baseline. To determine trajectories, clustering with the package kml (software R), a variant of k-means clustering adapted for longitudinal data, was performed using the NRS-data. The identified NRS-clusters and PGIC data after three months were tested for association with baseline variables using univariable logistic regression analyses, conditional inference trees and random forest plots. RESULTS: Two distinct NRS-clusters indicating a favourable (rapid improvement within one month from moderate pain to persistent minor pain or recovery after one year, 80% of patients) and an unfavourable trajectory (persistent moderate to severe pain, 20% of patients) were identified. Chronic (> 3 months) pain duration at baseline significantly predicted that a patient was less likely to follow a favourable trajectory [OR = 0.16, 95% CI = 0.05-0.50, p = 0.002] and to report subjective improvement after twelve months [OR = 0.19, 95% CI = 0.07-0.51, p = 0.001], which was confirmed by the conditional inference tree and the random forest analyses. CONCLUSIONS: This prospective exploratory study identified two distinct MBP trajectories, representing a favourable and an unfavourable outcome over the course of one year after chiropractic treatment. Pain chronicity was the factor that influenced outcome measures using NRS or PGIC.

An observational study on trajectories and outcomes of chronic low back pain patients referred from a spine surgery division for chiropractic treatment.

Background: A close collaboration between surgeons and non-surgical spine experts is crucial for optimal care of low back pain (LBP) patients. The affiliation of a chiropractic teaching clinic to a university hospital with a large spine division in Zurich, Switzerland, enables such collaboration. The aim of this study was to describe the trajectories and outcomes of patients with chronic LBP referred from the spine surgery division to the chiropractic teaching clinic. Methods: The patients filled in an 11-point numeric rating scale (NRS) for pain intensity and the Bournemouth Questionnaire (BQ) (bio-psycho-social measure) at baseline and after 1 week, 1, 3, 6 and 12 months. Additionally, the Patient's Global Impression of Change (PGIC) scale was recorded at all time points apart from baseline. The courses of NRS and BQ were analyzed using linear mixed model analysis and repeated measures ANOVA. The proportion of patients reporting clinically relevant overall improvement (PGIC) was calculated and the underlying factors were determined using logistic regression analyses. Results: Between June 2014 and October 2016, 67 participants (31 male, mean age = 46.8 ± 17.6 years) were recruited, of whom 46 had suffered from LBP for > 1 year, the rest for > 3 months, but < 1 year. At baseline, mean NRS was 5.43 (SD 2.37) and mean BQ was 39.80 (SD 15.16) points. NRS significantly decreased [F(5, 106.77) = 3.15, p = 0.011] to 4.05 (SD 2.88) after 12 months. A significant reduction was not observed before 6 months after treatment start (p = 0.04). BQ significantly diminished [F(5, 106.47) = 6.55, p < 0.001] to 29.00 (SD 17.96) after 12 months and showed a significant reduction within the first month (p < 0.01). The proportion of patients reporting overall improvement significantly increased from 23% after 1 week to 47% after 1 month (p = 0.004), when it stabilized [56% after 3 and 6 months, 44% after 12 months]. Reduction in bio-psycho-social impairment (BQ) was of higher importance for overall improvement than pain reduction. Conclusions: Chiropractic treatment is a valuable conservative treatment modality associated with clinically relevant improvement in approximately half of patients with chronic LBP. These findings provide an example of the importance of interdisciplinary collaboration in the treatment of chronic back pain patients.