ZMPCML041000.11.03 Bio-Back EMG full study

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ZMPCML041000.11.03 Bio-Back EMG full study

  1. 1. The effect of a novel lumbar orthosis on paraspinal muscle activity: a pilot study Charles W. Lindquist Jr. D.C. DACNB Correspondence: Frederick M. Graff, D.C. DABCO, Medical Director Medolutions, LLC Telephone: (614) 543.1743, ext 102 Email: fgraff@medolutions.com ABSTRACT Modifying the activity and improving the endurance of lumbar musculature during dynamic and static activities is a key component of treatment for low back pain. This paper presents a pilot study assessing the effect of a novel lumbar orthosis on lumbar muscle activity. Nine asymptomatic volunteers (7 males and 2 females) ranging in age from 22 to 55 years were recruited and six subjects were included in the final analysis. The electromyographic (EMG) signals of the paraspinal muscles at the L4 vertebral level were assessed while participants stood in a neutral position with or without the orthosis. When wearing the orthosis, the electrical muscle activity was reduced by 51.3% (p=.03) and 38.8% (p=.09) for longissimus and multifidus muscles, respectively. Collectively, use of the orthosis reduced the activity of the paraspinal musculature by 46.2% (p<.05). This pilot study suggests that this novel orthosis may provide external stability to the spine and relieve muscle strain by reducing the recruitment of the paraspinal muscles. Further well-controlled outcomes studies are needed to validate the effectiveness of this orthosis in a large symptomatic patient population. EMG muscle activity for longissimus and signals to measure paraspinal muscle activity at the multifidus with and without an orthosis. L4 vertebral level, pre and post utilization of a novel Error bars represent one standard deviation. Study Design: Used electromyographic (EMG) lumbar orthosis. 70 Objective: The orthosis evaluated utilizes a unique Summary of Background Data: There is limited evidence of efficiency of lumbar supports for treatment of low back pain. Results: When wearing the lumbar orthosis, the mean electrical muscle activity was reduced for the paraspinal muscles by an average of 46.2% (95% CI -5.6, 45.2). Conclusion: This pilot study provides initial data on the effectiveness of a novel lumbar orthosis at reducing paraspinal muscle activity. The decreased EMG activity may provide temporary symptomatic relief to patients suffering from low back pain. Key words: lumbar, orthosis, back pain, muscle endurance, electromyographic signal. 60 Spikes/sec and patented design and has been subjectively demonstrated to help relieve pain. Electromyography was utilized to determine the effect of this orthosis on paraspinal musculature. 50 40 longissimus 30 multifidus 20 10 0 No Othosis Orthosis Conditions
  2. 2. The effect of a novel lumbar orthosis on paraspinal muscle activity: a pilot study Charles W. Lindquist Jr. D.C. DACNB Study Design: Used electromyographic (EMG) signals to measure paraspinal muscle activity at the L4 vertebral level, pre and post utilization of a novel lumbar orthosis. Objective: The orthosis evaluated utilizes a unique and patented design and has been subjectively demonstrated to help relieve pain. Electromyography was utilized to determine the effect of this orthosis on paraspinal musculature. Summary of Background Data: There is limited evidence of efficiency of lumbar supports for treatment of low back pain. Results: When wearing the lumbar orthosis, the mean electrical muscle activity was reduced for the paraspinal muscles by an average of 46.2% (95% CI -5.6, 45.2). Conclusion: This pilot study provides initial data on the effectiveness of a novel lumbar orthosis at reducing paraspinal muscle activity. The decreased EMG activity may provide temporary symptomatic relief to patients suffering from low back pain. Key words: lumbar, orthosis, back pain, muscle endurance, electromyographic signal. BACKGROUND Low back pain is one of the most common disorders and is a leading cause of disability in the United States [1]. Non-operative management of the disease is the preferable treatment option, as surgical intervention is more economically costly, may have suboptimal long-term outcomes and may require extended periods of reduced physical activity during post-operative recovery [2]. Several non-operative treatments exist, including physical therapy, pharmacological interventions and bracing [2]. Lumbar orthoses are one of the most commonly utilized braces for recurrent low back pain. Despite the wide-spread use of over the counter and custom made lumbar orthotics, the effectiveness of these devices has been debated and the method of action of lumbar orthoses is largely unknown. Although chronic low back pain is a multifactorial disease, abnormal activity of the paraspinal musculature has been implicated as a potential source of lumbar pathologies. Increased activity of the erector spinae muscles is a typical finding among patients with low back pain [3]. Similarly, patients with a higher frequency spectrum width during electromyographic (EMG) analysis are at the highest risk for developing low back pain in the future [4]. It is suggested that this greater EMG signal and higher muscle activity arises as a result of structural or functional instability of the vertebral structures [5]. To overcome this instability, lumbo-sacral orthosis have been developed to provide external support. These lumbar braces have been theoretically and experimentally tested and the efficacy of these devices can be assessed through analysis of the EMG signal [6]. With increasing external support from the orthosis, there is a subsequent decrease in muscle activity of the paraspinal musculature [7]. Despite a large number of commercially available lumbar orthoses, few have been empirically evaluated for effectiveness using EMG analysis. Patient-reported outcomes with the use of low back braces offer important insight into the efficacy of bracing, however these reports are subjective, may be biased, and do not offer information into the mechanism of action of the pain relief. Additionally, many confounding variables may also affect the overall efficacy of lumbar orthotics. Previous investigators have found that body mass index (BMI) was negatively correlated with muscular endurance, suggesting that patients with greater BMI may have a greater response to a lumbar orthosis that decreases muscle activity and improves tolerance to static and dynamic movements [8]. Therefore, the purpose of this experimental pilot study was to evaluate the effect of a novel lumbar orthosis on paraspinal muscle activity. We hypothesized that this orthosis would reduce the muscular activity of the multifidus and longissimus during a static standing task. We also hypothesized that patients with a greater BMI would demonstrate a larger reduction in EMG activity when wearing the lumbar orthosis.
  3. 3. METHOD Participants Nine asymptomatic volunteers (7 males and 2 females) ranging in age from 22 to 55 years were recruited from Southwest Chiropractic Clinic. Written informed consent was obtained from each of the individuals prior to participating in any facet of the investigation. Of the nine volunteers, six were included in the final analysis. One volunteer was excluded because reliable EMG signal from the longissimus could not be obtained. Two volunteers were excluded due to a vasovagal reflex during the EMG. Apparatus The redesigned orthosis (Bio-Back Lumbar Orthosis, Medolutions, LLC) used in this study provided bilateral opposing forces on the lower back (lumbar) region posteriorly and the abdominal region anteriorly (Figure 1). The posterior aspect of the orthosis was 5 inches tall to provide adequate support to the lumbar region. The anterior panel was rounded to comfortably fit an individual’s abdomen. The anterior front panel contained 3 slots on each side through which the connective straps could be tightened to a comfortable fit. The posterior panel included a lumbar dome to comfortably support the lower back region. The posterior lumbar panel also contained three slots through which the posterior portion of the connective straps could be affixed to the lumbar panel. Two connective straps were used to connect the anterior and posterior panels and the length of this strap could be adjusted to accommodate differences in body sizes between each individual. The straps were available in one of two sizes: the standard straps (27” for each side) fit up to a 50” waist size, and the larger straps (40” for each side) were available for waist sizes up to 78”. Each strap included a Velcro Hook Tab and a removable Velcro Hook Pad, which allowed the strap to be inserted through the panel slots and then reconnected back to the panel. The Hook Pad was removable in the case that the straps need to be cut and modified to a shorter length. Figure 1. The Bio-Back Lumbar Orthosis (Medolutions, LLC) Front View Hook Pad is between folded Loop Strap Smooth side of attached Hook Tab Back View Participants were instructed to apply the lumbar orthosis in a comfortable standing position. First, the back panel with the Lumbar Dome was placed on their back. Then the front panel was centered over their abdomen. Participants were asked to find the tip of the loose strap and then
  4. 4. thread the end through the innermost slot of the front panel and back through the outermost slot (of the same panel) and temporarily reattach the strap to itself. Research staff examined each individual and made sure both panels were centered, and then adjusted the tension of the belt to 16 pounds. Tension was monitored through the use of Spring scales attached to the ends of the straps. Experimental procedure The muscle bellies of the longissimus and multifidus were identified by a licensed Chiropractic Neurologist and a Nihon Kohden Neuropak 2 electrodiagnostic device was used to evaluate muscle activity of these muscles. A 26 ga. Teflon coated monopolar electrode (needle) was inserted just lateral to the spinous process of L4 and oriented towards the mid-lamina area. The electrodes were placed within the longissimus and multifidus muscles through a ½ inch access hole in the orthosis that was positioned 4.5 cm lateral of midline on the right side. The depth of the longissimus needle insertion was 5 mm beyond first contact with the musculature. The needle of the multifidus muscle was made to contact the mid-lamina region and was then withdrawn approximately 3 mm. Appropriate sterilization procedures were employed during the application of the EMG electrodes. The reference electrode was 3 cm from the site and appropriate grounding was utilized. The muscular activity in these asymptomatic subjects was noted in the upright standing position. Neutral upright posture was standardized between all subjects. A plumb line fixed from the ceiling was made to pass through a line parallel with the external auditory meatus, the glenohumeral joint, slightly posterior to the hip joint, and slightly anterior to the lateral malleolus of the ankle. Muscular activity was measured in the neutral standing posture without any tension on the orthotic straps. The straps on the orthosis were then pulled to 16 pounds tension and the EMG signal was re-acquired. The frequency (spike/second) of the EMG signal was calculated for each of the trials. Only EMG waveforms (spikes) over 50 uV were counted towards the total frequency. Statistical Analysis Paired sample Wilcoxon signed rank test was used to compare the means and 95% confidence intervals (CI) of the EMG signal between the two conditions (with or without wearing an orthosis). Because of the variable nature of EMG and the preliminary nature of this study, a priori alpha level was set at p 0.10. All statistical analyses were performed using the SAS software, version 9.12 (SAS Institute Inc., Cary, NC). Because of the small sample size of this preliminary investigation, qualitative analysis was performed to determine if BMI was related to changes in EMG before and after wearing the lumbar orthosis. RESULTS Demographic information and EMG signals from the longissimus and multifidus of the six participants with and without wearing the orthosis are given in Table 1. Participants ranged in age from 25 to 55, with a mean age of 43.3 (SD=4.3). Participants included 1 female and 5 males. BMI ranged from 19.2 to 32.8, with one patient classified as normal weight (between 18.5 and 25 Kg/m2), four classified as overweight (between 25 and 29.9 Kg/m2), and one classified as obese (over 30 Kg/m2). Table 1. Demographic data and EMG signal of the electrical muscle activity for six participants. Subject ID 1 2 3 4 5 6 Gender F M M M M M Age 25 47 50 39 55 44 BMI 19.2 25.1 26.1 27.4 28.8 32.8 Longissimus (Spikes/sec) No orthosis Orthosis 27 13 75 45 62 12 82 13 48 37 39 28 Multifidus (Spikes/sec) No Orthosis Orthosis 13 10 48 23 68 36 67 41 52 23 31 26
  5. 5. Table 2. The effect of the lumbar orthosis on electrical muscle activity (Spikes/sec). No Orthosis Orthosis lumbar muscles Mean 95%CI Mean 95%CI longissimus 55.5 (33.2, 77.8) 24.7 (9.8, 39.6) multifidus 46.5 (24.1, 68.9) 26.5 (15.0, 38.0) Muscle group* 51.0 (29.6, 72.4) 25.6 (17.5, 33.6) * combine effect of both longissimus and multifidus. Difference Mean 95%CI 30.8 (7.6, 54.1) 20.0 (-1.8, 41.0) 25.4 (5.6, 45.2) P-value 0.03 0.09 <.05 Spikes/sec Table 2 and Figure 2 represent EMG activity pre and post-tightening of the lumbar orthosis. When wearing the lumbar orthosis, the mean electrical muscle activity was reduced 51.3% and 38.8% for the longissimus and multifidus, respectively (Figure 3). Mean muscle activity was 30.8 spikes/sec (95% CI 7.6, 54.1) for the Figure 2. EMG muscle activity for longissimus and multifidus longissimus and 20.0 spikes/sec with and without an orthosis. Error bars represent one (95% CI -1.8, 41.0) for the standard deviation. multifidus after tightening the straps and wearing the brace in the 70 standing position. When both of 60 the paraspinal muscles were 50 averaged, use of the orthosis 40 reduced the muscle activity by longissimus 30 46.2% to a mean of 25.4 spikes/sec multifidus 20 (95% CI -5.6, 45.2). The effect size 10 for this analysis was 1.64 which can be categorized as a moderate 0 No Othosis Orthosis effect size. Conditions Qualitative analysis of the relationship between BMI and change in EMG signal did not reveal any consistent trend. The greatest change in EMG signal for the longissimus and the multifidus occurred in patients with mid-range BMIs. There was no obvious relationship between BMI and percentage change or mean change in EMG activity. Figure 3. Mean reduction in EMG while wearing the orthosis. Error bars represent standard deviation. 60 Spikes/sec 50 40 30 30.8 20 20.0 25.4 10 0 longissimus multifidus Muscles Musle group
  6. 6. DISCUSSION This paper presents pilot work evaluating the effect of a novel lumbar orthosis on the paraspinal muscle activity during a static standing task by analyzing the EMG signal from two muscles often implicated in the pathogenesis of chronic low back pain. We hypothesized that 1) the use of the orthosis would significantly reduce the muscle activity of both the longissimus and the multifidus 2) participants with a higher BMI would have greater reductions in the muscle activity of both the longissimus and the multifidus. All six participants had an observed reduction in the muscle activity for both the longissimus and the multifidus while wearing the orthosis. Additionally, there was a clinically meaningful and significant reduction in mean muscle activity for the longissimus and multifidus. This supports our hypothesis that the orthosis would significantly reduce muscle activity of the paraspinal muscles in asymptomatic individuals. One potential explanation for the decreased muscle activity is a concomitant increase in lumbar stability provided by the lumbar orthosis. Patients with low back pain demonstrate altered muscle recruitment strategies in muscles that contribute to trunk support [5]. This pilot study suggests that this novel orthosis may provide external stability to the spine and relieve muscle strain by reducing the recruitment of the paraspinal muscles. This is in agreement with previous studies that found when patients donned a lumbar orthosis and performed a forward bending task, there was an increase in lumbar stability as measured via fluoroscopy compared to the non-braced condition [9, 10]. Although some may argue that decreased muscle activity may promote atrophy in the paraspinal muscles, a prior study found that follow-up evaluations of individuals who wore lumbar orthoses for extended periods of time did not demonstrate a decrease in isometric lumbar muscle strength. Perhaps more importantly, other studies have found decreased pain and improved functional improvements after long term use of lumbar orthosis [11-14]. When examining the effects of BMI on lumbar muscle activity, we found no obvious relationship between BMI and EMG changes. Regardless of BMI, subjects demonstrated a reduction in EMG activity. It is interesting to note that patients with mid-range BMI had a greater average and percentage reduction in EMG activity, suggesting that overweight patients may have a greater response to lumbar bracing than normal weight or obese individuals. Due to the small sample size, we were not able to stratify participants to determine which anthropometric or demographic variables influenced the response to the orthosis. Future research should be designed to evaluate the effectiveness of this orthosis in a large symptomatic population to examine the effects of BMI, age, and gender. In conclusion, this pilot study provides proof of concept and initial data on the effectiveness of a novel lumbar orthosis at reducing paraspinal muscle activity. The decreased EMG activity may provide temporary symptomatic relief to patients suffering from low back pain. Use of this device may play an important role in the comprehensive treatment plan of symptomatic patients. Appropriate, proper lifting techniques and ergonomic strategies should be re-trained while patients wear the lumbar orthosis. When using the device during retraining interventions, participants may be able to relearn proper movement strategies that were not possible previously because of lumbar pain or excessive and abnormal paraspinal activity. Future studies should be conducted using this device to validate its effectiveness and method of action in a large group of symptomatic individuals. These studies should utilize a large sample size to determine predictive factors of positive response to the orthosis, which would aid in appropriate clinical utilization of lumbar orthosis.
  7. 7. ACKNOWLEDGEMENTS: I would like to acknowledge the contribution of ScienceDocs Inc. to this article REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. Strine, T.W. and J.M. Hootman, US national prevalence and correlates of low back and neck pain among adults. Arthritis Rheum, 2007. 57(4): p. 656-65. Chou, R., et al., Interventional therapies, surgery, and interdisciplinary rehabilitation for low back pain: an evidence-based clinical practice guideline from the American Pain Society. Spine (Phila Pa 1976), 2009. 34(10): p. 1066-77. Arendt-Nielsen, L., et al., The influence of low back pain on muscle activity and coordination during gait: a clinical and experimental study. Pain, 1996. 64(2): p. 231-40. Heydari, A., et al., EMG analysis of lumbar paraspinal muscles as a predictor of the risk of low-back pain. Eur Spine J, 2010. 19(7): p. 1145-52. Hodges, P.W. and C.A. Richardson, Inefficient muscular stabilization of the lumbar spine associated with low back pain. A motor control evaluation of transversus abdominis. Spine (Phila Pa 1976), 1996. 21(22): p. 2640-50. Cholewicki, J., The effects of lumbosacral orthoses on spine stability: what changes in EMG can be expected? J Orthop Res, 2004. 22(5): p. 1150-5. Cholewicki, J., et al., Lumbosacral orthoses reduce trunk muscle activity in a postural control task. J Biomech, 2007. 40(8): p. 1731-6. Paasuke, M., et al., Back extensor muscle fatigability in chronic low back pain patients and controls: Relationship between electromyogram power spectrum changes and body mass index Journal of Back and Musculoskeletal Rehabilitation, 2002. 16(1): p. 17-24. Utter, A., et al., Video fluoroscopic analysis of the effects of three commonly-prescribed off-the-shelf orthoses on vertebral motion. Spine (Phila Pa 1976). 35(12): p. E525-9. Vander Kooi, D., et al., Lumbar spine stabilization with a thoracolumbosacral orthosis: evaluation with video fluoroscopy. Spine (Phila Pa 1976), 2004. 29(1): p. 100-4. Calmels, P., et al., Effectiveness of a lumbar belt in subacute low back pain: an open, multicentric, and randomized clinical study. Spine (Phila Pa 1976), 2009. 34(3): p. 21520. Dalichau, S. and K. Scheele, [Effects of elastic lumbar belts on the effect of a muscle training program for patients with chronic back pain]. Z Orthop Ihre Grenzgeb, 2000. 138(1): p. 8-16. Oleske, D.M., et al., Are back supports plus education more effective than education alone in promoting recovery from low back pain?: Results from a randomized clinical trial. Spine (Phila Pa 1976), 2007. 32(19): p. 2050-7. Roelofs, P.D., et al., Lumbar supports to prevent recurrent low back pain among home care workers: a randomized trial. Ann Intern Med, 2007. 147(10): p. 685-92.

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