Pascal Coorevits

Differences in electromyographic activity in the multifidus muscle and the iliocostalis lumborum between healthy subjects and patients with sub-acute and chronic low back pain

Abstract. The present study was carried out to examine possible mechanisms of back muscle dysfunction by assessing a stabilising and a torque-producing back muscle, the multifidus (MF) and the iliocostalis lumborum pars thoracis (ICLT), respectively, in order to identify whether back pain patients showed altered recruitment patterns during different types of exercise. In a group of healthy subjects (n=77) and patients with sub-acute (n=24) and chronic (51) low back pain, the normalised electromyographic (EMG) activity of the MF and the ICLT (as a percentage of maximal voluntary contraction) were analysed during coordination, stabilisation and strength exercises. The results showed that, in comparison with the healthy subjects, the chronic low back pain patients displayed significantly lower (P=0.013) EMG activity of the MF during the coordination exercises, indicating that, over the long term, back pain patients have a reduced capacity to voluntarily recruit the MF in order to obtain a neutral lordosis. In contrast, during the stabilisation exercises, no significant differences between patients and controls were found for the normalised EMG activity of the two muscles. These findings indicated that, during low-load exercises, no insufficiencies in back muscle recruitment were evident in either sub-acute or chronic back pain patients. During the strength exercises, the normalised activity of both back muscles was significantly lower in chronic low back pain patients (P=0.017 and 0.003 for the MF and ICLT, respectively) than in healthy controls. Pain, pain avoidance and deconditioning may have contributed to these lower levels of EMG activity during intensive back muscle contraction. The possible dysfunction of the MF during coordination exercises and the altered activity of both muscles during strength exercises may be of importance in symptom generation, recurrence or maintenance of low back pain.

Trunk muscle activity in healthy subjects during bridging stabilization exercises

BackgroundTrunk bridging exercises are often used as therapeutic exercises for lumbopelvic stabilization. These exercises focus on the retraining of muscle coordination patterns in which optimal ratios between local segmental stabilizing and global torque producing muscle activity are assumed to be essential. However, a description of such ratios is lacking. The purpose of this study was to investigate both relative (as a percentage of maximal voluntary isometric contraction) muscle activity levels and ratios of local to global muscle activity, during bridging stabilization exercises.MethodsThirty healthy university students (15 men, 15 women) with a mean age of 19.6 year volunteered to perform 3 bridging exercises (single bridging, ball bridge and unilateral bridging). The surface electromyographic activity of different trunk muscles was evaluated on both sides.ResultsDuring all bridging exercises, the ratio of the internal oblique to the rectus abdominis was very high due to minimal relative activity of the rectus abdominis. In general, the ratio of the internal/external abdominal oblique activity was about 1. However, during the unilateral bridging exercise, the ipsilateral internal/external abdominal oblique activity ratio was 2.79 as a consequence of the significant higher relative activity of the internal oblique compared to the external oblique. The relative muscle activity and the ratios of the back muscles demonstrated similar activity levels for all back muscles, resulting in ratios about 1.ConclusionBoth the minimal relative activity of the rectus abdominis and the high internal oblique to the rectus abdominis activity ratio reported in the present study are in accordance with results of other trunk stabilization exercises. The relative muscle activity and the ratio of the abdominal obliques seem to alter depending on the task and the presumable need for stability. The findings concerning the relative muscle activity and the ratios of the back muscles support the assumption that during these bridging exercises, all back muscles contribute in a similar way to control spine positions and movements in a healthy population.

Electronic health records: new opportunities for clinical research

Clinical research is on the threshold of a new era in which electronic health records (EHRs) are gaining an important novel supporting role. Whilst EHRs used for routine clinical care have some limitations at present, as discussed in this review, new improved systems and emerging research infrastructures are being developed to ensure that EHRs can be used for secondary purposes such as clinical research, including the design and execution of clinical trials for new medicines. EHR systems should be able to exchange information through the use of recently published international standards for their interoperability and clinically validated information structures (such as archetypes and international health terminologies), to ensure consistent and more complete recording and sharing of data for various patient groups. Such systems will counteract the obstacles of differing clinical languages and styles of documentation as well as the recognized incompleteness of routine records. Here, we discuss some of the legal and ethical concerns of clinical research data reuse and technical security measures that can enable such research while protecting privacy. In the emerging research landscape, cooperation infrastructures are being built where research projects can utilize the availability of patient data from federated EHR systems from many different sites, as well as in international multilingual settings. Amongst several initiatives described, the EHR4CR project offers a promising method for clinical research. One of the first achievements of this project was the development of a protocol feasibility prototype which is used for finding patients eligible for clinical trials from multiple sources.

Delayed Vastus Medialis Obliquus to Vastus Lateralis Onset Timing Contributes to the Development of Patellofemoral Pain in Previously Healthy Men A Prospective Study

Background Delayed onset of vastus medialis obliquus activity has been described in patellofemoral pain patients. No prospective study investigating the development of patellofemoral pain has tested the onset timing of electromyographic activity of the vastus medialis obliquus and vastus lateralis muscles during a functional task. Hypothesis Before the development of patellofemoral pain, subjects demonstrate an altered firing order of the vastus medialis obliquus and vastus lateralis muscles compared with healthy subjects during a functional task. Study Design Cohort study; Level of evidence, 2. Methods The onset of vastus medialis obliquus and vastus lateralis activity was measured with surface electromyography during a functional task (rocking back on the heels) in 79 healthy subjects subsequently submitted to a 6-week strenuous basic military training. Afterward, these subjects were reassessed. Results Thirty-two percent of the recruits developed patellofemoral pain during training. Patellofemoral pain subjects demonstrated a significant delay of onset of vastus medialis obliquus electromyographic activity compared with the healthy controls (P = .023), even before basic military training. In healthy subjects, no significant differences in electromyographic activity onset of the vastus medialis obliquus compared with the vastus lateralis could be identified before and after basic military training. A significant (P < .001) delay could be demonstrated in the patellofemoral pain group after basic military training. A binary logistic regression could be constructed wherein the onset of the electromyographic activity of the vastus medialis obliquus and vastus lateralis was withheld in the model. The most optimal cutoff value, which is based on the receiver operating characteristic curve, is a timing difference of −0.67 milliseconds (vastus medialis obliquus – vastus lateralis). The area under the receiver operating characteristic curve is considered as fair (0.68). Conclusion Delayed onset of electromyographic activity of the vastus medialis obliquus–vastus lateralis is one of the contributing risk factors to the development of patellofemoral pain.

Assessment of the validity of the Biering-Sørensen test for measuring back muscle fatigue based on EMG median frequency characteristics of back and hip muscles

The aims of the present study were (1) to investigate the differences in median frequency characteristics between back and hip muscles of healthy subjects during a Biering-Sørensen test, (2) to determine if the Biering-Sørensen test is a valid test for measuring back muscle fatigue, and (3) to standardise the Biering-Sørensen test by using objective movement analysis when defining endurance time, and compare this to the original method based on tactile feedback. Twenty healthy subjects participated in this experiment. The electromyographic activity of eight back and hip muscles was bilaterally measured. In addition three-dimensional data of the lumbar region were collected with an ultrasound movement analysis system. Median frequencies were computed from the EMG power spectra. Two methods of determining the endurance time of the Biering-Sørensen test yielded highly correlated but significantly different normalized median frequency slope values (NMF(slope)). Significant differences in NMF(slope) values between several back and hip muscles could be demonstrated. Low to moderate correlation coefficients were shown between NMF(slope) values and endurance time. Multiple stepwise linear regression analyses revealed that only NMF(slope) of the thoracic part of the iliocostalis lumborum muscle could significantly predict the test endurance time. The findings of the present study support the validity of the Biering-Sørensen test for measuring back muscle fatigue.

Using electronic health records for clinical research

OBJECTIVES To describe the IMI EHR4CR project which is designing and developing, and aims to demonstrate, a scalable, widely acceptable and efficient approach to interoperability between EHR systems and clinical research systems. METHODS The IMI EHR4CR project is combining and extending several previously isolated state-of-the-art technical components through a new approach to develop a platform for reusing EHR data to support medical research. This will be achieved through multiple but unified initiatives across different major disease areas (e.g. cardiovascular, cancer) and clinical research use cases (protocol feasibility, patient identification and recruitment, clinical trial execution and serious adverse event reporting), with various local and national stakeholders across several countries and therefore under various legal frameworks. RESULTS An initial instance of the platform has been built, providing communication, security and terminology services to the eleven participating hospitals and ten pharmaceutical companies located in seven European countries. Proof-of-concept demonstrators have been built and evaluated for the protocol feasibility and patient recruitment scenarios. The specifications of the clinical trial execution and the adverse event reporting scenarios have been documented and reviewed. CONCLUSIONS Through a combination of a consortium that brings collectively many years of experience from previous relevant EU projects and of the global conduct of clinical trials, of an approach to ethics that engages many important stakeholders across Europe to ensure acceptability, of a robust iterative design methodology for the platform services that is anchored on requirements of an underlying Service Oriented Architecture that has been designed to be scalable and adaptable, EHR4CR could be well placed to deliver a sound, useful and well accepted pan-European solution for the reuse of hospital EHR data to support clinical research studies.

Sagittal standing posture and its association with spinal pain: a school-based epidemiological study of 1196 Flemish adolescents before age at peak height velocity.

Study Design. Cross-sectional baseline data set on the sagittal standing posture of 1196 adolescents. Objective. To describe and quantify common variations in the sagittal standing alignment in boys and girls who are in the same phase of growth and to explore the association between habitual standing posture and measures for spinal pain. Summary of Background Data. Data on postural characteristics and spinal pain measures in adolescence are sparse, especially when somatic and biological maturity status is to be considered. Our understanding of the relationship between standing posture in the sagittal plane and spinal pain is also deficient. Methods. A total of 639 boys (age [mean ± SD], 12.6 ± 0.54 yr) and 557 girls (10.6 ± 0.47 yr), with predicted years from peak height velocity (PHV) being 1.2 ± 0.71 and 1.2 ± 0.59 pre-PHV, respectively, were studied. Postural examination included the assessment of global alignment and local spinopelvic characteristics, using post hoc analyses of digital images and direct body measurements (palpation, digital inclinometry, and wheeled accelerometry). Spinal pain experience was assessed by questionnaire. Results. A wide interindividual variation in sagittal posture characteristics was observed. Logistic regression analyses yielded global alignment parameters to be associated with low back pain (lifetime prevalence), neck pain (lifetime prevalence, 1-mo prevalence, and doctor visit), and thoracic spine pain (doctor visit) outcome measures. None of the included local spinopelvic parameters could be identified as an associated factor with measures of spinal pain. Conclusion. The orientation of gross body segments with respect to the gravity line seems superior to local spinopelvic features in terms of clinical importance, at least in the current pre-PHV cohort. Opportunities may exist for postural subgrouping strategies to begin with global alignment parameters in order to gain further insight into the relationship between sagittal alignment and the relative risk of developing spinal pain/seeking medical consultation for this pain.

Do pre-operative abdominal exercises prevent post-operative donor site complications for women undergoing DIEP flap breast reconstruction? A two-centre, prospective randomised controlled trial

The deep inferior epigastric perforator (DIEP) flap is the gold standard for breast reconstruction using abdominal tissue. Unlike the transverse rectus abdominis myocutaneous (TRAM) flap, no rectus abdominis muscle is removed with the flap, but intra-muscular scarring can still cause post-operative complications. Strong abdominal muscles have been advocated as a prerequisite for surgery, but without any evidence as to the potential benefits. This study aimed to investigate the effect of pre-operative abdominal exercises on inpatient pain levels, length of hospital stay, post-operative abdominal muscle strength and function following a DIEP flap.Ninety-three women undergoing delayed breast reconstruction with a DIEP flap between October 1999 and November 2000 were randomly allocated to either a control or exercise group. The exercise group performed pre-operative exercises using the Abdotrim abdominal exerciser. Pre-operatively, outcome measures included trunk muscle strength measured on an isokinetic dynamometer, SF-36, rectus muscle thickness measured using ultrasound, and submaximal fitness. Post-operative pain and length of hospital stay were recorded. Subjects were reassessed using the same outcome measures 1 year post-operatively. There was a statistically significant increase in static (isometric) muscle strength and thickness pre-operatively for the exercise group. One year following surgery, there was a significant decrease in dynamic (concentric and eccentric) flexion strength for both groups, although the clinical significance of this is questionable as the majority of women had returned to pre-operative fitness and the surgery had no impact on functional activities. The static flexion strength of the control group was reduced at 1 year, whereas it was maintained in the exercise group, although this was not statistically significant. One third of women in the control group complained of functional problems or abdominal pain post-operatively compared to one fifth of the exercise group. Overall, the DIEP flap had no major impact on abdominal muscle strength for either group, demonstrating its superiority over the TRAM flap. There was no statistically significant benefit to the exercise group of the pre-operative exercises 1 year following surgery. However, there was a subjective benefit, albeit statistically nonsignificant, in terms of reduced functional problems post-operatively and improved well-being prior to surgery.

Correlations between short-time Fourier- and continuous wavelet transforms in the analysis of localized back and hip muscle fatigue during isometric contractions

The aims of the current study were to examine the stationarities of surface electromyographic (EMG) signals obtained from eight bilateral back and hip muscles during a modified Biering-Sørensen test, and to investigate whether short-time Fourier (STFT) and continuous wavelet transforms (CWT) provided similar information with regard to EMG spectral parameters in the analysis of localized muscle fatigue. Twenty healthy subjects participated in the study after giving their informed consent. Reverse arrangement tests showed that 91.6% of the EMG signal epochs demonstrated no significant trends (all p>0.05), meaning 91.6% of the EMG signal epochs could be considered as stationary signals. Pearson correlation coefficients showed that STFT and CWT in general provide similar information with respect to the EMG spectral variables during isometric back extensions, and as a consequence STFT can still be used.

Computed tomographic analysis of the quality of trunk muscles in asymptomatic and symptomatic lumbar discectomy patients

BackgroundNo consensus exists on how rehabilitation programs for lumbar discectomy patients with persistent complaints after surgery should be composed. A better understanding of normal and abnormal postoperative trunk muscle condition might help direct the treatment goals.MethodsA three-dimensional CT scan of the lumbar spine was obtained in 18 symptomatic and 18 asymptomatic patients who had undergone a lumbar discectomy 42 months to 83 months (median 63 months) previously. The psoas muscle (PS), the paraspinal muscle mass (PA) and the multifidus muscle (MF) were outlined at the L3, L4 and L5 level. Of these muscles, fat free Cross Sectional Area (CSA) and fat CSA were determined. CSA of the lumbar erector spinae (LES = longissimus thoracis + iliocostalis lumborum) was calculated by subtracting MF CSA from PA CSA. Mean muscle CSA of the left and right sides was calculated at each level. To normalize the data for interpersonal comparison, the mean CSA was divided by the CSA of the L3 vertebral body (mCSA = normalized fat-free muscle CSA; fCSA = normalized fat CSA). Differences in CSA between the pain group and the pain free group were examined using a General Linear Model (GLM). Three levels were examined to investigate the possible role of the level of operation.ResultsIn lumbar discectomy patients with pain, the mCSA of the MF was significantly smaller than in pain-free subjects (p = 0.009) independently of the level. The mCSA of the LES was significantly smaller in pain patients, but only on the L3 slice (p = 0.018). No significant difference in mCSA of the PS was found between pain patients and pain-free patients (p = 0.462). The fCSA of the MF (p = 0.186) and of the LES (p = 0.256) were not significantly different between both populations. However, the fCSA of the PS was significantly larger in pain patients than in pain-free patients. (p = 0.012).The level of operation was never a significant factor.ConclusionsCT comparison of MF, LES and PS muscle condition between lumbar discectomy patients without pain and patients with protracted postoperative pain showed a smaller fat-free muscle CSA of the MF at all levels examined, a smaller fat- free muscle CSA of the LES at the L3 level, and more fat in the PS in patients with pain. The level of operation was not found to be of importance. The present results suggest a general lumbar muscle dysfunction in the pain group, in particular of the deep stabilizing muscle system.