INTRODUCTION:Changes in sensorimotor function and increased trunk muscle fatigability have been identified in patients with chronic low back pain (cLBP). This study assessed the control of trunk force production in conditions with and without local erector spinae muscle vibration and evaluated the influence of muscle fatigue on trunk sensorimotor control.METHODS:Twenty non-specific cLBP patients and 20 healthy participants were asked to perform submaximal isometric trunk extension torque with and without local vibration stimulation, before and after a trunk extensor muscle fatigue protocol. Constant error (CE), variable error (VE) as well as absolute error (AE) in peak torque were computed and compared across conditions. Trunk extensor muscle activation during isometric contractions and during the fatigue protocol was measured using surface electromyography (sEMG).RESULTS:Force reproduction accuracy of the trunk was significantly lower in the patient group (CE = 9.81 ± 2.23 Nm; AE = 18.16 ± 3.97 Nm) than in healthy participants (CE = 4.44 ± 1.68 Nm; AE = 12.23 ± 2.44 Nm). Local erector spinae vibration induced a significant reduction in CE (4.33 ± 2.14 Nm) and AE (13.71 ± 3.45 Nm) mean scores in the patient group. Healthy participants conversely showed a significant increase in CE (8.17 ± 2.10 Nm) and AE (16.29 ± 2.82 Nm) mean scores under vibration conditions. The fatigue protocol induced erector spinae muscle fatigue as illustrated by a significant decrease in sEMG median time-frequency slopes. Following the fatigue protocol, patients with cLBP showed significant decrease in sEMG root mean square activity at L4-5 level and responded in similar manner with and without vibration stimulation in regard to CE mean scores.CONCLUSIONS:Patients with cLBP have a less accurate force reproduction sense than healthy participants. Local muscle vibration led to significant trunk neuromuscular control improvements in the cLBP patients before and after a muscle fatigue protocol. Muscle vibration stimulation during motor control exercises is likely to influence motor adaptation and could be considered in the treatment of cLBP. Further work is needed to clearly identify at what levels of the sensorimotor system these gains are achievable.

Objective: The aims of this study were to determine whether the application of vibration on a postural lower limb muscle altered the sensorimotor control of its joint as measured by isometric force production parameters and to compare present findings with previous work conducted on trunk muscle.Methods: Twenty healthy adults were asked to reproduce submaximal isometric plantar flexion under 3 different conditions: no vibration and vibration frequencies of 30 and 80 Hz on the soleus muscle. Time to peak torque, variable error, as well as constant error and absolute error in peak torque were calculated and compared across conditions.Results: Under vibration, participants were significantly less accurate in the force reproduction task, as they mainly undershot the target torque. Applying an 80-Hz vibration resulted in a significantly higher negative constant error than lower-frequency vibration (30 Hz) or no-vibration condition. Decreases in isometric force production accuracy under vibration influence were also observed in a previous study conducted on trunk muscle. However, no difference in constant error was found between 30- and 80-Hz vibration conditions.Conclusion: The results suggest that acute soleus muscle vibration interferes with plantar flexion torque generation by distorting proprioceptive information, leading to decreases in accuracy of a force reproduction task. Similar results in an isometric trunk extension force reproduction task were found with vibration applied on erector spinae muscle. However, high-frequency vibration applied on soleus muscle elicited higher force reproduction errors than low-frequency stimulation.

Background: Vibration is known to alter proprioceptive afferents and create a tonic vibration reflex. The control of force and its variability are often considered determinants of motor performance and neuromuscular control. However, the effect of vibration on paraspinal muscle control and force production remains to be determined.Methods: Twenty-one healthy adults were asked to perform isometric trunk flexion and extension torque at 60% of their maximal voluntary isometric contraction, under three different vibration conditions: no vibration, vibration frequencies of 30 Hz and 80 Hz. Eighteen isometric contractions were performed under each condition without any feedback. Mechanical vibrations were applied bilaterally over the lumbar erector spinae muscles while participants were in neutral standing position. Time to peak torque (TPT), variable error (VE) as well as constant error (CE) and absolute error (AE) in peak torque were calculated and compared between conditions.Results: The main finding suggests that erector spinae muscle vibration significantly decreases the accuracy in a trunk extension isometric force reproduction task. There was no difference between both vibration frequencies with regard to force production parameters. Antagonist muscles do not seem to be directly affected by vibration stimulation when performing a trunk isometric task.Conclusions: The results suggest that acute erector spinae muscle vibration interferes with torque generation sequence of the trunk by distorting proprioceptive information in healthy participants.

OBJECTIVES:To investigate changes in muscular activity and strength of subjects diagnosed with lateral epicondylitis (LE). To assess the appropriateness of these measures in the patient's follow-up.METHODS:Twenty-four subjects (11 men and 13 women) with LE, were evaluated at baseline and after 5 weeks of an experimental treatment. Measurements included: the (1) pain-free grip (PFG), (2) maximal isometric strength, (3) surface electromyography (EMG) of forearm muscle (healthy and affected), (4) a visual analogue scale (VAS), and (5) the Patient Rated Tennis Elbow Evaluation (PRTEE) (Canadian-French version).RESULTS:All subjects showed improvement in VAS and PRTEE. The maximal isometric strength during flexion and extension of the wrist and the EMG analysis failed to discriminate the affected from the healthy elbow during the initial assessment. Only the PFG measured with the elbow in extension could discriminate elbows with LE from the healthy ones.CONCLUSIONS:The use of the PFG with the elbow in extension seems to be the most indicated strength measurement to monitor the recovery of patients with LE. The EMG acquisition protocol used in this research was not adequate to monitor effectively the recovery of LE.

OBJECTIVE:The purpose of this study was to evaluate the effect of augmented soft tissue mobilization (ASTM) on the treatment of lateral epicondylitis.METHODS:This randomized clinical study assessed 27 subjects (12 men and 15 women) with lateral epicondylitis and were divided randomly into 2 groups. The experimental group (n = 15) received ASTM twice a week for 5 weeks. The subjects of the control group (n = 12) received advice on the natural evolution of lateral epicondylitis, computer ergonomics, and stretching exercises. Patient-rated outcome was assessed at baseline and after 6 weeks and 3 months using a visual analog scale and the Patient-Rated Tennis Elbow Evaluation. The function was assessed using the pain-free grip strength at baseline and after 6 weeks.RESULTS:Both groups showed improvements in pain-free grip strength, visual analog scale, and Patient-Rated Tennis Elbow Evaluation. Sample size for larger future randomized clinical trial was 116 participants.CONCLUSION:A larger study investigating the same hypothesis is warranted to detect difference in the effects of these treatments strategies. The study design is feasible, and minor improvements will help to minimize the potential bias.

Introduction: No questionnaire is available to evaluate disability levels in French-speaking patients suffering from tennis elbow.Purpose of the Study: To perform a cross-cultural adaptation of the English version of the Patient-rated Tennis Elbow Evaluation (PRTEE) into Canadian French.Methods: The PRTEE was cross-culturally adapted to Canadian French according to well-established guidelines. Thirty-two patients with tennis elbow completed the prefinal version of the PRTEE. The construct validity, longitudinal validity, and responsiveness were assessed through comparisons with the Visual Analog Scale (VAS) measuring pain and the pain-free grip (PFG) at baseline, six weeks and three months. The internal consistency was assessed by Cronbach's alpha and the item-total correlations.Results: The adaptation process resolved the discrepancy between the forward and back translation. The scores of PRTEE were adequately distributed without floor or ceiling effect. Item completion was good. The correlation between the PRTEE and the VAS was moderate to high (r = 0.64-0.77) and statistically significant. There was also a low but significant correlation between the PRTEE and PFG (r = -0.38 to -0.48). For the longitudinal construct validity, the correlation with the VAS was moderate to high and statistically significant (r = 0.68 and 0.88, p <0.01). The effect size (0.8; 1.0) and the standardized response mean (0.9; 1.0) were high and at least as good as the other outcomes. Internal consistency of the total score was high (Cronbach alpha = 0.93) and item-total correlations were substantial for all items (0.58-0.85).Conclusions: This study supports linguistic and conceptual equivalence of our Canadian French version. Because this version of the PRTEE demonstrated good acceptability, construct validity, internal consistency, and responsiveness, it may be used in both research and clinical setting.Level of Evidence: N/A. J HAND THER. 2010;23:290-300.

Objective This study examines whether there is a relationship between clinical correlates of osteoarthritic changes of the cervical spine and changes in postural stability. Methods This was a control group study with repeated measures. Twenty-three patients were recruited from the chiropractic University Clinic to participate in this study. The presence and severity of osteoarthritic changes of the cervical spine were determined radiologically. Balance control was evaluated by testing subjects' postural stability on a force platform with and without vision. A general clinical assessment of the neuromusculoskeletal system was performed to screen for any physical condition that could affect postural stability. Participants' characteristics were compared between each group using a 1-way analysis of variance for independent samples, and postural stability variables were submitted to a 2-way repeated measures analysis of variance. Results Subjects with signs of osteoarthritis of the cervical spine showed an increased range of sway, a faster sway speed, and a greater excursion than control subjects. They also showed a larger degree of lower limb neuropathy than control subjects. Conclusion The postural instability shown by the osteoarthritic group may be due to the effects of the lower limb peripheral neuropathy alone or due to a combination of both cervical degenerative changes and peripheral changes. Further research is needed to clearly isolate the effects of the degeneration of the cervical spine on postural control.

Purpose: The aim of this study was to determine the accuracy in measuring the pelvic orientations of a phantom model using the PosturePrint method.Methods: In the Universite du Quebec A Trois-Rivieres biomechanics laboratory, Trois-Rivieres, Quebec, Canada, a mannequin was fixed on a rotating platform. For a set of 3 photographs (left lateral, anterior to posterior, right lateral) of each position, the mannequin pelvis was placed in 68 different postures on a stand, 61 ern from a wall, in front of a digital camera. The camera was at 83.8 cm in height and at 3.35 m from a calibrated wall grid. Mannequin postures were in 5 degrees of freedom: lateral translation (Tx), lateral flexion (Rz), axial rotation (Ry), flexion-extension (Rx), and anterior-posterior translation (Tz). Average errors were the differences of the positioned postures to the PosturePrint computed values.Results: Mean and SD of computational errors for rotation displacements were Rx = 0.5 degrees +/- 0.8 degrees, Ry 1.3 degrees +/- 0.8 degrees, and Rz = 0.5 degrees +/- 0.3 degrees, and for translation, Tz 1.2 +/- 0.6 mm and Tx = 0.9 +/- 0.5 mm.Conclusions: The PosturePrint system allowed for accurate postural measurement of rotations and translations of a mannequin pelvis. The next step in evaluation of this product would be a reliability study on human subjects.

Little information on quantitative sagittal plane postural alignment and evolution in children exists. The objectives of this study are to document the evolution of upright, static, sagittal posture in children and to identify possible critical phases of postural evolution (maturation).

Few digitizers can measure the complexity of upright human postural displacements in six degrees of freedom of the head, rib cage, and pelvis.

Objective This study correlates changes in trunk isometric force parameters and trunk muscle recruitment strategies in subjects with low back pain (LBP) and healthy participants. Methods A control group study with repeated measures was performed. Study participants included 15 control subjects and 14 patients with LBP. Participants were required to exert 50% and 75% of their maximal trunk flexion and extension. In a learning phase, feedback was provided, after which study participants were asked to perform 10 trials without any feedback. Spatiotemporal parameters of muscular activity and force production were recorded. Dependent variables included time to peak force, peak force variability, absolute error in peak force, electromyogram (EMG) burst duration for agonist muscles, and normalized integrated EMG. Results Average time to peak force was significantly longer for subjects with LBP than for healthy subjects. Subjects with LBP showed longer burst duration for all 4 muscles recorded. No group difference was noted in normalized integrated EMG. Conclusions We suggest that the observed changes in trunk motor control and trunk muscle recruitment strategies are not only mediated by a neurophysiologic adaptation to chronic pain but also by cognitive adaptations modulated by fear of movement and fear of reinjury.

Objective: The purpose of this study is to describe and evaluate the validity/accuracy of the computerized system PosturePrint for measuring head posture.Methods: Computer analysis was compared with 125 measured positions of a mannequin head in 5 degrees of freedom. For each mannequin position, 3 digital photographs were obtained (left lateral, anteroposterior, and right lateral) and were processed through the PosturePrint computer system. For the head analysis, a headgear with 3 reflective markers was placed on a subject; and there were additional click-on markers at the ear tragus, upper lip, acromioclavicular joints, and episternal notch. Head postures were calculated as lateral translation (T-x), lateral flexion (R-z), axial rotation (R-y), flexion-extension (R-x), and anterior-posterior translation (T-z). For an error analysis, PosturePrint algorithm calculations were compared with the true mannequin head positions. Furthermore, average head posture was determined in student volunteers (n = 40).Results: Mean computational errors were R-x = 1.3 degrees (SD 0.6 degrees) and T-z = 1.1 mm (SD 0.5 mm) for sagittal displacements and R-y = 1.1 degrees (SD 0.7 degrees), R-z = 0.6 degrees (SD 0.4 degrees), and T-x = 1.1 mm (SD 0.5 mm) for frontal view displacements. For the normal group, mean head displacements were 1.1 degrees or less for all rotations and 1 mm or less for lateral translations (T-x); and forward head posture (T-z) averaged 3 cm.Conclusion: From the mannequin positions, small mean errors indicate that the PosturePrint system is accurate. In the future, statistical research determining the correlation between head displacements, neck pain, function, and health status should be performed.

Since thoracic cage posture affects lumbar spine coupling and loads on the spinal tissues and extremities, a scientific analysis of upright posture is needed. Common posture analyzers measure human posture as displacements from a plumb line, while the PosturePrint™ claims to measure head, rib cage, and pelvic postures as rotations and translations. In this study, it was decided to evaluate the validity of the PosturePrint™ Internet computer system’s analysis of thoracic cage postures. In a university biomechanics laboratory, photographs of a mannequin thoracic cage were obtained in different postures on a stand in front of a digital camera. For each mannequin posture, three photographs were obtained (left lateral, right lateral, and AP). The mannequin thoracic cage was placed in 68 different single and combined postures (requiring 204 photographs) in five degrees of freedom: lateral translation (Tx), lateral flexion (Rz), axial rotation (Ry), flexion–extension (Rx), and anterior–posterior translation (Tz). The PosturePrint™ system requires 13 reflective markers to be placed on the subject (mannequin) during photography and 16 additional “click-on” markers via computer mouse before a set of three photographs is analyzed by the PosturePrint™ computer system over the Internet. Errors were the differences between the positioned mannequin and the calculated positions from the computer system. Average absolute value errors were obtained by comparing the exact inputted posture to the PosturePrint™’s computed values. Mean and standard deviation of computational errors for sagittal displacements of the thoracic cage were Rx=0.3±0.1°, Tz=1.6±0.7 mm, and for frontal view displacements were Ry=1.2±1.0°, Rz=0.6±0.4°, and Tx=1.5±0.6 mm. The PosturePrint™ system is sufficiently accurate in measuring thoracic cage postures in five degrees of freedom on a mannequin indicating the need for a further study on human subjects.

Objective: The aim of this study is to describe the clinical management of a young male patient with sciatica symptoms that developed after an avulsion of the ischial tuberosity. This is a rare injury, but complications may occur.Clinical Feature: A 19-year-old patient developed sciatica 6 months after a football injury. The patient described his symptoms as a shooting pain from the buttock to the lateral part of the foot, along the back of his thigh and calf, sometimes accompanied by paresthesia. Physical examination showed restricted hip range of motion and a positive Bonnet's test. X-ray analysis revealed a bony overgrowth of the right ischial tuberosity.Intervention and Outcome: A treatment plan was designed to decrease the pain level, increase sacroiliac and lumbar joint mobility, and augment muscular extensibility. The patient received 20 treatments over a period of approximately 3 months. Complete recovery was observed 5 months later.Conclusion: Although many differential diagnoses were contemplated, it is most likely that changes in muscular tension and gait pattern, resulting from the ischial tuberosity avulsion, contributed to overuse of the piriformis muscle leading to a piriformis syndrome.

Background context Spinal manipulation is a widely accepted therapeutic approach in the treatment of back pain. In standard training programs, feedback on student performances is provided by an instructor based on teaching and clinical experience. Systematic study of the type of augmented feedback provided and skill learning is lacking in the literature. Purpose The goal of this investigation is to compare the performance of two groups of chiropractic students, one receiving traditional training from experienced instructors, and the other, augmented feedback on specific biomechanical aspects of spinal manipulation therapy using an instrumented manikin. Study design Randomized controlled study. Patient sample Thirty-one fourth-year students from the Department of Chiropractic of Université du Québec à Trois-Rivières participated in this study. Outcome measures Kinetic parameters (force-time curves) of spinal manipulation were evaluated. Methods Spinal manipulation parameters were measured before and after a 5-week training period in which one group received standard chiropractic training while a second group received augmented feedback about specific biomechanical parameters of spinal manipulation. For both groups, practice scheduling and time duration were similar and consisted of a weekly practice session of 90 minutes for five consecutive weeks. Both groups had to practice thoracic spine manipulation throughout the training period. Results Both groups showed a decrease in peak force applied, with a diminution in the number of trials where a downward incisural point was present in preload force. Participants in the feedback training group significantly reduced their peak force variability and significantly increased their preload force. No significant difference was observed for time to peak force. Conclusions The results of this study highlight the merits of practicing with an instrumented manikin or other instrumented training aids. Such a device can provide specific feedback on specific parameters of the task during learning; it can also serve as a tool to assess the progress of students and eliminate the risks relating to repetitive spinal manipulative therapy practice on student colleagues.

For many patients with chronic low back pain, the lack of sleep and sufficient rest period that allows some relaxation is a major obstacle to a good quality of life. During sleep periods, neuromuscular activity is at a minimal level. The major factor influencing the forces on the body, and particularly the spine, is gravity. The force of gravity is sufficient to deform soft tissues when the body is resting on a mattress. Thus, the goal of this study is to measure the contact pressure forces acting on the spine with and without an inflatable support in various experimental conditions. Our hypothesis is that a lumbar support will distribute the force of gravity more uniformly over the pelvic, lumbar and thoracic areas, maintaining the lumbar lordosis, in a supine posture. In this study, 10 participants were tested when lying supine in six separate experimental conditions. These conditions varied according to the surface (no mattress, foam, mattress) and the fact that the support was inflated or not. The dependent variable measured was the contact pressure. It was measured using a pressure sensor mat (Tekscan). When the cushion was inflated the distribution of contact pressure in the different areas (pelvic, lumbar and thoracic) was modified. The comparison of the mean forces revealed that when the cushion was not inflated, the pressure distribution was mainly localized in the pelvic area. After the cushion was inflated, a significant decrease of contact pressure in the pelvic region and a significant increase in the lumbar area were observed. Our results confirm the hypothesis that a lumbar support inserted in a mattress allows a more homogenous distribution of contact pressure over the pelvic, lumbar and thoracic areas during supine posture. The use of an inflatable cushion favouring a transition of the contact pressure from the pelvic to the lumbar region could potentially limit unfavourable compressive and shearing forces acting on the lumbar spine.

OBJECTIVE:The goals of this study were to measure the kinetic profile of thrust in different groups of subjects with various levels of expertise and to quantify general coordination while performing thoracic spine manipulation.PARTICIPANTS:A total of 43 students and chiropractors from the Chiropractic Department of the Université du Québec à Trois-Rivières participated in this study.METHODS:Participants were asked to complete ten consecutive thoracic spine manipulations on an instrumented manikin. Peak force, preload force, time to peak force, time to peak force variability, peak force variability, rate of force production and unloading time were compared between groups. Hand-body delay obtained by calculating the temporal lag between the onset of unloading and the onset of peak force application was also compared between groups.RESULTS:No group difference was observed for the peak force, peak force variability and preload force variables. However, group differences were present for variables like time to peak force, time to peak force variability, rate of force production, unloading time and hand-body delay.CONCLUSION:This study demonstrates clear differences between groups of subjects with different levels of expertise in thoracic spine manipulation. This study also demonstrates the usefulness of a simple, instrumented manikin to analyze spinal manipulation and identify important parameters related to expertise.

Objective: To quantify the force-time and force-delivery characteristics of six commonly used handheld chiropractic adjusting devices.Methods: Four spring-loaded instruments, the Activator Adjusting Instrument-, Activator 11 Adjusting Instrument, Activator III Adjusting Instrument, and Activator IV Adjusting Instrument, and two electromechanical devices, the Harrison Handheld Adjusting Instrument and Neuromechanical Impulse Adjusting Instrument, were applied to a dynamic load cell. A total of 10 force-time histories were obtained at each of three force excursion settings (minimum to maximum) for each of the six adjusting instruments at preload of approximately 20 N.Results: The minimuin-to-maximum force excursion settings for the spring-loaded mechanical adjusting instruments produced similar minimum-to-maximum peak forces that were not appreciably different for most excursion settings. The electromechanical adjusting instruments produced short duration (similar to 2-4 ms), with more linear minimum-to-maximum peak forces. The force-time profile of the electromechanical devices resulted in a more uniform and greater energy dynamic frequency response in comparison to the spring-loaded mechanical adjusting instruments.Conclusions: The handheld, electromechanical instruments produced substantially larger peak forces and ranges of forces in comparison to the handheld, spring-loaded mechanical devices. The electromechanical instruments produced greater dynamic frequency area ratios than their mechanical counterparts. Knowledge of the force-time history and force-frequency response characteristics of spinal manipulative instruments may provide basic benchmarks and may assist in understanding mechanical responses in the clinical setting.

Objective: To measure the pressure applied during motion palpation for cervical spine rotation and to verify its effect on reliability when the kinematics of the test are standardized.Methods: The pressure of palpation used during the test of cervical spine rotation was measured by means of flexible and extra-fine pressure sensors linked to an electronic interface. Seven pressure measurements (left rotation from C1 to C7) for each of 24 examiners were taken. In addition, the examiners were asked to detect the presence of intervertebral fixation while palpating.Results: Pressure of palpation varied from 4.0 to 41.0 N/cm(2) among the examiners. Standardization of the kinematics of the test establishes a strong reliability of identifying a fixation (kappa varying from 0.701 to 0.748).Conclusions: The pressure applied during motion palpation for cervical spine rotation is light to moderate. It can vary tenfold (4-41 N/cm(2)) and remain reliable for identifying a fixation as long as the kinematics of the test are standardized.