Efficacy of neuromuscular electrical stimulation in improving ankle kinetics during walking in children with cerebral palsy

Neuromuscular electrical stimulation (NMES) applied to the triceps surae muscle is claimed to be effective in improving gait in children with cerebral palsy. The main aim of this study was to determine the effect of NMES on the triceps surae muscle in improving the gait and function of children with cerebral palsy. Twelve children with spastic diplegia or hemiplegia were recruited and randomly assigned to the two experimental groups. The period of the study was 8 weeks (2-4-2 week design). The initial 2 weeks was the control period, in which usual treatment was given to both groups of patients with a pre- and post-treatment assessment. The middle 4 weeks was the experimental period, in which the Treadmill+NMES group received NMES plus treadmill walking training and the Treadmill group underwent treadmill walking training only. Assessment was performed at 2-week intervals. The final 2 weeks was the carryover period, in which treatment to be tested was stopped and reassessment performed again at the end of week 8. An additional treatment and post-treatment assessment were given at weeks 2, 4 and 6 to test for the immediate effect of treatment. Altogether, eight repeated measures with three-dimensional gait analysis and five clinical measurements using the gross motor function measure (GMFM) were performed. Kinetic changes in ankle moment quotient (AMQ) and ankle power quotient (APQ) were not significant either immediately or cumulatively in both groups. Improvement in trend was observed in both groups immediately but not cumulatively. Using the GMFM, functional changes were detected in standing (GMST, p < 0.001) and in walking (GMWK, p = 0.003) using a 'time' comparison. Significant interaction was also detected in GMWK using 'treatment by time' (p = 0.035). The difference between the two groups was not significant on 'treatment' comparison of both GMST and GMWK. Both groups showed improvement in GMST and GMWK cumulatively but there was no difference between the two groups. The effects in both groups could be carried over to 2 weeks after interventions stopped. Both the Treadmill+NMES and Treadmill groups showed improvement in functional outcomes. The trend in the changes of the GMFM score suggested that improvements were greater in the Treadmill+NMES group. There was also a trend showing some immediate improvement in AMQ and APQ.

Reduced ankle dorsiflexion range may increase the risk of patellar tendon injury among volleyball players

Patellar tendon injury, a chronic overuse injury characterised by pain during tendon loading, is common in volleyball players and may profoundly restrict their ability to compete. This cross-sectional study investigated the association between performance factors and the presence of patellar tendon injury. These performance factors (sit and reach flexibility, ankle dorsiflexion range, jump height, ankle plantarflexor strength, years of volleyball competition and activity level) were measured in 113 male and female volleyball players. Patellar tendon health was determined by measures of pain and ultrasound imaging. The association between these performance factors and patellar tendon health (normal tendon, abnormal imaging without pain, abnormal imaging with pain) was investigated using analysis of variance. Only reduced ankle dorsiflexion range was associated with patellar tendinopathy (p < 0.05). As coupling between ankle dorsiflexion and eccentric contraction of the calf muscle is important in absorbing lower limb force when landing from a jump, reduced ankle dorsiflexion range may increase the risk of patellar tendinopathy.

High volume versus low volume balance training on postural sway in adults with previous ankle inversion injury

Balance training is commonly used in the rehabilitation process of ankle injuries; however, the exercise prescription guidelines for prescribing balance training are poorly understood. The aim of the present study was to determine if high or low volume balance training is more effective in improving postural sway after an 8 week balance training program utilising the same exercises. Seventeen subjects (14 male, 3 female) with a mean age of 24.06 ± 5.6 years were randomly allocated into a control group (CG), low volume training (LVT) or high volume training (HVT). All subjects had sustained at least two inversion ankle injuries within the last 18 months. Subjects completed 8 weeks of balance training of up to 30 mins duration, 3 times per week. LVT consisted of 40 repetitions for week 1, progressing to 90 repetitions by week 8. HVT consisted of 60 repetitions for week 1, progressing to 130 repetitions by week 8. The maximum centre of pressure (COP) excursion was obtained from the porce plate in the medial-lateral (ML) direction and subsequently used for pre-test and post-test analysis. After the 8 week training intervention, there was a significant (P<0.001) difference in postural sway between pre and post testing for both the LVT (pre = 88.69mm ± 25.08mm, post = 72.17mm ± 27.53mm) and HVT (pre = 77.47mm ±10.57mm, post = 58.54mm ± 7.01mm) groups. There was no significant (P>0.01) difference detected for improvements between the LVT and HVT, however reported effect sizes (ES) showed large effect size chances in the high volume training (ES = 1.7) whereas low volume training showed medium effect sizes changes (ES = 0.6). This preliminary study demonstrates the importance of training volume in the rehabilitation of ankle injuries, with the HVT being superior to LVT.

Influence of ankle functional instability on the ankle electromyography during landing after volleyball blocking

The purpose of this study was to describe, interpret and compare the EMG activation patterns of ankle muscles - tibialis anterior (TA), peroneus longus (PL) and gastrocnemius lateralis (GL) - in volleyball players with and without ankle functional instability (FI) during landing after the blocking movement. Twenty-one players with FI (IG) and 19 controls (CG) were studied. The cycle of movement analyzed was the time period between 200 ms before and 200 ms after the time of impact determined by ground reaction forces. The variables were analyzed for two different phases: pre-landing (200 ms before impact) and post-landing (200 ms after impact). The RMS values and the timing of onset activity were calculated for the three studied muscles, in both periods and for both groups. The co-activation index for TA and PL, TA and GL were also calculated. Individuals with FI presented a lower RMS value pre-landing for PL (CG = 43.0 perpendicular to 22.0; IG = 26.2 perpendicular to 8.4, p < 0.05) and higher RMS value post-landing (CG = 47.5 perpendicular to 13.3; IG = 55.8 perpendicular to 21.6, p < 0.10). Besides that, in control group PL and GL activated first and simultaneously, and TA presented a later activation, while in subjects with FI all the three muscles activated simultaneously. There were no significant differences between groups for co-activation index. Thus, the rate of contraction between agonist and antagonist muscles is similar for subjects with and without FI but the activation individually was different. Volleyball players with functional instability of the ankle showed altered patterns of the muscles that play an important role in the stabilization of the foot-ankle complex during the performance of the blocking movement, to the detriment of the ligament complex, and this fact could explain the usual complaints in these subjects. (C) 2007 Elsevier Ltd. All rights reserved.

Utilization of neuromuscular electrical stimulation in the acute phase of ankle immobilization at 90°: Study in rats

Objective: To evaluate the skeletal muscle glycogen content and plasmatic concentration of interleukin -6 (IL-6), interleukin-4 (IL-4), interleukin-10 (IL-10) and tumor necrosis factor-alpha (TNF-α) in rats submitted to electrical stimulation sessions during the first three days of ankle immobilization at the position of 90°. Methods: Albinomale Wistar rats(3-4 months) were maintained in vivarium. conditions with food and water ad libitum, Submitted to 12 h photoperiodic cycles of light/dark, and distributed into 7 experimental groups (n = 6): control(C), immobilized 1 day(I1) immobilized 1 day and electrically stimulated(IE1) immobilized 2 days(12), immobilized 2 days and electrically stimulated(IE2), immobilized 3 days(13) and immobilized 3 days and electrically stimulated(IE3). Groups I utilized an acrylic resin orthesis model and groups electrically stimulated (IE) utilized the orthesis and a session of electrotherapy by a Dualpex 961 (biphasic quadratic pulse, 10 Hz, 0.4 ms, 5.0 mA, one 20 min session a day). After the experimental period, the rats were anesthetized with pentobarbital sodium(40 mg/kg) and a blood sample was colleted to evaluate the plasmatic concentration of interleukins by means of the radioimmunoassay method. The soleus and the white portion of the gastrocnemius muscle were colleted for glycogen reserves analysis(GLY). Other groups of rats were used to apply the glucose tolerance test(GTT) and insulin tolerance test(ITT). For statistical analysis, the Kolmogorov-Smirnov normality test followed by ANOVA and the Tukey tests were utilized, with a critical level established at 5%. Results: In ITT test, groups IE enhanced the skeletal muscle glucose uptake, but no changes were observed in GTT after the therapy session, which indicates that electrical stimulation is a sensibilizing method to augment skeletal muscle glucose uptake. The GLY reserves were reduced in I groups, which indicate that disuse altered insulin sensitivity and compromised energetic homeostasis. However. the IE groups displayed an augment in GLY content, suggesting that electrical stimulation restores the enzymatic pathways altered by immobilization. The improvement in GLY was accompanied by an elevation of the plasmatic concentration of IL-6 and TNF-α, showing the participation of these interleukins in the control of metabolic profile. Plasmatic concentrations of IL-10 were elevated only after 3 days of IE while IL-4 did not display any modifications. Conclusion: The results suggest that neuromuscular electricaf stimulation is an important toot in the maintenance of energetic, conditions of musculature submitted to immobilization, and presents multifactor mechanisms linked to interleukins action that converge to maintain the energetic equilibrium of the tissue in disuse.

Muscle strength and ankle mobility for the gait parameters in diabetic neuropathies

Aims: To evaluate the spatio-temporal variables of gait and the isometric muscle strength component of the ankle in patients with peripheral diabetic neuropathy. Also, verify the relationship between these variables and gait parameters. Methods: This study involved 25 diabetic peripheral neuropathy (DPN) participants (62.4 ± 8.36 years) and 27 age-matched healthy control individuals (64.48 ± 6.21 years). The assessment of the spatio-temporal parameters of gait was performed using an electronic baropodometry treadmill. Prior to the collection data, each participant was instructed to walk on the treadmill in her/his habitual self-selected speed. Results: Diabetic neuropathy group showed impairment of gait, with a smaller stride and length speed of the cycle, and increased duration of support time. Restricted dorsiflexion mobility and increased plantarflexion mobility were found, with a decrease in muscle strength of the dorsiflexors and plantiflexors. There was a significant relationship between plantiflexor muscle strength and the length and speed of the gait cycle. Also the muscle strengths of the plantiflexors and dorsiflexors, and the range of motion of dorsiflexion were predictors of gait performance. Conclusions: The ankle, muscle strength and ankle mobility variables could explain changes in gait speed and range of motion in patients with DPN, allowing for the application of preventive strategies. © 2012 Elsevier Ltd.

Balance and ankle muscle strength predict spatiotemporal gait parameters in individuals with diabetic peripheral neuropathy

The aims of this study were to evaluate aspects of balance, ankle muscle strength and spatiotemporal gait parameters in individuals with diabetic peripheral neuropathy (DPN) and verify whether deficits in spatiotemporal gait parameters were associated with ankle muscle strength and balance performance. Thirty individuals with DPN and 30 control individuals have participated. Spatiotemporal gait parameters were evaluated by measuring the time to walk a set distance during self-selected and maximal walking speeds. Functional mobility and balance performance were assessed using the Functional Reach and the Time Up and Go tests. Ankle isometric muscle strength was assessed with a handheld digital dynamometer. Analyses of variance were employed to verify possible differences between groups and conditions. Multiple linear regression analysis was employed to uncover possible predictors of gait deficits. Gait spatiotemporal, functional mobility, balance performance and ankle muscle strength were affected in individuals with DPN. The Time Up and Go test performance and ankle muscle isometric strength were associated to spatiotemporal gait changes, especially during maximal walking speed condition. Functional mobility and balance performance are damaged in DPN and balance performance and ankle muscle strength can be used to predict spatiotemporal gait parameters in individuals with DPN.

When Is the Best Moment to Assess the Ankle Brachial Index: Pre- or Post-Hemodialysis?

Background: Cardiovascular disease is an important cause of death in patients on dialysis. Peripheral arterial disease (PAD) is a prognostic factor for cardiovascular disease. The ankle brachial index (ABI) is a noninvasive method used for the diagnosis of PAD. The difference between ABI pre- and post-dialysis had not yet been formally tested, and it was the main objective of this study. Methods:The ABI was assessed using an automated oscillometric device in incident patients on hemodialysis. All blood pressure readings were taken in triplicate pre- and post-dialysis in three consecutive dialysis sessions (times 1, 2, and 3). Results: One hundred and twenty-three patients (85 men) aged 53 +/- 19 years were enrolled. We found no difference in ABI pre- and post-dialysis on the right or left side, and there was no difference in times 1, 2, and 3. In patients with a history of PAD, the ABI pre- versus post-dialysis were of borderline significance on the right side (p = 0.088). Conclusion: ABI measured pre- and post-dialysis presented low variability. The ABI in patients with a history of PAD should be evaluated with caution. The applicability of the current method in predicting mortality among patients on hemodialysis therefore needs further investigation. Copyright (C) 2012 S. Karger AG, Basel

EVALUATION OF THE PASSIVE RESISTIVE TORQUE IN FEMALE ATHLETES WITH ANKLE SPRAIN

Introduction: The ankle sprain is one of the most common injuries in athletes. Direct evaluation of the ligament laxity can be obtained through the objective measurement of extreme passive inversion and eversion movements, but there are few studies on the use of the evaluation of the passive resistive torque of the ankle to assess the capsule and ligaments resistance. Objective: The aim of this study was to compare the inversion and eversion passive torque in athletes with and without ankle sprains history. Method: 32 female basketball and volleyball athletes (16.06 +/- 0.8 years old; 67.63 +/- 8.17 kg; 177.8 +/- 6.47 cm) participated in this study. Their ankles were divided into two groups: control group (29), composed of symptom-free ankles, and ankle sprain group, composed of ankles which have suffered injury (29). The resistive torque at maximum passive ankle movement was measured by the isokinetic dynamometer and the muscular activity by electromyography system. The athletes performed 2 repetitions of inversion and eversion movement at 5, 10 and 20 degrees/s and the same protocol only at maximum inversion movement. Results: The resistive passive torque during the inversion and eversion was lower in the ankle sprain group. This group also showed lower torques at the maximum inversion movement. No differences were observed between inversion and eversion movement. Conclusions: Ankle sprain leads to lower passive torque, indicating reduction of the resistance of the lateral ankle ligaments and mechanical laxity.

Ankle-Brachial Index: A Simple Way to Predict Mortality among Patients on Hemodialysis - A Prospective Study

Background: Ankle-brachial index (ABI) can access peripheral artery disease and predict mortality in prevalent patients on hemodialysis. However, ABI has not yet been tested in incident patients, who present significant mortality. Typically, ABI is measured by Doppler, which is not always available, limiting its use in most patients. We therefore hypothesized that ABI, evaluated by a simplified method, can predict mortality in an incident hemodialysis population. Methodology/Principal Findings: We studied 119 patients with ESRD who had started hemodialysis three times weekly. ABI was calculated by using two oscillometric blood pressure devices simultaneously. Patients were followed until death or the end of the study. ABI was categorized in two groups normal (0.9-1.3) or abnormal (<0.9 and >1.3). There were 33 deaths during a median follow-up of 12 months (from 3 to 24 months). Age (1 year) (hazard of ratio, 1.026; p = 0.014) and ABI abnormal (hazard ratio, 3.664; p = 0.001) were independently related to mortality in a multiple regression analysis. Conclusions: An easy and inexpensive technique to measure ABI was tested and showed to be significant in predicting mortality. Both low and high ABI were associated to mortality in incident patients on hemodialysis. This technique allows nephrologists to identify high-risk patients and gives the opportunity of early intervention that could alter the natural progression of this population.

Diabetic patients with and without peripheral neuropathy reveal different hip and ankle biomechanical strategies during stair descent

Background: The progression of diabetes and the challenge of daily tasks may result in changes in biomechanical strategies. Descending stairs is a common task that patients have to deal with, however it still has not been properly studied in this population. Objectives: We describe and compare the net joint moments and kinematics of the lower limbs in diabetic individuals with and without peripheral neuropathy and healthy controls during stair descent. Method: Forty-two adults were assessed: control group (13), diabetic group (14), and neuropathic diabetic group (15). The flexor and extensor net moment peaks and joint angles of the hip, knee, and ankle were described and compared in terms of effect size and ANOVAs (p<0.05). Results: Both diabetic groups presented greater dorsiflexion [large effect size] and a smaller hip extensor moment [large effect size] in the weight acceptance phase. In the propulsion phase, diabetics with and without neuropathy showed a greater hip flexor moment [large effect size] and smaller ankle extension [large effect size]. Conclusion: Diabetic patients, even without neuropathy, revealed poor eccentric control in the weight acceptance phase, and in the propulsion phase, they showed a different hip strategy, where they chose to take the leg off the ground using more flexion torque at the hip instead of using a proper ankle extension function.

Isokinetic analysis of ankle and ground reaction forces in runners and triathletes

OBJECTIVE: To analyze and compare the vertical component of ground reaction forces and isokinetic muscle parameters for plantar flexion and dorsiflexion of the ankle between long-distance runners, triathletes, and nonathletes. METHODS: Seventy-five males with a mean age of 30.26 (±6.5) years were divided into three groups: a triathlete group (n=26), a long-distance runner group (n = 23), and a non-athlete control group. The kinetic parameters were measured during running using a force platform, and the isokinetic parameters were measured using an isokinetic dynamometer. RESULTS: The non-athlete control group and the triathlete group exhibited smaller vertical forces, a greater ground contact time, and a greater application of force during maximum vertical acceleration than the long-distance runner group. The total work (180º/s) was greater in eccentric dorsiflexion and concentric plantar flexion for the non-athlete control group and the triathlete group than the long-distance runner group. The peak torque (60º/s) was greater in eccentric plantar flexion and concentric dorsiflexion for the control group than the athlete groups. CONCLUSIONS: The athlete groups exhibited less muscle strength and resistance than the control group, and the triathletes exhibited less impact and better endurance performance than the runners.

Spatial mechanisms for modelling the human ankle passive motion

Knowledge on how ligaments and articular surfaces guide passive motion at the human ankle joint complex is fundamental for the design of relevant surgical treatments. The dissertation presents a possible improvement of this knowledge by a new kinematic model of the tibiotalar articulation. In this dissertation two one-DOF spatial equivalent mechanisms are presented for the simulation of the passive motion of the human ankle joint: the 5-5 fully parallel mechanism and the fully parallel spherical wrist mechanism. These mechanisms are based on the main anatomical structures of the ankle joint, namely the talus/calcaneus and the tibio/fibula bones at their interface, and the TiCaL and CaFiL ligaments. In order to show the accuracy of the models and the efficiency of the proposed procedure, these mechanisms are synthesized from experimental data and the results are compared with those obtained both during experimental sessions and with data published in the literature. Experimental results proved the efficiency of the proposed new mechanisms to simulate the ankle passive motion and, at the same time, the potentiality of the mechanism to replicate the ankle’s main anatomical structures quite well. The new mechanisms represent a powerful tool for both pre-operation planning and new prosthesis design.

An New Energetic Approach to the Modeling of Human Joint Kinematics: Application to the Ankle

The objective of this dissertation is to develop and test a predictive model for the passive kinematics of human joints based on the energy minimization principle. To pursue this goal, the tibio-talar joint is chosen as a reference joint, for the reduced number of bones involved and its simplicity, if compared with other sinovial joints such as the knee or the wrist. Starting from the knowledge of the articular surface shapes, the spatial trajectory of passive motion is obtained as the envelop of joint configurations that maximize the surfaces congruence. An increase in joint congruence corresponds to an improved capability of distributing an applied load, allowing the joint to attain a better strength with less material. Thus, joint congruence maximization is a simple geometric way to capture the idea of joint energy minimization. The results obtained are validated against in vitro measured trajectories. Preliminary comparison provide strong support for the predictions of the theoretical model.

New mechanisms for modelling the motion of the human ankle complex

The relevance of human joint models was shown in the literature. In particular, the great importance of models for the joint passive motion simulation (i.e. motion under virtually unloaded conditions) was outlined. They clarify the role played by the principal anatomical structures of the articulation, enhancing the comprehension of surgical treatments, and in particular the design of total ankle replacement and ligament reconstruction. Equivalent rigid link mechanisms proved to be an efficient tool for an accurate simulation of the joint passive motion. This thesis focuses on the ankle complex (i.e. the anatomical structure composed of the tibiotalar and the subtalar joints), which has a considerable role in human locomotion. The lack of interpreting models of this articulation and the poor results of total ankle replacement arthroplasty have strongly suggested devising new mathematical models capable of reproducing the restraining function of each structure of the joint and of replicating the relative motion of the bones which constitute the joint itself. In this contest, novel equivalent mechanisms are proposed for modelling the ankle passive motion. Their geometry is based on the joint’s anatomical structures. In particular, the role of the main ligaments of the articulation is investigated under passive conditions by means of nine 5-5 fully parallel mechanisms. Based on this investigation, a one-DOF spatial mechanism is developed for modelling the passive motion of the lower leg. The model considers many passive structures constituting the articulation, overcoming the limitations of previous models which took into account few anatomical elements of the ankle complex. All the models have been identified from experimental data by means of optimization procedure. Then, the simulated motions have been compared to the experimental one, in order to show the efficiency of the approach and thus to deduce the role of each anatomical structure in the ankle kinematic behavior.