Opposite Limb Research Articles

Mechanical properties and structure-function relationships in articular cartilage repaired using IGF-I gene-enhanced chondrocytes.

Several studies have demonstrated the benefits of IGF-I gene therapy in enhancing the histologic and biochemical content of cartilage repaired by chondrocyte transplantation. However, there is little to no data on the mechanical performance of IGF-I augmented cartilage grafts. This study evaluated the compressive properties of full-thickness chondral defects in the equine femur repaired with and without IGF-I gene therapy. Animals were randomly assigned to one of three study cohorts based on chondrocyte treatment provided in each defect: (i) IGF-I gene delivered by recombinant adeno-associated virus (rAAV)-5; (ii) AAV-5 delivering GFP as a reporter; (iii) naïve cells without virus. In each case, the opposite limb was implanted with a fibrin carrier without cells. Samples were prepared for confined compression testing to measure the aggregate modulus and hydraulic permeability. All treatment groups, regardless of cell content or transduction, had mechanical properties inferior to native cartilage. Overexpression of IGF-I increased modulus and lowered permeability relative to other treatments. Investigation of structure-property relationships revealed that Ha and k were linearly correlated with GAG content but logarithmically correlated with collagen content. This provides evidence that IGF-I gene therapy can improve healing of articular cartilage and can greatly increase the mechanical properties of repaired grafts.

Indeterminate cauda equina syndrome: A case report

The presentation of cauda equina syndrome (CES) varies from its classical presentation, especially in its early stages of compression. We present a case of lumbar disc prolapse causing CES in an uncharacteristic way, knowledge of which is essential for orthopaedicians to diagnose this condition early and prevent neurological complications. A 32-year-old male patient presented to us with complaints of inability to lift his left ankle and numbness over his left leg and ankle for 14 days. Clinical examination showed involvement of left L3, L4, L5 and S1 nerve roots as evidenced by weakness of quadriceps, extensor hallucis longus, extensor digitorum longus muscles and tendo achilles. Knee jerk was absent. The opposite lower limb was normal and there was no evidence of bowel bladder involvement or saddle anaesthesia. The MRI showed L2 L3 posterocentral disc prolapse compressing the cauda equina. The patient underwent laminectomy and discectomy. Post-operatively, the patient showed significant improvement in his sensory symptoms with complete recovery of motor power in 12 weeks. In contrast to the classical presentation of CES, several case series have been reported with varied clinical manifestations like unilateral leg symptomatology, unilateral or bilateral saddle anaesthesia with or without leg symptoms and CES with complete absence of signs and symptoms in the lower limbs. The disc prolapse in our case at L2-L3 level has compressed the left-sided L3, L4, L5 roots with minimal compression of S1. The classical features of CES would have occurred due to the lateral shift of the cauda equina in our case but for our early diagnosis and intervention.

The Use of Micronized Allograft Articular Cartilage (BioCartilage) and Platelet Rich Plasma to Augment Marrow Stimulation in an Equine Model of Articular Cartilage Defects

Objectives:Microfracture continues to be a dominant treatment strategy for symptomatic articular cartilage defects. Improving the histologic and clinical outcomes with biologic adjuncts offers promise to enhance this widely utilized technique. Specifically, the use of a novel scaffold that is potentially conductive and inductive such as micronized allograft articular cartilage (BioCartilage-BC) combined with platelet rich plasma (PRP) was investigated as an adjunct to microfracture in an equine model of articular cartilage defects.Methods:Five adult horses were anesthetized and 2 - 10mm diameter full thickness cartilage defects were created in the trochlear ridge in both knees; one proximal (high load) and another distal (low load). In one knee, microfracture (MFx) followed by grafting with BioCartilage(BC). BioCartilage was mixed with PRP and injected into the defect with a touhey needle and sealed with fibrin under CO2 arthroscopy. The opposite limb served as a control and received MFx only. Horses were euthanized at 13 months post-operatively. Outcome was assessed with serial arthroscopy, 3T T2 and T1rho MRI, microCT, and histology. Statistics were performed using a mixed effect model with response variable contrasts. P≤0.05 was considered significant.Results:No complications such as joint inflammation, infection or lameness were encountered. The score for overall repair (12=normal, 0=complete degeneration) in both the proximal and distal defects was significantly better in the BC group compared to MFx (proximal BC 7.4±0.51, MFx 4.8±.1; p=0.041)(distal BC 5.6±0.98, MFx 2.6±1.5; p=0.022). All significant findings on histology (100=normal, o=complete degeneration) were confined to the proximal, high load defects. Graft perimeter integration (BC 96±8.9, MFx 68±19; p=0.02), graft base integration (BC 100+/- 0.0, MFx 70±37;p=0.044), subchondral bone architecture under the graft (BC 66±18, MFx 34±16; p=0.050) and collagen type II BC 82+/-8, MFx 58±11; p=0.051. There were no significant differences between BC and MFx in MRI or uCT analyses.Conclusion:Micronized allograft articular cartilage (BioCartilage) and PRP improve cartilage repair compared to marrow stimulation alone in an equine model of articular cartilage defects. This technology offers promise for the use of homologous allograft tissue as a low-cost and safe augmentation procedure for traditional microfracture surgery.

Micronized Allograft Articular Cartilage (BioCartilage) and Platelet-Rich Plasma to Augment Marrow Stimulation in an Equine Model of Articular Cartilage Defects

Micronized Allograft Articular Cartilage (BioCartilage) and Platelet-Rich Plasma to Augment Marrow Stimulation in an Equine Model of Articular Cartilage Defects

A Comparative Study of Range of Motion of Forelimb and Hind Limb in Walk Pattern and Trot Pattern of Chihuahua Dogs Affected and Non-Affected with Patellar Luxation

The study compared the Ranges of Motion (ROM) of forelimb and hind limb, and the cycle speeds of healthy and Patellar Luxation (PL) dogs in walking and trotting. 21 dogs were divided into three groups: The 5 normal dogs, 6 unilateral PL (PL-1) dogs and 10 bilateral PL (PL-2) dogs. All dogs with PL did not present lameness. The dogs were walking and trotting on a treadmill for the video record. The Kinovea program was employed to evaluate the cycle speed, Maximum Extension Angle (MEA), Maximum Flexion Angle (MFA) and ROM of the shoulder, elbow, carpal, hip, stifle and tarsal joints. The results showed that both the limb sides of the dogs in all the groups in both walking and trotting motions had no significant difference (p>0.05). It was found that the ROM of the shoulder, carpal, hip and tarsal joints in PL dogs had significant difference (p<0.05) compared to the normal dog. In conclusion, the unilateral PL limb dogs showed no effect on the opposite limb, the unilateral and the bilateral PL dogs was an effect on the locomotion of the forelimb and the hind limb compared with the normal dogs.

Single Limb Fatigue Compromises The Ability To Generate Force In The Opposite Limb

Performing strong voluntary contractions with a single limb produces unintended muscle activity in the homologous muscle of the opposite resting limb. The mechanisms underlying these crossed-effects are likely to involve supraspinal centres, as neural activity in the active motor cortex is known to spread within and between motor cortices during repeated muscle contractions. Although strong contractions result in unintended activity in the resting opposite limb, it is unknown how brief contractions or fatigue inducing contractions affect the maximum force generating ability of the opposite limb. PURPOSE: To determine how intermittent maximal contractions of a single limb influences the ability to produce force in the opposite limb. METHODS: Twelve healthy participant (age: 23 ± 3.4 yr) were recruited into the study. Motor evoked potentials (MEP), EMG of the first dorsal interosseous (FDI), and index finger abduction forces were obtained before, during, and after a single limb intermittent maximal contraction protocol. The contraction sets consisted of four 4 s contractions separated by 2 s of rest for the dominant limb- followed a 10 s period where MEP, FDI EMG and force data were collected for the non-dominant limb. Contractions were continued until MVC reduced by 50%. RESULTS: In unfatigued muscles, only small increases in unintended activity occurred when the opposite limb was maximally contracting (∼5% increase in force with no changes in MEP amplitude). After one contraction set was performed by the dominant limb, the capacity to generate force in the non-dominant limb was significantly reduced by 15% which corresponded to a 20% reduction in MEP amplitude. Maximal force output for both limbs significantly reduced across the duration of contraction sets, where maximum force output declined by 52% for the exercising limb and 36% for the contralateral limb when the criteria for termination was achieved. CONCLUSIONS: Crossed-effects were evident across all conditions; however fatiguing contractions were most effective in eliciting responses in the contralateral limb. Given that repeated single limb contractions reduced the maximal force generating capacity in the opposite limb, it appears that inhibitory mechanisms were activated on the opposite side of the body, presumably at the level of the motor cortex.

Bilateral Asymmetry of Radius and Tibia Bone Macroarchitecture and Microarchitecture: A High-Resolution Peripheral Quantitative Computed Tomography Study

Studies assessing bone health often select the dominant or nondominant limb to scan, but not both, for efficiency reasons. New scanning technology allows 3-dimensional (3D) visualization of the microarchitecture in bone, but it is not well understood whether there are differences between the dominant and nondominant limbs. Using 3D high-resolution peripheral quantitative computed tomography (HR-pQCT), the aim of this study is to investigate the effect of limb dominance on bone macroarchitecture and microarchitecture. Healthy male and female participants (N = 100; 59 female, 41 male), mean age 30.7 ± 12.1 years, were scanned at both radii and tibiae using HR-pQCT. Hand and foot dominance were determined by the participant's self-report. Most participants were right hand dominant (94.0%) and right foot dominant (91.0%). In the pooled cohort, the dominant radius had significantly greater cortical area (2.11%; p = 0.002) and failure load (3.00%; p = 0.001). At the tibia, the dominant foot had significantly lower bone mineral density (−0.77%; p = 0.042), cortical area (−1.05%; p = 0.031), and thickness (−1.51%; p = 0.017). For females, there were no differences at the radius, but at the tibia, the dominant side had greater cross-sectional area (1.03%; p = 0.044). Our data suggest that dominance has a small yet significant effect on macroarchitecture at both the ultradistal radius and tibia but not microarchitecture. This work emphasizes that it is important to be consistent in the selection of either dominant or nondominant limbs for HR-pQCT cohort studies; however, in the case where the opposite limb needs to be scanned, there would be small differences in macroarchitecture and no significant differences in microarchitecture anticipated.

Implantation of rAAV5-IGF-I Transduced Autologous Chondrocytes Improves Cartilage Repair in Full-thickness Defects in the Equine Model

Cartilage injury often precipitates osteoarthritis which has driven research to bolster repair in cartilage impact damage. Autologous chondrocytes transduced with rAAV5-IGF-I were evaluated in chondral defects in a well-established large animal model. Cartilage was harvested from the talus of 24 horses; chondrocytes were isolated and stored frozen. Twenty million cells were cultured and transduced with 10(5) AAV vg/cell prior to implantation. Chondrocytes from eight horses were transduced with rAAV5-IGF-I, chondrocytes from eight horses with rAAV5-GFP, and chondrocytes from eight horses were not transduced. A 15 mm full-thickness chondral defect was created arthroscopically in the lateral trochlear ridge of the femur in both femoropatellar joints. Treated defects were filled with naive or gene-enhanced chondrocytes, in fibrin vehicle. Control defects in the opposite limb received fibrin alone. rAAV5-IGF-I transduced chondrocytes resulted in significantly better healing at 8 week arthroscopy and 8 month necropsy examination when compared to controls. At 8 months, defects implanted with cells expressing IGF-I had better histological scores compared to control defects and defects repaired with naive chondrocytes. This included increased chondrocyte predominance and collagen type II, both features of hyaline-like repair tissue. The equine model closely approximates human cartilage healing, indicating AAV-mediated genetic modification of chondrocytes may be clinically beneficial to humans.

Effect of Irradiation by Proprioceptive Neuromuscular Facilitation on Lower Limb Extensor Muscle Force in Adults

Background and purpose: This study aims at comparing the effectiveness of PNF technique applied by upper extremity and lower extremity on opposite lower limb muscle strength in adults. Method: 200 subjects including both males and females of age 20-35 years were recruited. All selected subjects were randomly divided into 4 groups according to the PNF pattern applied to them through lottery system. PNF patterns were applied isometrically at final position and isotonically throughout the ROM on contralateral upper and lower limb (dominant). A pre-test post-test same subject design was used in which the maximum voluntary isometric contractions (MVIC) of the extension forces of non-dominant lower limb was measured during isometric PNF pattern at final position and after isotonic PNF patterns. Each subject received a two session of PNF. A strain gauge measured the extension force of lower limb. Results: In subjects, the maximum voluntary isometric contraction (MVIC) of extension force of non-dominant lower limb improved significantly while performing extension PNF pattern (extension-abduction-internal rotation) on dominant lower limb. Discussion and conclusion: The extension force of the opposite lower limb increased more with PNF pattern of contralateral lower limb than contralateral upper limb and in lower limb homologous pattern was most effective than non-homologous pattern. The result suggests that possible mechanism can be explained by “cross activation” hypothesis and the excitability of non-decussated descending motor fibers, coticospinal tract fibers.

Inter-limb generalization of visuomotor adaptation is more automatic when the perturbation is aligned in extrinsic and joint-based coordinates

Event Abstract Back to Event Inter-limb generalization of visuomotor adaptation is more automatic when the perturbation is aligned in extrinsic and joint-based coordinates Timothy Carroll1*, Eugene Poh1, Tania Duarte Ferreira1 and Aymar De Rugy1, 2 1 The University of Queensland, School of Human Movement Studies, Australia 2 Université Bordeaux Segalen, Institut de Neurosciences Cognitives et Intégratives d'Aquitaine, France Many questions remain regarding how and why new visuomotor maps obtained with one limb can benefit the other. In an isometric aiming context, we recently found strong, immediate transfer of adaptation between limbs for a sagittal plane workspace where the visuomotor distortion had identical effects in eye- and joint-based coordinates bilaterally, but no transfer in a frontal plane workspace where an identical visual distortion had opposite effects for the two limbs in joint-based coordinates. This suggests that mixed transfer results reported previously for reaching tasks in the horizontal plane might be explained by coordinate frame conflicts associated with the mirror symmetry of the limbs. Here we compared cross-limb transfer of adaptation to visuomotor rotation (45 deg) in a planar reaching task (16 targets) when the limb and visual feedback were oriented in the sagittal (n=8) or the horizontal plane (n=8). Each person completed two sessions in counterbalanced order; one to assess transfer from the right arm to the left and another from left to right. There was significant transfer of feedforward performance to the untrained limb in both horizontal and sagittal conditions (angular error at 20% of target distance: Sagittal = 45%, Horizontal = 18%), but transfer of overall reach performance was significantly greater for the Sagittal than Horizontal group (total path length to target: Sagittal = 58%, Horizontal = 30%. Moreover, reaction times were significantly higher during the first trials in the transfer phase for horizontal than sagittal groups (497 ms versus 380 ms), suggesting a greater cognitive component to horizontal plane error reduction. The results contrast markedly with previous data for isometric force aiming and reaching with veridical, virtual reality feedback, which suggests that the location of the visual display relative to the physical workspace critically influences transfer of new visuomotor maps to the opposite limb. Keywords: reaching, motor learning, visuomotor rotation, Sensorimotor adaptation, Hemispheric asymmetries, Inter-limb Transfer Conference: XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014. Presentation Type: Poster Topic: Motor Behaviour Citation: Carroll T, Poh E, Duarte Ferreira T and De Rugy A (2015). Inter-limb generalization of visuomotor adaptation is more automatic when the perturbation is aligned in extrinsic and joint-based coordinates. Conference Abstract: XII International Conference on Cognitive Neuroscience (ICON-XII). doi: 10.3389/conf.fnhum.2015.217.00072 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 19 Feb 2015; Published Online: 24 Apr 2015. * Correspondence: Prof. Timothy Carroll, The University of Queensland, School of Human Movement Studies, Brisbane, Australia, timothy.carroll@uq.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Timothy Carroll Eugene Poh Tania Duarte Ferreira Aymar De Rugy Google Timothy Carroll Eugene Poh Tania Duarte Ferreira Aymar De Rugy Google Scholar Timothy Carroll Eugene Poh Tania Duarte Ferreira Aymar De Rugy PubMed Timothy Carroll Eugene Poh Tania Duarte Ferreira Aymar De Rugy Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Transfemoral Amputation Following Chronic Spinal Cord Injury: A Prosthetic Solution for Improved Balance, Seating, Dynamic Function and Body Image

Background: Advances in the care and rehabilitation of patients with spinal cord injuries (SCI) have resulted in extended survival. As SCI patients age, chronic lower extremity ischemic complications are resulting in amputations. The literature relating to lower extremity amputation and prosthesis in SCI patients is sparse. Limb amputation may cause weight distribution imbalances, leading to back pain and increased risk of pressure ulcer formation. Lower extremity amputation challenges skin management, sitting balance, functional range and body image. Case Description and Methods: We report a systematic retrospective review of a disability adaptation equipment entrepreneur with T4 AIS B paraplegia patient who underwent right transfemoral amputation because of poor wound healing in the setting of severe peripheral vascular disease. The prosthetic prescription included a total-contact socket with a knee-flexed formed prosthesis, mirroring the opposite limb. The socket design allowed decompression of the right ischium and secured the patient in the wheel chair for seated reach and leverage in work. The patient consistently used the prosthesis over 10 years and recognized a variety of benefits including improved seating stability, functional reach, transfers, cosmesis, dressing options and body image, and documented increase in community activity. Conclusion: Lower extremity prosthesis fitting for patients with SCI and amputation can improve posture, seating, transfers, static and dynamic balance, participation in functional activities, and community reintegration. Clinical Significance: Active patients with paraplegia and new transfemoral amputation should be offered a trial of a prothesis to enhance mobility. Many of the medical and functional consequences of amputation after SCI can be prevented with careful prosthesis selection, prescription, and training patients in the use of lower extremity prosthesis.

The effect of weightbearing and limb load cycling on equine lamellar perfusion and energy metabolism measured using tissue microdialysis.

Lamellar perfusion is thought to be affected by weightbearing and limb load cycling; this may be critical in the development of supporting limb laminitis. To document the effects of unilateral weightbearing and altered limb load cycling on lamellar energy metabolism and perfusion. Randomised, controlled (within subject), experimental trial. Nine Standardbred horses were instrumented with microdialysis probes in the foot lamellar tissue and skin (over the tail base). Urea (20 mmol/l) was added to the perfusate. Samples were collected every 15 min for a 1 h control period, then during periods of unilateral weightbearing (opposite limb held off the ground for 1 h); enhanced static limb load cycling (instrumented limb lifted every 10 s for 30 min); reduced limb load cycling activity (i.v. detomidine sedation) and continuous walking (30 min). Dialysate concentrations of glucose, lactate, pyruvate and urea were measured and lactate:glucose (L:G) and lactate:pyruvate (L:P) ratios were calculated. For each intervention, values were compared with baseline using nonparametric statistical testing. Lamellar dialysate glucose increased and L:G decreased significantly during enhanced static limb load cycling. Glucose and pyruvate increased, and L:G, L:P and urea decreased significantly during walking. Simultaneous skin dialysate values did not change significantly. There were no significant dialysate changes during unilateral weightbearing or after detomidine administration, but only the latter resulted in a significant decrease in limb load cycling frequency. Increases in limb load cycling frequency (particularly walking) caused dialysate changes consistent with increased lamellar perfusion. Unilateral weightbearing (1 h) and a sedation-induced reduction in limb load cycling frequency did not have a detectable effect on lamellar perfusion. More research is needed to confirm the role of hypoperfusion in supporting limb laminitis, but strategies to increase limb load cycling may be important for prevention.

Original Rehabilitation Programme after Anatomical ACL Reconstruction Based on MRI Evaluated Graft Remodelling

Objectives:This study was carried out to design a rehabilitation program allowing for complete functional post-surgical recovery of the limb, that would not affect the remodelling process of the transplanted graft evaluated on MRI imaging. The main reason for changing the rehabilitation protocol was the 14 months of observation of the MRI images (a series of 9 MRIs performed over a two year period) among the patients after ACL reconstruction, in whom the adverse characteristics in remodelling of the graft were observed in line with the implementation of the traditional rehabilitation program.Methods:A 23 years old patient, a professional hi-rank skateboarder, took part in this pilot study. He had a torsion injury of the left knee joint. The main concepts of the rehabilitation program were: functional training in CKC that would involve muscles of the entire kinetic chain of the operated limb; the co-contraction training under the axial load, active extension training, the avoidance of static flexor stretching for at least 24 weeks after the surgery, no passive movements while exercising, the use of posterior translation of the tibia while doing the exercises, and no knee joint extensor strengthening activities in OKC for at least six months after the surgery. In order to evaluate the remodelling of the graft, seven oblique axial MR images (DOA) were taken, on which the graft’s cross-sectional area was measured. The MRI's were performed in the second, sixth, and twelfth week; then in the fourth, sixth, and ninth month, and, finally a year after the surgery. The angle of the graft and PCL was also measured. Additionally, the quality of tendon signal was assessed. For the functional evaluation, isokinetic and isometric tests of the knee extensor and the flexor muscles, along with the tibial rotator functions were performed using Humac Norm device. Postural stability based on COP parameter was established, as well, using the stabilometric platform HUR. For the dynamic stabilography assessment Biodex Balance System device was used. In order to indicate the subjective functional evaluation by the patient, the Lyshom scale and IKDC questionnaires were used.Results:The MRI 12 months after the surgery showed good tendon signal, and no significant changes characteristic for the anterior subluxation of the tibia were observed. In the functional evaluation, very good values of flexor and extensor muscle strength were recorded. These values were comparable to those achieved by the opposing limb. The strength of the left knee rotator muscles was comparable to that of the opposite limb. Additionally, very good stability index was recorded in both static and dynamic conditions. The results the two limbs were comparable. Patient’s subjective evaluation was also assessed to be on a very good level (the results of the IKDC questionnaires were 98,85 and 100/100 on the Lysholm’s scale).Conclusion:The original rehabilitation program in CMC seems to be a valuable protocol conditioning the return to sport activities without disrupting the the remodelling process of the graft. The case described is a part of a bigger project which includes the total of over 30 patients.

Quantifying saphenous reflux.

Quantification of reflux is desirable in advanced chronic venous disease as clinical features are based on its adverse impact on ambulatory venous pressure (AMVP). Prior clinical observation suggests that reflux in a saphenous vein > 5 mm is likely significant. On the basis of normal calf pump mechanics, we hypothesized that a reflux volume ≥ 30 mL was necessary to upset pump equilibrium. Venous laboratory data in 119 limbs with isolated saphenous reflux were analyzed. Reflux volume was calculated by duplex ultrasound (area × velocity × duration). The relationship of reflux volume to saphenous size, calf pump function (air plethysmography, AMVP), flow resistance (Poiseuille equation), and clinical severity were examined. Saphenous size had a bimodal relationship to reflux volume. Reflux volume of ≥ 30 mL occurred mostly (97% of limbs) with saphenous size of ≥ 5.5 mm, but 51% of saphenous veins >5.5 mm had reflux volumes <30 mL. This is because saphenous veins invariably carried less than their maximum reflux potential indicated by their size (Poiseuille equation). Variable additional focal resistance across refluxive valve cusps and narrower re-entry perforators is not taken into account when only saphenous truncal size is used for resistance calculation. Furthermore, the association of AMVP with reflux was found not to be based on a set (≥ 30 mL) threshold but was variable, depending on existing calf pump mechanics, compensatory in some (12% of limbs) and aggravating reflux effects in others (26%). Calf pump abnormalities were found in 70% of refluxive limbs and in 44% (n = 16) of contralateral limbs without any reflux. Reflux volume was significantly higher overall in limbs with ulcer (C6), but the range overlapped with lesser clinical classes. Seven of 14 limbs with active ulcers had reflux volume >30 mL; six of seven limbs with active ulcers and reflux volume of <30 mL had calf pump abnormalities that would be poorly tolerant of reflux even at these smaller volumes. Saphenous size alone cannot be used as an indicator of significant reflux. More than two thirds of the limbs with isolated saphenous reflux have calf pump abnormalities, which also occurred without reflux in the opposite limb--a novel finding. This means that in addition to quantification of reflux volume, calf pump assessment such as with air plethysmography and AMVP is desirable in clinical classes 3 and higher for proper assessment.

A preliminary study of silver sodium zirconium phosphate polyurethane foam wound dressing on wounds of the distal aspect of the forelimb in horses.

To determine if application of silver sodium zirconium phosphate polyurethane semi-occlusive foam (SPF) dressing would improve measures of wound healing and decrease bacterial contamination compared with a non-adherent, absorbent dressing applied to wounds created on the distal aspect of the equine limb. Controlled randomized experimental study. Adult Quarter Horse and Thoroughbred horses (n = 5). One 6.25 cm(2) wound was created on the dorsomedial aspect of the proximal metacarpus on each forelimb. A SPF dressing was applied to 1 randomly assigned limb as a treatment and a non-adherent, absorbent dressing was applied to the opposite limb as control. Bandages were changed every 3 days for 60 days. Granulation tissue was scored every 3 days, wound area measured every 6 days, and wound bed was cultured every 12 days. SPF-treatment wounds had significantly decreased wound area and decreased granulation tissue scores when evaluated <30 days and over the 60 day study, although complete wound healing times were not significantly different. Bacteria were cultured from all wounds at varying times throughout the study. The SPF wound dressing improved some measures of wound healing compared with the control dressing, most significantly during the first 30 days. This suggests that the SPF wound dressing may be useful in the early management of wounds on the equine lower limb. Further studies using the SPF dressing are needed to characterize the temporal and cellular effects on wound healing and evaluate this dressing in a clinical environment.

Muscle coactivation during obstacle crossing corresponding to increasing obstacle height in patients with hemiplegia after stroke

Introduction and aim: Stroke patients often encounter difficulties when crossing obstacles, which contribute to a high rate of falls [1]. Previous studies indicated that patients after stroke excessively elevate their leading limbwhile crossing an obstacle to minimize their risk of falling [1]. This adaptive behaviour occurred even though it is difficult to maintain balance by prolonging the single stance time. However, previous studies generally focused on the leading limb in obstacle crossing tasks; therefore, there is little information regarding the trailing limb. More recently, muscle coactivation during gait was reported as a compensation strategy to enhance postural stability in individuals after stroke [2]. Thus, a change in muscle coactivation in the trailing limb corresponding to an increase in obstacle height may be an indicator of postural stability during obstacle crossing. The aim of this study was to investigate changes in muscle coactivation patterns in the trailing limb using electromyography (EMG); these changes corresponded to an increasing obstacle height in stroke patients with hemiplegia. Patients/materials and methods: Twelve sub-acute patients who suffered a stroke less than 6 months previously participated in this study. Each patient performed several trials in an obstacle crossing task. First, patients performed two self-paced normal walking trials on a 5-m walkway. Subsequently, an obstacle was placed 2–2.5m ahead of the start position at a height that was randomly selected from three heights (0 cm, 4 cm, or 8 cm). The patients were instructed to walk at a self-selected speed and step over the obstacle without stopping. In each condition, EMG activity was recorded in the trailing limb from the tibialis anterior and lateral gastrocnemius muscles. The coactivation index (CoI) was calculated for both the paretic and non-paretic limbs when the trailing limb was in the stance phase. The stance phase was further divided into the three following sub-phases: the first and second double stance (DS1 and DS2), and the single stance (SS). Using the Friedman and Wilcoxon signed-rank tests (with Bonferroni correction),weevaluated theCoI calculatedduring each stance sub-phase. Results: Patients tripped over the obstacle in 16.6% trials when the paretic limb trailed and in 3.7% when the non-paretic limb trailed. When the paretic limb trailed, the paretic limb CoI significantly increased only during DS2 corresponding to an increasing obstacle height (p<0.01). In contrast, when the non-paretic limb trailed, the non-paretic limb CoI significantly increased during both SS (p<0.01) and DS2 (p<0.01) corresponding to an increasing obstacle height. The results for the multiple comparisons are shown in Fig. 1. Discussion and conclusions:When the paretic limb trailed, the paretic limb CoI significantly increased only during DS2. However, muscle coactivation decreased during DS2 in normal gait because the postural stability was no longer mainly required in the trailing limb as the weight was shifted to the opposite limb during this phase [3]. Thus, increased muscle coactivation occurring only during DS2 in the paretic limb with an increasing obstacle height may beanunnecessary adaptation that caused thepatients to frequently trip in these trials. In contrast, the non-paretic limb CoI also significantly increased during SSwith increasing an obstacle heightwhen the non-paretic limb trailed. Thus, although instability increased in the SS phase during obstacle crossing, muscle coactivation in the non-paretic limb increased postural stability during this phase, which resulted in a lower rate of trip trials.

Knee extension fatigue attenuates repeated force production of the elbow flexors

Non-local muscle fatigue has been demonstrated with unilateral activities, where fatiguing one limb alters opposite limb forces. Fewer studies have examined if non-local fatigue occurs with unrelated muscles. The purpose of this study was to investigate if knee extensors fatigue alters elbow flexors force and electromyography (EMG) activity. Eighteen males completed a control and fatiguing session (randomised). Blood lactate was initially sampled followed by three maximal voluntary contractions (MVC) with the elbow flexors and two with the knee extensors. Thereafter, subjects either sat (control) or performed five sets of bilateral dynamic knee extensions to exhaustion using a load equal to the dominant limb MVC (1-min rest between sets). Immediately afterwards, subjects were assessed for blood lactate and unilateral knee extensors MVC, and after 1 min performed a single unilateral elbow flexor MVC. Two minutes later, subjects performed 12 unilateral elbow flexor MVCs (5 s contraction/10 s rest) followed by a third blood lactate test. Compared to control, knee extensor force dropped by 35% (p < 0.001; ES = 1.6) and blood lactate increased by 18% (p < 0.001; ES = 2.8). Elbow flexor forces were lower after the fatiguing protocol only during the last five MVCs (p < 0.05; ES = ∼0.58; ∼5%). No changes occurred between conditions in EMG. Elbow flexor forces significantly decreased after knee extensors fatigue. The effect was revealed during the later stages of the repeated MVCs protocol, demonstrating that non-local fatigue may have a stronger effect on repeated rather than on single attempts of maximal force production.

Validation of surrogate limb analysis for body composition in children by dual energy X-ray absorptiometry (DXA)

Dual energy X-ray absorptiometry (DXA) is a recognized tool for measurement of body composition and provides benefits of low dose radiation, quick scan time and multiple measurement options. Challenges arise in scanning children, particularly with limb movement. We aimed to validate the use of surrogate limb substitutions compared with whole-body scans by DXA for measuring fat, lean and bone mass in children. DXA scans were obtained from 3-year-old children who had normal positioning and no limb movement (n=246) or movement of a single limb (n=55). By replacing the measurements of one scanned limb with those of the opposite limb, we obtained an estimate value that was compared with the original whole-body scan measures for fat, lean and bone mass, percent whole-body fat and total mass for scans without or with movement. Original normal scan analyses were highly correlated with estimates using substitution of the surrogate limb for all body compartments (R(2)=0.986-0.999, P<0.005). The Bland-Altman analysis demonstrated high levels of agreement between the estimates using surrogate limb and original whole-body measurements. Differences in estimate values and variance were greater with limb substitution in scans with movement compared to without movement. Use of limb surrogate methodology for fat mass, lean mass, bone mineral content, percent fat and total mass, is a valid alternative that minimizes variation in estimates of body composition from DXA scans in young children in which a single limb is affected by movement. This will allow inclusion of scans with movement artifact in a single limb for data analysis.

Systematic changes in position sense accompany normal aging across adulthood

BackgroundDevelopment of clinical neurological assessments aimed at separating normal from abnormal capabilities requires a comprehensive understanding of how basic neurological functions change (or do not change) with increasing age across adulthood. In the case of proprioception, the research literature has failed to conclusively determine whether or not position sense in the upper limb deteriorates in elderly individuals. The present study was conducted a) to quantify whether upper limb position sense deteriorates with increasing age, and b) to generate a set of normative data that can be used for future comparisons with clinical populations.MethodsWe examined position sense in 209 healthy males and females between the ages of 18 and 90 using a robotic arm position-matching task that is both objective and reliable. In this task, the robot moved an arm to one of nine positions and subjects attempted to mirror-match that position with the opposite limb. Measures of position sense were recorded by the robotic apparatus in hand-and joint-based coordinates, and linear regressions were used to quantify age-related changes and percentile boundaries of normal behaviour. For clinical comparisons, we also examined influences of sex (male versus female) and test-hand (dominant versus non-dominant) on all measures of position sense.ResultsAnalyses of hand-based parameters identified several measures of position sense (Variability, Shift, Spatial Contraction, Absolute Error) with significant effects of age, sex, and test-hand. Joint-based parameters at the shoulder (Absolute Error) and elbow (Variability, Shift, Absolute Error) also exhibited significant effects of age and test-hand.ConclusionsThe present study provides strong evidence that several measures of upper extremity position sense exhibit declines with age. Furthermore, this data provides a basis for quantifying when changes in position sense are related to normal aging or alternatively, pathology.

New visuomotor maps are immediately available to the opposite limb

Humans can learn to make accurate movements when the required map between vision and motor commands changes, but can visuomotor maps obtained through experience with one limb benefit the other? Complete transfer would require new maps to be both fully compatible and accessible between limbs. However, when this question is addressed by providing subjects with rotated visual feedback during reaching, transfer is rarely apparent in the first few trials with the unpracticed limb and is sometimes absent altogether. Partial transfer might be explained by limited accessibility to remapped brain circuits, since critical visuomotor transformations mediating unilateral movements appear to be lateralized. Alternatively, if adaptation involves movement representations associated with both extrinsic (i.e., direction of motion in space) and intrinsic (i.e., joint or muscle based) frames of reference, new visuomotor maps might be incompatible with opposite limb use when visual distortions have opposite effects for the two limbs in intrinsic coordinates. Here we addressed this issue when subjects performed an isometric aiming task with the index finger. We manipulated the alignment of visuomotor distortion for the two hands in different reference frames by altering body posture relative to the orientation of the finger and the visual display. There was strong, immediate transfer of adaptation between limbs only when visuomotor distortion had identical effects in eye- and joint-based coordinates bilaterally. This implies that new visuomotor maps are encoded in neural circuits associated with both intrinsic and extrinsic movement representations and are available to both limbs.