Unrestricted Walking Research Articles

Critical scaling of lattice polymers confined to a box without endpoint restriction

We study self-avoiding walks on the square lattice restricted to a square box of side L weighted by a length fugacity without restriction of their end points. This is a natural model of a confined polymer in dilute solution such as polymers in mesoscopic pores. The model admits a phase transition between an ‘empty’ phase, where the average length of walks are finite and the density inside large boxes goes to zero, to a ‘dense’ phase, where there is a finite positive density. We prove various bounds on the free energy and develop a scaling theory for the phase transition based on the standard theory for unconstrained polymers. We compare this model to unrestricted walks and walks that whose endpoints are fixed at the opposite corners of a box, as well as Hamiltonian walks. We use Monte Carlo simulations to verify predicted values for three key exponents: the density exponent alpha =1/2, the finite size crossover exponent 1/nu =4/3 and the critical partition function exponent 2-eta =43/24. This implies that the theoretical framework relating them to the unconstrained SAW problem is valid.

Low- to moderate-intensity blood flow restricted walking is not an acute equivalent for unrestricted jogging in young active adults

ABSTRACT This study investigated whether walking with blood flow restriction (BFR) increases acute cardio-respiratory demands to the point that it can be considered an alternative for jogging. Sixteen physically active adults completed five experimental sessions (order randomised), comprising 10 min of treadmill exercise. Two sessions included unrestricted walking, two sessions required walking with BFR cuffs positioned on the lower limbs inflated to 60% of individualised arterial occlusion pressure, and one session was conducted at a jogging pace. Comfortable walking and jogging speeds were calculated during the familiarisation session. Walking speeds were individualised to either 100% (speed: 6.0 ± 0.3km·h-1[low-intensity]) or 120% (speed: 7.2 ± 0.3km·h-1[moderate-intensity]) of comfortable walking speed. The jogging session was unrestricted (speed: 9.1 ± 0.7km·h-1). Initial analysis compared walking conditions across heart rate, left cardiac work index, systolic blood pressure, relative oxygen consumption, minute ventilation, rating of perceived exertion and limb discomfort. Secondary analysis compared the walking session with the highest cardio-respiratory demands to jogging. Initial analysis identified that moderate-intensity with BFR induced the highest cardio-respiratory and perceptual responses compared with any other walking sessions (p < 0.01). Secondary analysis revealed that all cardio-respiratory measures were higher during jogging when compared with moderate-intensity with BFR (p < 0.01), except systolic blood pressure (p = 0.10). All perceptual measures were higher during moderate-intensity with BFR (p < 0.01) compared with jogging. Low- to moderate-intensity BFR-walking produces lower acute cardio-respiratory responses at higher ratings of perceived exertion and discomfort compared with jogging. Overall, BFR-walking does not seem to provide an equivalent exercise modality for unrestricted jogging in physically active adults. Highlights In young active adults, walking with blood flow restriction increases cardio-respiratory demands, yet not to a level equivalent to jogging. Moderate-intensity blood flow restricted walking elicits higher exercise-related sensation of exertion and leg discomfort than jogging. Blood flow restriction application increases exercise severity whereby moderate-intensity BFR-walking and jogging are both considered vigorous-intensity exercise.

The identification of fall risk through tests of mediolateral stability during gait.

Many falls in older adults are due to a loss of mediolateral stability during gait. This investigation examines if a simple beam-walking task can assess fall risk in older adults by taxing mediolateral control during gait. 50 older adults (65-96yrs.) and 20 younger adults (20-35yrs.) walked along three 6m long beams (12, 9 and 6cm wide). Distance walked, number of steps and velocity were recorded. Participants also completed the Narrow Path Walking Test on a computerized gait mat and walked unrestricted across the mat. The number of falls in the 6months pre- and post-testing were recorded. The beam data revealed significant differences between fallers and non-fallers in distance walked and number of steps taken on the 9cm beam but not on the other beam widths. The coefficient of variation (CV) for step time and step length for unrestricted walking and for the NPWT were also significantly different between fallers and non-fallers. Falls in the 6months before testing was not correlated with gait velocity but was significantly correlated with the number of steps and the distance walked on the 9cm beam and with step length and step time CV. Falls in the 6months following testing were strongly correlated with distance walked on the 9cm beam. This research suggests that examining an older adult's ability to walk on a 9cm wide beam might contribute significantly to the assessment of that person's fall risk.

Navigation of a Freely Walking Fruit Fly in Infinite Space Using a Transparent Omnidirectional Locomotion Compensator (TOLC).

Animal behavior is an essential element in behavioral neuroscience study. However, most behavior studies in small animals such as fruit flies (Drosophila melanogaster) have been performed in a limited spatial chamber or by tethering the fly’s body on a fixture, which restricts its natural behavior. In this paper, we developed the Transparent Omnidirectional Locomotion Compensator (TOLC) for a freely walking fruit fly without tethering, which enables its navigation in infinite space. The TOLC maintains a position of a fruit fly by compensating its motion using the transparent sphere. The TOLC is capable of maintaining the position error < 1 mm for 90.3% of the time and the heading error < 5° for 80.2% of the time. The inverted imaging system with a transparent sphere secures the space for an additional experimental apparatus. Because the proposed TOLC allows us to observe a freely walking fly without physical tethering, there is no potential injury during the experiment. Thus, the TOLC will offer a unique opportunity to investigate longitudinal studies of a wide range of behavior in an unrestricted walking Drosophila.

Distributed Multimodal Path Queries

Multimodal path queries over transportation networks are receiving increasing attention due to their widespread applications. A multimodal path query consists of finding multimodal journeys from source to destination in transportation networks, including unrestricted walking, driving, cycling, and schedule-based public transportation. Transportation networks are generally continent-sized. This characteristic highlights the need for parallel computing to accelerate multimodal path queries. Meanwhile, transportation networks are often fragmented and distributively stored on different machines. This situation calls for exploiting parallel computing power for these distributed systems. Therefore, in this paper, we study distributed multimodal path (DMP) queries over large transportation networks. We develop algorithms to explore parallel computation. When evaluating a DMP query Q on a distributed multimodal graph Gmult, we show that the algorithms possess the following performance guarantees, irrespective of how Gmult is fragmented and distributed: (1) each machine is visited only once; (2) the total network traffic is determined by the size of Q and the fragmentation of Gmult, independent of the size of Gmult; (3) the response time is decided by the largest fragment of Gmult; and (4) the algorithm is parallel scalable. Using real-life and synthetic data, we experimentally verify that the algorithms are scalable on large graphs.

Postoperative Care Pathways Following Lumbar Total Disc Replacement: Results of a Modified Delphi Approach.

A modified Delphi method was used to establish consensus. Subject matter experts were invited to participate as the expert panel. Best practice statements were distributed to the panel. Panel members were asked to mark "agree" or "disagree" after a series of statements during several rounds until either consensus could be obtained or the practice method was deemed unable to achieve consensus. Lumbar total disc replacement (TDR) is acknowledged as an alternative to spinal fusion in appropriately selected patients. There is a lack of unanimity on the appropriate postoperative patient protocols and rehabilitation expectations for the procedure. The long-term viability of Lumbar TDR, further adoption in the community setting and specific patient outcomes are contingent on the existence of appropriate postoperative recovery programs. Currently there are no established methods for postoperative care following lumbar TDR. Establishing a postoperative clinical pathway algorithm may improve patient outcomes with respect to lumbar TDR. A lumbar TDR expert panel of 22 spine surgeons employed a modified Delphi method to drive consensus on postoperative care following single-level Lumbar TDR. The panel first reviewed literature and guidelines relevant to postoperative care following lumbar TDR. Panel members considered 21 survey questions intended to determine "standard-practice" postoperative care recommendations for patients who have undergone lumbar TDR for the initial recovery phase (0-4 wk) and rehabilitation (4-20 wk). Each panel member participated in a round of anonymous voting followed by a group discussion. Consensus was defined as 80% agreement or higher among the respondents. Consensus was achieved in 11 of the 21 survey questions. There was a high degree of consensus around the key goals for both the initial recovery and rehabilitation phases, ceased use of narcotics for pain management by 4 weeks postoperative, unrestricted walking immediately following surgery, timelines for physical therapy (within 2-4 wk) and return to work based on level of activity (as early as 1 wk postoperative). Lack of agreement included the use of back bracing and timing of postoperative visits. Generally, panel members felt that patient expectations regarding return to function were different following lumbar TDR versus fusion and warrant further study. Surgeon and patient alignment around postoperative expectations may significantly affect the long-term results of lumbar TDR. This surgeon consensus study found agreement for immediate postoperative ambulation, rapid reduction in opioids within the first month, and early return to work. When expectations are appropriately set with patients preoperatively, both provider and patient have shared goals in the return-to-function process. 5.

Hip circumduction is not a compensation for reduced knee flexion angle during gait

It has long been held that hip abduction compensates for reduced swing-phase knee flexion angle, especially in those after stroke. However, there are other compensatory motions such as pelvic obliquity (hip hiking) that could also be used to facilitate foot clearance with greater energy efficiency. Our previous work suggested that hip abduction may not be a compensation for reduced knee flexion after stroke. Previous study applied robotic knee flexion assistance in people with post-stroke Stiff-Knee Gait (SKG) during pre-swing, finding increased abduction despite improved knee flexion and toe clearance. Thus, our hypothesis was that hip abduction is not a compensation for reduced knee flexion. We simulated the kinematics of post-stroke SKG on unimpaired individuals with three factors: a knee orthosis to reduce knee flexion, an ankle-foot orthosis commonly worn by those post-stroke, and matching gait speeds. We compared spatiotemporal measures and kinematics between experimental factors within healthy controls and with a previously recorded cohort of people with post-stroke SKG. We focused on frontal plane motions of hip and pelvis as possible compensatory mechanisms. We observed that regardless of gait speed, knee flexion restriction increased pelvic obliquity (2.8°, p < 0.01) compared to unrestricted walking (1.5°, p < 0.01), but similar to post-stroke SKG (3.4°). However, those with post-stroke SKG had greater hip abduction (8.2°) compared to unimpaired individuals with restricted knee flexion (4.2°, p < 0.05). These results show that pelvic obliquity, not hip abduction, compensates for reduced knee flexion angle. Thus, other factors, possibly neural, facilitate exaggerated hip abduction observed in post-stroke SKG.

Very long-term results of post-traumatic bone defect reconstruction by the induced membrane technique

IntroductionThe induced membrane technique for bone defect reconstruction is now well recognized, and short-term results for bone healing are consistent between published reports. ObjectivesTo assess very long-term functional results in post-traumatic reconstruction using the induced membrane technique. MethodResults for 18 patients undergoing bone defect reconstruction by induced membrane were retrospectively analyzed at 10 to 22years’ follow-up. Initial lesions were multitissue with infection in 14 cases. Reconstruction concerned the tibia in 14 cases, and the humerus, elbow, radius or ulna in 1 case each. Soft-tissue reconstruction was performed in 17 cases, by free flap (n=8) or pedicle flap (n=9). Fixation used a single-plane external fixator in 15 cases, screwed plate in 1 case (humerus), or intramedullary nail in 1 case (ulna). There was 1 crossover from external fixator to internal plate fixation (radius). Assessment comprised radiology, functional assessment, clinical examination and patient satisfaction. All patients were followed up in individual consultation. ResultsEight of the 14 patients with lower limb lesions had unrestricted walking distance; 4 resumed leisure sports. Limb shortening ranged from 0.5 to 4cm and was well-tolerated, although dorsiflexion was abolished or limited in most cases. Several patients underwent second procedures to improve limb function: ankle fusion, Achilles lengthening, tendon transfer, or realignment osteotomy. Radiology found a neotubular aspect, indicating peripheral densification and central resorption. Despite the multiple procedures, no patients regretted the original limb-conserving surgery. All reported that it took 2 to 3years after consolidation and resumption of walking to achieve stable final functional improvement. No recurrent sepsis in the reconstruction zone was found. ConclusionThe present results encourage implementing limb-conserving strategies in young patients after severe multitissue limb trauma, on condition that lesions are properly assessed, notably in terms of infection, and that the reconstruction protocol is feasible and has the patient's consent. Level of evidenceIV, retrospective series.

Preserved gait kinematics during controlled body unloading

BackgroundBody weight supported locomotor training was shown to improve walking function in neurological patients and is often performed on a treadmill. However, walking on a treadmill does not mimic natural walking for several reasons: absent self-initiation, less active retraction of leg required and altered afferent input. The superiority of overground training has been suggested in humans and was shown in rats demonstrating greater plasticity especially in descending pathways compared to treadmill training. We therefore developed a body weight support system allowing unrestricted overground walking with minimal interfering forces to train neurological patients. The present study investigated the influence of different amounts of body weight support on gait in healthy individuals.MethodsKinematic and electromyographic data of 19 healthy individuals were recorded during overground walking at different levels of body weight support (0, 10, 20, 30, 40, and 50%). Upper body inclination, lower body joint angles and multi-joint coordination as well as time-distance parameters were calculated. Continuous data were analyzed with regard to distinct changes within a gait cycle across all unloading conditions.ResultsTemporal gait parameters were most sensitive to changes in body unloading while spatial variables (step length, joint angles) showed modest responses when unloaded by as much as 50% body weight. The activation of the gastrocnemius muscle showed a gradual decrease with increasing unloading while the biceps femoris muscle showed increased activity levels at 50% unloading. These changes occurred during stance phase while swing phase activity remained unaltered.ConclusionsHealthy individuals were able to keep their walking kinematics strikingly constant even when unloaded by half of their body weight, suggesting that the weight support system permits a physiological gait pattern. However, maintaining a given walking speed using close-to-normal kinematics while being unloaded was achieved by adapting muscle activity patterns. Interestingly, the required propulsion to maintain speed was not achieved by means of increased gastrocnemius activity at push-off, but rather through elevated biceps femoris activity while retracting the leg during stance phase. It remains to be investigated to what extent neurological patients with gait disorders are able to adapt their gait pattern in response to body unloading.

Endovascular treatment for chronic lower extremity ischaemia with sub-acute deterioration.

The purpose of this study is to report the efficacy of endovascular treatment for patients with sub-acute (14-day to 2-month) deterioration of chronic lower extremity ischaemia. Between June 2013 and May 2015, 26 consecutive patients (22 men, 4 women; mean age, 68.6 years; range, 50-86 years) were treated for sub-acute deterioration of chronic lower extremity ischaemia in our hospital. All patients were treated with catheter-directed thrombolysis initially and then adjunctive percutaneous transluminal angioplasty and/or stenting was performed to correct underlying lesions. The 26 intra-arterial thrombolysis procedures were all performed in native lower arteries including 8 iliac, 13 femoropopliteal and 5 diffuse occlusions involving the iliac and femoropopliteal segments. Lesion length decreased from 194 mm (70-350 mm) to 92 mm (20-270 mm) after the thrombolytic procedures, and the residual lesions were corrected with percutaneous transluminal angioplasty alone in 4 (15.4%) limbs and stenting in 22 (84.6%) patients. No cross-joint stenting was seen in the 22 affected limbs that used stents. Throughout the treatment process, nine patients with intermittent claudication achieved an unrestricted walking distance, and 17 patients with rest pain or foot ulcers showed significant symptom improvement. The mean ankle-brachial index increased from 0.42 ± 0.16 preoperatively to 0.81 ± 0.25 postoperatively ( p < 0.01). Endovascular therapy with catheter-directed thrombolysis and percutaneous transluminal angioplasty/stenting is feasible for sub-acute deterioration of chronic lower extremity ischaemia patients with favourable midterm results.

Gaze shifts during dual-tasking stair descent.

To investigate the role of vision in stair locomotion, young adults descended a seven-step staircase during unrestricted walking (CONTROL), and while performing a concurrent visual reaction time (RT) task displayed on a monitor. The monitor was located at either 3.5 m (HIGH) or 0.5 m (LOW) above ground level at the end of the stairway, which either restricted (HIGH) or facilitated (LOW) the view of the stairs in the lower field of view as participants walked downstairs. Downward gaze shifts (recorded with an eye tracker) and gait speed were significantly reduced in HIGH and LOW compared with CONTROL. Gaze and locomotor behaviour were not different between HIGH and LOW. However, inter-individual variability increased in HIGH, in which participants combined different response characteristics including slower walking, handrail use, downward gaze, and/or increasing RTs. The fastest RTs occurred in the midsteps (non-transition steps). While gait and visual task performance were not statistically different prior to the top and bottom transition steps, gaze behaviour and RT were more variable prior to transition steps in HIGH. This study demonstrated that, in the presence of a visual task, people do not look down as often when walking downstairs and require minimum adjustments provided that the view of the stairs is available in the lower field of view. The middle of the stairs seems to require less from executive function, whereas visual attention appears a requirement to detect the last transition via gaze shifts or peripheral vision.

Age- and Sex-Related Walking Patterns in Unrestricted Inner City Park Trail Walkers

The present study examined age- and sex-related differences in the walking patterns of recreational park walkers during unrestricted walking. Three video cameras were unnoticeably and sequentially positioned along a paved park trail. Each camera continuously filmed free walkers who consecutively passed three segments of trail: down slope (DS; 5.83o, 83.5 m long), level (LV; 0o, 10 m long), and up slope (US; 8.90o, 98.4 m long, 2.23 m width), for one hour. Cameras recorded a 9-m distance of each representative segment, which was marked by plastic tape 2 cm wide. The visual image was stored on a digital video cassette, and a video digital program (Dart Fish) was utilized for analyzing step length (SL) and walking speed (WS). Only adults and clear images were included for analysis. The sex was identified and the age span was categorized visually into three groups (20 ? 39 years, young; 40 ? 59 years, middle; and ≥ 60 years, old age) by a technician. All recordings were conducted on a clear spring day. A total of 56 men and 121 women passed through all the trail segments analyzed. For men, the average SL was 81.3 ± 9.6, 82.3 ± 7.6, and 80.2 ± 8.8 cm, and the average WS was 1.42 ± 0.20, 1.40 ± 0.18, and 1.29 ± 0.19 m/sec on the DS, LV, and US trail segments, respectively, and was not different between age groups and the segments. For women, both SL (70.2 ± 5.2, 71.7 ± 3.7, and 68.6 ± 8.7 cm) and WS (1.23 ± 0.07, 1.22 ± 0.11, and 1.07 ± 0.18 m/s on the DS, LV, and US trail segments) of the old age group were significantly less than those of the other two age groups as well as that of aged men in corresponding trail segments (p < 0.05). No differences were observed in WS on all the trail segments between men and women. Based on the results, walking patterns of older women were distinctive compared to the youngers and the older men indicating age- and sexrelated differences of free walking in terrestrial environment.

Nutrition, tobacco use, and physical activity in the West Bank, occupied Palestinian territory: an environmental profile of community health

<h3>Background</h3> With the epidemiological transition in the occupied Palestinian territory (oPt), cardiovascular diseases are becoming the leading cause of death. This increase might be partly attributed to changes in tobacco use, physical activity, and nutrition adversely affecting the health of the Palestinian population. Our aim is to describe the environmental factors that might unfavourably contribute to the health-related behaviours of communities in the oPt. <h3>Methods</h3> We used the environmental profile of a community's health (EPOCH) questionnaire to gather data about walking and environmental factors that affect tobacco use and diet in the Palestinian population. The questionnaire was modified for use in the oPt—eg, because Israeli checkpoints create a barrier to walking through or between communities, we included information about the presence and distance of the checkpoints from community centres. 24 communities (nine urban, nine rural, and six refugee camps) were randomly selected from the north, centre, and south of the West Bank. Trained researchers directly noted and systematically recorded physical aspects of the environment, using standardised definitions from the EPOCH questionnaire. This study was approved by the Research Ethics Board at McMaster University, Hamilton, ON, Canada, and the Institute of Community and Public Health Ethical Review Committee, West Bank. <h3>Findings</h3> 17 (71%) of 24 stores had one or more advertisement for unhealthy food and soft drinks; advertisements were more common in urban communities and refugee camps than in rural communities (seven [78%], five [83%], and five [56%], respectively). Food labelling on packets of locally made unhealthy food complied with the Palestinian laws of packaged food items, whereas imported packets did not. Different brands of cigarettes (mean 16 [SD 7]) were widely available in the stores, with urban communities having the highest choice (23 [5] <i>vs</i> 12 [4] in rural and 12 [8] in refugee-camp communities). Local and imported packets of cigarettes did not comply with the Palestinian smoking laws or the WHO Framework Convention on Tobacco Control—eg, warning labels on packets covered less than 20% of the area and none stated the percentage of nicotine or tar. Pavements were present on at least one side of the roads in five (21%) communities and were less common and of poor quality in rural communities. The mean score for pavement quality (maximum score of 10 indicating highest quality) was 5 (range 1–9) in the 24 communities: 8 (5–9) in urban, 3 (1–6) in rural, and 4 (1–7) in refugee camps. In ten (42%) communities (five [56%] urban, one [11%] rural, and four [67%] refugee camp), individuals had to pass through an Israeli army checkpoint to enter the community; checkpoints were a mean distance of 9 km (SD 8) from the community centre. <h3>Interpretation</h3> These findings indicate several environmental factors that could be affecting the health-related behaviours of the Palestinian communities. Existing policies for tobacco and food labelling should be enforced and policies need to be developed to improve unrestricted walking in the local environment. <h3>Funding</h3> Population Health Research Institute.

Physical Activity in Multiple Sclerosis: A Comparative Study of Vitamin D, Brain-Derived Neurotrophic Factor and Regulatory T Cell Populations

Background: Previous studies suggest beneficial effects of exercise in multiple sclerosis (MS). However, knowledge on the effects of physical activity on the immune system is limited. Objective: To assess potential relationships between cardiorespiratory fitness, cognitive function, and immune parameters in physically active and inactive MS patients. Methods: We identified 83 patients with relapsing-remitting disease, an unrestricted walking range, and stable interferon-β treatment from our data base. Based on the subjective report of physical activity, the lower/inactive (n = 21) and upper/active quartiles (n = 21) of patients were selected. We assessed the frequency of T cells, B cells, NK cells, monocytes and regulatory T cell populations by flow cytometry, measured brain-derived neurotrophic factor and vitamin D serum levels by ELISA, and conducted spiroergometry and transcranial sonography. Results: Physical activity and cardiorespiratory fitness were not associated with brain-derived neurotrophic factor, frequency of T regulatory cells or any other immune cell subpopulation. However, we found a positive correlation of vitamin D serum levels with cardiorespiratory fitness. Conclusion: Overall, we found no negative effect of physical activity on the immune system. The association between vitamin D and cardiorespiratory fitness most likely reflects longer hours of sunlight exposure in active patients, suggesting a desirable ‘side- effect’ of physical activity.

Chronic exertional compartment syndrome in diabetes mellitus

Intermittent claudication is common in diabetes mellitus and usually (attributed to arterial disease) . However, a proportion of patients with diabetes have symptoms of claudication without signs of vascular disease and these patients were evaluated for chronic exertional compartment syndrome. Forty-two patients with diabetes (10 men, 32 women), earlier investigated at diabetic clinics because of claudication with no explanation for the symptoms, were examined. Their median age was 48 years (18-72 years) and the median duration of diabetes was 29 years (1-45 years). Thirty-one patients had Type 1 diabetes, 11 had Type 2 diabetes and 29 had diabetic complications. All were investigated clinically, with radiography, bone scan and intramuscular pressure measurements. Thirty-eight of 42 patients with diabetes were diagnosed with chronic exertional compartment syndrome of the lower leg and 32 were treated surgically. Thirty-one patients were operated with fasciotomy of the anterior compartment and 18 also with fasciotomy of the posterior compartment. Additionally, one patient had only fasciotomy of the posterior compartment. Fourteen of 32 surgically treated patients (27 legs) were followed for more than 2 years and rated the post-operative outcome as excellent or good in 21 of the treated legs. The walking distance before lower leg pain increased in all but one patient and seven patients reported unrestricted walking ability. Chronic exertional compartment syndrome should be considered as a differential diagnoses in patients with diabetes and exercise-related lower leg pain. The results after surgery are encouraging and the increased walking ability is beneficial in the treatment of diabetes.

Characteristics of Gait in Restricted Vertical Space versus Unrestricted Walking

Upright walking is not a viable gait option in work environments that have restricted vertical space, such as underground low-seam coal mines (&lt; 1.2 m vertical height). In such circumstances, stoopwalking and crawling must be used. The objective of the current manuscript is to assess the difference between free cadence walking versus stoopwalking (under a 1.2 m ceiling), four-point crawling (hands and knees), and two-point crawling (knees only), both with and without kneepads. Compared to upright walking, stoopwalking resulted in a 24% reduction in gait velocity and exhibited reduced stride length (1.04 versus 1.51 meters). Four-point crawling further slowed gait (to 0.50 m/s) and showed evidence of both trot-like and pace-like interlimb coordination patterns. Gait speed for two-point crawling was only 0.32 m/s.

Muscle Force and Gait Performance: Relationships After Spinal Cord Injury

Wirz M, van Hedel HJ, Rupp R, Curt A, Dietz V. Muscle force and gait performance: relationships after spinal cord injury. Objectives To relate locomotor function improvement, within the first 6 months after spinal cord injury (SCI), to an increase in Lower Extremity Motor Score (LEMS) and to assess the extent to which the level of lesion influenced the outcome of ambulatory capacity. Design Longitudinal and cross-sectional analyses. Setting Seven SCI rehabilitation centers. Participants Patients (N=178) were analyzed longitudinally (group A, motor complete; group B, motor incomplete; nonwalking or group C, motor incomplete and able to stand). The cross-sectional analysis included 86 patients (paraplegic, n=46; tetraplegic, n=40; group 1 with limited and group 2 with unrestricted walking function 6mo after SCI). Interventions Not applicable. Main Outcome Measures Walking Index for Spinal Cord Injury (WISCI), gait speed, and LEMS. Results For group A, 24.8% of the patients improved in LEMS (median range, 0–10) and 7.7% in walking function (WISCI median range, 0–8; mean gait speed range, 0 to .14±.10m/s). For group B, LEMS improved in 93.5% of the patients (median range, 14–28) and walking function in 84.8% of the patients (WISCI median range, 0–10; mean gait speed range, 0 to .41±.45m/s) ( P<.001). For group C, LEMS and walking function improved in 100% of the patients (LEMS median range, 29–41; WISCI median range, 8–16; mean gait speed range, .36±.29m/s to .88±.44m/s) ( P=.001). In groups B and C, the improvement of walking function was greater than in LEMS. The cross-sectional analysis showed that group 1 patients with tetraplegia had more muscle strength (median LEMS, 31.5), and equal walking function (WISCI, 8; walking speed, 0.4±0.3m/s) compared with patients with paraplegia (LEMS, 23; P<.01; WISCI, 12; P=0.6; speed, 0.4±0.3m/s; P=.68). In group 2, patients with tetraplegia had slightly more strength (LEMS, 48) and equal walking function (WISCI, 20; walking speed, 1.4±0.4m/s) compared with patients with paraplegia (LEMS, 45; P<.05; WISCI, 20; P=1.0; speed, 1.4±0.3m/s; P=.89). Conclusions An improvement in locomotor function does not always reflect an increase in LEMS, and LEMS improvement is not necessarily associated with improved locomotor function. LEMS and ambulatory capacity are differently associated in patients with tetra- and paraplegia. Functional tests seem to complement clinical assessment.

A 25-Year-Old Patient With Spontaneous Hemothorax

A 25-year-old African-American woman with a chief complaint of progressive dyspnea and cough presented to the inpatient service after her primary care physician noted a significant right-sided pleural effusion on a chest radiograph. She had a 2to 3-year history of intermittent, sharp, pleuritic chest pain radiating from the right subscapular region, across the anterior chest, and down the right arm that worsened with cough and accompanied this episode. Three months prior to hospital admission, dyspnea had developed with exertion and cough productive of white sputum. She sought medical attention 2 months prior to hospital admission, but two courses of outpatient antibiotic therapy did not ameliorate her condition. Her activity level deteriorated from unrestricted walking to dyspnea at rest. She was receiving no medications, and did not drink alcohol, smoke cigarettes, or use recreational drugs. Coccidioidomycosis was previously diagnosed in a family member. The patient had noted occasional abdominal bloating, night sweats, and chills without fever, and an 8-lb unintentional weight loss over the previous 3 months. She had no known tuberculosis exposures, and a recent tuberculin skin test result was negative. She denied rash, joint pain, nausea, hemoptysis, orthopnea, hematochezia, dizziness, visual changes, dyspareunia, or dyschezia. She has a history of dysmenorrhea and was on her menses at the time of hospital admission. In the emergency department, she was noted to have a large, right-sided pleural effusion (Fig 1). Thoracentesis revealed bloody fluid. A chest tube was inserted and drained 2.6 L of bloody pleural fluid. On examination, the patient was a thin, AfricanAmerican woman in no distress. Her chest examination revealed an appropriately placed chest tube, a soft-tissue fullness over her right scapula, which was tender to palpation, and absent breath sounds on the right side. Ascites, without organomegaly, was present on abdominal examination. The remainder of the examination was normal.

Anatomical repair of lateral ligaments in patients with chronic ankle instability

In a prospective study, 19 patients with chronic ankle instability underwent clinical and radiographic reexaminations 36 months after anatomical reconstruction. In addition, dynamic pedography was conducted and peroneal reaction time measured on a tilting platform for an evaluation of functional aspects. Prior to this examination, 32 patients had been asked to fill in a questionnaire and make a detailed subjective evaluation of current discomfort, stability, flexibility and sporting abilities. Eighty-eight percent of the patients reported satisfactory results; only 3% complained of persistent instability. In 71% the ability to take part in sports had improved after surgery, and 85% of the patients reported unrestricted walking abilities. Supination ability was impaired in 5% of the patients at the follow-up. The radiographic examination showed restored ankle stability with a significant reduction of talar tilt and talar translation; a postoperative increase in signs and symptoms of arthrosis was not observed. Dynamic pedography showed a large degree of symmetry of plantar pressure distribution after surgery. There were no significant differences in peroneal reaction time in the repaired and intact ankles. The results of the study show that it is possible to restore ankle stability with anatomical reconstruction without impairing the range of movement in the ankle joint complex. Progressive osteoarthrosis can be prevented.

Restricting arm use enhances compensatory reactions of leg muscles during walking

A number of recent studies have indicated that whole-body coordinated reactions are employed to regain balance following disturbances during walking. However, it is not always the case that all body segments are available to contribute to balance corrective strategies. We hypothesize that balance corrective strategies will adapt to task and environment constraints such that greater responses are generated in the available body segments when other body segments are unable to participate. In this study, we tested the hypothesis that voluntarily restricting the arms during walking would result in an increase in the amplitude of the electromyographic responses evoked in leg muscles when subjects are perturbed at the torso during walking. To do so, subjects were asked to walk on a motorized treadmill while either crossing their arms across their front or back, or with their arms swinging normally. Periodic perturbations, forwards and backwards, were applied at the pelvis randomly throughout the step cycle. This resulted in short latency responses in leg muscles. The amplitude of these responses was increased when subjects walked with their arms crossed, as compared with normal, unrestricted walking. Facilitation of these evoked responses was restricted to the early part of the stance phase, particularly at heel-strike. The pattern of muscle activation and the latency of the responses were not affected by restricting the arms. We suggest that this finding indicates that whole-body balance corrective strategies employed during walking are selected based upon the demands of the general features of the task, but that components of the strategy are scaled according to the specific context-dependent needs of the task.