The Effects of Varying Ankle Foot Orthosis Stiffness on Gait in Children with Spastic Cerebral Palsy Who Walk with Excessive Knee Flexion

Introduction

Rigid Ankle-Foot Orthoses (AFOs) are commonly prescribed to counteract excessive knee flexion during the stance phase of gait in children with cerebral palsy (CP). While rigid AFOs may normalize knee kinematics and kinetics effectively, it has the disadvantage of impeding push-off power. A spring-like AFO may enhance push-off power, which may come at the cost of reducing the knee flexion less effectively. Optimizing this trade-off between enhancing push-off power and normalizing knee flexion in stance is expected to maximize gait efficiency. This study investigated the effects of varying AFO stiffness on gait biomechanics and efficiency in children with CP who walk with excessive knee flexion in stance. Fifteen children with spastic CP (11 boys, 10±2 years) were prescribed with a ventral shell spring-hinged AFO (vAFO). The hinge was set into a rigid, or spring-like setting, using both a stiff and flexible performance. At baseline (i.e. shoes-only) and for each vAFO, a 3D-gait analysis and 6-minute walk test with breath-gas analysis were performed at comfortable speed. Lower limb joint kinematics and kinetics were calculated. From the 6-minute walk test, walking speed and the net energy cost were determined. A generalized estimation equation (p<0.05) was used to analyze the effects of different conditions. Compared to shoes-only, all vAFOs improved the knee angle and net moment similarly. Ankle power generation and work were preserved only by the spring-like vAFOs. All vAFOs decreased the net energy cost compared to shoes-only, but no differences were found between vAFOs, showing that the effects of spring-like vAFOs to promote push-off power did not lead to greater reductions in walking energy cost. These findings suggest that, in this specific group of children with spastic CP, the vAFO stiffness that maximizes gait efficiency is primarily determined by its effect on knee kinematics and kinetics rather than by its effect on push-off power.

Trial Registration

Dutch Trial Register NTR3418     

The Effect of Static Stretch on Elastin Degradation in Arteries

Previously we have shown that gradual changes in the structure of elastin during an elastase treatment can lead to important transition stages in the mechanical behavior of arteries [1]. However, in vivo arteries are constantly being loaded due to systolic and diastolic pressures and so understanding the effects of loading on the enzymatic degradation of elastin in arteries is important. With biaxial tensile testing, we measured the mechanical behavior of porcine thoracic aortas digested with a mild solution of purified elastase (5 U/mL) in the presence of a static stretch. Arterial mechanical properties and biochemical composition were analyzed to assess the effects of mechanical stretch on elastin degradation. As elastin is being removed, the dimensions of the artery increase by more than 20% in both the longitude and circumference directions. Elastin assays indicate a faster rate of degradation when stretch was present during the digestion. A simple exponential decay fitting confirms the time constant for digestion with stretch (0.11±0.04 h⁻¹) is almost twice that of digestion without stretch (0.069±0.028 h⁻¹). The transition from J-shaped to S-shaped stress vs. strain behavior in the longitudinal direction generally occurs when elastin content is reduced by about 60%. Multiphoton image analysis confirms the removal/fragmentation of elastin and also shows that the collagen fibers are closely intertwined with the elastin lamellae in the medial layer. After removal of elastin, the collagen fibers are no longer constrained and become disordered. Release of amorphous elastin during the fragmentation of the lamellae layers is observed and provides insights into the process of elastin degradation. Overall this study reveals several interesting microstructural changes in the extracellular matrix that could explain the resulting mechanical behavior of arteries with elastin degradation.     

Complications of Open Elbow Arthrolysis in Post-Traumatic Elbow Stiffness: A Systematic Review

Objective

The objective of this study was to systematically review the literature for a more comprehensive understanding of the complications of open elbow arthrolysis in patients with post-traumatic elbow stiffness and provide a reference for better prevention and treatment of them.

Methods

The PubMed, EMBASE, Cochrane Library, and Google Scholar databases were searched for therapeutic studies with a set of inclusion and exclusion criteria. Data were extracted from selected articles, and a statistical analysis was performed to evaluate related factors and management of the complications.

Results

Twenty-eight articles published between 1989 and 2013, involving 810 patients, were included. Most of the complications included in the selected articles were nerve complications, heterotopic ossification, elbow instability, infection, pin-related complications and repeat elbow contracture. The total complication rate was 24.3% ± 3.0%, and the reoperation rate was 34.0%. Furthermore, the statistical analysis revealed that preoperative range of motion (β = -0.004, P = 0.01) and proportion of female (β = 0.336, P = 0.04) were the independent factors affecting the total complication rate.

Conclusions

Various risk factors are related to each of the complications, and we found that patients with less preoperative ROM and a higher proportion of female gender may point to a higher total complication rate. Therefore, to further improve the overall outcomes of this procedure, more and larger prospective studies should be performed to further elucidate the effects of prophylactic interventions targeting the risk factors, thus improving the methods of prevention and treatment of complications.     

How Physician Obesity Specialists Use Drugs to Treat Obesity

Specialist physicians may have prescribing habits that are different from nonspecialist physicians. Little is known about the prescribing habits of physicians specializing in the treatment of obesity. An anonymous survey was given to the physician members of the American Society of Bariatric Physicians (ASBP). There was a 35% response rate (266 physicians) to the questionnaire that was represented nationally. Almost all prescribed medications and all of them recommended phentermine. The average maximal dose of phentermine was above that approved in the package insert, and these physicians disagreed with the National Institutes of Health (NIH) Obesity Treatment Guidelines. Phendimetrazine, metformin, and phentermine plus l ‐5‐hydroxytryptophan (5‐HTP) with carbidopa were all used more frequently than either orlistat or sibutramine. The combination of sibutramine and orlistat as well as 5‐HTP/carbidopa were prescribed by 14 and 20%, respectively. As 5‐HTP‐carbidopa was a combination not previously reported for the treatment of obesity, a retrospective chart review was performed in a single obesity practice, which may not be representative. Twenty‐two subjects had a 16% weight loss with phentermine over 6 months and an additional 1% weight loss with the addition of 5‐HTP/carbidopa for an additional 6 months. One subject who started on 5‐HTP/carbidopa alone lost 24.4% of initial body weight over 6 months. This questionnaire revealed that 20% of the obesity specialists responding to the survey used phentermine plus of 5‐HTP/carbidopa, an unreported combination. A controlled, randomized, clinical trial to evaluate the safety and efficacy of this combination in treating obesity should be considered.     

Use of Self-Selected Postures to Regulate Multi-Joint Stiffness During Unconstrained Tasks

Background

The human motor system is highly redundant, having more kinematic degrees of freedom than necessary to complete a given task. Understanding how kinematic redundancies are utilized in different tasks remains a fundamental question in motor control. One possibility is that they can be used to tune the mechanical properties of a limb to the specific requirements of a task. For example, many tasks such as tool usage compromise arm stability along specific directions. These tasks only can be completed if the nervous system adapts the mechanical properties of the arm such that the arm, coupled to the tool, remains stable. The purpose of this study was to determine if posture selection is a critical component of endpoint stiffness regulation during unconstrained tasks.

Methodology/Principal Findings

Three-dimensional (3D) estimates of endpoint stiffness were used to quantify limb mechanics. Most previous studies examining endpoint stiffness adaptation were completed in 2D using constrained postures to maintain a non-redundant mapping between joint angles and hand location. Our hypothesis was that during unconstrained conditions, subjects would select arm postures that matched endpoint stiffness to the functional requirements of the task. The hypothesis was tested during endpoint tracking tasks in which subjects interacted with unstable haptic environments, simulated using a 3D robotic manipulator. We found that arm posture had a significant effect on endpoint tracking accuracy and that subjects selected postures that improved tracking performance. For environments in which arm posture had a large effect on tracking accuracy, the self-selected postures oriented the direction of maximal endpoint stiffness towards the direction of the unstable haptic environment.

Conclusions/Significance

These results demonstrate how changes in arm posture can have a dramatic effect on task performance and suggest that postural selection is a fundamental mechanism by which kinematic redundancies can be exploited to regulate arm stiffness in unconstrained tasks.     

The Use of Free Vibrations to Measure Peduncle Stiffness in Triticale

The possibility of using the period of free vibrations to determineelastic modulus and flexural rigidity of plant material withcontrasting elasticity to viscosity ratios was tested. A simple,easy-to-operate method is described. Both the mature sectionsof Triticale peduncle as well as those sampled from the meristematiczone were found to behave like a lightly damped linear oscillator,providing that the excitements were of a very small amplitude.Elastic modulus calculated from the period of free vibrationsfor the meristematic zone was consistent with most data reportedin the literature for other growing tissues investigated bythe resonance technique. A high gradient of elastic modulus,from 33 MPa to 2·89 GPa per 8 cm was found within thezone of differentiation and development of strengthening tissues.The applicability of the free vibration technique to study plantrigidity as compared to other methods is discussed. Key words: Triticosecale, free vibrations, peduncle, stiffness measurement, Young's modulus     

山莨菪碱作为常规药治疗毒蛇咬伤的研究报告

山莨菪碱是我国首先从茄科植物唐古特莨菪中分离出的一种生物碱, 是改善微循环衰竭的一种特效药物, 特别是在防治蛇伤 Ｄ Ｉ Ｃ或急性肾衰的病例往往收到意想不到的好结果, 另外, 该药在抢救过程中大剂量 ５００ｍ ｇ／ｄ（是普通剂量１０ｍ ｇ 的 ５０ 倍） 使用而未见明显副作用, 因此, １９８７ 年以来我们常规使用山莨菪碱治疗 （重症者配合抗蛇毒血清） 各种毒蛇咬伤７９７ 例, 均收到明显效果, 认为山莨菪碱是防治蛇伤血液毒引起 Ｄ Ｉ Ｃ 出血、急性肾衰、微循环衰竭、 Ｍ Ｓ Ｏ Ｆ的有效药物, 并可减轻神经毒引起的气道分泌物阻塞、提高血氧分压, 减轻缺氧对大脑的损害,竟争保护胆碱能受体、减轻神经毒性、加快自主呼吸恢复的功能。     

龙津降纤酶治疗急性缺血性卒中临床疗效观察

目的 观察龙津降纤酶对急性缺血性情卒中的治疗效果。方法 选择诊断明确的急性因性卒中病人８０例,随机分为２组,对照组４０例,５％葡萄糖液５００ｍｌ加血塞通小射液０．４ｇ静脉滴注,连用１４天,降纤酶组４０例,入院后第１～３天分别给降酶１０ｕ加入生理盐水１００ｍｌ,静脉主１ｈ以上,按临床神经功能缺失程度评分标准于治疗前及治疗在进行疗效评定。结果 降纤酶组总有效率达９２．５％,显效率为７２．５％,明显优于     

Progressive ataxia due to a missense mutation in a calcium-channel gene.

We describe a family with severe progressive cerebellar ataxia involving the trunk, the extremities, and speech. The proband, who has prominent atrophy of the cerebellum, shown by magnetic resonance imaging, was confined to a wheelchair at the age of 44 years. Two sons have episodes of vertigo and ataxia that are not responsive to acetazolamide. Quantitative eye-movement testing showed a consistent pattern of abnormalities localizing to the cerebellum. Genotyping suggested linkage to chromosome 19p, and SSCP showed an aberrant migrating fragment in exon 6 of the calcium-channel gene CACNA1A, which cosegregated with the disease. Sequencing of exon 6 identified a G-->A transposition in one allele, at nucleotide 1152, resulting in a predicted glycine-to-arginine substitution at codon 293. The CAG-repeat expansion associated with spinocerebellar ataxia 6 was not present in any family members. This family is unique in having a non-CAG-repeat mutation that leads to severe progressive ataxia. Since a great deal is known about the function of calcium channels, we speculate on how this missense mutation leads to the combination of clinical symptoms and signs.     

Testing the Use of Static Chamber Boxes to Monitor Greenhouse Gas Emissions from Wood Chip Storage Heaps

This study explores the use of static chamber boxes to detect whether there are fugitive emissions of greenhouse gases (GHGs) from a willow chip storage heap. The results from the boxes were compared with those from 3-m stainless steel probes inserted into the core of the heap horizontally and vertically at intervals. The results from probes showed that there were increases of carbon dioxide (CO₂) concentrations in the heap over the first 10 days after heap establishment, which were correlated with a temperature rise to 60 °C. As the CO₂ declined, there was a small peak in methane (CH₄) concentration in probes orientated vertically in the heap. Static chambers positioned at the apex of the heap detected some CO₂ fluxes as seen in the probes; however, the quantities were small and random in nature. A small (maximum 5 ppm) flux in CH₄ occurred at the same time as the probe concentrations peaked. Overall, the static chamber method was not effective in monitoring fluxes from the heap as there was evidence that gases could enter and leave around the edges of the chambers during the course of the experiment. In general, the use of standard (25 cm high) static chambers for monitoring fluxes from wood chip heaps is not recommended.     

Use of Methotrexate to Treat Isolated Graves Ophthalmopathy Developing Years After Thyroidectomy and Iodine 131 Treatment of Papillary Thyroid Cancer

ObjectiveTo describe a case of Graves ophthalmopathy developing years after subtotal thyroidectomy and radioactive iodine treatment of papillary thyroid cancer.MethodsWe present a case report including clinical and laboratory data. Current relevant literature is reviewed and summarized with regard to Graves ophthalmopathy.ResultsIn 2001, a 51-year-old woman presented with an asymptomatic thyroid nodule. Fine-needle aspiration biopsy results showed Hürthle cells, and the patient had a subtotal thyroidectomy in 2002. Stage 2 follicular variant of papillary thyroid carcinoma was diagnosed. She received radioactive iodine (I 131) therapy (94.8 mCi and 147.2 mCi) in 2003. Thyrotropin was suppressed with levothyroxine. The patient remained asymptomatic and had undetectable thyroglobulin antibodies. In 2007, her eyes became irritated (ie, erythematous, pruritic, watery). Thyroperoxidase and thyroglobulin antibodies were undetectable, but thyrotropin receptor antibody was elevated to 44% (reference range, < 16%). On physical examination, moderate periorbital edema and conjunctival injection were present; orbital magnetic resonance imaging was normal. Computed tomography of her orbits showed symmetric bilateral exophthalmos and prominence of orbital fat. Other ophthalmologic etiologies were ruled out by 2 independent ophthalmologists. She had minimal improvement with oral and intravenous steroids. Subsequent treatment with methotrexate resulted in marked symptomatic improvement and lowered the thyrotropin receptor antibody level to 24%.ConclusionsIsolated Graves ophthalmopathy in a patient after treatment of thyroid cancer and radioactive iodine ablation has not been previously reported. Methotrexate therapy may be a useful therapeutic approach in this setting. (Endocr Pract. 2008;14:422-425)