Lateral wedge insoles for medial knee osteoarthritis: effects on lower limb frontal plane biomechanics

Background

Lateral wedges reduce the peak knee adduction moment and are advocated for knee osteoarthritis. However some patients demonstrate adverse biomechanical effects with treatment. Clinical management is hampered by lack of knowledge about their mechanism of effect. We evaluated effects of lateral wedges on frontal plane biomechanics, in order to elucidate mechanisms of effect.

Methods

Seventy three participants with knee osteoarthritis underwent gait analysis with and without 5° lateral wedges. Frontal plane parameters at the foot, knee and hip were evaluated, including peak knee adduction moment, knee adduction angular impulse, center of pressure displacement, ground reaction force, and knee-ground reaction force lever arm.

Findings

Lateral wedges reduced peak knee adduction moment and knee adduction angular impulse (− 5.8% and − 6.3% respectively, both P < 0.001). Although reductions in peak moment were correlated with more lateral center of pressure (r = 0.25, P < 0.05), less varus malalignment (r values 0.25-0.38, P < 0.05), reduced knee-ground reaction force lever arm (r = 0.69, P < 0.01), less hip adduction (r = 0.24, P < 0.05) and a more vertical frontal plane ground reaction force vector (r = 0.67, P < 0.001), only reduction in knee-ground reaction force lever arm was significantly predictive in regression analyses (B = 0.056, adjusted R² = 0.461, P < 0.001).

Interpretation

Lateral wedges significantly reduce peak knee adduction moment and knee adduction angular impulse. It seems a reduced knee-ground reaction force lever arm with lateral wedges is the central mechanism explaining their load-reducing effects. In order to understand why some patients do not respond to treatment, future evaluation of patient characteristics that mediate wedge effects on this lever arm is required.     

Face and object encoding under perceptual load: ERP evidence

According to the perceptual load theory, processing of a task-irrelevant distractor is abolished when attentional resources are fully consumed by task-relevant material. As an exception, however, famous faces have been shown to elicit repetition modulations in event-related potentials - an N250r - despite high load at initial presentation, suggesting preserved face-encoding. Here, we recorded N250r repetition modulations by unfamiliar faces, hands, and houses, and tested face specificity of preserved encoding under high load. In an immediate (S1-S2) repetition priming paradigm, participants performed a letter identification task on S1 by indicating whether an "X" vs. "N" was among 6 different (high load condition) or 6 identical (low load condition) letters. Letter strings were superimposed on distractor faces, hands, or houses. Subsequent S2 probes were either identical repetitions of S1 distractors, non-repeated exemplars from the same category, or infrequent butterflies, to which participants responded. Independent of attentional load at S1, an occipito-temporal N250r was found for unfamiliar faces. In contrast, no repetition-related neural modulation emerged for houses or hands. This strongly suggests that a putative face-selective attention module supports encoding under high load, and that similar mechanisms are unavailable for other natural or artificial objects.     

脑卒中患者居家照顾负荷因素分析

目的通过了解脑卒中患者居家照顾者负荷的现状（包括生理、心理、社会和经济方面的负荷）,探讨主要照顾者负荷的影响因素（如病人的残障程度、照顾者的特征、社会支持系统等）。方法以问卷调查的方式,抽样2011年4月-6月期间,在我院神经内科门诊复诊的脑卒中患者的居家主要照顾者96例。结果脑卒中患者的日常生活能力需要协助者占55．2％,照顾者所承受的压力明显存在,社会支持系统不足。照顾者负荷的主要因素为患者病程、日常生活能力、照顾者年龄、性别和每日照顾时间等。结论脑卒中患者居家主要照顾者存在压力性负荷,在关注患者的同时也应关注照顾者,完善社区服务,提高社会支持系统的作用。     

The effects of body armour on mobility and postural control of police officers

BackgroundPolice officer use of Individual Light Armour Vests (ILAVs) is increasing due to potential occupational hazards that include blunt trauma, stabbing, and light calibre bullets. It is unclear how addition of this extra load will affect the officer's mobility or postural control.ObjectivesThe aim of this study was to determine the effects of various ILAVs on the mobility and postural control of police officers when compared to wearing their normal station wear.MethodsA prospective, within-subjects, repeated measures study was conducted in which officers wore one of three different ILAV variants or normal station wear (N) and acted as their own controls. Officer mobility was assessed via the Functional Movement Screen (FMS) and postural sway (including total sway, average sway velocity, medial-lateral velocity, anterior-posterior velocity, and total excursion area) via force plate.ResultsSignificant differences were found between ILAV or N conditions in various components of the FMS, including right Straight Leg Raise, left shoulder mobility, and both right and left quad rotary stability. No significant differences were found in any of the balance measures between these conditions.ConclusionIt appears ILAVs can significantly affect police officer mobility and therefore may contribute to injury risk and decreased ability to complete occupational tasks, though this should be weighed against protective benefits. ILAVs should therefore be carefully selected to minimise injury risk without detracting from occupational performance.     

Risks and benefits of timely screw removal after thoracolumbar spine fractures treated with non-fusion technique

BackgroundPercutaneous-short segment screw fixation (SSSF) without bone fusion has proven to be a safe and effective modality for thoracolumbar spine fractures (TLSFs). When fracture consolidation is confirmed, pedicle screws are no longer essential, but clear indications for screw removal following fracture consolidation have not been established.MethodsIn total, we enrolled 31 patients with TLSFs who underwent screw removal following treatment using percutaneous-SSSF without fusion. Plain radiographs, taken at different intervals, measured local kyphosis using Cobb’ angle (CA), vertebra body height (VBH), and the segmental motion angle (SMA). A visual analogue scale (VAS) and the Oswestry disability index (ODI) were applied pre-screw removal and at the last follow-up.ResultsThe overall mean CA deteriorated by 1.58° (p < 0.05) and the overall mean VBH decreased by 0.52 mm (p = 0.001). SMA preservation was achieved in 18 patients (58.1%) and kyphotic recurrence occurred in 4 patients (12.9%). SMA preservation was statistically significant in patients who underwent screw removal within 12 months following the primary operation (p = 0.002). Kyphotic recurrence occurred in patients with a CA ≥ 20° at injury (p < 0.001) with a median interval of 16.5 months after screw removal. No patients reported worsening pain or an increased ODI score after screw removal.ConclusionScrew removal within 12 months can be recommended for restoration of SMA with improvement in clinical outcomes. Although, TLSFs with CA ≥ 20° at the time of injury can help to predict kyphotic recurrence after screw removal, the clinical outcomes are less relevant.     

Instrumented rod rotator system for spinal surgery

An electronically instrumented rod rotator has been developed to monitor forces and moments applied by surgeons during the derotation manoeuver to correct spinal curvature. This instrumented rod rotator consisted of an inclinometer and two pairs of strain gauges, with all the support circuitry. The strain gauge and the inclinometer data were sampled with a data-acquisition system, and the results were displayed in real time. The device was calibrated in the laboratory and used on seven subjects. The precision of the load measurement of this device was ±5 N in the range of 5–65 N. The distance between the middle of the rod rotator handle to the rod position was 0.21 m. The maximum loads applied by the surgeon during seven surgeries were from 22 to 57 N, with a torque (force x distance) from 4.6 to 12 Nm.     

慢性乙型肝炎患者外周血树突状细胞功能状态与HBV载量的关系

目的：探讨慢性乙型肝炎（CHB）患者外周血树突状细胞功能状态与HBV载量的关系。方法：采集23例CHB患者和8例健康人的抗凝外周静脉血，分离外周血单个核细胞（PBMCs），在重组人白细胞介素4和重组人粒细胞-巨噬细胞集落刺激因子的作用下培养使DCs增殖、成熟，以间接免疫荧光流式细胞技术分别检测DCs表面CD80、CD86、HLA-DR及ICAM-1的表达；以ELISA法检测DCs培养上清液中IL-12的水平；将培养成熟的DCs与HBsAg共同孵育，用丝裂霉素C处理后再与自体PBMCs共同培养，在培养结束前12小时加入^3H-TDR，收集细胞，以β液闪计数仪测定cpm值；同期用定量聚合酶链反应技术测定CHB患者外周血HBV载量。结果：患者DCs表面CD86、HLA-DR和ICAM-1的表达水平，DCs的抗原提呈能力及其分泌IL-12的水平均显著低于健康对照组；CD80、CD86、HLA-DR及ICAM-1的表达与HBV载量呈显著负相关关系（分别为P〈0．01、P〈0．01、P〈0．001和P〈0．001）；DCs的抗原提呈能力及其分泌IL-12的水平也与HBV载量呈显著负相关关系（分别为P〈0．001和P〈0．01）。结论：CHB患者外周血DCs的成熟和功能存在障碍，DCs的功能状态与血液中HBV的载量密切相关，并可能对HBV的清除产生重要的影响。     

Load distribution and postural changes in young adults when wearing a traditional backpack versus the BackTpack

Backpacks lead to poor posture due to the posterior placement of the load, which overtime may contribute to low back pain and musculoskeletal complications. This study examined postural and load distribution differences between a traditional backpack (BP) and a nontraditional backpack (BTP) in a young adult population. Using a 3D motion analysis system, 24 healthy young adults (22.5 ± 2.5 years, 12 male) completed both static stance and walking trials on a treadmill with No Load and with 15% and 25% of their body weight using the two different backpacks. There was a significant difference in trunk angle, head angle, and lower extremity joint mechanics between the backpack and load conditions during walking (p < .05). Notably, relative to the No Load condition, trunk angle decreased approximately 14° while head angle increased approximately 13° for the BP 25% state on average. In contrast, average trunk and head angle differences for the BTP 25% state were approximately 7.5° and 7°, respectively. There was also a significant difference in head angle from pre- to post-walk (p < .05) across backpacks, loads, and time. Taken together, the results indicate that the BTP more closely resembled the participants’ natural stance and gait patterns as determined by the No Load condition. The more upright posture supported by the BTP may help reduce characteristics of poor posture and, ideally, help to reduce low back pain while carrying loads.     

杜仲酒抗疲劳作用的实验研究

〔目的〕 观察杜仲酒对小鼠抗疲劳能力的影响。〔方法〕 按卫生部《保健食品的功能学评价程序和检验方法》中抗疲劳检验方法进行测定。〔结果〕 高剂量组负重游泳时间明显高于对照组（Ｐ〈０．０１）;血清尿素氮中、高剂量明显低于对照组（Ｐ〈０．０５或Ｐ〈０．０１）;肝糖元高剂量组明显高于对照组（Ｐ〈０．０１）。〔结论〕 杜仲酒具有抗疲劳作用。     

Loading during the stance phase of walking in humans increases the extensor EMG amplitude but does not change the duration of the step cycle

 Prior work from mammals suggests that load experienced by extensor muscles of the hindlimbs (i.e. Duysens and Pearson 1980; Pearson and Collins 1993; Fouad and Pearson 1997) or cutaneous afferents from the plantar surface of the foot (Duysens and Pearson 1976; Guertin et al. 1995) enhances activity in extensor muscles during the stance phase, and delays the onset of flexor activity associated with the swing phase. The presumed functional significance of this phenomenon is that extensor activity of the supporting limb during walking can: (a) reinforce the supporting function in proportion to the load experienced, and (b) prolong the stance phase until unloading of the limb has occurred. Whether a similar functional role exists for load-sensitive afferents during walking in the human is unknown. In this study, the effect of adding or removing a substantial load (30% of body weight) at the centre of mass was studied in healthy adult human subjects. Loads were applied near the centre of mass to avoid the need for postural adjustments which might confound the interpretation of the results. Subjects walked on a treadmill with either: (a) a sustained increase or decrease in load, or (b) a sudden unexpected increase or decrease in load. In general, subjects responded to the changes in load by changing the amplitude of the extensor electromyographic (EMG) bursts. For example, with sudden unexpected additions in load, the average increase in amplitude was 40% for the soleus across the stance phase, and 134% for the quadriceps during the early part of the stance phase. Extensor EMGs increased with both sustained and sudden increases in load. Extensor EMG durations also increased (average increase in duration of 4% for soleus with sudden loading, and 7% for sustained loading). Cycle duration hardly changed (average increase of 0.5% with both sudden and sustained loading). These results differ from those of infants subjected to a similar perturbation during supported walking. A large change in timing (i.e. an increase in the duration of the stance phase by 30% and the step cycle by 28%) was seen in the infants, with no change in the amplitude of the EMG burst (Yang et al. 1998). These results suggest that the central nervous system can control the timing and amplitude of extensor EMG activity in response to loading independently. Maturation of the two components most likely occurs independently. In the adult, independent control of the two components may provide greater flexibility of the response. Received: 28 April 1998 / Accepted: 3 September 1998