Assessment of neuromuscular response characteristics at the knee following a functional perturbation.

Previous research indicates that both the extent and timing of muscular activation at the knee can be influenced by muscle activity state, joint angle, weight-bearing status and trunk position. However, little research to date has evaluated protective neuromuscular response times and activation patterns to an imposed perturbation with the knee joint in a functional, weight-bearing stance. Hence, we designed a lower extremity perturbation device to produce a sudden, forward and either internal or external rotation moment of the trunk and femur relative to the weight-bearing tibia. Surface electromyography (EMG) recorded long latency reflex times of the medial and lateral quadriceps, hamstring and gastrocnemius muscles in 64 intercollegiate lacrosse and soccer players in response to both internal and external rotation perturbation. We found the gastrocnemius fired significantly faster that the hamstring, which in turn fired significantly faster than the quadriceps. There was also a significant difference in activation times of the medial and lateral hamstring not found for the quadriceps or gastrocnemius muscles. Our findings confirmed that reactive neuromuscular responses following this functional perturbation differ markedly from those previously reported using seated, partial weight-bearing and/or uni-planar models under relaxed conditions.     

Effect of daily short-duration weight-bearing on disuse-induced deterioration of musculoskeletal system

Objectives:

To investigate deterioration of musculoskeletal system due to prolonged disuse and the potential of daily short-duration weight-bearing as countermeasures.

Methods:

Twenty-four adult male Sprague-Dawley rats were divided into Control Group (CG, no intervention), Tail-suspension Group (TG, tail-suspension without treatment), and Weight-Bearing Group (WBG, tail-suspension with 20 min/day, 5 days/week body weight loading). After four weeks of treatment, femur and tibia, soleus and extensor digitorum longus were evaluated for bone and muscle quality respectively. Tensile properties of bone-tendon insertion (BTI) were evaluated using patella-patellar tendon complex.

Results:

Disuse induced deterioration on bone, muscle, and BTI after four weeks. Compared with CG, TG and WBG showed significant decrease in bone mineral density (BMD) of trabecular bone in distal femur (4.3-15.2%), muscle mass (31.3-52.3%), muscle cross-sectional area (29.1-35%), and failure strength of BTI (23.9-29.4%). Tensile test showed that the failure mode was avulsion of bone at the BTI. No significant difference was detected between TG and WBG for all assessments on bone, muscle, and BTI.

Conclusions:

Disuse caused deterioration of bone, muscle, and BTI while daily short-duration of weight-bearing did not prevent this deterioration. Mechanical stimulation with higher intensity and longer duration may be necessary to prevent musculoskeletal deterioration resulted from prolonged disuse.     

The nutrient flap: a new concept of the role of the flap and application to the salvage of arteriosclerotic lower limbs

The nutrient flap is a new concept of the role of the flap. It has three functions: (1) it provides supplementary blood flow to ischemic zones, (2) it assists venous drainage in regions of venous insufficiency, and (3) it induces the formation of a capillary network. Its skin covering role is only accessory. We have applied this principle to osteitis, pseudoarthrosis, and arteriosclerosis. The nutrient flap constitutes a new type of treatment for stage IV arteriosclerosis of the lower limbs when classical revascularization techniques cannot be performed and when high amputation is indicated. Four clinical cases and the surgical techniques used are described. The flap, usually raised from the latissimus dorsi, is anastomosed to the popliteal artery by means of an inverted saphenous vein graft. It is applied to the distal extremity of the limb after excision of the necrotic tissues. The nutrient flap preserves weight-bearing by maintaining the heel.     

Muscle forces during running predicted by gradient-based and random search static optimisation algorithms

Muscle forces during locomotion are often predicted using static optimisation and SQP. SQP has been criticised for over-estimating force magnitudes and under-estimating co-contraction. These problems may be related to SQP's difficulty in locating the global minimum to complex optimisation problems. Algorithms designed to locate the global minimum may be useful in addressing these problems. Muscle forces for 18 flexors and extensors of the lower extremity were predicted for 10 subjects during the stance phase of running. Static optimisation using SQP and two random search (RS) algorithms (a genetic algorithm and simulated annealing) estimated muscle forces by minimising the sum of cubed muscle stresses. The RS algorithms predicted smaller peak forces (42% smaller on average) and smaller muscle impulses (46% smaller on average) than SQP, and located solutions with smaller cost function scores. Results suggest that RS may be a more effective tool than SQP for minimising the sum of cubed muscle stresses in static optimisation.     

Muscle forces during running predicted by gradient-based and random search static optimisation algorithms

Muscle forces during locomotion are often predicted using static optimisation and SQP. SQP has been criticised for over-estimating force magnitudes and under-estimating co-contraction. These problems may be related to SQP's difficulty in locating the global minimum to complex optimisation problems. Algorithms designed to locate the global minimum may be useful in addressing these problems. Muscle forces for 18 flexors and extensors of the lower extremity were predicted for 10 subjects during the stance phase of running. Static optimisation using SQP and two random search (RS) algorithms (a genetic algorithm and simulated annealing) estimated muscle forces by minimising the sum of cubed muscle stresses. The RS algorithms predicted smaller peak forces (42% smaller on average) and smaller muscle impulses (46% smaller on average) than SQP, and located solutions with smaller cost function scores. Results suggest that RS may be a more effective tool than SQP for minimising the sum of cubed muscle stresses in static optimisation.     

Effect of biceps-to-triceps transfer on rotator cuff stress during upper limb weight-bearing lift in tetraplegia: A modeling and simulation analysis

Rotator cuff stress during upper limb weight-bearing lifts presumably contribute to rotator cuff disease, which is the most common cause of shoulder pain in individuals with tetraplegia. Elbow extension strength appears to be a key determinant of rotator cuff stress during upper limb weight-bearing lifts since individuals with paraplegia who generate greater elbow extensor moments experience lower rotator cuff stress relative to individuals with tetraplegia. Biceps-to-triceps transfer surgery can increase elbow extension strength in individuals with tetraplegia. The purpose of this study was to determine whether active elbow extension via biceps transfer decreases rotator cuff stress during weight-bearing lifts in individuals with tetraplegia. A forward dynamics computational framework was used to estimate muscle stress during the lift; stress was computed as muscle force divided by the peak isometric muscle force. We hypothesized that rotator cuff stresses would be lower in simulated lifting with biceps transfer relative to simulated lifting without biceps transfer. We found that limited elbow extension strength in individuals with tetraplegia, regardless of whether elbow strength is enabled via biceps transfer or is residual after spinal cord injury, results in muscle stresses exceeding 85% of the peak isometric muscle stress in the supraspinatus, infraspinatus, and teres minor. The rotator cuff stresses we estimated suggest that performance of weight-bearing activities should be minimized or assisted in order to reduce the risk for shoulder pain. Our results also indicate that biceps transfer is unlikely to decrease rotator cuff stress during weight-bearing lifts in individuals with tetraplegia.     

A new ambulatory foot pressure device for patients with sensory impairment. A system for continuous measurement of plantar pressure and a feed-back alarm

Abnormal and excessive plantar pressure is a major risk factor for the development of foot ulcers in patients with loss of protective pain sensation. Repeated pressure with each step can result in inflammation at specific points, followed by ulcer formation. Patients with peripheral nerve disease are unable to prevent the development of such lesions, which often lead to amputation. For this reason, it has been suggested that a fundamental therapeutic intervention should be the reduction of high plantar pressure. We have developed a portable, battery-operated ambulatory foot pressure device (AFPD) which has two important functions: (1) to determine the areas of high plantar pressure, and (2) to provide an acoustic alarm, adjusted to a specific pressure load, which is triggered when weight-bearing exceeds the predetermined plantar pressure. A memory of plantar pressure parameters allows for downloading of the data and sequential analysis during the investigation period. Such an alarm device could replace the lack of pain sensation and may play an important role in the prevention of ulcer development and lower extremity amputation.     

A model-based study of passive joint properties on muscle effort during static stance

This study examined the impact of lower extremity joint stiffnesses and simulated joint contractures on the muscle effort required to maintain static standing postures after a spinal cord injury (SCI). Static inverse computer simulations were performed with a three-dimensional 15 degree of freedom musculoskeletal model placed in 1600 different standing postures. The required lower extremity muscle forces were calculated through an optimization routine that minimized the sum of the muscle stresses squared, which was used as an index of the muscle effort required for each standing posture. Joint stiffnesses were increased and decreased by 100 percent of their nominal values, and contractures were simulated to determine their effects on the muscle effort for each posture. Nominal muscle and passive properties for an individual with a SCI determined the baseline muscle effort for comparisons. Stiffness changes for the ankle plantar flexion/dorsiflexion, hip flexion/extension, and hip abduction/adduction directions had the largest effect on reducing muscle effort by more than 5 percent, while changes in ankle inversion/eversion and knee flexion/extension had the least effect. For erect standing, muscle effort was reduced by more than 5 percent when stiffness was decreased at the ankle plantar flexion/dorsiflexion joint or hip flexion/extension joint. With simulated joint contractures, the postural workspace area decreased and muscle effort was not reduced by more than 5 percent for any posture. Using this knowledge, methods can be developed through the use of orthoses, physical therapy, surgery or other means to appropriately augment or diminish these passive moments during standing with a neuroprosthesis.     

植物提取物槲皮素调节小鼠的能量代谢和氧化应激

为了探讨植物提取物槲皮素对负重游泳小鼠的能量代谢和氧化应激的影响,本研究将45只SPF级雄性昆明小鼠随机分为正常对照组、游泳组和槲皮素组,每组15只。槲皮素组小鼠喂养2 g/kg的槲皮素饲料,其他组小鼠喂养标准饲料,共喂养14 d。然后将游泳组和槲皮素组小鼠按照体重的3%进行负重游泳1 h,测定各组小鼠的血糖、乳酸、尿素氮、游离脂肪酸、琥珀酸脱氢酶、三磷酸腺苷、丙二醛、谷胱甘肽过氧化物酶和总抗氧化活性。结果显示,负重游泳后,槲皮素组血清乳酸和尿素氮水平显著低于游泳组,并且槲皮素组游离脂肪酸水平显著高于游泳组。负重游泳后,游泳组小鼠的肝脏和肌肉组织中的琥珀酸脱氢酶含量均显著降低,槲皮素组小鼠游泳后未见明显降低。负重游泳后,游泳组小鼠肌肉组织中的ATP酶活性显著降低,槲皮素组小鼠游泳后未见明显降低。负重游泳后,槲皮素组的丙二醛含量显著低于游泳组。游泳组和槲皮素组小鼠负重游泳后的谷胱甘肽过氧化物酶含量均显著降低,槲皮素组小鼠的谷胱甘肽过氧化物酶含量未见明显降低。游泳组小鼠血清总抗氧化活性显著低于对照组,而槲皮素组与对照组无显著差异。本研究初步表明,槲皮素可调节负重游泳小鼠的能量代谢来起到抗疲劳作用,主要机制与增加脂肪动员、抑制蛋白质分解和加强三羧酸循环有关。另外,槲皮素可通过抑制脂质过氧化、清除超氧阴离子自由基来防止运动过程中的氧化应激损伤。     

Lower extremity muscle perforator flaps for lower extremity reconstruction

A true muscle perforator flap is distinguished by the requisite intramuscular dissection of its musculocutaneous perforator to capture the same musculocutaneous territory but with total exclusion of the muscle, and thereby results in minimal functional impairment. Adhering to this definition, several lower extremity donor sites now are available, each with specific attributes especially useful for consideration in the treatment of lower extremity defects. In this author's experience over the past two decades, 20 lower extremity muscle perforator flaps using multiple donor sites proved advantageous for lower extremity coverage problems as either a local pedicled flap or as a microsurgical tissue transfer. Significant complications occurred in 30 percent of flaps (six of 20) in that further intervention was required. Venous insufficiency and bulkiness were found to be the major inherent shortcomings. However, giant flaps, lengthy and large-caliber vascular pedicles, and the possibility for combined flaps were important assets. The choice of a lower extremity muscle perforator flap for lower extremity reconstruction limited the surgical intervention and morbidity to a single body region.     

Lower extremity microsurgical reconstruction

LEARNING OBJECTIVES: After studying this article, the participant should be able to: 1. Understand the indications for the use of free-tissue transfer in lower extremity reconstruction. 2. Understand modalities to enhance the healing and care of soft tissue and bone before free-tissue transfer. 3. Understand the lower extremity reconstructive ladder and the place of free-tissue transfer on the ladder. 4. Understand the specific principles of leg, foot, and ankle reconstruction. 5. Understand the factors that influence the decision to perform an immediate versus a delayed reconstruction. Free-tissue transfer using microsurgical techniques is now routine for the salvage of traumatized lower extremities. Indications for microvascular tissue transplantation for lower extremity reconstruction include high-energy injuries, most middle and distal-third tibial wounds, radiation wounds, osteomyelitis, nonunions, and tumor reconstruction. The authors discuss the techniques and indications for lower extremity reconstruction.     

Perception of unsteadiness in patients with dizziness: association with handicap and imbalance

Dizziness is a common problem in patients seeking medical help and is often associated with imbalance and handicap. This study aimed to reveal whether the perception of unsteadiness could be an indication of greater imbalance and handicap in these patients. Patients with dizziness were categorized into two groups, steady patients (n = 15) and unsteady patients (n = 23), based on the presence or absence of self-perceived unsteadiness. The level of self-perceived handicap was evaluated by the Dizziness Handicap Inventory. Static balance ability was evaluated using a force platform and the center of pressure motion was calculated during various quiet standing conditions. Dynamic balance ability was evaluated by the functional forward reach test and Dynamic Gait Index. All the patients also went through isometric strength tests of the lower extremities. It was found that all patients reported themselves to be handicapped by dizziness. Patients who perceived themselves to be unsteady had greater handicap and poorer static standing, but did not differ from the steady patients in regard to muscle strength or functional balance tests. Thus, self- perceived unsteadiness was associated with greater handicap and poorer static balance in dizzy patients. In clinical management of these patients, special attention should be paid to balance and handicap.     

The radial forearm flap: reconstructive applications and donor-site defects in 35 consecutive patients

Thirty-five consecutive patients treated with the radial forearm flap were reviewed. This flap was used in head and neck reconstruction in 25 patients, soft-tissue cover of an extremity in 9 patients, and as a new technique for penile reconstruction in 1 patient. Osteocutaneous flaps were used for mandibular reconstruction in 13 patients. In 6 patients innervated flaps were used to provide sensation on the dorsum of the hand or on the weight-bearing surface of the foot. There was only one total flap failure and no partial failures. Recipient-site complications were few, with prompt healing and very acceptable appearance. Donor-site complications included partial loss of the skin graft with tendon exposure in 10 patients (33 percent), an unsatisfactory appearance in 5 patients (17 percent), and one case of radial fracture (8 percent). On functional testing, there was no significant loss of strength or joint mobility in the donor extremity in 19/20 patients. The authors recommend measures to reduce donor-site morbidity and conclude that, with an acceptable donor site, this flap is valuable in a variety of reconstructive applications.     

Predicting asymmetrical lower extremity strength deficits in college-aged men and women using common horizontal and vertical power field tests: a possible screening mechanism

Strength deficits in the quadriceps and hamstrings have been linked to several lower extremity injuries. The most common protocol used in testing for these deficits is isokinetic strength testing, which is both costly and time consuming. Therefore, the purpose of this study was to employ common vertical and horizontal power field tests to identify those protocols that best predict lower extremity strength deficits. Data describing 22 healthy collegiate graduate students' vertical and horizontal power were collected using standard field tests (i.e., 2 feet vertical jump, single leg vertical jump, 40-, 50-, and 60-yd runs). In addition, data describing each subject's lower extremity strength deficits were collected by using the Biodex 840-000 Multi Joint System Isokinetic Dynamometer (Biodex Medical Systems, Shirley, NY, USA) set to report peak torque at 60° · s of flexion and extension and 180° · s of flexion and extension. Regression analyses indicated that 3 of the 4 strength deficit parameters could be predicted from a linear combination of field test results (p < 0.05). Of the strength deficits measured, hamstring deficits at flexion velocities of both 60° · s and quadriceps strength deficits at 60° · s were those that could be predicted using field test results. The results of this study, by increasing the diagnostic power of the clinician, may make it easier to develop strength training protocols designed specifically to target weak musculature in the lower extremity. This targeting of specific musculature, in an effort to return symmetrical strength to the lower extremity, may ultimately decrease the likelihood of lower extremity injury in college-aged men and women.     

D-二聚体、P-选择素及血管内皮生长因子与下肢骨折患者深静脉血栓形成的关系

摘要 目的：探究D-二聚体(D-D)、P-选择素及血管内皮生长因子(VEGF)与下肢骨折患者深静脉血栓(DVT)形成的关系。方法：选取2017年2月至2019年10月期间我院诊治的80例下肢骨折并发DVT患者作为DVT组,选择同期治疗的95例下肢骨折但未并发DVT患者作为无DVT组。比较两组患者的各项临床资料,采用多因素Logistic回归分析下肢骨折患者DVT发生的危险因素,采用受试者工作特征（ROC）曲线分析血清D-D、P-选择素、VEGF对下肢骨折患者DVT的诊断价值。结果：与无DVT组相比,DVT组血清D-D、P-选择素和VEGF水平明显升高（P<0.05）。多因素Logistic回归分析结果显示血清D-D、P-选择素、VEGF是下肢骨折患者DVT发生的危险因素（OR=1.996、2.335、1.743,P<0.05）。ROC曲线分析结果显示血清D-D、P-选择素、VEGF诊断下肢骨折患者DVT的曲线下面积（AUC）分别为0.771、0.790、0.812,血清D-D、P-选择素、VEGF联合诊断下肢骨折患者DVT的AUC为0.945。结论：下肢骨折合并DVT患者血清D-D、P-选择素、VEGF水平明显升高,并且血清D-D、P-选择素和VEGF是下肢骨折患者发生DVT的危险因素,三者联合检测在下肢骨折患者发生DVT的诊断和预测中具有一定临床意义。     

An instrumented wheel for kinetic analysis of wheelchair propulsion.

An instrumented wheel system for three-dimensional kinetic analysis of upper extremity during wheelchair propulsion has been designed and validated. This system allows the direct measurements of three-dimensional dynamic forces and moments on the handrim during wheelchair propulsion in a laboratory setting as well as in the field. Static loading tests showed a high linearity and little drift (coefficient of determination, r2 > 0.999). Under dynamic loading, the instrumented wheel provided the well-matched measurement forces and moments with the predicted values from the inverse dynamic method using video-based kinematic data (correlation coefficient, p > 0.97). The three-dimensional handrim forces and moments during wheelchair propulsion by a non-disabled subject were demonstrated.     

Soft-tissue expansion in the lower extremities

Soft-tissue expansion enjoys ever-wider use, but to date an experience using this technique in the lower extremity has never been presented. We reviewed our first 16 patients to describe the indications and contraindications for the use of tissue expansion in the lower extremity. Guidelines evolved from study of the data. Soft-tissue expansion merits consideration for coverage of problem wounds, in preparation for removal of large benign lesions, and for the repair of contour defects. The operator should know that an open wound below the knee predicts a complication if soft-tissue expansion is attempted in that location. In the thigh, incisions can be confidently placed at the edge of the defect. In every location, large expanders should be chosen so that they are as long as or longer than the adjacent defect. The increase in circumference of the limb should be followed. Simple designs for advancement flaps usually work well. As our experience has grown, reconstruction using soft-tissue expansion in the lower extremity has become safer and the results more predictable through better patient selection and diligent monitoring of intraluminal pressures, even if only by ensuring that the patient is always comfortable. Soft-tissue expansion has a role in reconstruction of the lower extremity.     

2型糖尿病患者血糖波动与心律失常和下肢血管病变的关系及其影响因素分析

目的:探讨2型糖尿病(T2DM)患者血糖波动与心律失常和下肢血管病变的关系,分析影响T2DM心律失常和下肢血管病变的因素。方法:选择2019年7月到2020年6月我院收治的82例T2DM患者,根据是否合并心律失常分为心律失常组28例和无心律失常组54例,根据是否合并下肢血管病变分为下肢血管病变组31例和无下肢血管病变组51例。所有患者均通过72 h监测血糖获得日内平均血糖波动幅度(MAGE)、日间血糖平均绝对差(MODD)、全天血糖标准差(SDBG)、全天血糖波动次数(NGE)。比较组间差异,分析影响T2DM患者心律失常和下肢血管病变的因素。结果:心律失常组MAGE、MODD、SDBG、NGE、糖化血红蛋白(HbA1c)、胰岛素抵抗指数(HOMA-IR)、T2DM病程、同型半胱氨酸(Hcy)、丙二醛(MDA)高于无心律失常组(P<0.05)。下肢血管病变组T2DM病程、Hcy、MDA、HOMA-IR、MAGE、MODD、SDBG、NGE均高于无下肢血管病变组(P<0.05)。Logistic回归分析结果显示MDA、HOMA-IR、MAGE、MODD是T2DM患者心律失常的危险因素(P<0.001),MAGE、MODD、SDBG是T2DM患者下肢血管病变的危险因素(P<0.001)。结论:T2DM患者血糖波动与心律失常和下肢血管病变均有关,血糖波动增加是T2DM心律失常和下肢血管病变的危险因素。     

2型糖尿病合并下肢动脉粥样硬化的危险因素

下肢动脉粥样硬化是2型糖尿病(T2DM)患者最常见的大血管并发症之一。作为T2DM患者严重的慢并发症之一,下肢动脉粥样硬化可引起糖尿病足的发生,严重情况下可导致足坏疽。因此,阐明T2DM合并下肢动脉粥样硬化的危险因素,早期预防和治疗糖尿病合并下肢动脉粥样硬化症,不仅提高了患者的生活质量,而且减轻了家庭和社会的经济负担,具有较大的现实意义。影响T2DM患者下肢动脉粥样硬化的因素错综复杂,分为不可调控的和可调控的因素,不可调控的危险因素包括年龄、种族、遗传等,可调控的危险因素包括吸烟、高血糖、高血脂、高血压,以及近年提出的肥胖、胰岛素抵抗、高纤维蛋白血症、炎症等。本文就T2DM合并下肢动脉粥样硬化的危险因素做一综述。     

NLR、MPVLR、MPV在全膝关节置换术后急性下肢深静脉血栓形成诊断中的影响价值

摘要 目的：分析全膝关节置换术后急性下肢深静脉血栓（DVT）形成中NLR、MPVLR、MPV的临床诊断价值。方法：于本院2020年10月-2021年10月接受全膝关节置换术患者中筛选80例开展研究,纳入对象接受手术治疗后3到5日内接受彩色超声下肢DVT检查,依据检查证实是否发生下肢DVT作为分组标准,将结果证实发生下肢DVT患者43例纳入观察组,未发生的37例纳入对照组。两组同时接受血常规检查,汇总平均血小板体积（MPV）、淋巴细胞计数、中性粒细胞,并依据结果计算中性粒细胞/淋巴细胞计数（NLR）,平均血小板体积/淋巴细胞计数（MPVLR）,对患者临床资料展开回顾性分析,判断发生/未发生组别患者各项指标从差异,进而评价MPV、NLR、MPVLR对术后急性下肢DVT形成诊断的诊断价值。结果：发生下肢DVT与未发生下肢DVT患者,在性别、年龄、慢性病史（高血压、糖尿病）、吸烟史、体质量指数等方面,未见明显差异（P>0.05）。和未发生下肢DVT患者相比,发生下肢DVT患者中心粒细胞相对较低,淋巴细胞和血小板计数相对加高（P<0.05）。两组在白细胞上差异不大（P>0.05）。发生下肢DVT患者MPV、NLR、MPVLR明显高于未发生手术患者（P<0.05）;肿胀天数在7天及以上、高于7天患者在NLR指标上差异不大（P＞0.05）,而在MPVLR上组间有统计学差异（P<0.05）。结论：MPV、NLR、MPVLR指标对于判断全膝关节置换术治疗后判断是否发生急性下肢DVT具有较高诊断价值,其中MPVLR可作为下肢DVT早期诊断典型指标,为临床提供疾病判断依据,值得重视。