A system to measure the forces and moments at the knee and hip during level walking

The forces and moments in the sagittal plane at the knee and hip were calculated using gait data collected during level walking. Accelerations were measured by accelerometers attached to the legs, and the force reactions at the foot were measured by a force plate. The recorded accelerations and the foot forces were used to determine the joint reactions through a Newtonian formulation modeling the leg as articulated, rigid links. Twelve normal subjects were included in this study along with nine lower limb amputees. Obvious differences were observed when comparing amputee data to normal data both at the knee and hip. Gait data obtained by this system can be readily used to form criteria for objective gait analysis and improved prosthesis design.     

Idiopathic scoliosis and balance organisation in seated position on a seesaw

The aim was to determine the biomechanical processes involved in postural regulation when self-imposed disturbances occur in the seated position in the antero-posterior direction. Twelve female adolescents with right thoracic scoliosis (SG) (Cobb = 30.4° ± 9.7) and 15 control adolescents (CG) were included in this study. The ground reaction forces (GRF) were studied whilst the subjects maintained their balance in the sitting position on a seesaw. Six conditions were tested: eyes open and closed; with an additional load placed on the subject’s right or left shoulder; and with an additional load on the subject’s right or left pelvis. The SG showed significantly higher force amplitudes and variability and fewer oscillations than the CG in all the conditions. In the SG, the time analysis showed that the duration of the GRF was significantly higher in forward and left directions. Whatever the condition tested, the intra-group differences were not significant. The scoliotic patients in seated position were characterised by larger changes of the GRF, especially with a postural control in the forward and left directions, corresponding to that on the concave side of their spinal curvature. No significant differences were found to exist between the various conditions (load and unload, eyes open and eyes closed). Clinical tests and rehabilitation methods should include assessments of seated patients’ spatio-temporal adaptation to GRF.     

Influence of Drop-Landing Exercises on Bone Geometry and Biomechanical Properties in Prepubertal Girls: A Randomized Controlled Study

We conducted a 28-week school-based exercise trial of single-leg drop-landing exercise with 42 girls (Tanner stage 1, 6–10 years old) randomly assigned to control (C), low-drop (LD), or high-drop (HD) exercise groups. The LD and HD groups performed single-leg drop-landings (three sessions/week and 50 landings/session) from 14 and 28 cm, respectively, using the nondominant leg. Single-leg peak ground-reaction impact forces in a subsample ranged between 2.5 and 4.4 times body weight. Dependent variables were bone geometry and biomechanical properties using magnetic resonance imaging. No differences (P > 0.05) were found among groups at baseline for age, stature, lean tissue mass (DXA - Lunar 3.6-DPX), leisure-time physical activity, average daily calcium intake, or measures of knee extensor or flexor torque. A series of ANOVA and ANCOVA tests showed no within- or between-group differences from baseline to posttraining. Group comparisons assessing magnitude of change in side-to-side differences in geometry (area cm²) and cross-sectional moment of inertia (cm⁴) at proximal, mid, and distal sites revealed negligible effect sizes. Our findings suggest that strictly controlled unimodal, unidirectional single-leg drop-landing exercises involving low to moderate peak ground-reaction impact forces do not influence geometrical or biomechanical measures in the developing prepubertal female skeleton.     

Contact pressures in the patellofemoral joint during impact loading on the human flexed knee

Currently, a bone fracture criterion is used by the automotive industry to assess the potential for a lower extremity injury from impact directed on the flexed knee. However, recent studies with animal models indicate irreversible damage to articular cartilage due to overpressures generated within the patellofemoral (P-F) joint without bone fracture, and suggest this injury may lead to a progressive, degenerative disease of the joint. The purpose of this investigation was to measure contact pressure in the human P-F joint during impact loading on the isolated, flexed knee. Loads were delivered on the patella with a free-flight inertial mass that had a rigid or foam padded interface. The experiments were conducted by serially increasing the impactor velocity in repeated tests until bone fracture was observed. The distribution of maximum pressures generated within the joint was recorded with a pressure-sensitive film. Fracture of the patella or the femur occurred at impact loads of approximately 8.5 kN. The average P-F pressure was approximately 25 MPa for 8 kN of impact load on the 90 degrees flexed joint. The P-F contact area varied with the level of contact load and degree of joint flexion. The distribution of P-F pressures was nonuniform. At approximately 70% of the fracture load for the 90 degrees flexed knee, nearly 35% of the contact area was exposed to pressures greater than 25 MPa. In an earlier study by others using subchondral bone-cartilage preparations, this level of pressure resulted in fissures and lacerations of the cartilage.     

Ligament tension pattern in the flexed knee in combined passive anterior translation and axial rotation.

Twenty-two fresh-frozen specimens were used to measure tensions generated in selected bands of the major ligaments of the flexed knee (40-90 degrees) when an axially prerotated tibia is subjected to passive anterior shear and when an anteriorly pretranslated tibia is subjected to passive axial torque. The tensions were measured using the buckle transducer attached to the anteromedial band of the anterior cruciate ligament [ACL (am)], the posterior fibers of the posterior cruciate ligament [PCL (pf)], the long fibers of the medial collateral ligament [MCL (lf)], and in the total lateral collateral ligament [LCL]. The knee specimens were subjected to the combined motions in a 6-df passive loading apparatus. The results indicated that the joint resistance to anterior translation increased markedly with internal prerotation and only marginally with external prerotation. This increase in joint resistance, however, was associated with a decrease in ACL function. It has been inferred that the posterior structures, capsular and meniscal, contribute significantly to joint resistance when the tibia is prerotated in either sense. For internal prerotation, the interference between the medial femoral condyle and the central tibial eminence was found to be an additional mechanism of resistance to anterior translation. Also, it has been found that although the ACL (am) tension increased with internal rotation in the normal case, it decreased with internal rotation in the presence of an anterior pretranslation. It is concluded that ACL response to combined joint motion cannot be ascertained by a simple summation of its responses to individual motions.     

后交叉韧带断裂和重建对兔膝关节软骨退变的影响

目的 探讨后交叉韧带（PCL）断裂和重建对膝关节软骨退变的影响。方法将33只新西兰大白兔共分3组,实验Ⅰ组：21只兔右膝关节PCL切断,左膝行单纯关节切开术作为对照组;实验Ⅱ组：12只兔右膝关节PCL切断后即刻重建。对照组、实验Ⅰ组术后6、12、26周处死动物,实验组Ⅱ术后12、26周处死动物。通过墨汁染色、HE染色、甲苯胺蓝染色、免疫组化染色（Ⅰ型胶原,Ⅱ型胶原和Ⅲ型胶原单克隆抗体）及扫描电镜方法对各组膝关节软骨退变的情况进行观察分析。结果实验Ⅰ组：PCL切断后26周标本有明显膝关节退行性改变;PCL切断后26周标本关节软骨继发损伤明显重于对照组术后同期标本;内髁软骨可见范围较大的软骨纤维化现象,达深层,细胞数量减少,Mankin评分平均7．7;纤维化的软骨层Ⅰ、Ⅲ型胶原染色阳性,Ⅱ型胶原染色较浅。扫描电镜上股骨内髁各时间段内都可见软骨损伤,而对照组只表现有垄沟样结构的紊乱。实验Ⅱ组：仅部分标本有轻度软骨损伤,术后26周时滑车及内髁处软骨继发损伤较实验Ⅰ组明显减轻。结论PCL断裂可以继发关节软骨的退行性改变,且以内侧间室和髌股关节为主,并随时间的延长逐渐加重。PCL断裂后即刻重建可以有效阻止关节软骨继发损伤的发生。     

前交叉韧带断裂和重建对膝关节软骨退变影响的实验研究

目的：研究前交叉韧带（ACL）断裂和不同时期重建对膝关节软骨继发损伤的影响。方法：以新西兰大白兔为实验对象,共14只。共分4组,每组7个膝关节,实验组Ⅰ：右膝前交叉韧带切断后随即重建,左膝的前交叉韧带切断后不予重建作为对照组Ⅰ;组Ⅱ：右膝前交叉韧带切断后3周重建,左膝行单纯关节切开术作为对照组Ⅱ。术后8周通过墨汁染色,常规组织学及扫描电镜方法观察各组膝关节软骨退变的情况。结果：（1）实验组Ⅰ关节软骨退变程度明显轻于对照组Ⅰ（Hc=5.9889,P=0.0144);(2)实验组Ⅱ关节软骨退变程度和对照组Ⅰ相比差异无显著性意义（Hc=0.7143,P=0.785)。结论：（1）ACL断裂后即刻重建可以有效阻止关节软骨继发损伤的发生;（2）ACL断裂后已继发关节软骨退变时再行重建,其对关节软骨退行性变的缓解作用不明显。ACL 裂后应进行早期重建,恢复膝关节稳定性,减少或延缓远期骨性关节炎的发性。     

Forces and torques during fracture reduction: Intraoperative measurements in the femur.

Reduction is a crucial step in fracture treatment. We determined intraoperative peak forces and torques during fracture reduction in seven patients with eight fractures of the femoral shaft. All fractures were temporarily stabilized by external fixation. Force and torque measurements were performed during the subsequent intramedullary nailing procedure. A three-dimensional load cell was attached to the distal femur fragment using two Schanz screws. All forces and torques were registered on-line during the reduction process. The maximum resulting force was 411 N, the maximum resulting torque 74 N x m. The highest force was observed along the shaft axis with 396 N for distraction. The maximum torque value was measured around the frontal axis, being 74 N x m for antecurvature. These results may assist the development of new reduction techniques and devices.     

Role of intra-abdominal pressure in the unloading and stabilization of the human spine during static lifting tasks

The role of intra-abdominal pressure (IAP) in unloading the spine has remained controversial. In the current study, a novel kinematics-based approach along with a nonlinear finite-element model were iteratively used to calculate muscle forces, spinal loads, and stability margin under prescribed postures and loads measured in in vivo studies. Four coactivity levels (none, low, moderate, and high) of abdominal muscles (rectus abdominis, external oblique, and internal oblique) were considered concurrently with a raise in IAP from 0 to 4 kPa when lifting a load of 180 N in upright standing posture and to 9 kPa when lifting the same load in forward trunk flexions of 40° and 65°. For comparison, reference cases with neither abdominal coactivity nor IAP were investigated as well. A raise in IAP unloaded and stabilized the spine when no coactivity was considered in the foregoing abdominal muscles for all lifting tasks regardless of the posture considered. In the upright standing posture, the unloading action of IAP faded away even in the presence of low level of abdominal coactivity while its stabilizing action continued to improve as abdominal coactivity increased to moderate and high levels. For lifting in forward-flexed postures, the unloading action of IAP disappeared only with high level of abdominal coactivities while its stabilizing action deteriorated as abdominal coactivities increased. The unloading and stabilizing actions of IAP, hence, appear to be posture and task specific.     

Effect of sympathetic inhibition on maximal muscle blood flow in the normal and atherosclerotic human leg.

The control of blood flow in skeletal muscle is incompletely understood, and for this reason the effect of sympathetic inhibition on muscle blood flow in the leg was studied. One group of patients selected for study comprised 20 patients without evidence of vascular disease; a second comprised 20 with peripheral occlusive arterial disease, in whom the site of occlusion varied from the aorta to the lower leg arteries. None had undergone previous vascular surgery or sympathectomy. Variables studied included resting muscle blood flow; maximal muscle blood flow; interval from tourniquet release to onset of peak flow; duration of peak blood flow; muscle blood flow after tourniquet release; and skin temperature in the foot. Muscle blood flow was calculated from xenon-133 clearance. The variables were studied before and after ischemic (thigh tourniquet) and before and after sympathetic inhibition (immersion of hands and wrists in water at 45 degrees C). The significant differences between the two groups related to peak flow after ischemic exercise, the interval from tourniquet release to peak flow and duration of peak flow. Sympathetic inhibition was followed by no significant changes in maximal muscle blood flow, though there was a significant decrease in resting muscle blood flow. The results of the present study, in which noninvasive sympathetic blockade was used, confirm the findings of others that muscle blood flow does not change after operative sympathectomy.     

动静力失衡对大鼠颈椎不同节段椎间盘退变影响的显微CT形态学和组织学研究

目的:评价大鼠动静力失衡颈椎退变模型对C4～C7各节段终板磨损面积、椎间高度和椎间盘退变的影响,并分析终板磨损面积和椎间高度与椎间盘退变的相关性.方法:24只3月龄雌性SD大鼠随机分为模型组(14只)和对照组(10只).对照组仅做皮肤切口;模型组大鼠横向切断颈背部肌肉以及韧带,制作大鼠动静力失衡颈椎退变模型.术后12周、18周、24周分三次取大鼠颈椎标本.标本取材后进行显微CT扫描以及番红O快绿染色.测量C4/5、C5/6、C6/7各个节段椎间高度,计算上述三个节段的终板磨损比例,并对椎间盘退变程度进行评分.应用SPSS 13.0比较不同组相同节段椎间盘的终板磨损率,椎间高度和退变评分,并分析终板磨损率与椎间盘退变之间的相关性.结果:显微CT扫描发现模型组术后12周各个节段软骨终板均出现明显的磨损,磨损主要位于终板的腹侧.颈椎节段越高,磨损程度越轻.术后18周、24周,模型组C5/6、C6/7软骨终板磨损比例明显大于对照组,有统计学意义(P＜0.05).术后各个时间点,模型组不同节段终板磨损率情况不同,其中C6/7节段明显大于C4/5节段(P＜0.05).组织学切片显示,软骨终板的形态学改变早期以磨损为主,晚期则出现了大量钙化.术后12周,模型组C5/6、C6/7椎间高度明显低于对照组,术后18周、24周时高度进一步下降.术后12周,模型组的各节段椎间盘退变评分明显高于对照组(P＜0.05).术后24周时,模型组C4/5退变评分为11.5±1.0分,C5/6为11.8±1.0分,C6/7为12.8±0.8分.不同节段椎间盘退变评分差异有显著性(P＜0.05),其中C6/7椎间盘退变评分最高,明显大于C4/5、C5/6节段(P＜0.05).相关分析显示:终板磨损比例与椎间盘高度、椎间盘退变评分具有明显的相关性.结论:在大鼠动静力失衡颈椎退变模型中C6/7终板磨损比例较大,椎间盘高度降低出现较早,组织学上椎间盘退变程度也较严重,是该模型椎间盘退变的主要节段.软骨终板的形态学改变与椎间高度的降低和椎间盘退变程度有明显的相关性.     

Dissociable effects of frontal cortical lesions on measures of visuospatial attention and spatial working memory in the rat

Frontal cortex controls voluntary movement through projections to striatum that continue as parallel pallido-thalamic loops. In previous studies we found evidence of a double dissociation in rat striatum between visuospatial response time (RT) and radial maze delayed non-matching (DNM) tasks. Here we compare the effects of frontal cortical lesions on these tasks. We found that lesions involving sensorimotor areas in dorsolateral cortex affect RT for responding to visuospatial stimuli without affecting other measures of response speed or producing signs of attentional or sensory impairment. These deficits were equivalent to impairments observed with lesions in sensorimotor areas of dorsolateral striatum. Dorsal prefrontal lesions produced RT deficits indicative of attentional impairment that have not been observed with striatal or thalamic lesions. This suggests contributions of prefrontal cortex to attention independent of striatum and thalamus. Prefrontal lesions had significant but circumscribed effects on DNM consistent with effects of lesions in anatomically related areas of striatum or thalamus observed in earlier studies. These results are consistent with evidence implicating prefrontal cortex in aspects of spatial memory mediated by anatomically related pathways in the basal ganglia and thalamus.     

3072名大学生髌骨软骨软化症患病率及其与运动创伤的相关研究

目的 :研究髌骨软骨软化症在大学生中的患病率及其与运动创伤的关系。方法 :通过对某师范大学非体育系 3 0 72名大学生进行随机整群抽样 ,筛选出膝关节疼痛的大学生 42 9名 ,采用随机抽样方法调查了膝关节疼痛的大学生 3 42名 ,髌骨软骨软化症临床诊断人数为 119(男 62 ,女 5 7)。调查表中包括每个大学生的运动量和运动创伤史 ,用Spssforwindow 10 .0统计软件对资料进行处理。结果 :髌骨软骨软化症患病率男大学生为 4.92 % ,女大学生为 5 .61% ,男女之比为 1/1.12 ,总患病率为 5 .3 %。男女大学生膝关节疼痛患者中髌骨软骨软化症发生率男为 3 3 .7% ,女为 3 7.1% ,男女无显著性差异 (P >0 .0 5 )。男女大学生髌骨软骨软化症患者运动量和创伤大于正常大学生。结论 :男女大学生髌骨软骨软化症的患病率无差异 (P >0 .0 5 )。运动创伤是髌骨软骨软化症发生的重要原因。     

Incidence and cost of osteoporotic fractures in France during 2001. A methodological approach by the national hospital database

The objective of this study was to describe the hospital incidence rate and the in-patient costs of three peripheral osteoporotic fractures (proximal humerus and hip, distal radius and/or ulna) in women and men aged over 45 in France during 2001. Each stay for fracture was selected from the dataset of the French national hospital database in 2001. The incidence rate (CI 95%) was standardized by age and gender according to the last census of the French population (1999). The effect of age and existence of geographical difference in incidence rates has been studied. For each fracture, we described the number of stays, rate of surgical procedure and in-patient costs according to the 2004 French list of cost per diagnosis-related group (2004 Euros); 118,839 fractures were registered during 2001 (61% hip, 28% distal radius and 11% proximal humerus; sex ratio 0.26). The incidence rate for all fracture was 7,567 (7,519–7,615) and 2,312 (2,283–2,341) for 10⁶ inhabitants in women and men aged over 45 years, respectively. The incidence increased significantly whatever type of fracture and gender. There were more fracture incidents in the east of France compared to the west and in the south compared to the north, whatever type of fracture in women and only for hip fracture in men. Surgical procedures were performed in 91% of proximal hip fractures, 83% of distal radius fractures and 53% of proximal humerus fractures. The median in-patient costs were 3,786 Euros for the humerus, from 2,363 to 2,574 Euros for the radius and from 8,048 to 8,727 Euros for the hip. The evaluation of the burden of peripheral fractures is possible using national hospital data in France. The incidence of fractures increased with age and is more common in women. Hip fracture with its higher occurrence, rate of procedure and in-patient costs could be used as a marker of osteoporosis for evaluating strategies of management.     

Histological and morphometric studies on the kinetics of germ cells and immature Sertoli cells during human prespermatogenesis.

Human prespermatogenesis between the 8th week of pregnancy and six months after birth was studied in testis material of 28 male foetuses from spontaneous abortions and 81 infants who died from sudden infant death. The foetuses and infants were grouped in 10 age groups. A first steep raise in the numbers of germ cells per 20 tubular cross sections from 22.3 in the first group up to 69.5 in group 3 was observed, i.e. up to the end of the 22nd week of pregnancy. Thereafter, a continuous decrease could be observed modulated by a second slighter increase during the first 4 months after birth. The ratio of germ cells and immature Sertoli cells improves from about 1:20 at the beginning to 1:8 in group 3; afterwards it changes in favour of the immature Sertoli cells down to 1:140 at the end of the study. The initial augmentation of germ cells is interpreted as the effect of a first proliferation wave comparable to that of M-prospermatogonia in other species. The decrease of germ cells is due to the stop of germ cell proliferation and simultaneous high proliferative activity of the immature Sertoli cells.     

矢状面成角植钉相邻节段固定治疗胸腰椎骨折

目的 观察矢状面成角植钉相邻节段固定治疗胸腰椎骨折疗效.方法 将49例符合条件的胸腰椎骨折患者矢状面成角植钉相邻节段固定治疗.结果 所有患者术后均获得随访,平均随访17.9个月,均获得坚强骨性植骨融合,无内固定失败现象发生.结论 伤椎矢状成角植钉相邻段内固定术减少了一个同定融合的节段,使脊柱内同定技术向前迈进了空前的一步.