Three-dimensional analysis of age and sex differences in femoral head asphericity in asymptomatic hips in the United States

BACKGROUND The sphericity of the femoral head is a metric used to evaluate hip pathologies and is associated with the development of osteoarthritis and femoral-acetabular impingement.AIM To analyze the three-dimensional asphericity of the femoral head of asymptomatic pediatric hips.We hypothesized that femoral head asphericity will vary significantly between male and female pediatric hips and increase with age in both sexes.METHODS Computed tomography scans were obtained on 158 children and adolescents from a single institution in the United States(8-18 years;50%male)without hip pain.Proximal femoral measurements including the femoral head diameter,femoral head volume,residual volume,asphericity index,and local diameter difference were used to evaluate femoral head sphericity.RESULTS In both sexes,the residual volume increased by age(P<0.05).Despite significantly smaller femoral head size in older ages(>13 years)in females,there were no sex-differences in residual volume and aspherity index.There were no age-related changes in mean diameter difference in both sexes(P=0.07)with no significant sex-differences across different age groups(P=0.06).In contrast,there were significant increases in local aspherity(maximum diameter difference)across whole surface of the femoral head and all quadrants except the inferior regions in males(P=0.03).There were no sex-differences in maximum diameter difference at any regions and age group(P>0.05).Increased alpha angle was only correlated to increased mean diameter difference across overall surface of the femoral head(P=0.024).CONCLUSION There is a substantial localized asphericity in asymptomatic hips which increases with age in.While 2D measured alpha angle can capture overall asphericity of the femoral head,it may not be sensitive enough to represent regional asphericity patterns.

A novel motion tracking system for evaluation of functional rehabilitation of the upper limbs

Upper limb function impairment is one of the most common sequelae of central nervous system in jury, especially in stroke patients and when spinal cord injury produces tetraplegia. Conventional assessment methods cannot provide objective evaluation of patient performance and the effec tiveness of therapies. The most common assessment tools are based on rating scales, which are inefficient when measuring small changes and can yield subjective bias. In this study, we designed an inertial sensorbased monitoring system composed of five sensors to measure and analyze the complex movements of the upper limbs, which are common in activities of daily living. We devel oped a kinematic model with nine degrees of freedom to analyze upper limb and head movements in three dimensions. This system was then validated using a commercial optoelectronic system. These findings suggest that an inertial sensorbased motion tracking system can be used in patients who have upper limb impairment through data integration with a virtual realitybased neurorehabili tation system.

Effect of fluoride treatment on corrosion behavior of Mg-Ca binary alloy for implant application

The influence of hydrofluoric acid（HF） treatment on the corrosion behavior of the Mg-0.5Ca alloys was investigated by immersion specimen in sodium hydroxide and HF solutions with various concentrations and durations at room temperature.Microstructural evolutions of the specimens were characterized by atomic force microscopy,X-ray diffraction,field-emission scanning electron microscopy.The corrosion resistance was examined through potentiodynamic polarization and immersion test in Kokubo solution.The results revealed that the fluoride treated Mg-0.5Ca alloys produced by immersion in 40% HF provided more uniform,dense and thicker coating layer（12.6 μm） compared with the 35% HF treated specimen.The electrochemical test showed that the corrosion resistance of fluoride treated specimen was 35 times higher compared with the untreated Mg-0.5Ca alloy specimen in Kokubo solution.In vitro degradation rate of the fluoride treated specimens was much lower than untreated Mg-0.5Ca alloy in Kokubo solution.After immersion test the surface of 40% HF treated sample showed a few corrosion dots,while untreated specimens were fully covered by corrosion products and delamination.Fluoride treated Mg-0.5Ca alloy with 40% HF is a promising candidate as biodegradable implants due to its low degradation kinetics and good biocompatibility.

Influences of load carriage and physical activity history on tibia bone strain

Background:Military recruits are often afflicted with stress fractures.The military’s strenuous training programs involving load carriage may contribute to the high incidence of tibia stress fractures in the army.The purpose of this study was to assess the influences of incremented load carriage and history of physical activity on tibia bone strain and strain rate during walking.Methods:Twenty recreational basketball players and 20 recreational runners performed 4 walking tasks while carrying 0 kg,15 kg,25 kg,and35 kg loads,respectively.Tibia bone strain and strain rate were obtained through subject-specific multibody dynamic simulations and finite element analyses.Mixed model repeated-measures analyses of variance were conducted.Results:The mean±SE of the runners’ bone strain(μs)during load carriages(0 kg,15 kg,25 kg,and 35 kg)were 658.11±1.61,804.41±1.96,924.49±2.23,and 1011.15±2.71,respectively,in compression and 458.33±1.45,562.11±1.81,669.82±2.05,and 733.40±2.52,respectively,in tension.For the basketball players,the incremented load carriages resulted in compressive strain of 634.30±1.56,746.87±1.90,842.18±2.16,and 958.24±2.63,respectively,and tensile strain of 440.04±1.41,518.86±1.75,597.63±1.99,and 700.15±2.47,respectively.A dose-response relationship exists between incremented load carriage and bone strain and strain rate.A history of regular basketball activity could result in reduced bone strain and reduced strain rate.Conclusion:Load carriage is a risk factor for tibia stress fracture during basic training.Preventative exercise programs,such as basketball,that involved multidirectional mechanical loading to the tibia bones can be implemented for military recruits before basic training commences.

Biomechanical characteristics of bone in streptozotocin-induced diabetic rats:An in-vivo randomized controlled experimental study

AIM: To investigate the in vivo effects of type Ⅰdiabetes on the mechanical strength of tibial bone in a rodent model.METHODS: The biomechanical effect of diabetes on the structural integrity of the tibia in streptozotocin induced diabetic Wistar rats was analysed. Induction of diabetes was achieved by an intra-peritoneal injection and confirmed by measuring serial blood glucose levels(> 150 mg/d L). After 8 wk the tibiae were harvested and compared to a control group. Biomechanical analysis of harvested tibiae was performed using a threepoint bending technique on a servo hydraulic MTS 858 MiniB ionix frame. Maximum force applied to failure(N), stiffness(N × mm) and energy absorbed(N/mm) were recorded and plotted on load displacement curves. A displacement control loading mode of 1 mm/min was selected to simulate quasi-static loading conditions. Measurements from load-displacement curves were directly compared between groups.RESULTS: Fourteen streptozotocin induced diabetic Wistar rats were compared against nineteen non-diabetic controls. An average increase of 155.2 g in body weight was observed in the control group compared with only 5 g in the diabetic group during the experimental study period. Levels of blood glucose increased to 440.25 mg/d L in the diabetic group compared to 116.62 mg/d L in the control group.The biomechanical results demonstrate a highly significant reduction in the maximum load to failure from 69.5 N to 58 N in diabetic group compared to control(P = 0.011). Energy absorption to fracture was reduced from 28.2 N in the control group to 23.5 N in the diabetic group(P = 0.082). No significant differences were observed between the groups for bending stiffness.CONCLUSION: Streptozotocin-induced diabetes in rodents reduces the maximum force and energy absorption to failure of bone, suggesting a predisposition for fracture risk.

Osseointegration of porous titanium and tantalum implants in ovariectomized rabbits:A biomechanical study

BACKGROUND Today,biological fixation of uncemented press-fit acetabular components plays an important role in total hip arthroplasty.Long-term stable fixation of these implants depends on the osseointegration of the acetabular cup bone tissue into the acetabular cup implant,and their ability to withstand functional loads.AIM To compare the strength of bone-implant osseointegration of four types of porous metal implants in normal and osteoporotic bone in rabbits.METHODS The study was performed in 50 female California rabbits divided into nonovariectomized(non-OVX)and ovariectomized groups(OVX)at 6 mo of age.Rabbits were sacrificed 8 wk after the implantation of four biomaterials[TTM,CONCELOC,Zimmer Biomet's Trabecular Metal(TANTALUM),and ATLANT]in a 5-mm diameter defect created in the left femur.A biomechanical evaluation of the femur was carried out by testing implant breakout force.The force was gradually increased until complete detachment of the implant from the bone occurred.RESULTS The breakout force needed for implant detachment was significantly higher in the non-OVX group,compared with the OVX group for all implants(TANTALUM,194.7±6.1 N vs 181.3±2.8 N;P=0.005;CONCELOC,190.8±3.6 N vs 180.9±6.6 N;P=0.019;TTM,186.3±1.8 N vs 172.0 N±11.0 N;P=0.043;and ATLANT,104.9±7.0 N vs 78.9 N±4.5 N;P=0.001).In the OVX group,The breakout forces in TANTALUM,TTM,and CONCELOC did not differ significantly(P=0.066).The breakout force for ATLANT in the OVX group was lower by a factor of 2.3 compared with TANTALUM and CONCELOC,and by 2.2 compared with TTM(P=0.001).In the non-OVX group,the breakout force for ATLANT was significantly different from all other implants,with a reduction in fixation strength by a factor of 1.9(P=0.001).CONCLUSION TANTALUM,TTM,and CONCELOC had equal bone-implant osseointegration in healthy and in osteoporotic bone.ATLANT had significantly decreased osseointegration(P=0.001)in healthy and in osteoporotic bone.

Effects of Sedentarism and Treadmill Training in Mechanical Properties of Muscles of Ovariectomized Rats with High-Fat Diet

The aim of this study is to evaluate the ability of physical training in the maintenance of muscle strength in rats with HFD （high-fat diet） after OVX （ovariectomy）. Eighty Wistar rats are at eight weeks of age and weight 200 g which divided into 8 groups （n = 10） and treated for 12 weeks： GA： OVX ＋ ND （normal diet）, GB： OVX ＋ ND ＋ training, GC： sham ＋ ND, GD： sham ＋ ND ＋ training, GE： OVX ＋ HFD, GF： OVX ＋ HFD ＋ training, GG： sham ＋ HFD and GH： sham ＋ HFD ＋ training. HFD consists of standard ration for rats with addition of 30% lipids. In training groups, physical training five training/week was conducted on a treadmill with adaptation period of three weeks up to 18 m/s for one hour, training were performed for 12 weeks. The sedentary animals remained in individual box. To analyze the effects of training and diet, tensile strength tests of the gastrocnemius muscles were conducted： the speed of 0.1 mm/min. Analysis of variance was performed to compare groups. The mean （SD） obtained for the maximum load （N） were： GA 57.77 （6.89）, GB 62.74 （5.07）, GC 49.45 （6.06）, GD 59.42 （5.26） and GE 55.58 （4.72）, GF 62.50 （4.56）, GG 58.35 （4.54） and GH 56.67 （5.87）, respectively. There were no differences for maximum load between surgeries （p = 0.004） and between treatments （p = 0.000）. Differences were found also for the relationship surgery diet treatment （p = 0.007）. For the variable stiffness （N/mm）, there were not statistically significant differences： GA 5.03 （0.72）, GB 5.08 （1.09）, GC 5.17 （0.53）, GD 5.35 （0.80）, GE 5.52 （1.20）, GF 5.36 （1.07）, GG 4.83 （1.03） and GH 5.40 （0.73）. For the toughness （N/mm）, there were differences between treatments （p = 0.010） and the ratio diet treatment （p = 0.024）： GA 455.00 （107.21）, GB 541.96 （126.80）, GC 394.97 （84.67）, GD 566.90 （157.07）; GE 424.63 （113.03）, GF 478.07 （106.03）; GG 517.44 （98.65） and GH 481.26 （129.45）. OVX causes decrease in muscle maximum load; exercise treadmill provides increased muscular endurance, regardless of the diet and the OVX in groups, the increased resistance observed in the groups submitted to HFD can result in weight gain associated with the presence estrogen.

Changes in Postural Control in Mastectomized Women

Background:?Women undergoing mastectomy may have postural asymmetries due to mutilation, culminating in changes in postural balance. Aim:?This study aimed to evaluate the influence of the mastectomy in the postural control of women undergoing surgical treatment of breast cancer. Methods: We evaluated 40 volunteers divided into two groups: women undergoing mastectomy (MG) with a mean age of 51.45 (SD 6.49) years old and mean BMI of 30.71 (SD 5.21) kg/m2, and a control group of women without the disease (CG) with a mean age of 50.50 (SD 7.85) years old and mean BMI of 30.50 (SD 5.77). Static balance was assessed using the displacement of the center of pressure (COP), with voluntary bipedal support with eyes open and closed on a force platform. Statistical analysis was performed using the software SPSS 21.0 with a significance level of 5%. Results: The MG showed an increase in the displacement area along the x-axis (P?= 0.003) and total displacement (P?< 0.001) with eyes open (EO), and an increase in the x-axis (P?= 0.002) and total displacement (P?< 0.001) with eyes closed (EC). Velocity in the x-axis (P?< 0.001), y-axis (P?< 0.001) and total velocity (P?< 0.001) was higher with EO than EC. A rise in velocity was also observed in the x- and y-axis, and in total velocity with EC, when compared with the CG (P?< 0.001). Displacement was higher for all variables in both groups with EC (P?< 0.001). Conclusions: Surgery for unilateral mastectomy may significantly alter postural control in women with breast cancer.

New simulation model for bone formation markers in osteoporosis patients treated with once-weekly teriparatide

Daily 20-mg and once-weekly 56.5-mg teriparatide（parathyroid hormone 1–34） treatment regimens increase bone mineral density（BMD） and prevent fractures, but changes in bone turnover markers differ between the two regimens. The aim of the present study was to explain changes in bone turnover markers using once-weekly teriparatide with a simulation model. Temporary increases in bone formation markers and subsequent decreases were observed during once-weekly teriparatide treatment for 72 weeks. These observations support the hypothesis that repeated weekly teriparatide administration stimulates bone remodeling, replacing old bone with new bone and leading to a reduction in the active remodeling surface. A simulation model was developed based on the iterative remodeling cycle that occurs on residual old bone. An increase in bone formation and a subsequent decrease were observed in the preliminary simulation. For each fitted time point, the predicted value was compared to the absolute values of the bone formation and resorption markers and lumbar BMD. The simulation model strongly matched actual changes in bone turnover markers and BMD. This simulation model indicates increased bone formation marker levels in the early stage and a subsequent decrease. It is therefore concluded that remodeling-based bone formation persisted during the entire treatment period with once-weekly teriparatide.

Kinematic Analysis of a Posterior-stabilized Knee Prosthesis

Background：The goal of total knee arthroplasty （TKA） is to restore knee kinematics.Knee prosthesis design plays a very important role in successful restoration.Here,kinematics models of normal and prosthetic knees were created and validated using previously published data.Methods：Computed tomography and magnetic resonance imaging scans of a healthy,anticorrosive female cadaver were used to establish a model of the entire lower limbs,including the femur,tibia,patella,fibula,distal femur cartilage,and medial and lateral menisci,as well as the anterior cruciate,posterior cruciate,medial collateral,and lateral collateral ligaments.The data from the three-dimensional models of the normal knee joint and a posterior-stabilized （PS） knee prosthesis were imported into finite element analysis software to create the final kinematic model of the TKA prosthesis,which was then validated by comparison with a previous study.The displacement of the medial/lateral femur and the internal rotation angle of the tibia were analyzed during 0-135° flexion.Results：Both the output data trends and the measured values derived from the normal knee＇s kinematics model were very close to the results reported in a previous in vivo study,suggesting that this model can be used for further analyses.The PS knee prosthesis underwent an abnormal forward displacement compared with the normal knee and has insufficient,or insufficiently aggressive,＂rollback＂ compared with the lateral femur of the normal knee.In addition,a certain degree of reverse rotation occurs during flexion of the PS knee prosthesis.Conclusions：There were still several differences between the kinematics of the PS knee prosthesis and a normal knee,suggesting room for improving the design of the PS knee prosthesis.The abnormal kinematics during early flexion shows that the design of the articular surface played a vital role in improving the kinematics of the PS knee prosthesis.

Landing in Ski Jumping: A Review About its Biomechanics and the Connected Injuries

The present review deals with the current scientific knowledge related with ski jump landing.A specific focus is given on the landing biomechanics,the methods utilized for its analysis and the injuries connected to the landing phase.Despite the demonstrated importance for the safety and the performance of ski jumpers,the landing and its preparation are rarely inves-tigated.In this paper,after having firstly described the execution of landing and its preparation and the reason why is impor-tant to analyze it,an overview of the current status of the research related to the landing biomechanics is reported(kinetics,kinematics,electromyographic activation,aerodynamics,computer simulation).The third part describes the methods and technologies utilized in literature to analyze the landing and its preparation(video cameras,inertial sensors,force insoles,wind tunnel and computer simulation).After that,an overview of the injuries related to landing is reported.The final section proposes future research in the field of biomechanics of ski jump landing in different fields,such as computer simulations,kinematic analysis,equipment development and biomechanics of female athletes.

A numerical analysis on different-generation prototypes of ventricular assist device

The ventricular assist device(VAD)assists the patients with heart diseases for limited and prolonged periods.This device synchronizes with normal heart activities to help foster its performance.Consequently,its sensitive design requires high accuracy.The pumps are the essential part of every VAD which should operate in wide ranges of flow and pressure.As there are various types of VAD under different designs,it is neither practical nor plausible to experimentally/clinically investigate their performances.Therefore,in the concurrent study,a numerical study was carried out on four different generation prototypes of VAD pumps for reaching an optimum design.Using computational fluid dynamics(CFD)method,the software derived,showed and streamlined the flow field shear stress both inside the VAD and its blades.Furthermore,the vortices and flow rate-pressure curves were observed.The results showed that the curved blade pumps operate better compared to that of the straight blade types,concerning the provision of enough pressure and less damage to the red blood cells.The results have implications not only for comparing different types of VAD designs but also for understanding the resulted shear stresses and pressures as a result of the blade’s structure.

Detection and identification of S1 and S2 heart sounds using wavelet decomposition method

Phonocardiogram （PCG）, the digital recording of heart sounds is becoming increasingly popular as a primary detection system for diagnosing heart disorders and it is relatively inexpensive. Electrocardiogram （ECG） is used during the PCG in order to identify the systolic and diastolic parts manually. In this study a heart sound segmentation algorithm has been developed which separates the heart sound signal into these parts automa- tically. This study was carried out on 100 patients with normal and abnormal heart sounds. The algorithm uses discrete wavelet decomposition and reconstruction to pro- duce PCG intensity envelopes and separates that into four parts： the first heart sound, the systolic period, the second heart sound and the diastolic period. The performance of the algorithm has been evaluated using 14,000 cardiac periods from 100 digital PCG recordings, including normal and abnormal heart sounds. In tests, the algorithm was over93% correct in detecting the first and second heart sounds. The presented automatic seg- mentation Mgorithm using w^velet decomposition and reconstruction to select suitable frequency band for envelope calculations has been found to be effective to segment PCG signals into four parts without using an ECG.

Ankle and foot mechanics in individuals with chronic ankle instability during shod walking and barefoot walking:A cross-sectional study

Purpose:This study evaluated the angular kinematic and moment of the ankle and foot during shod walking and barefoot walking in individuals with unilateral chronic ankle instability(CAI).Methods:Recreational soccer players with unilateral CAI were recruited for this cross sectional study conducted between January and August 2019.A total of 40 participants were screened for eligibility but only 31 met the inclusion criteria based on the methods of Delahunt et al and Gribble et al.Except for 3 participants not attending the evaluation session,28 participants were finally included.A three dimensional motion analysis system made up of ProReflex motion capture unit and an AMTIb Kistler force plate,embedded in the middle of nine meter walkway,were used to assess the ankle and foot angles and moment during shod walking and barefoot walking conditions.A Statistical Package for Social Sciences(version 20.0)was used to analyze data.Results:During shod walking,the ankle joint plantar-flexion range of motion(ROM)at 10%of the gait cycle(GC)and dorsiflexion ROM at 30%of the GC were significantly higher than those during barefoot walking for both feet(p=0.001,0.001,0.027,and 0.036 respectively).The inversion ROM during shod walking was significantly higher than that during barefoot walking for both feet at 10%and 30%of the GC(p=0.001.0.001,0.001,and 0.042 respectively).At 10%of the GC,the eversion moment was significantly higher between barefoot and shod walking for both feet(both p=0.001).At 30%of the GC,there was no significant difference between shod and barefoot walking plantar-flexion moment of both feet(p=0.975 and 0.763 respectively),and the eversion moment of both feet(p=0.116 and 0.101 respectively).Conclusion:At the early stance,shod walking increases the ankle plantar-flexion and foot inversion ROM,and decreases the eversion moment for both feet in subjects with unilateral CAI.Therefore,the foot wearing condition should be considered during evaluation of ankle and foot kinematics and kinetics.

内植物的材料学（上）

介绍：用于矫形外科植入物的生物材料必须具有生物相容性，即在体内不引起局部或全身的不良反应。要有很好的抗侵蚀和抗化学降解性能，具有足够的机械强度以承载从骨骼传递来的较强的力；在关节置换中作为负重关节面的材料必须能够承受数千万次的循环使用；另外必须能在相对较低的成本下制造高质量的产品。