测试新鲜猪股骨干钻削进给力

目的 采集新鲜猪股骨干不同骨质层和骨段的钻削进给力数据,为骨科虚拟现实手术系统钻削力反馈信号的输出提供依据。方法 改装万能材料试验机和手持可调速电钻(Φ5.0 mm钻头),构建生物骨骼钻削性能参数采集系统,分别以转速n ＝500,800,1 200 r/min和进给速度v ＝30,50,70 mm/min采集6具新鲜成熟猪股骨干162个标记点的钻削进给力f,分析其与相应组织和部位的关系。结果 新鲜猪股骨干同一标记点双侧骨皮质处进给力最大（fmax＝103.63~142.59 N）,髓腔处最小（接近于0）,股骨干中段进给力（f4,5,6＝124.69N）较两端（f1,2,3,7,8,9＝121.84 N）大;当v ＝30 mm/min、n ＝1 200 r/min时,钻削进给力最小（fmin＝106.04 N）;当v ＝ 70 mm/min、n ＝500 r/min时,钻削进给力最大（fmax＝139.84 N）。结论 改装的生物骨骼切削性能参数采集系统能有效采集生物骨骼的钻削进给力数据;骨骼钻削进给力与骨质的组织结构、电钻转速及进给速度有密切关系,其中骨质结构越密、电钻转速越小、进给速度越大,骨骼钻削进给力越大,反之越小。实验所获得新鲜猪股骨干钻削进给力数据及其变化趋势,可为虚拟骨科手术系统力反馈输出信号设置提供依据。     

原子力显微镜在生物医学中的应用

原子力显微镜是观察样品表面结构的一种新的工具 ,它具有比传统扫描电子显微镜更高的分辨率 ,并且可以在生理条件下进行实时观察。同时在分子水平上它还是检测样品之间相互作用力的一个强有力的工具。近年来 ,原子力显微镜越来越多地应用到生物医学的各个方面 ,并且取得了很多令人鼓舞的结果     

Force-length relationship in the pelvic floor muscles under transverse vaginal distension: a method study in healthy women

AIMS: The purpose of this study was to investigate whether there is a relationship between changes in the diameter of the urogenital hiatus and force developed in pelvic floor musculature. In addition, we wanted to examine the reliability of the method that measures force development in the pelvic floor in the transverse direction of the urogenital hiatus. MATERIALS AND METHODS: Passive and total force in the pelvic floor was measured with an intra-vaginal device in 20 healthy parous volunteers. The measurements were done with a consecutively increasing diameter in the transverse plane of the urogenital hiatus. The procedure was repeated with a few days interval. RESULTS: The measurements show an increase in force with an increasing device-diameter. The results are reliable at all the diameters tested, estimated by the within-subject day-to-day variability which was non-significant. The 40 mm diameter device is most favourable, estimated by Bland Altman plots of the test-retest measurements. CONCLUSIONS: Force development in pelvic floor muscles increased as a function of vaginal diameter when measured in the frontal plane. The measurements were reliable at all the different diameters chosen.     

Intensidad de la señal en T1 en el núcleo dentado tras la administración del agente de contraste con gadolinio macrocíclico gadoterato de meglumina: un estudio observacional

Introduction and aimsContradictory results have been reported about hyperintensity of the globus pallidus and/or dentate nucleus on unenhanced T1-weighted magnetic resonance (MR) images after exposure to various gadolinium-based contrast agents. This change in signal intensity varies with different gadolinium-based contrast agents. We aimed to determine whether signal intensity in the dentate nucleus is increased in unenhanced T1-weighted images in patients who have undergone multiple studies with the macrocyclic gadolinium-based contrast agent gadoterate meglumine. We thoroughly reviewed the literature to corroborate our results.Materials and methodsWe included patients who had undergone more than 10 MR studies with gadoterate meglumine. We quantitatively analyzed the signal intensity in unenhanced T1-weighted MR images measured in regions of interest placed in the dentate nucleus and the pons, and we calculated the dentate nucleus-to-pons signal intensity ratios and the differences between the ratio in the first MR study and the last MR study. We used t-tests to evaluate whether the differences between the signal intensity ratios were different from 0. We also analyzed the subgroups of patients who had been administered < 15 and ≥15 doses of gadoterate meglumine. We used Pearson correlation to determine the relationships between the differences in the signal intensity ratios and the number of doses of gadoterate meglumine administered.ResultsThe 54 patients (26 men) had received a mean of 13.8 ± 3.47 doses (range, 10-23 doses). The difference in the dentate nucleus-pons signal intensity ratio between the first and last MR study was -0.0275 ± 0.1917 (not significantly different from 0; p = 0.2968) in the entire group, -0.0357 ± 0.2204 (not significantly different from 0; p = 0.351 in the patients who had received < 15 doses (n = 34), and -0.0135 ± 0.1332 (not significantly different from 0; p = 0.655) in those who had received ≥15 doses (n = 20). Differences in signal intensity ratios did not correlate significantly with the accumulated dose of gadoterate meglumine (P = 0.9064; ρ = -0.0164 [95%]).ConclusionsReceiving more than 10 doses of gadoterate meglumine was not associated with increased signal intensity in the dentate nucleus.     

Analysis of landing performance and ankle injury in elite British artistic gymnastics using a modified drop land task: A longitudinal observational study

ObjectivesTo determine whether differences in landing force and asymmetry of landing force exist between gymnasts at the time of data collection versus those that subsequently experienced an ankle injury 12-months later.Study designProspective longitudinal observational design with baseline measures and 12 month follow up.SettingBritish Gymnastics National Training Centre.ParticipantsThirty-two asymptomatic elite level gymnasts from three artistic gymnastic squads (n = 15 senior female, n = 10 junior female and n = 7 senior male).Main outcome measuresA modified drop land task was used to quantify measures of landing performance. Peak Vertical Ground Reaction Force (PVGRF) was used to measure landing force. The level of inter-limb asymmetry of landing force was calculated using the Limb Symmetry index (LSI). Other measures included injury incidence and percentage coefficient of variation (% CV).ResultsThere was no statistical difference for landing force (p = 0.481) and asymmetry of landing force (p = 0.698) when comparing injured and non-injured gymnasts. Most participants (69%) demonstrated inter-limb asymmetry of landing forces.ConclusionsOur findings observed inter-limb asymmetry of landing force in injured gymnasts, although uninjured gymnasts also exhibited asymmetry of landing force. Both magnitude of landing force and inter-limb asymmetries of landing force failed to identify the risk of ankle injury.     

Preclinical assessment of novel longer-duration wear negative pressure wound therapy dressing in a porcine model

While reticulated open cell foam (ROCF) is a well-established dressing for negative pressure wound therapy (NPWT), there is the known potential for granulation tissue ingrowth if left in place for longer than 72 h. This may cause wound bed disruption, bleeding, and pain upon dressing removal. In addition, any retained foam fragments may elicit an adverse tissue reaction. A novel, easy to use dressing designed to utilise the advantages of ROCF while addressing its challenges has recently been created. This 7 day study investigated the utility of a novel NPWT dressing under longer-duration wear circumstances while assessing the prevalence of tissue ingrowth and ease of dressing removal in full-thickness excisional wounds utilising a porcine model. Histopathology and morphometry evaluations indicated thicker granulation tissue with, depending on the parameters assessed, either comparable or better tissue quality for wounds treated with the novel dressing. Greater re-epithelialization levels were also evident compared with ROCF. Three-dimensional imaging analysis indicated faster wound fill with a corresponding decrease in wound area with the novel dressing. Furthermore, tissue ingrowth was limited to only ROCF-treated wounds, which was not unexpected in this longer-duration wear study. The force required to remove the novel dressing was considerably lower compared with ROCF, correlating to the tissue ingrowth results. Results of this study illustrate that the novel dressing provided more favourable wound healing results compared with traditional ROCF. In addition, reduction in the risk of tissue ingrowth and low dressing peel force may allow it to be used as a longer-wear dressing.     

Acute and Subacute Changes in the Ultrasound Measurements of the Calcaneus Following Intense Exercise

The amount of exercise necessary to cause bone structural change in humans is unknown. We examined whether a single bout of intense exercise in vivo leads to acute and subacute changes in the physical properties of bone as measured by ultrasound. It was hypothesized that structural changes such as accumulation of fatigue microdamage would result in a decrease in velocity of sound (VOS) and broadband ultrasound attenuation (BUA) across the calcaneus. We performed a prospective cohort study in 111 (97 M, 14 F) entrants of the 1996 Melbourne marathon (42.3 km) and 28 (10 M, 18 F) nonrunning controls. Runners had a mean (SD) age of 45.3 ± 11.4 years (range 20–75), had completed 15.2 ± 17.3 prior marathons (0–88), and had been running regularly for 14.2 ± 9.2 years (0.25–50). An ultrasound densitometer (Cuba Clinical, McCue) was used to measure VOS and BUA across the right calcaneus. Runners were tested on three occasions: 1-3 days prior to, immediately after (<2 hours), and 5-6 days following the marathon. Seventy-three (66%) runners presented for all three measurements. Controls were tested on three occasions with the same time intervals as the runners. BUA values in the runners were significantly elevated by 5.0% immediately after the marathon but returned to baseline levels by the third test session (P= 0.0001). Changes in BUA values in the controls were not significant and all were less than 0.7% (P= 0.88). Age was a significant independent predictor of the BUA change between test 1 and test 2 in the runners (β= 0.2094; SE = 0.0917; P= 0.03). VOS measurements were not significantly different across the three testing sessions in both the runners (P= 0.07) and the controls (P= 0.33). Therefore, ultrasound measurements of BUA and VOS did not detect evidence of lasting structural change in the calcaneus following a marathon. Received: 15 July 1997 / Accepted: 11 May 1998     

Passive Pneumatic Stabilization Device for Assisting in Reduction of Femoral Shaft Fractures

Abstract During treatment of femoral shaft fractures, not only the actual fracture reduction but also the retention of the achieved reduction is essential. Substantial forces may apply to the bone fragments, due to multidirectional muscular contraction. Furthermore, forces from manipulation of one bone fragment may be transferred over the soft tissues onto the other fragments, thus hindering accurate fracture reduction. Once a sufficient reduction has been achieved, this position must be retained whilst definitive internal fixation is performed. Conventional methods comprise mounting patients on a traction table and applying manual distraction or employing special distraction devices, such as the AO distractor device. These approaches, however, only insufficiently stabilize both main fragments. For example, on the traction table the proximal femoral fragment can pivot around the hip joint thus complicating precise reduction. A novel pneumatic stabilization device to assist surgeons during operative procedures is described. This passive holding device “Passhold” connects to one main fragment through a minimally invasive bone interface and statically locks the fragment’s position. Thereafter, only the other main fragment is manipulated to achieve reduction. Mutual interference of the reciprocal fragment positions, due to soft-tissue force transfer during manipulation, is avoided. The authors examined the stability of the novel retention device on a test rig and proved its functionality under sterile settings using cadaver tests. It is concluded that this device largely facilitates the operative procedure in femoral shaft fractures, is sufficiently stable and ergonomically suitable for intraoperative deployment.     

Evaluation of hip fracture risk in relation to fall direction

The purpose of this study is to evaluate hip fracture risk in relation to fall direction, and to elucidate factors that influence the impact force in falls on the hip. Eight healthy volunteers performed deliberate falls in three directions (lateral, posterolateral and posterior) on a force platform covered by a mattress of 13 cm thickness. Fall descent motions and impact postures were examined by a three-dimensional analyzer. The maximum ground force reaction, velocity of the greater trochanter at impact, and activity of quadriceps and gluteus medius were measured. In all trials of lateral and posterolateral falls, but not of posterior falls, the subjects hit their greater trochanter directly on the mattress. The impact forces were between 2,000 N and 4,000 N. Posterolateral falls showed significantly higher velocity at impact than did posterior falls. The height and the lower limb length exhibited positive correlations with the impact force in all directions of fall. In the lateral fall, there was a positive correlation between the activity of quadriceps and the impact force. In view of the impact point, force, and velocity, the posterolateral fall seemed to carry the highest risk of hip fracture.