下腰椎失稳合并椎管狭窄症的手术治疗

目的：观察下腰椎失稳合并椎管狭窄症患者经椎弓根螺钉系统及椎体融合器治疗的效果。方法：采用后路减压，椎弓根螺钉系统内固定，椎体间融合器BAK融合。结果：术后随访1年一4年3个月(平均2年4个月)，椎体间骨性融合率1年89．6％，2年2个月100％，临床症状消失满意率92％。结论：采用椎管减压、椎弓根螺钉系统加椎间融合器固定，可使滑脱失稳的椎体部分或全部复位，保证脊柱骨性融合，达到脊柱稳定、解除症状的目的。     

经皮椎体成形术与椎弓根螺钉固定治疗骨质疏松性胸腰椎骨折的生物力学研究

目的比较经皮椎体成形术(PVP)和椎弓根螺钉内固定(PSF)治疗骨质疏松性胸腰椎骨折的生物力学强度,为临床应用和离床活动指导提供实验依据。方法18具冻存的新鲜尸体,应用双能X线骨密度仪(DEXA)测定脊柱的骨密度(BND),取胸腰段脊椎(T_(12)～L_2 12具,L_1 6具)随机分成三组：PVP组、PSF组(T_(12)L_2)和正常对照组(L_1),每组6具。PVP组和PFS组实验椎体均制成骨折模型,PVP组给予经双侧椎弓根注入低粘度的含显影剂骨水泥各2．5mL。PSF组于T_(12)、L_2椎弓根置入钉棒系统固定,测试并比较两组和对照组静态最大抗压强度及刚度。结果PVP组骨水泥分布面积皆大于50%,其平均最大抗压强度与刚度分别为(2645±478)N,(117±81)N/mm；PSF组平均最大抗压强度与刚度分别为(1862±620)N,(125±33)N/mm。两组比较平均最大抗压强度差异有显著性意义(P＜0．05),最大刚度差异无显著性意义(P＞0．05)。结论骨折椎体内注入骨水泥PMMA,其抗压强度优于椎弓根钉方法,对于轻度骨质疏松者尤为适用。PVP术后患者可早期(3～5d)下床活动,而PSF术后患者离床活动时间可适当延后。     

枢椎后路侧块螺钉与椎弓根螺钉固定强度的生物力学评价

目的评价单皮质和双皮质枢椎侧块螺钉与枢椎椎弓根螺钉的固定强度,为临床选择枢椎后路螺钉的固定方式提供生物力学依据。方法利用12具新鲜尸体枢椎标本,进行单皮质和双皮质的椎弓根螺钉或侧块螺钉固定,测试比较其螺钉拔出强度。结果双皮质枢椎椎弓根螺钉的拔出力量最大,为(1 726.5±433.3)N;单皮质枢椎椎弓根螺钉〔(1 279.9±432.0)N〕与双皮质枢椎侧块螺钉〔(1 054.8±411.3)N〕之间差异无统计学意义;单皮质枢椎侧块最小为(689.4±128.0)N。结论枢椎后路螺钉固定宜首选椎弓根螺钉,侧块螺钉可作为补充固定技术,且以双皮质骨固定为宜。     

对徒手置入胸椎椎弓根螺钉的安全性评价

目的：评价徒手置入胸椎椎弓根螺钉的安全性并探讨其置钉方法.方法：372例患者采用徒手方法置入胸椎椎弓根螺钉,记录置入操作中和术后并发症,其中37例患者术后行CT断层扫描检查判断螺钉的位置,记录所有穿透骨皮质螺钉的数目和距离.结果：共徒手置入胸椎椎弓根螺钉2261枚,平均每例患者置入螺钉6.08枚,术中6例次置钉过程中出现脑脊液从钉道中流出,术中和术后未出现神经、血管和内脏损伤等并发症.37例患者术后行CT扫描判断螺钉位置,405枚螺钉中124枚（30.62%）穿透骨皮质,1枚（0.02%）穿透椎弓根内侧壁超过4mm.结论：徒手置入胸椎椎弓根螺钉穿透骨皮质的发生率较高,应该根据每个椎体旋转、倾斜等差异个体化确定置钉位置和方向,操作仔细认真,保证准确、安全、可靠地置入胸椎椎弓根螺钉.     

卵巢肿瘤蒂扭转的CT诊断价值探讨(附12例报告)

目的:评价CT对卵巢肿瘤蒂扭转的诊断,探讨囊壁局限性增厚对卵巢肿瘤蒂扭转的诊断价值。方法:对12例卵巢肿瘤蒂扭转的CT征象作回顾性分析,对卵巢肿瘤蒂扭转囊壁局限性增厚CT表现与文献报道的B超特征性表现双肿块声像图作对照分析。结果:本组12例病例中11例为卵巢囊性或者囊实性肿瘤,其中6例有局限性囊壁增厚,除此之外卵巢肿瘤蒂扭转还有其它许多CT征象,如卵巢肿瘤囊肿壁及囊肿内出血,附件输卵管增粗、显示,盆腔内积液,子宫位置偏位。结论:只要我们能密切结合临床,CT能对大多数卵巢肿瘤蒂扭转作出正确诊断。     

Surgical treatment of symptomatic degenerative lumbar spondylolisthesis by decompression and instrumented fusion

Degenerative spondylolisthesis is characterized by the slippage of one vertebral body over the one below, with association of intervertebral disc degeneration and degenerative arthritis of the facet joints, which cause spinal stenosis. The aim of this study was to evaluate the clinical and radiographic results of 22 patients with symptomatic degenerative spondylolisthesis, operated on by decompressive laminectomy and instrumented posterolateral fusion associated with interbody fusion (PLIF). Mean age at surgery was 64 years (range, 57–72). Clinical results were evaluated on a questionnaire at the last follow-up visit concerning postoperative low back and leg pain, restriction of daily life activities, and resumption of sports activity. Lumbar spine radiographs were used to evaluate the status of fixation devices, the reduction of the spondylolisthesis, the lumbar sagittal balance and the presence of spinal fusion. No intraoperative or postoperative complications were encountered. There were no superficial or deep infections, fixation device loosening, or hardware removal. Mean follow-up time was 4 years (range, 3–6 years). Clinical outcome was excellent or good in 19 patients and fair in 3 patients. Preoperatively, mean forward vertebral slipping on neutral lateral radiographs was 5 mm, while postoperatively it decreased to 3 mm. Preoperatively, mean sagittal motion was 3 mm and angular motion was 8°, while postoperatively these values decreased to 1 mm and 1°, respectively. This study demonstrated that spinal decompression followed by transpedicular instrumentation associated with PLIF technique is a valid surgical option for the treatment of degenerative spondylolisthesis with symptomatic spinal stenosis. Clinical outcome, intended as relief of pain and resumption of activity, was improved significantly and fusion rate was high.     

Mixed H2/H∞ control with pole placement in a class of regions

The problem of mixed H₂/H_∞ control with pole placement is considered for linear time-invariant systems. This is the problem of determining a controller for linear time-invariant systems which minimizes the H₂-norm of a certain closed-loop transfor function subject to an H_∞-norm constraint on another closed-loop transfer function and an additional constraint on the location of the closed-loop poles in the complex plane. An optimization problem is posed for the pole-constrained H₂/H_∞, problem in such a way that the objective function is expressed as a weighted sum of the actual H₂ cost and its upper bound. A necessary condition for the optimization problem is derived via the Lagrange multiplier technique. The condition involves a set of highly coupled equations. By sacrificing the H₂ performance, an alternative optimization problem is posed in order to simplify the necessary condition. An iterative algorithm for solving the coupled equations arising in the necessary conditions is proposed and numerical examples are presented.     

逆行半比目鱼肌带蒂肌瓣修复小腿远端软组织缺损

目的总结逆行半比目鱼肌带蒂肌瓣修复小腿远端软组织缺损的临床应用结果。方法 2006年10月~2012年10月,应用逆行半比目鱼肌带蒂肌瓣修复12例小腿远端软组织缺损,年龄16~42岁(平均35岁)。肌瓣表面行一期中厚网状游离植皮,供区直接缝合。结果所有的肌瓣全部成活,取得了满意的临床效果。随访1.5~3.5年,平均2.5年,8例伴有胫骨骨折者骨折全部愈合。结论逆行半比目鱼肌带蒂肌瓣具有血管解剖恒定、血运丰富以及操作简单等优点,适宜修复小腿远端软组织缺损。     

胸腰椎椎弓根的解剖学测量及其临床意义

目的　观测胸腰椎椎弓根形态结构特征 ,为临床提供解剖学参数。方法　测量 31例成年男性椎骨T1～L5的横径、矢径、椎弓根间距及椎弓根通道长度。结果　横径 :T1～T6逐渐变小 ,T6～T12 逐渐增大 ,L1和L2 小于T12 ,L2 ～L5逐渐增大 ;矢径 :T1～T3 逐渐增大 ,T4～T7均小于T3 和T8,T7～T12 又逐渐增大 ,L1～L3 逐渐变小 ,L3 ～L5又逐渐增大 ,T1～L5均明显大于其横径 (P <0 0 1) ;模仿弓根通道长 :T1～T10 逐渐增长 ,T11和T12 均较T10 和L1短 ,L1～L4逐渐增长 ,L5较L4短 ;椎弓根间距 :T1～T4逐渐变窄 ,T5～L5逐渐增宽 ;左右侧比较无显著性差异 (P >0 0 5 )。结论　进行椎弓根螺钉固定时应根据不同节段椎弓根形态特点 ,结合影像学资料 ,选择相应的螺钉直径、长度、进钉部位及方向。     

Strategies and determinants for selection of alternate foot placement during human locomotion: influence of spatial and temporal constraints

During locomotion in a cluttered terrain, certain terrain surfaces such as an icy one are not appropriate for foot placement; an alternate choice is required. In a previous study we showed that the selection of foot placement is not random but systematic; the dominant choices made are not uniquely defined by the available or predicted sensory inputs. We argued that selection is guided by specific rules and involves minimal displacement of the foot from its normal landing spot. The experimental protocol involved implicit spatial constraint by requiring individuals to step on the force plate that could trigger a lighted area to be avoided, thereby requiring individuals to respond within one step-cycle. Alternate foot placement was visually identified, but not measured. The purpose of this study was to directly measure foot placement, validate and/or refine the rules used to guide selection, and identify whether the alternate foot placement choices are influenced by spatial and temporal constraints on response selection. The area to be avoided was visible from the start and therefore individuals could plan and implement appropriate avoidance strategies without any temporal constraint. Spatial constraint introduced in this experiment included requirement both to step on a specific location and to avoid stepping on a specific location on the next step. The results provide support for the rules previously identified in guiding foot placement to an alternate location. Minimal displacement of the foot from its normal landing spot was validated as an important factor for selecting alternate foot placement. When several choices satisfied this factor, additional factors guide alternate foot placement. Modifications in the plane of progression are preferred while stepping wide is avoided. When no temporal constraints are imposed on the response selection, enhancing forward progression of the body becomes the dominant determinant followed by stability and lastly by energy costs associated with the modifications. A decision algorithm for selecting foot placement is proposed based on these findings. It is clear that while visual input plays a critical role in guiding foot placement, it is not entirely based on reactive control. This has implications for implementing visually guided adaptive locomotion in legged robots.