Finite Element Modeling of Stress Distribution in Intervertebral Spacers of Different Surface Geometries

Intervertebral disc spacers using bioactive ceramics have been used to treat degenerative spinal disease. Tooth‐shaped spacers are commonly used to prevent migration, but there is a possibility of fracture when inserted or after insertion. Intervertebral disc spacers with either an isosceles triangle‐shaped tooth (T1) or a right triangle‐shaped tooth (T2) were used as a control group. The design factors for the experimental group were modified to prevent fractures induced by stress concentration, and the surfaces of the spacers were designed as either an isosceles triangle‐shaped valley (V1) or a right triangle‐shaped valley (V2). Linear analysis using finite element model (FEM) was performed, and Von Mises stress distribution was calculated by applying 1000 N of uniformly distributed load. Samples of the V2 design were made with bioactive glass‐ceramics (BGS‐7) and evaluated for compressive strength, fatigue degree, and impact strength. Von Mises stress was highest at the first tooth from the posterior side for the control group and at the center for the experimental group. Compared with the control group, the experimental group showed 18.4% and 82.5% reduction (V1 vs. T1 and V2 vs. T2, respectively) in the maximum stress at the bottom of the valleys. The FEM analysis revealed that the V2 design had the most even load distribution. The V2 samples with bioactive glass‐ceramics were evaluated for compressive strength, and all six samples were not fractured up to 24 000 N. However, the average impact strength was 19.42 kN, suggesting that momentary force caused damage at a lower load than compression with a steady speed. The BGS‐7 intervertebral disc spacer with V2 design was not fractured during the fatigue test at maximum pressure of 8000 N, R ≥10, 5 Hz, and 5 million cycles. These data confirm that the BGS‐7 spacer with the V2 design may be clinically applicable. Collectively, the modified surface geometry of the experimental group significantly lowered Von Mises stress values at the bottom of the valleys, and thus the possibility of fracture by compressive load was greatly reduced. Also, impact during insertion was confirmed to cause fracture more easily, as the impact strength was lower than the compressive strength in the experimental group.     

颈前路多节段融合术后吞咽困难的原因分析

目的 比较多节段颈前路椎间盘切除减压融合术中采用传统钢板+cage和“零切迹”颈椎椎间融合器植入患者术后吞咽困难的发生情况,并分析其原因.方法 2008年9月至2011年9月,接受颈前路椎间盘切除减压+前路钢板+cage植入的118例多节段颈椎病患者为钢板cage组,接受颈前路椎间盘切除减压+Zero-p颈椎椎间融合器植入的108例患者为Zero-p组.分别于术前、术后第2天、术后3、6、12个月及末次随访时采用日本矫形外科学会评分法(Japan orthopedic association,JOA)对患者的神经功能情况进行评估;摄颈椎X片评价植骨融合程度、内固定相关并发症及椎前软组织肿胀程度;采用Bazaz吞咽困难分级及改良吞咽生活质量量表(swallowing-quality of life,SWAL-QOL)评估患者吞咽困难的发生率及相关症状发生情况.结果 随访时间平均为2.4年(1.0～3.5年).术后第2天钢板cage组发生吞咽困难49例(41.53％)明显高于Zero-p组(36例,33.33％);钢板cage组术后第2天及术后2个月椎前软组织厚度明显大于Zero-p组.术后第2天Zero-p组中手术范围为C3～C6的患者吞咽困难发生率(43.1％)明显高于手术范围为C4～C7的患者(22％).结论 颈前路多节段融合术后吞咽困难不可避免,内固定的选择和手术范围是术后吞咽困难发生的重要影响因素.使用颈椎“零切迹”植入物可以减少术后吞咽困难的发生率,手术节段越高术后吞咽困难的发生率越高.     

Factores pronósticos del tratamiento endoscópico del reflujo vesicoureteral en pacientes con lesión medular

IntroductionVesicoureteral reflux (VUR) is an important complication in patients with spinal cord injury due to its frequency and morbidity. One of the most extended therapeutic options is endoscopic injection of obliteration substances in the urethral meatus.ObjectiveTo analyze the prognostic factors of VUR treatment using obliterative substances in patients with spinal cord injury.Material and methodsA prospective study was performed in a cohort of 76 patients (age 48.9 ± 14.4 years), of both genders, with spinal cord injuries, who underwent endoscopic treatment of the VUR during the years 2008 to 2011. In all the patients, a clinical history was obtained and a pre-operative videourodynamic study was performed. Another study was carried out at 7.32 months (standard deviation: 6.28 months) of the intervention. Treatment consisted in endoscopic injection of dextranomer/hyaluronic acid copolymer (62 cases) and polydimethylsiloxane (14). The statistical tests applied were the Fisher's exact test and the Student's T test comparing the means. Bilateral significance level was established at 95%.ResultsResolution of VUR was achieved in 46 cases (61%). The statistically significant prognostic factors were age (younger aging cured patients), bilaterality and reflects great (greater grade in bilaterality in the cases with persistence of reflux) and presence of neurogenic detrusor overactivity (greater percentage in the cases of reflux persistence). Stress urinary incontinence (greater percentage in cured patients), contractile potency (lower percentage in cured patients) and urethral resistance (greater percentage in cured patients) were also statistically significant prognostic factors.ConclusionsAmong the prognostic factors that affected the endoscopic treatment results of the VUR in patients with neurogenic lower urinary tract dysfunction (NLUTD), anatomical as well as functional factors were found.     

棘突劈开、单侧进入双侧减压与椎板切除减压治疗退变性腰椎管狭窄症的比较

目的 比较棘突劈开、单侧进入双侧减压与椎板切除、椎管减压治疗腰椎管狭窄症的疗效.方法 前瞻性研究2009年6月至2010年5月手术治疗56例退变性腰椎管狭窄症或椎管狭窄合并间盘突出患者资料.术前随机将患者分为棘突劈开、单侧进入双侧减压组(简称棘突劈开组)及传统腰椎椎板切除、椎管减压组(简称椎板切除组).棘突劈开组共27例,男15例,女12例;年龄49～71岁,平均59.4岁.椎板切除组29例,男18例,女11例;年龄52～69岁,平均61.1岁.术后第3天行血肌酸激酶测定.应用日本矫形外科学会(Japanese Orthopaedic Association,JOA)腰痛评分及疼痛视觉模拟评分(visual analogue scale,VAS)作为手术前后主、客观评分标准.术后6个月CT扫描评价棘突愈合情况.测量术前及末次随访时多裂肌MR面积.结果 棘突劈开组21例、椎板切除组24例获得2年以上有效随访.棘突劈开组术前腰痛及下肢痛VAS、JOA评分、多裂肌MR面积分别为:(5.6±1.7)分、(7.1±0.4)分、(11.6±2.6)分、(5.8±1.8)cm2;椎板切除组分别为(6.2±1.2)分、(7.9±1.3)分、(10.9±1.0)分、(6.1±2.0) cm2.棘突劈开组术后第3天血肌酸激酶测定值明显小于椎板切除组.棘突劈开组术后6个月随访时劈开棘突均完全愈合.末次随访时棘突劈开组下肢痛VAS、JOA评分及改善率分别与椎板切除组比较均无显著性差异.棘突劈开组腰痛VAS评分、多裂肌萎缩比分别为(1.0±0.5)分、6.4％±1.2％;椎板切除组分别为(2.6±0.7)分、l5.7％±3.0％,棘突劈开组均优于椎板切除组.两组动力位X线片均未见继发性腰椎不稳.结论 棘突劈开、单侧进入双侧减压可有效减少手术创伤及术后腰痛发生率,保护双侧多裂肌棘突止点及对侧多裂肌在椎板的附着点.     

Stargazin在切口痛大鼠脊髓背角GluR1-AMPA受体胞浆至胞膜转运中的作用

目的 评价Stargazin在切口痛大鼠脊髓背角含谷氨酸受体1亚基的使君子酸(GluR1-AMPA)受体胞浆至胞膜转运中的作用.方法 成年雄性清洁级SD大鼠45只,体重280 ～ 300 g,6～8周龄,采用随机数字表法,将其分为5组:正常对照组(C组)、假手术组(S组)、切口痛+生理盐水组(P组)、切口痛+ Stargazin小干扰RNA(siRNA)组(I组)和切口痛+Stargazin无意义siRNA组(N组).P组、I组和N组分别鞘内注射生理盐水10μl、20 μmol/L siRNA、20μmol/L无意义siRNA 10μl,2次/d,连续3d,4d后制备右足底切口痛模型.切口痛术后3h时测定大鼠累计痛评分(CPS)和机械缩足阈(PWT).然后处死大鼠,取L3-6节段脊髓背角,采用Westem blot法检测胞浆和胞膜GluR1和GluR2亚基表达,采用免疫共沉淀技术检测脊髓背角Stargazin与GluR1或GluR2亚基的共表达.结果 与C组比较,P组和N组CPS评分升高,PWT降低,脊髓背角胞浆GluR1表达下调,脊髓背角胞膜GluR1表达上调,I组CPS评分升高(P＜0.05或0.01);与P组比较,I组CPS评分降低,PWT升高,脊髓背角胞浆GluR1表达上调,脊髓背角胞膜GluR1表达下调,脊髓背角Stargazin和Stargazin与GluR1共表达下调(P＜ 0.05或0.01).结论 Stargazin介导了切口痛大鼠GluR1-AMPA受体从胞浆至胞膜转运.     

维持性血液透析7年 进行性呼吸困难1个月

1病历资料患者男,57岁。患者2003年4月起颜面部及双下肢水肿,伴尿量减少,在外院诊断为"慢性肾脏病5期,肾小动脉硬化,高血压病3级极高危",予行规律血液透析治疗。6个月前出现左下肢疼痛,1个     

老年人畸形脊柱的活动能力

目的分析存在脊柱畸形的老年人的椎体运动能力。方法应用脊柱功能测量仪,测量76名存在脊柱畸形的老年人脊柱的直立位、前屈、后伸的椎间夹角,以及前屈位到直立位、直立位到后伸位、前屈位到后伸位的活动度改变,并对比椎体夹角在各个体位的改变情况。结果脊柱畸形老年人椎间活动明显减小,躯干的整体倾角范围并未发生非常明显的变化,胸腰段的活动能力相对增强;与前屈相比,后伸位增加了T7～T9节段椎体活动。脊柱长度在立位到前屈时增加(9.447±32.831)mm,立位到后伸时减少(10.553±21.737)mm。结论脊柱畸形老年人部分胸腰段椎体的代偿活动改善了脊柱的整体活动能力,但这种运动可能会引起局部损伤机会增加。日常老年人脊柱倾角处于较明显的前倾状态,这将造成躯干质心的明显偏移。     

Proteome profiling of spinal cord and dorsal root ganglia in rats with trinitrobenzene sulfonic acid-induced colitis

AIM: To investigate proteomic changes in spinal cord and dorsal root ganglia (DRG) of rats with trinitrobenzene sulfonic acid (TNBS)-induced colitis.METHODS: The colonic myeloperoxidase (MPO) activity and tumor necrosis factor-α (TNF-α) level were determined. A two-dimensional electrophoresis (2-DE)-based proteomic technique was used to profile the global protein expression changes in the DRG and spinal cord of the rats with acute colitis induced by intra-colonic injection of TNBS.RESULTS: TNBS group showed significantly elevated colonic MPO activity and increased TNF-α level. The proteins derived from lumbosacral enlargement of the spinal cord and DRG were resolved by 2-DE; and 26 and 19 proteins that displayed significantly different expression levels in the DRG and spinal cord were identified respectively. Altered proteins were found to be involved in a number of biological functions, such as inflammation/immunity, cell signaling, redox regulation, sulfate transport and cellular metabolism. The overexpression of the protein similar to potassium channel tetramerisation domain containing protein 12 (Kctd 12) and low expression of proteasome subunit α type-1 (psma) were validated by Western blotting analysis.CONCLUSION: TNBS-induced colitis has a profound impact on protein profiling in the nervous system. This result helps understand the neurological pathogenesis of inflammatory bowel disease.     

Is closed-suction drainage necessary after intradural primary spinal cord tumor surgery?

Purpose

The efficacy of closed-suction drainage in primary intradural spinal cord tumor surgery has not been addressed. We investigated whether closed-suction drainage is essential after primary intradural spinal cord tumor surgery.

Methods

From January 2003 to October 2011, 169 consecutive patients with primary intradural spinal cord tumors operated by a single surgeon were selected. Closed-suction drainage was inserted in patients before August 2007, but was not used after August 2007. After removal of tumor and meticulous hemostasis, the opened dura was closed and made watertight using 4-0 silk with interrupt suture and 1.0 cm³ of surgical glue was applied in common. Closed-suction drainage was inserted below the muscular fascia in 75 patients (group I, M:F = 39:36; 46.20 ± 15.63 years) and was not inserted in 94 patients (group II, M:F = 46:48; 51.05 ± 14.89 years).

Results

Neurological deficit precluding ambulation did not occur in all patients. Between group I and II, there were no significant differences in body mass index (22.75 ± 3.16 vs. 23.51 ± 3.22 kg/m²; p = 0.13), laminectomy level (2.45 ± 1.46 vs. 2.33 ± 1.91; p = 0.65), operation time (260.65 ± 109.08 vs. 231.52 ± 90.08 min; p = 0.06), estimated intraoperative blood loss (456.93 ± 406.62 vs. 383.94 ± 257.25 cm³; p = 0.18), and hospital stay period (9.25 ± 5.01 vs. 9.35 ± 5.75 days; p = 0.91). Two patients in group I underwent revision surgery due to wound problems, while revision surgery was not performed in group II (p = 0.20).

Conclusion

Closed-suction drainage may not be essential after primary intradural spinal cord tumor surgery.     

Predisposing factors for surgical site infection of spinal instrumentation surgery for diabetes patients

Purpose

Diabetes mellitus (DM) is known as an important risk factor for surgical site infection (SSI) in spine surgery. It is still unclear however which DM-related parameters have stronger influence on SSI. The purpose of this study is to determine predisposing factors for SSI following spinal instrumentation surgery for patients with DM.

Methods

110 DM patients (66 males and 44 females) who underwent spinal instrumentation surgery in one institute were enrolled in this study. For each patient, various preoperative or intraoperative parameters were reviewed from medical records. Patients were divided into two groups (SSI or non-SSI) based on the postoperative course. Each parameter between these two groups was compared. Univariate and multivariate analyses were performed to determine predisposing factor for SSI.

Results

The SSI group consisted of 11 patients (10 %), and the non-SSI group of 99 patients (90 %). Univariate analysis revealed that preoperative proteinuria (p = 0.01), operation time (p = 0.04) and estimated blood loss (p = 0.02) were significantly higher in the SSI group compared to the non-SSI group. Multivariate logistic regression identified preoperative proteinuria as a statistically significant predictor of SSI (OR 6.28, 95 % CI 1.58–25.0, p = 0.009).

Conclusions

Proteinuria is a significant predisposing factor for SSI in spinal instrumentation surgery for DM patients. DM patients with proteinuria who are likely to suffer latent nephropathy have a potential risk for SSI. For them less invasive surgery is recommended for spinal instrumentation. In this retrospective study, there was no significant difference of preoperative condition in glycemic control between the two groups.