UKA胫骨托盘背部设计对骨-假体固定界面的生物力学影响

目的 研究UKA胫骨托盘背部设计对单髁膝关节置换（unicompartmental knee arthroplasty, UKA）骨-假体固定界面的生物力学影响。方法 构建膝关节内侧置换的固定式UKA有限元模型,以膝关节行走运动下的关节载荷和关节运动为边界条件,对比研究大龙骨型、小龙骨型、两立柱带鳍骨型、三斜立柱型和三直立柱型UKA胫骨托盘背部设计下胫骨von Mises等效应力、骨-假体固定界面接触应力以及微动的差异。结果 在膝关节内侧最大受力时刻,相对于两立柱带鳍骨型的胫骨von Mises等效应力、骨-假体固定界面接触应力和微动;大龙骨型分别减小8%和15.9%、增大9.9%;小龙骨型分别减小12.3%、增大7.5%和1.6%;三斜立柱型分别减小10%和10.5%、增大1.2%;三直立柱型分别减小7.7%、14.7%、1.6%。而骨-假体固定界面的最大微动发生在步态周期21%时刻,相对于两立柱带鳍骨型的骨-假体固定界面微动,大龙骨型增大1.2%,小龙骨型增大1.6%,三斜立柱型减小0.4%,三直立柱型减小2.3%。结论 为了提高胫骨假体的长期固定效果,建议UKA胫骨托盘设计应重点考虑两直立柱带鳍骨或小龙骨的组合设计,从而有效地平衡应力传递和界面微动,在保证假体稳定性的同时降低无菌性松动的风险。     

UKA假体后倾角安装位置对衬垫磨损的影响

目的 研究单髁膝关节置换(unicompartmental knee arthroplasty, UKA)假体不同后倾角度安装对膝关节承载、运动及衬垫磨损的影响。方法 联合UKA骨肌多体动力学模型、有限元模型和磨损模型,分析固定式UKA假体5种后倾角安装位置情况对术后膝关节力和运动、衬垫接触应力、线性磨损深度和体积磨损量的影响。结果 后倾角0°时,衬垫的最大von Mises等效应力为24.84 MPa,接触应力为47.61 MPa, 5百万次循环(million cycle, MC)周期的磨损量为47.29 mm³。随着UKA胫骨假体后倾角的增加,步态周期内旋和后移运动均增大,摆动相的内侧关节力增大,5 MC磨损周期后衬垫von Mises等效应力与接触应力显著减小,衬垫的磨损面积、最大线性磨损深度和体积磨损量随之减少。相对于后倾角0°,后倾角为3°、5°、7°时衬垫的线性磨损深度分别减小了17.8%、19.2%、20.6%;衬垫体积磨损量分别下降了24.5%、30.9%、34.3%。结论 UKA假体考虑后倾角安装超过3°时会显著增加步态周期内旋运动和后移运动,...     

如何实现Oxford单髁置换的准确截骨和术后稳定

Oxford单髁置换(UKA)准确截骨、间隙平衡、获得稳定及良好运动轨迹是手术成功的关键.UKA首先建立的是屈曲间隙,然后根据屈曲间隙大小再建立伸直间隙.其间隙平衡是指,在完成内侧胫骨平台截骨后,通过对股骨髁远端研磨调整股骨假体相对于股骨放置的高度,获得相等的屈伸间隙.UKA截骨一环扣一环,不能失误.胫骨截骨量不能过多...     

活动式与固定式 UKA 衬垫的接触力学和磨损对比研究

目的 采用计算机模拟方法对比研究 ISO 14243 - 1 ∶ 2009 力控制标准测试条件下单髁膝关节置换术(unicompartmental knee arthroplasty,UKA)活动式与固定式衬垫的接触力学和磨损性能。 方法 采用有限元方法分析两种衬垫在测试条件下的接触应力和 von Mises 应力,并采用磨损预测模型模拟 5 MC(million cycles, 百万次循环)步态周期工况获得两种衬垫的线性磨损深度、磨损体积。 结果 磨损前活动式与固定式衬垫的最大接触应力分别为 15. 7、44. 3 MPa,最大 von Mises 应力分别为 11. 94、23. 33 MPa。 随着磨损加剧,活动式衬垫的最大接触应力和 von Mises 应力先减小后趋于稳定,而固定式衬垫的基本保持不变。 固定式衬垫的线性磨损深度为活动式的1. 5 倍,但活动式衬垫的磨损体积是固定式的 5. 4 倍,且活动式衬垫的背部磨损体积占其总磨损体积的 70% 。 结论 与固定式 UKA 衬垫相比,活动式 UKA 衬垫具有较低的接触应力与 von Mises 应力,但有较大的磨损体积。 活动式衬垫背部磨损是磨屑增加的另一个重要来源。     

Mobile bearing UKA compared to fixed bearing TKA: a randomized prospective study

We prospectively evaluated a consecutive series of 56 patients with unicompartmental knee arthritis who underwent unicompartmental knee replacement or total knee arthroplasty and received an average of 52months of follow-up. These patients were enrolled in a prospective randomized clinical trial. There were no significant differences in the pre-operative parameters of both groups. All the patients were followed up and evaluated preoperatively and yearly, the data was collected and statistical analysis was performed. At an average of 52months after surgery the mean Knee Society score was 80.5 (range: 70-100) and 78.9 (range: 70-87) for Unicompartmental knee replacement and total knee arthroplasty, mean range of postoperative motion for TKA is 115(0)±4(0) and 117(0)±7(0) for the group of UKA, with the numbers available, the difference between the two groups could not be shown to be significant. The average operation time of UKA and TKA is 68.8min and 81.5min(p<0.01). Blood drainage after operation had a significant difference between the two groups (p<0.01). Seven cases of UKA were converted to total knee arthroplasty - all of them within the first 2years of starting the procedure and all of them in relatively young patients. From the study we concluded that mobile bearing UKA can obtain similar clinical effect with TKA by surgeons who have the adequate training and experience. After the learning curve UKA should be considered the primary treatment option for unicompartmental knee arthritis.     

Survivorship of constrained polyethylene inserts in primary total knee replacements

BackgroundVarus–valgus constrained (VVC) inserts are used in primary total knee arthroplasty (TKA) when stability cannot be achieved with a traditional insert. Concern has been raised regarding premature loosening and failure of these primary TKAs due to the increased load transfer through the prosthesis. This study seeks to assess the survival, clinical outcomes and radiographic assessment of VVC total knee inserts used in a single primary TKA system without diaphyseal stem extensions.MethodsA consecutive cohort of 74 primary TKAs with VVC inserts was identified from an institutional database. A two-to-one matched group of 136 posterior-stabilized (PS) primary TKAs was generated from the same database. Survival analysis was assessed for all-cause revision surgery. Patient outcome measures were the Oxford Knee Score (OKS) and patient reported satisfaction. Radiographs were assessed in accordance with the Knee Society radiographic scoring system for radiolucency.ResultsSurvival rates at three and five years were 98.1% and 95.1% for the VVC liner group and 98.1% and 98.1% for the PS liner group, respectively. OKS improved from pre-op to post-op for both groups (p < .001). OKS was reduced in the VVC liner group compared to the PS liner group at latest available follow-up (p = .012). However, clinical satisfaction rates did not differ between the two groups. Small, non-progressive radiolucent lines existed on several radiographs; however, no components in either group were deemed radiographically loose.ConclusionThe survivorship, clinical, and radiographic outcomes of VVC knees were similar to the PS comparison group at short- to mid-term follow-up.     

术者经验对膝关节单髁置换术中的间隙平衡的影响：一项尸体研究

目的通过传感器技术,研究不同经验的术者在UKA术中所实现的间隙平衡是否有差别。方法依据术者既往单髁手术经验将术者分为无经验组、经验不足组及经验成熟组,通过压力传感器测量45例解冻尸体标本的单髁手术中的间隙压力,研究术者的手术经验是否与屈伸间隙平衡有关。结果经验成熟组术者的间隙平衡差为(53.19±43.47)N,显著低于经验不足组的(194.18±102.92)N和无经验组的(314.86±129.64)N(P<0.05)。而经验不足组与无经验组间差异无统计学意义(P>0.05)。结论术者的单髁手术经验与术中屈伸间隙平衡密切相关,而传感器技术可以帮助术者更加准确地判断间隙压力。     

UKA 关节线安装误差对膝关节接触力学和运动学影响

目的 针对单髁膝关节置换(unicompartmental knee arthroplasty, UKA)内侧假体松动和外侧关节软骨退化问题,通过骨肌多体动力学方法研究不同生理活动中UKA关节线安装误差对膝关节接触力学和运动学的影响。方法 以内侧自然关节线为0 mm误差,分别考虑±2 mm、±4 mm、±6 mm共6种关节线安装误差情况,建立7个内侧UKA置换的骨肌多体动力学模型,对比研究步行和下蹲运动中膝关节接触力学和运动学的变化。结果 在步行步态周期70%时,相比于0 mm误差UKA假体关节线升高2 mm时内侧假体接触力增大127.3%,外侧软骨接触力减少12.0%;在UKA假体关节线降低4 mm时内侧假体接触力接近0 N,外侧软骨接触力增大10.1%;胫股关节总接触力在关节线升高和降低2 mm时分别增大19.7%和减小14.2%。在下蹲屈膝100°时,相比于0 mm误差膝关节内侧假体接触力和胫股骨关节总接触力在UKA假体关节线升高2 mm时分别增大31.6%和11.1%,在UKA假体关节线降低2 mm时分别减小24.5%和8.5%,而膝关节外侧软骨接触力变化不大。同时,在步行步态...     

Advancing Uterine Cancer Survivorship Among African American Women

Background

Few studies have examined health behavior interventions for African American women who are uterine cancer survivors. Black-white differences in uterine cancer survival suggest that there are unmet needs among these survivors.

Congenital absence of the portal vein in a middle-aged man

Congenital absence of the portal vein with systemic diversion of mesenteric blood is extremely rare. We report a case of a congenital absence of the portal vein, accidentally discovered in a 59-year-old man, completely asymptomatic and not associated with other malformations or biochemical disorders. Ultrasonography imaging showed the absence of the portal vein and the distal tract of superior mesenteric and splenic veins draining together into a dilated left renal vein. Computed tomography and magnetic resonance confirmed the presence of a congenital portosystemic venous shunt and also revealed two hepatic arteries: one arising from the celiac trunk and the other from the superior mesenteric artery.     

Libido and orgasm in middle-aged woman

OBJECTIVES: Determine which social, demographic and sexual function variables that most influence libido or desire and orgasm domains in the premenopausal and postmenopausal women. METHODS: A cross-sectional analysis of 231 Colombian-born women, aged 40-62 years. The sexual function was measured by self-questionnaire. The analysis was performed by using the chi2-test and multivariate regression analysis. The sexual function was divided in five domains: desire, arousal, lubrication, orgasm, pain; additionally satisfaction was included. RESULTS: The women with a higher level of education and with a good perception of their satisfaction with their partners, reported better performance in the desire. Age and the non existence of sexual partner influenced in a negative way on the desire. In sexual active women the orgasm was negatively influenced by low satisfaction scores, lack of emotional closeness with their partners and low educational level. High scores in lubrication and desire were associated with a good performance in the orgasm. The hormone therapy (HT) was associated with better scores in orgasm. CONCLUSIONS: Age, level of education, the presence or lack of sexual partner, degree of satisfaction with emotional closeness with the partner and adequate lubrication, influence the desire and orgasm domains in a significant way. By identifying these associations we can then perform some inexpensive interventions. Improving lubrication for menopausal women. Including men in educational activities to sensitize them toward women's feelings. Organizing educational campaigns for middle-aged women to demystify that sexuality is only for young people.     

Rhabdomyosarcoma in middle-aged and elderly individuals

In a review of a national series of malignant tumors in middle-aged and elderly individuals (over 40 years of age), in all 107 cases primarily diagnosed and reported to the Swedish Cancer Registry as rhabdomyosarcomas during the period 1972-1981, 4 cases were accepted as botryoid, embryonal or alveolar rhabdomyosarcoma, using light-microscopic criteria for the diagnosis. An electron-microscopic and immunohistochemical analysis was performed on the 4 cases along with 7 cases of botryoid, embryonal and alveolar rhabdomyosarcoma in patients of over 40 years of age obtained from our own files. Rhabdomyoblastic differentiation was established ultrastructurally by the presence of myofilaments and Z-like densities in 10 of these 11 cases. There were tumor cells in the formaldehyde-fixed, paraffin-embedded material which were positively stained for desmin in all cases, for myoglobin in 7/11 cases, for vimentin in 5/11 cases and for actin in all cases, using monoclonal antibodies. The demonstration of desmin by the monoclonal antibody which was used on the formaldehyde-fixed, paraffin-embedded material is of particular value in the diagnosis of rhabdomyosarcoma. Another tumor, located in the minor pelvis, lacked the light-microscopic features of botryoid, embryonal or alveolar rhabdomyosarcoma, but presented ultrastructural and immunohistochemical evidence of a rhabdomyoblastic differentiation. This tumor was epithelioid in appearance and shared features with alveolar soft part sarcoma. The label epithelioid rhabdomyosarcoma is proposed for this tumor. Nine pleomorphic sarcomas were selected from the national series as possible pleomorphic rhabdomyosarcomas because of the presence of ribbon-shaped tumor cells with an eosiniphilic cytoplasm. There was no electron-microscopic or immunohistochemical evidence of a myogenic differentiation in any of these 9 tumors. The present investigation indicates that a pleomorphic type of rhabdomyosarcoma, indistinguishable from embryonal, botryoid and alveolar rhabdomyosarcoma, is extremely rare or non-existent.