单髁置换术后膝关节内外侧间室应力变化有限元分析

目的:采用有限元分析方法研究单髁置换术后膝关节表面应力变化,为深入了解单髁置换术优势及劣势提供依据。方法:对6例单髁置换术后及6例正常人膝关节屈伸活动时关节表面应力变化进行动态有限元分析,并与项目组前期全膝关节置换术后关节表面应力分析进行对比。结果:正常组屈曲30°以后内侧间室应力大于外侧间室(P<0.05);单髁置换组屈曲0°、60°、90°时内侧间室应力大于外侧间室(P<0.05);全膝置换组在所有屈曲角度下内侧间室应力大于外侧间室(P<0.05)。屈曲60°及90°时单髁置换组内侧间室应力大于全膝置换组(P<0.05);所有屈曲角度下,单髁置换组外侧间室应力大于全膝置换组外侧间室应力(P<0.05);屈曲0°、30°、60°及120°时,单髁置换组外侧间室应力都大于正常膝组(P<0.05)。结论:单髁置换术可增加膝关节关节面应力及加速对侧间室关节炎发展,从而影响手术远期疗效,但在严格把握手术适应症、优化手术操作、假体适当改良、指导患者合理康复后,该术式仍具有优势。     

股骨髁髌股、胫股关节运动重叠接触区域测定

 目的描记膝关节运动过程中胫股、髌股关节在股骨髁关节面接触的重叠区域,明确其具体范围,为进一步研究膝关节髌骨、胫骨和股骨三者对应解剖关系以及生物力学特性,为优化股骨假体设计奠定基础.方法Instron 8501生物力学测试仪模拟生理状态下膝关节站立到下蹲屈膝过程,收集8具新鲜膝关节尸体标本,通过染色法分别描记髌股、胫股关节运动在股骨髁面的接触区域,标记其重叠范围.结果髌股、胫股关节在股骨髁关节面运动存在重叠接触区域,范围大致相当股骨髁面全髌股关节接触区域的开始于屈膝75°髌股接触区域的后部分.结论膝关节股骨假体的设计应该考虑股骨髁与髌股关节、胫股关节运动的重叠接触区域解剖特点.     

创伤性膝关节炎的全膝关节置换

目的评价膝关节骨折后创伤性膝关节炎全膝关节置换的疗效。方法对1997～2002年间膝关节骨折后创伤性关节炎行全膝关节置换的11例患者进行回顾性研究。男10例,女1例;年龄31～76岁,平均59岁。骨折至全膝置换手术的间隔时间2～27年,平均8.7年。有7例患者曾进行手术内固定治疗。全膝置换手术同时拆除内固定4例,分期手术拆除内固定后行全膝关节置换3例。手术时有2例股骨骨折畸形愈合,全膝置换时行外侧支持带松解4例,伸膝装置重建1例,侧副韧带重建2例。结果平均随访时间36个月(12～72个月)。无失访病例。膝关节协会评分从术前的平均37分(10～69分)提高到随访时的85分(10～100分),功能评分从术前的42分(0～60分)提高到随访时的75分(20～100分)。膝活动度从术前的83°增加到随访时的93°。术后由于膝关节活动度差而进行麻醉下手法松解4例。未发现需要进行翻修的假体无菌性松动。有1膝发生切口浅表感染行清创术,假体保留而愈合。结论先前骨折所造成的创伤性关节炎,采用全膝置换可明显改善功能,缓解疼痛。术中恢复肢体的良好对线,确保假体置入正确,达到软组织平衡可促进全膝置换的效果。     

Legion假体在膝外翻畸形初次全膝关节置换手术中应用疗效

目的探讨Legion假体在膝外翻畸形初次全膝关节置换手术中的临床应用疗效。方法回顾性分析沈阳军区总医院骨科2012年1月至2015年12月收治的膝外翻畸形患者32例(37膝)。记录患者术后髌股轨迹、切口愈合情况、膝外翻矫正角度、膝关节Harris评分(HSS)。结果所有患者术后均获得随访。32例患者膝关节髌股轨迹良好,切口愈合情况佳,无感染发生。34膝完全矫正了膝外翻畸形,仅余3膝存在3°~5°膝外翻遗留。患者HSS评分由术前34.5分提升至术后87.0分。结论在膝外翻畸形患者的初次膝关节置换手术中应用Legion假体可以达到满意的手术疗效,术后患者膝关节稳定,大部分患者的膝外翻畸形得到了纠正,患者在术后早期功能锻炼即可达到屈曲90°、伸直0°。     

不同股骨假体植入角度的髋关节表面置换术后股骨近端力学的有限元研究

目的探讨不同股骨假体植入角度对髋关节表面置换术后股骨近端力学变化的影响,为临床髋关节表面置换术股骨假体植入角度选择提供生物力学依据。方法采用16层螺旋CT扫描正常成人髋关节数据,建立植入角度为120°、125°、130°、135°、140°、145°的髋关节表面置换术后三维有限元分析模型,对所有模型施加人体缓慢行走时的载荷及约束,观察不同模型间股骨近端不同结构应力分布的变化。结果髋关节表面置换术后应力集中部位位于股骨金属假体-股骨骨质交界面处。随着股骨金属假体植入角度的增加,有效应力峰值呈逐渐减小趋势,135°～145°应力总体变化趋势不明显。结论骨质正常时,髋关节表面置换术的股骨金属假体植入适宜角度为135°～145°。     

全膝关节置换术中股骨假体旋转对线的比较研究

目的 比较全膝关节置换术(TKA)中以经上髁轴和股骨后髁轴外旋3°置放股骨假体外侧支持带的松解率.方法 150例膝关节骨性关节炎患者随机分成两组,一组采用股骨上髁轴确定股骨假体的旋转对线(股骨上髁组),另一组参照股骨后髁连线外旋3°确定股骨假体旋转对线(股骨向髁组).假体安装完毕后以"无拇指"技术评价髌骨轨迹,决定是否需要做外侧支持带松解.结果 股骨上髁轴组外侧支持带松解率为6.3%,股骨后髁轴组外侧支持带松解率为15.8%(P＜0.05). 结论 TKA中股骨假体旋转对线对于髌股轨迹的优劣有着显著影响,股骨上髁轴作为旋转对线的参照可以显著改善髌股轨迹,降低外侧支持带松解率.     

全膝置换术中股骨假体旋转参照轴的影像学比较研究

目的比较全膝置换术中确定股骨假体旋转对线的参照方法———股骨上髁轴与Whiteside′s线的准确性,旨在为国人的人工膝关节手术技术提供实验依据,以减少术后髌股关节并发症的发生率。方法选择80例正常人(年龄19～42岁,男女各半)的膝关节作为研究对象,应用螺旋CT扫描(层厚0.5mm)获取股骨远端精确的横断面图像,通过测量比较股骨上髁轴、Whiteside′s线与股骨后髁轴之间的关系,运用统计学方法分析其准确性。结果股骨上髁轴与股骨后髁轴的夹角(股骨后髁角)为男性6.7°±1.5°,女性6.4°±1.8°,Whiteside′s线与股骨后髁轴的夹角为男性7.2°±3.1°,女性7.8°±3.2°。性别之间无显著性差异(P>0.05)。结论股骨上髁轴作为股骨假体旋转对线的参照较为恒定可靠,而Whiteside′s线的变异度较大、重复性较差。国人的股骨后髁角比西方人大,术中如以股骨后髁轴外旋3°来放置股骨假体,容易出现假体内旋。     

人工全膝关节置换术治疗老年膝关节骨性关节炎18例

我院于 1999年 3月～ 2 0 0 0年 11月对 18例老年膝关节骨性关节炎患者进行人工全膝关节置换术 ,经过 6～ 2 6月的门诊随访 ,临床疗效满意。现报告如下。1　临床资料　本组 18例 19膝 ,男 5例 ,女 13例 14膝。年龄 62～ 75岁 ,平均 68岁。左膝 11例 ,右膝 8例 ,同侧全膝、全髋关节置换 1例 ,同例双侧全膝关节置换 1例。 18例患者均被随访 ,随访时间为 6～ 2 6月。应用假体 :均为全髁型膝关节假体。1 1　手术要点　 ( 1)膝关节前正中纵切口髌内侧进入关节 ;( 2 )彻底清除关节内炎性滑膜组织 ,切除ＡＣＬ、ＰＣＬ、半月板等 ;( 3 )分别作胫骨…     

全膝关节置换假体的生物力学分析

目的：通过有限元分析方法,探究全膝关节置换（TKA）后膝关节假体在不同角度屈膝过程中的应力变化。方法：通过计算机模拟手术截骨,并装配后稳定型（PS）和后交叉韧带替代型（CS）两种膝关节假体。根据步态过程中屈膝角度和轴向载荷间的变化,选择0°、10°、20°和30°四个角度进行有限元分析。观察股骨假体、胫骨假体和衬垫上的Mises应力分布和接触面积,探究术后膝关节的生物力学行为变化。结果：在同一角度下PS型衬垫的应力峰值大于CS型衬垫,屈膝20°和30°时衬垫上出现Mises应力峰值最大值。PS型衬垫内侧的应力峰值大于外侧,而CS型则相反。衬垫的接触面积在多数情况下,外侧大于内侧。PS型衬垫内、外侧的接触面积相对平衡,但CS型衬垫则相差较多,且在屈膝10°时内侧的接触面积最小,这可能会引起衬垫磨损。金属假体的应力峰值位置多出现在与骨组织的连接部位。结论：随着屈膝角度的增加,衬垫内、外侧的Mises应力峰值表现出相应增大的趋势,应尽量减少大角度的屈膝行为,并配合适量的康复运动。同时,注意日常行走的步伐,避免内、外翻带来的假体单侧应力过大。     

人工全膝关节置换术后早期并发症的预防

全膝关节置换(TKA)是人体较大的重建手术,由于膝关节周围软组织覆盖少,位置表浅,假体作为异物本身也会对局部软组织的修复造成影响,使得TKA术后并发症发生率较高。与手术有关的并发症有切口不良,神经血管损伤,感染,深静脉血栓(DVT),伸膝障碍,膝关节僵硬,假体周围骨折,假体松动等。有些并发症可以引起严重的膝关节功能障碍,有些并发症后果可能是致命的,所以应采取有效的预防措施以降低其发生率。我院自2001年至2005年共开展了17例22膝全膝关节置换。1资料与方法1.1一般资料:本组病例17例22膝,男性6例,女性11例,年龄47～69岁,平均年龄65.4…     

Stress MR imaging for evaluation of popliteal artery entrapment

The popliteal artery entrapment (PAE) syndrome has been recognized as a cause of arterial occlusion in young people. It is the result of an anomaly of the relationship between the popliteal artery and the gastrocnemius muscle. Eight young healthy volunteers (16 legs) and six patients (10 legs) with suspected PAE underwent magnetic resonance (MR) imaging. Gradient-echo images were obtained in axial planes with the leg at rest and during active plantar flexion against resistance. Imaging at rest allowed identification of PAE signs in only one leg, which had an anomalous medial course of the popliteal artery. In the other cases, only the stress technique was able to show signal loss in the popliteal artery due to muscular compression (two legs) or the presence of accessory muscle slip around the vessel (two legs), as confirmed at surgery. MR imaging is therefore a useful technique for the diagnosis of PAE because of its capability of combining information obtainable with other modalities.     

MR imaging of muscle and tender points in fibromyalgia

Fibromyalgia is a syndrome manifested by chronic, diffuse muscu-loskeletal aching and soreness, palpable muscle tender points, and other symptoms. Standardized clinical diagnostic criteria have recently been developed. Skeletal muscle has been postulated as the end organ in this disease. Biochemical, histologic, electromyographic, and conventional radiographic studies have demonstrated no definitive abnormality. This study sought to establish whether magnetic resonance (MR) imaging could demonstrate any abnormality in these patients. Eighteen patients were entered in the study, 14 of whom were able to complete their examinations. T1 -weighted, T2-weighted, gradient-echo, and STIR (short-tau inversion-recovery) sequences were performed in all patients, with selected patients examined with T1weighted, gadopentetate dimeglu-mine-enhanced sequences. The trapezius and suboccipital regions were imaged in patients who, clinically, had active fibro-myalgia. No abnormalities could be detected. The authors conclude that the conventional MR imaging used in this study was unable to depict any primary skeletal muscle abnormality in fibromyalgia.     

Uterine contractions: Possible diagnostic pitfall at MR imaging

A total of 206 nongravid patients with various gynecologic problems underwent pelvic magnetic resonance (MR) examinations that included both sagittal T2-weighted and contrast agent–enhanced T1-weighted images. MR images were retrospectively reviewed to identify changes in endometrial configuration on serial images obtained during the same MR examination. In 20 MR examinations (all in women of reproductive age), endometrial distortion due to myometrial bulging was noted on T2-weighted or contrast-enhanced T1-weighted images. It was absent on other MR images obtained at different times. Myometrial bulging exhibited low signal intensity in 18 examinations. The finding resembled adenomyosis or leiomyoma on T2-weighted or contrast-enhanced T1-weighted images. These results evidence the presence of transient myometrial bulging and transient low-intensity myometrium in the nongravid uterus. This phenomenon is thought to represent uterine contraction. Clinicians should be aware of the potential presence of transient low-signal-intensity myometrial bulging that could present diagnostic problems in the normal uterus.     

Controversies in cervical spine imaging in trauma patients

No area of emergency radiology has generated as much discussion in recent years as the subject of cervical spine imaging for trauma patients. This review will be in three parts. The first will examine the indications for cervical imaging and will focus on those factors that make patients at high risk or low risk for cervical injury. The second part will discuss the merits of radiography and computed tomography as the main screening diagnostic examination. In addition to the roles of each modality in the evaluation process, such factors as efficacy of diagnosis, time (duration) of study, and cost will be discussed. Finally, the third part will explore the methods currently employed to clear the cervical spine in comatose patients.Presented at the Annual Meeting of the American Society of Emergency Radiology, Las Vegas, Nevada, 22–25 October, 2003     

Brodie Abscess: MR imaging appearance in 10 patients

The magnetic resonance (MR) imaging features of Brodie abscess have not yet been fully evaluated. Ten patients with Brodie abscess, eight of long bone and two of vertebra, were studied with MR imaging. Long bone abscess had a characteristic “target” appearance with four layers: (a) a center with low signal intensity on T1-weighted images and high signal intensity on T2-weighted and STIR (short-inversion-time inversion recovery) images, (b) an inner ring isointense to muscle on T1-weighted images and with high signal intensity on T2-weighted and STIR images, (c) an outer ring hypoin-tense on all images, and (d) a peripheral halo hypointense on T1-weighted images. In six of eight cases, a soft-tissue mass was found. The two vertebral abscesses had a less specific appearance, with low signal intensity on T1-weighted images and high signal intensity on T2-weighted and STIR images. Only the peripheral halo was clearly identified in both cases.     

Dynamic contrast-enhanced MR imaging assessment of vascularized free fibular grafts

Magnetic resonance (MR) imaging may be a noninvasive method for assessing perfusion of vascularized bone grafts placed for treatment of avascular necrosis. One proximal femur of seven beagles was devascularized, with insertion of a vascularized fibular graft. MR imaging at 1 week (seven dogs) and 6 weeks (five dogs) after surgery included pre- and postcontrast spin-echo sequences, unenhanced twodimensional time-of-flight (TOF) vascular imaging, and dynamic gradient-echo imaging during infusion of gadolinium. Relative signal intensity values of selected regions obtained from the dynamic gradientecho images were plotted as percent enhancement versus time. In the operated hip, MR imaging did not show enhancement in six of seven femoral heads and greater trochanters at 1 week after surgery, with similar results after 6 weeks. MR imaging of fibular grafts 6 weeks after surgery showed an initial rapid increase in enhancement and a subsequent slower increase in five of five dogs, although no enhancement was seen in six of seven dogs at 1 week. These findings contrasted with a rapid initial increase in enhancement followed by slow decline in non-operated hips. Two-dimensional TOP imaging did not show the vascular pedicle of the graft in any dog. Findings of radionuclide bone scanning performed 1 week after surgery were consistent with devascularization of the operated femur and fibular graft. However, tetracycline distribution and histologic findings confirmed the viability of five of five grafts within the devascularized femurs 6 weeks after surgery. Thus, dynamic contrast-enhanced MR imaging at 6 weeks after surgery is valuable for assessing vascular bone graft perfusion, while similar imaging at 1 week may suggest otherwise.     

Adrenal tissue characterization with 0.5-T MR imaging: Value of T2*-weighted images

The authors investigated the value of magnetic resonance (MR) imaging at 0.5 T for distinguishing adrenal adenomas from adrenal metastases. The series included 23 adrenal adenomas (18 nonhyperfunctioning, five hyperfunctioning) and 23 adrenal metastases from various organs. Adrenal tumor–liver signal intensity ratios on T1-, T2-, and T2*-weighted images were calculated for adrenal tissue characterization. Adrenal adenomas were more precisely distinguished from adrenal metastases on T2*-weighted images (21 of 23, 91%) than on T2-weighted images (15 of 23, 65%). T1-weighted images were not useful for this distinction. In conclusion, T2*-weighted images were better than routine T2-weighted images for distinguishing adrenal adenomas from adrenal metastases. It can be postulated that the total signal intensity of adrenal adenomas, which contain some fat components, decreased on T2*-weighted images because of an out-of-phase effect.     

Right-side aortic arch with aneurysm of aberrant left subclavian artery: MR imaging appearance.

Reports of aneurysms of the subclavian artery in both normal and anomalous aortic arches have been rare. The authors describe a patient with a right-side aortic arch and an aneurysm of the aberrant left subclavian artery, which, to the authors' knowledge, is a previously unreported association. At presentation, the aneurysm appeared as a calcified left superior mediastinal mass. Magnetic resonance imaging enabled preoperative diagnosis and guided surgical planning.     

MR angiography of congenital heart disease: Value of segmented two-dimensional inflow technique and maximum-intensity-projection display

Magnetic resonance (MR) angiography of the cardiovascular system was evaluated in 41 patients with congenital heart disease by using a two-dimensional (2D) inflow technique based on a magnetization-prepared gradient-echo pulse sequence with segmented k-space data acquisition and electrocardiographic gating at 0.5 T. Inversion and saturation prepulses were used to suppress stationary tissue and enhance intravascular signal. Presaturation slabs were applied where certain vascular structures had to be suppressed. Sequence parameters were optimized by evaluating signal intensity and contrast characteristics for various flip angles and inversion and saturation delay times. The heart and intrathoracic vasculature were encompassed with 40–50 overlapping sections. Both 2D angiograms and maximum-intensity-projection images were evaluated. Combining data sets acquired in the sagittal and transverse orientations provided the most satisfactory information about the pulmonary arteries. The highest signal-to-noise ratios were obtained with a flip angle of 65° and short prepulse delay times. Two-dimensional MR angiography can provide useful diagnostic information but requires a thorough understanding of in-plane and hemodynamically induced signal intensity changes.