数字化骨科手术新方法的建立及其临床广泛应用

目的研究出独特的数字化骨科手术新方法 ,广泛应用于脊柱外科手术、骨关节创伤治疗、韧带重建修复、骨肿瘤切除重建、骨关节严重畸形矫正等骨科各分支领域,探讨数字化骨科手术的特点和临床效果,以期运用现代计算机辅助技术和图像分析处理技术提高骨科疾患诊治水平。方法按反求工程的基本原理,通过CT/MRI扫描获取患者骨骼的二维图像资料,采用计算机辅助三维重建技术建立骨关节解剖模型,将骨关节解剖模型输入计算机辅助设计(computer assisted design,CAD)软件进行精确分析,进一步采用先进制造技术——快速成型(rapid prototyping,RP)技术制作骨关节原型并进行实物原型分析,而后将骨关节解剖模型输入计算机进行外科手术过程的设计和预演,合适内固定材料的选择以及基于CAD-RP技术外科手术辅助模板、个性化植入物的制作等,最后精确实施骨科手术。结果采用该方法治疗123例骨科疾患,在以下临床数字骨科学领域获得成熟经验:(1)计算机辅助骨关节畸形精确数字化矫形;(2)计算机辅助设计个性化假体:如全膝、全髋、半骨盆等;(3)计算机辅助前、后交叉韧带重建;(4)计算机辅助特殊疑难假体置换:如发育不良性髋脱位假体置换及翻修手术、髋臼发育不良并骨性关节炎全髋置换手术等;(5)计算机辅助特殊疑难骨折、关节内骨折以及陈旧性骨折的复位固定等;(6)骨肿瘤个性化切除的设计、结构与功能重建;(7)脊柱侧弯的个性化矫形设计与精确实施;(8)脊柱后凸的个性化矫形设计与精确实施;(9)计算机辅助齿状突骨折复位固定;(10)计算机辅助寰枢椎后路内固定的手术设计和精确置钉技术;(11)计算机辅助颈椎椎弓根的形态分析、测量与精确置钉技术。结论借助现代计算机技术和先进制造技术,术者可以通过CAD、骨关节原型制作、计算机辅助手术设计和预演、个性化辅助手术模板及个性化骨缺损修复植入物制作等手段精确实施骨科手术,实现骨科手术的数字化、个性化和精确化,从而进一步提高手术安全性,改善临床效果。     

Crowe IV 型髋关节发育不良全髋关节置换术前计算机辅助设计

 目的 探索采用计算机辅助技术, 对接受全髋关节置换(total hip arthroplasty, THA)的 Crowe IV型髋关节发育不良患者进行术前评估, 确定髋臼大小、骨缺损程度, 并在此基础上辅助手术设 计、假体选择及骨缺损修复。 方法2011 年3 月至10 月, 共10 例(13 髋)Crowe IV型高位脱位髋关节发 育不良患者接受THA 治疗。患者均为女性;年龄32~74 岁, 平均42 岁。所有患者术前行髋关节三维CT 扫描, 然后将扫描数据输入SuperImage 软件重建骨盆及髋臼。重建后在不同角度精确评估真臼位置, 测 量真臼大小及前后柱厚度, 评估骨缺损程度;将髋臼试模、骨缺损修复材料(钽金属垫块)按1颐1 大小扫 描输入计算机系统, 进行术前模拟安放, 确定髋臼假体大小、安放位置;髋臼假体安放后评估遗留的骨缺 损, 确定骨缺损修复材料, 进行骨缺损修复模拟测试。 结果 9 例(12 髋)术中实际安放髋臼假体型号与 术前计算机辅助设计一致, 1 例(1髋)假体型号较术前设计大一号。所有患者髋臼安放位置与术前计划 一致, 均安放于真臼。髋臼骨缺损修复按术前设计:4 髋因髋臼顶部骨缺损明显(臼顶部骨性覆盖 < 70%), 采用钽金属垫块修复骨缺损, 以增强髋臼的稳定性;7 髋采用Harris 法自体股骨头植骨修复骨缺 损;2 髋髋臼杯植入后臼顶覆盖可, 术中未植骨。 结论 对Crowe IV型髋关节发育不良者行计算机辅助 下THA术前设计, 有助于术前精确评估真臼发育情况、大小及髋臼骨缺损, 提高手术治疗精确性。     

髋部骨肿瘤的全髋关节置换和保肢

目的：研究髋部骨肿瘤的全髋关节置换和保肢疗效。方法：总结分析29例29髋髋部骨肿瘤病例，男18例，女11例，年龄32－67岁，平均43．7岁。骨巨细胞瘤14例，软骨肉瘤4例，骨成纤维细胞瘤2例，骨肉瘤4例，复发性软骨瘤2例，骨囊肿骨折3例，27例采用肿瘤型人工全髋关节假体置换，2例采用人工半骨盆全髋关节假体置换。股骨切除长度14－21cm。结果：29例均安全渡过围手术期，获平均4年10个月随访，除2例髋骨肿瘤人工半骨盆全髋置换术后分别于2年后急性肺炎和1年7个月肿瘤复发转移死亡外，其余27例均存活，并从事家务和工作，结论：根据髋骨肿瘤的类型，切除后选择适当假体和治疗方法，对重建髋关节功能、保留肢体是安全可行的。     

Neglected congenital dislocation of the hip: Role of computed tomography and computer-aided design for total hip arthroplasty

Computed tomography (CT) provides important three-dimensional anatomic details in congenital dislocation of the hip that are useful for total hip arthroplasty (THR) and are not obtainable with conventional radiographic evaluation. In this study, 84 patients (119 hips) with congenital dislocation of the hip were evaluated with CT before surgery. Specifically, both the acetabulum and the femur were analyzed to make the best selection of the prosthesis. The average anteversion of the acetabulum was 23°, with an opening of 30.9 mm and a depth of 14.7 mm. The bone stock of the true acetabulum was calculated and the average available diameter for the acetabular implant was 44.9 mm. The CT topogram revealed the true leg-length discrepancy (average, 0.5–1.9 cm), and the amount of a shortening osteotomy when necessary was determined. Finally, to determine the stem with optimum fit and fill, a three-dimensional reconstruction of the femoral canal using CT data and computer-aided design (CAD) was matched with a three-dimensional geometry of several stem designs and sizes obtained from a CAD system.     

Femoral anatomy,computed tomography and computer-aided design of prosthetic implants

Precise digital data of the internal femoral anatomy are necessary to develop new prosthetic implants with computer-aided design (CAD) techniques. Thirty human cadaveric femurs of central European origin were analysed by high precision computed tomography (CT) using thin slice and high resolution imaging. The CT data were image processed with thresholding to obtain a reconstruction of the cortical bone geometry. The CT threshold for cortical bone was optimized by comparison with saw cuts of macerated femurs. For each specimen a three-dimensional (3D) model of the cortical femur was calculated by the CAD system based on the processed CT data. Virtual 3D models of the 30 femurs were used to adjust a hypothetical stem to the proximal femur anatomy by repeated virtual implantations. The CAD system allowed for evaluation of anatomical parameters after hip reconstruction, amount of bone removal, and cortical bone contact. The fit and fill of the stem could be tested before clinical application and implant-related problems could be corrected.     

Impingement simulation of the hip in SCFE using 3D models.

OBJECTIVE: Affecting as it does the geometry of adolescent hips, slipped capital femoral epiphysis (SCFE) and its evaluation represent a major three-dimensional problem. The current methods of clinical assessment-geometric measurements of the femur on plain radiographs or on axial computed tomographic (CT) cross-sections-address only one of the two joint components. MATERIALS AND METHODS: We have developed a system to simulate motion of hip joints with physiologic joint contact. In our system, CT-based computer models of the femur, pelvis, etc., are fitted with oriented bounding boxes (OBBs) and manipulated. Collision detection algorithms control the hip motion, which, in this virtual joint, is based on the surface geometry of the joint partners rather than on a predefined fixed rotation center. RESULTS: An illustrative case is presented to show the advantages of the new biomechanical evaluation method over conventional radiological assessments for SCFE. The proposed system provides remarkably high speed, and the necessary data can be prepared in a reasonable time. CONCLUSION: The range-of-motion assessment provides the surgeon with information about the site and the impact of nonphysiologic contact in the hip joint. The information thus obtained can be valuable for indication and planning of corrective surgery in cases of SCFE.     

CT三维重建应用于成人发育性髋关节发育不良股骨近端形态学研究的进展及意义

目的对CT三维重建技术应用于成人发育性髋关节发育不良（DDH）股骨近端形态研究的相对优势,以及DDH CroweⅠ~Ⅳ型股骨近端的测量参数与形态特点进行综述。 方法在近年DDH股骨形态研究中以"股骨近端形态"成人DDH"全髋关节置换"及"CT三维重建"为关键词,在PubMed和中国知网数据库中检索近年发表的相关文献,对CT三维重建的DDH股骨近端的应用优势、CroweⅠ~Ⅳ型DDH股骨近端的测量参数与形态特点进行分析总结。 结果DDH是髋关节发生骨性关节炎的重要原因之一。全髋关节置换术（THA）是目前治疗DDH的最有效治疗方法。DDH的髋关节常伴有股骨侧严重的病理改变,尤以CroweⅣ型DDH股骨畸形程度最为严重。术前应用CT三维重建技术可以帮助医生充分认识这些解剖变异,从而可以优化术前设计,缩短手术时间,继而获得良好的手术效果,降低术后并发症。 结论采用CT三维重建技术能全面显示髋关节的立体形态和各部位解剖结构的空间关系,在DDH的诊断、分型,股骨近端形态个体化建立、股骨侧假体的选择,THA中股骨假体植入准确度的提高及术后并发症的降低都发挥着重要的作用。     

个性化纯钛假体矫治半侧颜面短小畸形的临床应用

目的:探索应用计算机辅助设计和制造技术制备的个性化纯钛假体治疗半侧颜面短小畸形的效果。方法:采集4例半侧颜面短小畸形患者的CT图像数据,利用快速成型技术制作患者头颅树脂模型,并进行精确数字化设计,将设计数据输入数控车床,制备出个性化纯钛假体,置入患者下颌骨预定的位置。结果:利用计算机辅助设计和制造技术,为患者制备出个性化纯钛假体,假体置入下颌骨预定位置。术后4例患者伤口均I期愈合。随访1～4年,面部形态恢复满意。结论:利用计算机辅助设计和制造技术制备出的纯钛假体可以治疗半侧颜面短小畸形,该方法具有设计精确,手术时间短,面部形态改善明显的优点。具有一定的临床应用价值。     

个性化定制手术导板在全髋关节置换术中的应用

目的 设计并验证一种全髋关节置换术（total hip arthroplasty, THA）个性化定制手术导板（patient specific instrumentation, PSI）的安全性、有效性。方法 对患有髋关节疾病且须行THA的病人进行层厚为0.8 mm的三维CT扫描,获取该病人的CT数据。将数据导入三维手术规划软件中进行处理,根据病人术前影像学检查结果,利用计算机辅助技术（computer aided design, CAD）,由经验丰富的外科医生对CT图像进行分割并重建,获得骨盆及双下肢三维模型,并在此模型基础上进行三维手术规划。通过3D打印技术,制作病人个性化定制的手术导板,用于在术中提供相应手术操作的定位导航,使假体安放的实际位置和角度与术前计划一致。结果 导板与髋臼、股骨侧的骨骼标志性结构贴合度为100%,截骨高度与术前计划一致,均为股骨小转子上9 mm,髋臼杯磨锉、压配角度控制在外展40°,前倾20°,与术前计划一致。手术时间缩短至54 min,术中失血量减少至376.9 ml。结论 此个性化定制THA手术导板可精确贴合手术部位骨质,显著提高THA的精准性,具有良好的安全性、有效性。     

Imageless computer assistance to orientate the cup of total hip arthroplasties: a new system based on joint kinematics

Purpose of the study  Most imageless navigation systems for computer-assisted (CAS) total hip arthroplasty (THA) aim at orientating the cup with regard to the anterior pelvic plane (APP). However, these systems have some limitations: 1) the adequate position is not well defined to prevent impingement and dislocation; 2) dynamic variation of the APP according to activities (sitting, climbing stairs, etc.) are not integrated in determining the adequate orientation; 3) intraoperative assessment of the APP is not reliable with conventional tools, requiring ultrasound or two-stage identification. To address these issues, we developed an imageless CAS system without using APP, based on a kinematic approach of the hip joint. This system does not use the APP as the reference plane to orient the cup. The systemhelps the surgeon to orient the cup in relation to the cone describing the hip joint range of motion. The purpose of this study was to detail the technique and to analyze preliminary results. Materials and methods  Twenty-four primary cementless THAs were implanted using CAS Pleos™ with optoelectronic tracking system (18 women, 6 men; mean age, 67 ± 7.8 years, age range, 54–83 years) because of primary osteoarthritis. Two optoelectronic sensors are fixed percutaneously on the pelvis and the distal femur. The acetabulum is prepared first, followed by the femur using reamers and broaches of increasing size. The last broach placed in the femur was equipped with a large head adapted to the newly prepared acetabulum. The range of hip motion is recorded to determine the maximal range of motion cone. The acetabular cup is thus positioned so that the prosthesis range of motion totally covers the maximal range of motion of the hip joint. Results  The Postel-Merle-d’Aubigné score improved from 8.1 ± 3.2 (range, 3–13) preoperatively to 17.1 ± 0.8 (range, 16–18) at last follow-up. There were no complaints of patients about the sensor insertion and no cases of hematoma or fracture. Operative time was 35–40 min longer for the first four cases and was progressively reduced by 15–20 min for the last four cases. Mean leg length discrepancy was 5.6 ± 7.5 mm (range, 0–25 mm) before implantation and 0.6 ± 3 mm (range, −5 to 10 mm) at last follow-up, eighteen were equal. Mean frontal cup inclination was 47 ± 7° (range, 38–60°). After CT-scan measurement, mean anteversion of the femoral implant was 16.8 ± 9.2° (0–31°). The mean cup anteversion was 25.2 ± 9.2° (range, 8–40°) for “anatomical anteversion”. Only 10 of the 24 cups were orientated inside the Lewinnek safe zone (there was only one dislocation that was traumatic with a cup orientated in the safe zone). Conclusion  This method can be used in routine procedures without lengthening operative time significantly. It safely controls leg length and helps position the cup. This study demonstrates that there is no ideal position for the cup that can be used for all patients. Because of the wide range of inclination and anteversion figures, 58% of the cups were outside the safe zone recommended by Lewinnek.     

Erosion with loosening of an aluminum oxide ceramic acetabulum. Case report

The arthrodised hip of a 52 year-old female patient that had been absolutely trouble free for 9 years was remobilised by implanting a Mittelmeier, Autophor prosthesis (Al2O3 socket, Al2O3 head). Two years later, the hip joint had to be revised because of loosening of the socket. Since the shaft of the prosthesis was still firmly anchored within the femur, only the socket und the head were replaced. About three years following this revision, signs of loosening of the acetabular component again developed. Finally 4 1/3 years after the first revision (6 1/3 years after primary implantation) the hip was again revised. A polyethylene socket was then cemented into an acetabulum supporting shell and the prosthesis shaft furnished with a ceramic head of 32 mm diameter. Possible disadvantages of ceramic-ceramic bearing surfaces in patients with an altered bone structure of the pelvis and with a high risk of subluxation, due to weakened pelvi-trochanter muscles, are discussed.     

股骨头骨坏死范围对髋关节表面置换术后股骨近端力学分布的影响

目的探讨髋关节表面置换术后股骨头骨坏死范围对股骨近端与假体松动或股骨颈骨折相关的应力分布的影响。方法依据基于连续CT断层图像构建的股骨三维图形和髋关节表面置换假体，采用计算机辅助技术，建立股骨头部无坏死和前后位坏死角分别为60°、80°、100°、120°、140°的表面置换三维有限元模型，单腿负重条件下，模拟坏死骨未清除及清除后填充骨水泥的情形进行受力分析。结果骨坏死范围对股骨颈部的应力分布影响微小。股骨头近端骨质出现明显的应力遮挡。当坏死角≤80°时，骨水泥界面和头颈交界骨质中的Von Mises等效应力峰值变化较小；当坏死角≥100°时，应力峰值变化明显，其中水泥层外上缘的峰值增幅为22．3％和27．3％（坏死角120°和140°），头颈交界外上缘骨质的峰值增幅为13．2％、28．3％和53．3％（坏死角100°、120°和140°）。填充骨水泥后，主要应力集中区的等效应力峰值逐渐减小或变化不明显。结论髋关节表面置换术改变了股骨头内应力分布；股骨头近端出现明显的应力遮挡，允许股骨头负重区出现小的骨坏死（坏死角≤80°）；坏死角≥100°的骨坏死，是否适于髋关节表面置换术还需深入研究。     

股骨骨质疏松对骨水泥非骨水泥髋假体置换近期疗效之影响的临床对比研究

目的探讨股骨骨质疏松对骨水泥、非骨水泥髋假体置换近期疗效的影响,以期对其影响作出临床评价。方法对99例（99髋）术前有股骨干骺段骨密度测定值的人工髋关节置换患者进行了平均30个月的随访调查,回顾性分析骨水泥假体和非骨水泥假体在治疗正常骨密度患者和骨质疏松患者上的近期疗效的差别,采用Harris评分、大腿处疼痛、患者满意度三个方面进行比较。结果股骨骨质疏松患者,如选用非骨水泥假体置换,Harris评分及患者满意度均比骨水泥组低（P〈0．05）,而大腿处疼痛率却比骨水泥组高（P〈0．05）;与其在股骨正常骨密度患者上的治疗效果比较,Harris评分及患者满意度也较低（P〈0．05）,大腿处疼痛率较高（P〈0．05）。结论在治疗有股骨骨质疏松的患者时,采用非骨水泥假体置换的近期疗效降低,较骨水泥型假体置换组差,大腿处疼痛率也明显增高。所以,对骨质疏松的患者,以选用骨水泥假体为好。     

个体化钛合金掌指关节假体设计及快速成型制造的研究

目的 探讨运用计算机辅助设计及快速成型技术制造出个体化钛合金人工掌指关节假体的方法,为掌指关节的假体置换提供一种新的假体.方法 应用3DMSR软件对掌指关节二维CT轮廓数据进行三维重建,然后在图像处理软件Surface9.0上进行个体化人工假体及其髓内假体柄的计算机辅助设计.输出的数据模型在FS-320QZ激光快速成型机上制造出快速成型树脂模型,经硅胶翻模、制作蜡模、成壳、浇铸,抛光后获得钛合金个体化人工掌指关节假体.结果 经过对螺旋CT扫描的掌指关节的二维图像进行三位重建和CAD得到的个体化掌指关节假体模型,假体模型关节面表面光滑,设计的假体柄体现了原始髓腔的基本形态及大小,转换成快速成型机通用的STL格式数据,输入快速成型机便获得树脂模型,经过一系列铸造过程完成个体化钛合金假体的制造.结论 利用CT数据获得掌指关节三维轮廓信息,利用快速成型技术、熔模制造,可获得满意的个体化钛合金人工掌指关节假体.     

Bicentric bipolar hip prosthesis: A radiological study of movement at the interprosthetic joint

Background:

The bipolar hip prostheses after some time functions as a unipolar device. There is a need to change the design of bipolar hip prostheses to make it function as a bipolar device over a prolonged period of time. A bicentric bipolar hip prosthesis was used as an implant for various conditions of the hip. We evaluated the movement of this newly developed prosthesis at the interprosthetic joint radiologically at periodic intervals.

Materials and Methods:

Fifty two cases were operarted with the Bicentric bipolar prosthesis for indications like fracture neck of femur and various other diseases of the hip and were followed up with serial radiographs at periodic intervals to evaluate, what fraction of the total abduction at the hip was occurring at the interprosthetic joint.

Results:

In cases of intracapsular fracture neck of femur, the percentage of total abduction occurring at the interprosthetic joint at 3 months follow-up was 33.74% (mean value of all the patients), which fell to 25.66% at 1.5 years. In indications for bipolar hemireplacement other than fracture neck of femur, the percentage of total abduction occurring at the interprosthetic joint at 3 months follow-up was 71.71% (mean value) and at 1.5 years it was 67.52%.

Conclusion:

This study shows the relative preservation of inner bearing movement in the bipolar hip prosthesis with time probably due its refined design. Further refinements are needed to make the prosthesis work better in patients of intracapsular fracture neck femur.     

The effect of femoral component head size on posterior dislocation of the artificial hip joint

BACKGROUND: Posterior dislocation continues to be a relatively common complication following total hip arthroplasty. In addition to technical and patient-associated factors, prosthetic features have also been shown to influence stability of the artificial hip joint. In this study, a dynamic model of the artificial hip joint was used to examine the influence of the size of the head of the femoral component on the range of motion prior to impingement and posterior dislocation following total hip replacement. METHODS: Six fresh cadaveric specimens were dissected, and an uncemented total hip prosthesis was implanted in each. Each specimen was mounted in a mechanical testing machine and loaded with use of a system of seven cables attached to the femur and pelvis that simulated the action of the major muscle groups crossing the hip joint. The hip was taken through a range of motion similar to that experienced when rising from a seated position. The three-dimensional position of the femur at the points of impingement and dislocation was recorded electronically. The range of joint motion was tested with prosthetic femoral heads of four different diameters (twenty-two, twenty-six, twenty-eight, and thirty-two millimeters). RESULTS: Significant associations were noted between the femoral head size and the degree of flexion at dislocation in ten (p = 0.001), twenty (p < 0.001), and thirty (p = 0.003) degrees of adduction. Increasing the femoral head size from twenty-two to twenty-eight millimeters increased the range of flexion by an average of 5.6 degrees prior to impingement and by an average of 7.6 degrees prior to posterior dislocation; however, increasing the head size from twenty-eight to thirty-two millimeters did not lead to more significant improvement in the range of joint motion. The site of impingement prior to dislocation varied with the size of the femoral head. With a twenty-two-millimeter head, impingement occurred between the neck of the femoral prosthesis and the acetabular liner, whereas with a thirty-two-millimeter head, impingement most frequently occurred between the osseous femur and the pelvis. CONCLUSIONS: With the particular prosthesis that was tested, increasing the diameter of the femoral head component increased the range of motion prior to impingement and dislocation, decreased the prevalence of prosthetic impingement, and increased the prevalence of osseous impingement. CLINICAL RELEVANCE: These results suggest that femoral heads with a twenty-eight-millimeter diameter increase the range of motion after total hip replacement. This may be beneficial when additional factors compromising joint stability are encountered.     

计算机辅助个体化人工半骨盆的设计与应用

目的总结应用计算机辅助技术进行半骨盆假体个体化设计、制作及8例临床应用经验。方法应用CT数据及快速原型技术,生成病变骨盆的精确模型,模拟半骨盆切除并设计假体。假体应能同时固定在对侧耻骨支或同侧耻骨支的残留部分及骶骨关节面或髂骨的残余部分。如坐骨可部分保留,则同时固定在坐骨上。髋臼假体的高度、方向及与中线的距离应与对侧对称。半骨盆假体以松质骨螺钉、螺栓及钩状突起固定在残余骨盆上,安放具有骨水泥臼与非骨水泥柄的传统全髋假体。临床应用8例,7例为巨大的单侧骨盆肿瘤,包括软骨肉瘤2例、巨细胞瘤3例、纤维软骨性结构不良伴髋臼损害和转移性肿瘤各1例;另1例为全髋关节置换术后严重骨溶解。6例于术前行肿瘤血管栓塞。结果术中平均输血4971ml,假体安装顺利。1例伤口遗留窦道,行背阔肌皮瓣移植后愈合。术后6周持双拐下地不负重行走,3个月后逐渐弃拐。1例软骨肉瘤患者术后9个月因肺转移死亡,其他患者随访1～4年,平均2.5年。假体无松动,双髋位置对称,均恢复生活自理能力。2例分别于术后7个月及8个月恢复工作。局部复发1例。结论计算机辅助设计与加工的人工半骨盆置换,在提高假体于骶骨、耻骨和坐骨上固定效果的同时,可确保髋臼部件位置与方向的准确及手术的顺利进行。     

Cementless total hip arthroplasty in Paget’s disease of bone: a retrospective review

Paget’s disease of bone (PDB) is a localised chronic osteopathy leading to bone deformities, bone hypervascularity, structural weakness and altered joint biomechanics. The pelvis and upper femur are frequently involved, resulting in disabling hip disease, and total hip arthroplasty (THA) may be required. We performed a retrospective study on the management and the outcome of 39 uncemented hydroxyapatite fully-coated THA in patients with PDB of the hip. The follow-up averaged 79.4 months (range 24–194). Functional scores improved significantly and, using the Harris hip score, 84% of patients had an excellent clinical outcome at the latest follow-up. Despite one case of an uncemented acetabular component with probable loosening, no implant revision had been required at our latest follow-up. Signs of implant loosening were found to be significantly more frequent in patients with active disease. For this reason, we advocate the use of pre-operative medication with bisphosphonates to reduce disease activity. Another benefit of this treatment is the significant decrease of intra-operative blood loss. Provided the control of disease activity in the pre-operative period with bisphosphonates is achieved, good outcome of cementless THAs can be expected. Bisphosphonates reduced the risk of implant loosening and excessive intra-operative blood loss.     

Application of the rapid prototyping technique to design a customized temporomandibular joint used to treat temporomandibular ankylosis

Anthropometric variations in humans make it difficult to replace a temporomandibular joint (TMJ), successfully using a standard “one-size-fits-all” prosthesis. The case report presents a unique concept of total TMJ replacement with customized and modified TMJ prosthesis, which is cost-effective and provides the best fit for the patient. The process involved in designing and modifications over the existing prosthesis are also described. A 12-year- old female who presented for treatment of left unilateral TMJ ankylosis underwent the surgery for total TMJ replacement. A three-dimensional computed tomography (CT) scan suggested features of bony ankylosis of left TMJ. CT images were converted to a sterolithographic model using CAD software and a rapid prototyping machine. A process of rapid manufacturing was then used to manufacture the customized prosthesis. Postoperative recovery was uneventful, with an improvement in mouth opening of 3.5 cm and painless jaw movements. Three years postsurgery, the patient is pain-free, has a mouth opening of about 4.0 cm and enjoys a normal diet. The postoperative radiographs concur with the excellent clinical results. The use of CAD/CAM technique to design the custom-made prosthesis, using orthopaedically proven structural materials, significantly improves the predictability and success rates of TMJ replacement surgery.     

Total hip arthroplasty in young patients using the thrust plate prosthesis: clinical and radiological results

Introduction The standard treatment for patients who require total hip replacement is the implantation of an intramedullary diaphyseal anchored hip prosthesis. A bone-sparing thrust plate hip prosthesis (TPP) can be used as an alternative device for young patients. The TPP relies on proximal femoral metaphyseal fixation. The theoretical advantage of leaving diaphyseal bone intact is easier conversion to a stemmed prosthesis. This retrospective study evaluated the medium- and short-term results after total joint replacement using the third generation TPP.Materials and methods Between 1997 and 2001, 58 TPPs were used for 52 patients. Clinical and demographic data were obtained from the patients charts and our electronic database. Their average age at time of surgery was 40.9±11.4 years. At follow-up, the Harris hip score, residual pain, required pain medication, and the ability to lie on the operated side were documented. Radiographic evaluation included standardized radiographs of the hip joint and the pelvis.Results Four patients required revision surgery (6.9%). For 51 of the remaining 54 TPPs, a postoperative functional and radiological status was obtained. The average follow-up was 26±11.0 months. 88% of the patients experienced some or complete relief of pain. The median Harris hip score at follow-up was 73±20.5 points. A postoperative hip dislocation occurred in 5 patients (8.6%).Conclusion Since many patients experienced some or complete relief of pain, the TPP can be recommended as a feasible implant for the treatment of hip disorders requiring total hip arthroplasty in young patients. Revision surgeries are facilitated by the good bone stock remaining in the proximal femur.