A radiological assessment of interprosthetic movement in the Charnley-Hastings hemiarthroplasty

Forty-six patients with acute displaced subcapital fractures of the femur were treated between December 1982 and December 1984 with Charnley-Hastings bipolar prostheses. The interprosthetic movement in 23 patients was assessed radiologically at least 1 year after surgery. Four patients (17.4 per cent) had no interprosthetic movement in abduction but the remainder (82.6 per cent) had some movement, although only 3 patients (13 per cent) had more than 5 degrees of abduction within the prosthesis.     

Total hip replacement with a straight stem prosthesis: A 2-year follow-up of 126 CAD operations

The clinical and radiographic results in 126 primary CAD total hip replacements were assessed after 2 years in a prospective study. The clinical overall results were satisfactory, with 89 per cent of the hips being free from significant pain. Femoral component loosening was radiographically evident in 6 per cent. The walking speed was increased by 83 per cent in patients with unilateral hip disease. This increase was partly achieved during the second postoperative year.     

Bacterial adherence to separated modular components in joint prosthesis: A clinical study

Bacterial adherence on total joint replacement implants may lead to biofilm formation and implant‐related osteoarticular infection. It is unclear if different biomaterials in the prosthetic components are more prone to facilitate this bacterial adherence, although ultrahigh molecular weight polyethylene (UHMWPE) component exchange in modular systems has been clinically utilized in the early management of these infections. To clarify if the amount of clinically adhered microorganisms was related to the material or the component, we investigated retrieved implants from infected joint replacements. Thirty‐two patients were revised after confirmed implant‐related infection through positive cultures. Eighty‐seven total joint components (hip and knee) were obtained and separately sonicated following a previously published protocol. Cultures were quantified, and detected colony forming units (CFU) were adjusted according to the component surface and compared based on the component material and location. Variable adherence of bacteria to chrome cobalt alloys, UHMWPE, hydroxyapatite coated components, and titanium alloys. The commonest isolated organisms were Staphylococcus epidermidis (23 of 87 components) and Staphylococcus aureus (10 of 87). Twelve components did not show any microorganism adhered despite location in an infected joint, with positive cultures in other components. A mixed linear model adjusted for random effects (the random effect being the infected patient) obtained convergence for the CFU/mm² variable, but could not confirm a significantly higher adherence to a particular component or to a particular biomaterial. Therefore, the bacterial adherence primarily depends on the infective microorganism and the response of each individual patient, rather than materials or components. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1634–1639, 2012     

改良髋直接外侧入路在人工髋关节置换术中的应用

目的 探讨改良髋直接外侧入路（改良Bauer入路）在人工髋关节置换术中应用的可靠性。方法 采用改良Bauer入路用于人工髋关节置换43例。结果 术中显露满意，患肢功能恢复快，疗效优良率达96．97％，未发现髋外展肌力减退及臀上神经损伤。结论 改良Bauer入路安全有效，可推荐用于初次人工髋关节置换术。     

Bacterial adherence to different components of total hip prosthesis in patients with prosthetic joint infection

Purpose

The purpose of our study was to evaluate and quantify the bacterial adherence to the different components of total hip prosthesis.

Methods

The bacterial load of 80 retrieved hip components from 24 patients was evaluated by counting of colony-forming units (CFU) dislodged from component surfaces using the sonication culture method.

Results

Micro-organisms were detected in 68 of 80 explanted components. The highest bacterial load was detected on the polyethylene liners, showing a significant difference in distribution of CFU between the liner and metal components (stem and cup). Staphylococcus epidermidis was identified as the pathogen causing the highest CFU count, especially from the polyethylene liner.

Conclusions

Results of our study confirm that sonicate culture of the retrieved liners and heads, which revealed the highest bacterial loads, are reliable and sufficient for pathogen detection in the clinical diagnostic routine.     

A clinical,radiological and biomechanical study of the TARA hip prosthesis

Summary We reviewed 60 patients with 72 TARA (total articular replacement arthroplasty) resurfacing hip prostheses. To analyse the behaviour of the femoral component a radiographic study was done and a two-dimensional finite element model was constructed. The stem of the femoral component plays a role in the load transfer mechanism. Stress shielding is seen in the proximal femur but depends on the interface conditions. When only the dome of the cup is assumed to be bonded to the bone, the stresses in the head increase dramatically and there is no more stress shielding. Five years after implantation radiographic signs of loosening of the femoral component were seen in 6.8% of the implants placed without notching in the femoral neck and in 28.6% of the components with notching (significant difference, P = 0.0005). Signs of loosening of the acetabular component were seen in 37.7% 5 years postoperatively. The cumulative survival rates of the femoral and acetabular components were 89.7% and 85.6% respectively 5 years after implantation. The overall clinical results are represented by an integration of the clinical results (Harris Hip Score System), the radiographic results and the survival analysis. This gave a success rate of only 72% 5 years after implantation.     

Outcome of uncemented trapeziometacarpal prosthesis for treatment of thumb carpometacarpal joint arthritis

Background:

Osteoarthritis of the trapeziometacarpal joint of thumb occurs frequently and can be very disabling. Numerous surgical techniques including trapeziectomy with or without tendon interposition arthrodesis and partial or total joint arthroplasty with cemented and noncemented prosthesis have been described for the treatment of trapeziometacarpal joint osteoarthritis. Initial problems of osteolysis and implant loosening have been substantially reduced with improvement in implant design. The aim of this study is to demonstrate that trapeziometacarpal osteoarthritis of the thumb can be effectively treated with uncemented total joint replacement prosthesis.

Materials and Methods:

We retrospectively collected data for 16 trapeziometacarpal joint replacements in 14 patients. One patient was excluded as they required revision with trapeziectomy and ligament reconstruction following fracture of Trapezium. The trapeziometacarpal joint prosthesis was used in all cases and all operations were carried out by one surgeon. Clinical outcome was determined by a pre and postoperative patient rated wrist evaluation (PRWE) and Michigan Hand Questionnaire Score. Range of motion, grip, tip pinch and key pinch strength were measured and compared with the unoperated hand. Radiological assessment was carried out by plain radiographs for preoperative staging of arthritis and postoperative radiographs at latest followup for evaluation of osteolysis and implant loosening. Average followup period was 26 months.

Results:

There was an improvement in hand function and pain level based on PRWE and Mischigan Hand outcome Questionnaire Score. One patient had intraoperative fracture of Trapezium and subsequent radiographs at 14 months followup showed loosening of the trapezial component due to nonunion of the fracture and complete disintegration of the trapezium. There were no cases of dislocation or implant loosening for the remaining 15 CMC joints at the latest followup.

Conclusion:

The use of uncemented prosthesis in treatment of Questionnaire Score. Range of motion joint osteoarthritis gives excellent short term results in improving hand function in terms of strength and stability and achieving pain relief.     

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.     

骨基质明胶颗粒/骨水泥复合材料固定人工关节假体的实验研究

[目的]探讨骨基质明胶颗粒(BMG)复合骨水泥(PMMA)用于人工关节假体固定的可行性.[方法]制备成年新西兰白兔股骨中上段15 mm骨缺损,于髓腔内置入直径3 mm的钛棒并以骨水泥或BMG/PMMA复合材料固定,模拟人工股骨头置换术之动物模型,分别进行术后步态、X线检查、生物力学、组织学检查观察.[结果]术后第2d～12周两组动物均可正常行走;术后24h力学检测示两种固定方法无显著性差异;随着时间的延长,骨缺损无短缩;X线及组织学检查示复合材料组钛棒周围有成骨现象,扫描电镜见复合材料内有骨长入.[结论]BMG颗粒/PMMA复合材料固定假体时显示出可靠的力学性能及诱导成骨能力,将可能使其成为一种新的假体固定方法.     

Quantitative anatomic study of atlanto-odontoid joint and design of an artificial atlanto.odontoid joint for the orthopedic clinic

OBJECTIVE: To observe and measure morphological parameters of the Chinese atlanto-odontoid joint anatomically in order to provide an anatomic data for designing artificial atlanto-odontoid joint used for substituting the destroyed atlanto-odontoid joint in the orthopedic clinic. METHODS: The relative anatomic parameters of 32 sets of fresh Chinese adults'atlanto-odontoid joint specimens were measured with a digital caliper and a goniometer, including the width of anterior arch of atlas (AW), the thickness of atlas at the junction of anterior arch and lateral mass (AD), the thickness and height of anterior tubercle of atlas (AT and AH), the middle height, length and width of the lateral mass (MHL, L and LW), the height, transverse and anteroposterior distance of odontoid process (DH, DW and DD), the retroversion angle of odontoid process (beta degree),the facial angle of odontoid process (theta degree) and so on. The data were statistically analyzed in order to ascertain the morphological parameter ranges of artificial atlanto-odontoid joint. An artificial atlanto-odontoid joint was designed according to these data. The operations of anlanto-odontoid joint arthroplasty were conducted in 3 cases of adult cadaver specimens. RESULTS: The width of AW was (20.45+/-1.53) mm, AD (3.91+/-1.32) mm, AT and AH (9.43+/-1.93)mm and (10.23+/-1.32) mm, respectively, MHL and LW (13.68+/-1.38) mm and (12.98+/-1.52) mm, respectively, DH (15.25+/-2.11) mm, DW and DD (9.69+/-1.38) mm and (11.26+/-1.02) mm, respectively, beta degree (12.23+/-4.27) degree, theta degree (65.48+/-2.17) degree. The prosthesis was composed of atlas part, axis part and accessories. Neither the vertebral artery nor the medulla oblongata was injured. CONCLUSIONS: The design of artificial atlanto-odontoid joint is feasible according to these parameters. The artificial joint can not only rebuild the stability of atlanto-axial joint, but also reserve the rotation function between atlas and axis. Every part of the joint has their own parameter ranges in purpose to firm fixation, convenient operation and good motion without further injury. The prosthesis can be used for patients suffering from compression of medulla oblongata and resection of dens when it is required.     

Instability, migration and laxity of total hip prostheses: A roentgen stereophotogrammetric study

Roentgen stereophotogrammetric analysis was used in the evaluation of clinical and/or radiographic problems in 28 total hip replacements without suspicion of infection. Instability of the acetabular and/or the femoral component was revealed in 14 cases. In 21 cases, examined twice, migration of the acetabular component was found in eight cases and migration of the femoral component in 15 cases. The method allows instability and migration of the prosthetic components as well as joint laxity to be determined with a high degree of accuracy.     

非骨水泥型髋假体进行髋关节翻修的四年随访研究

目的　评价非骨水泥型髋关节系统治疗人工全髋关节翻修术的术后中期临床随访效果。方法　自1996年11月至2001年1月,对55例56髋关节行翻修术,采用了Zweymüller非骨水泥人工髋关节系统,年龄30~80岁,平均59岁。均有至少两年以上的临床和放射学追踪资料,平均随访时间4年。结果　32例32髋得到随访, 23例24髋失访。有3例出现围手术期并发症: 1例为假体取出时大转子骨折, 1例为术后2d脱位并成功闭合复位, 1例为伤口深部感染需要再次清创。无髋臼及股骨柄假体需要再度翻修。Harris评分由术前平均40 6分提高到最末次随访平均80 4分。X线片示髋臼和股骨柄假体位置满意,无松动和感染征象,周围骨质内向长入。结论　中期临床结果显示,初次用骨水泥和非骨水泥固定人工髋关节置换失败的病例,若髋臼环完整,使用非骨水泥型髋关节假体可以获得良好的临床效果。     

Experience with the bipolar prosthesis in hip arthroplasty. A clinical study

Hip arthroplasty using a bipolar prosthesis was performed in 73 patients (75 hips) with femoral neck fracture, osteoarthritis, rheumatoid arthritis, or degenerative arthritis. Bipolar hip arthroplasty is more conservative than conventional total hip arthroplasty, because methyl methacrylate usually is not needed to fix the bipolar prosthesis to bone. Overall results were 67.1% good to excellent, 20.5% fair, and 12.3% poor; among the arthritic patients, the results were 72.9% good to excellent, 19.1% fair, and 8.5% poor. Complications included one deep wound infection and one arterial embolus; no dislocations occurred.     

Fixed-head and bipolar hip endoprostheses: A retrospective clinical and roentgenographic study

A retrospective review of 1,001 hip hemiarthroplasties was performed. The prosthetic designs were grouped into fixed-head types (682 cases) and bipolar types (319 cases) for comparison. The main indications for operation were femoral neck fracture and avascular necrosis of the femoral head. Clinical and roentgenographic data for different follow-up periods were compared between prosthetic types, using multivariate analysis. Roentgenographic loosening of the femoral component was noted in 25.4% of cases but was significantly higher (P less than .05) in the bipolar groups for a follow-up period less than 2 years, regardless of the method of fixation. The acetabular erosion rate was significantly higher (P less than .05) in the fixed head group, but this finding was related to length of follow-up period, bone porosity, and prosthesis/acetabulum fit. The reoperation rate, including revision to total hip arthroplasty, was higher in the fixed-head group (12.5%) than the bipolar group (7.2%). Based on Kaplan-Meier survivorship analysis, 13.7% of the bipolar and 22.9% of the fixed-head hip endoprostheses are expected to be reoperated 8 years after initial implantation. Cement fixation of the femoral component led to a higher prosthesis survival rate, regardless of type. Both prosthetic types are useful in hip surgery, but the bipolar type appears to be indicated in younger and more active patients, whereas the fixed-head design is more suitable for older patients with femoral neck fractures.     

人工寰齿关节研究进展

探讨如何既可达到牢固的固定,同时又可最大限度地保留脊柱的运动功能,这将是未来脊柱内固定生物力学发展的趋势。人工寰齿关节的研制是既能重建寰枢关节稳定性,又能保留寰枢关节旋转功能的可行性技术。作者从人工寰齿关节的理念、人工寰齿关节解剖、生物力学、人工寰齿关节置入的可行性分析等方面综述了近年来的一些研究进展。     

全膝关节置换术中股骨假体屈曲对髌股关节生物力学影响的实验研究

[目的]探讨全膝置换术中股骨假体矢状位上屈曲对髌股关节生物力学的影响,为临床指导人工膝关节置换的手术技术提供实验依据,以减少术后髌股关节的并发症。[方法]取正常国人新鲜冷冻尸体的5个膝关节作为研究对象,模拟膝关节自站立位屈膝下蹲的动作,设计制作膝关节实验架,与生物力学测试仪共同搭建实验平台。人工膝关节采用DePuy PFC假体全膝系统,手术由同一位有经验的术者实施以控制实验误差,置换髌骨。比较股骨假体相对于按下肢力线位、前屈5°、10°及后屈5°、10°、15°位置时的髌股关节的生物力学指标。选择屈膝30°、60°、90°、120°为观察角度,采用美国Tecscan公司生产的感测片测定髌股关节接触压峰值,最后软件处理得到数字化的结果。[结果]除了在膝关节屈曲30°、60°、90°,股骨假体前屈5°时,髌股关节内侧间隙接触压峰值与下肢力线位相比较无显著性差异(P>0.05),其余各种屈膝角度下,股骨假体不同屈曲角度所致髌股关节内外侧间隙接触压峰值与下肢力线位比较有显著性差异(P<0.05)。股骨假体后屈角度越大,峰值的升高越明显。[结论]全膝关节置换术中,股骨假体在矢状位上争取按下肢力线位置入,以降低术后并发症的发生。     

特制人工髋关节假体在髋部骨肿瘤的应用分析

目的探讨特制人工假体在髋部肿瘤保肢术中的应用价值。方法回顾性分析我院自1999年3月至2005年5月髋部原发肿瘤患者行特制人工假体置换术后疗效、并发症及处理资料。本组肿瘤病例中,髋臼11例,股骨近端15例;肿瘤类型:软骨肉瘤3例,骨肉瘤6例,滑膜肉瘤1例,骨巨细胞瘤12例,良性纤维组织瘤2例,动脉瘤样骨囊肿2例。假体类型:人工全髋关节假体17例,人工双极股骨头7例,马鞍式关节假体2例。结果随访时间为18个月～6年,平均4年3个月;10例恶性肿瘤局部复发率40%,保肢率60%,16例中间性及良性肿瘤复发率12.5%,保肢率87.5%,参照Enneking(MSTS)评定标准平均得分19分,优良率76.9%。结论特制人工髋关节假体具有良好的术后肢体功能,是髋部骨肿瘤较为满意的保肢治疗方法之一。     

Motion of the bipolar hip prosthesis components

It has been postulated that most hip motion occurs at the inner bearing in bipolar hip prosthesis. However, radiography and cineradiography analyses have shown that the inner bearing is not always the primary articulation. We studied the frictional behavior of bipolar prosthesis and Austin-Moore prostheses and the motion of the bipolar prosthesis using a pendulum apparatus.

The primary articulation was altered according to the amount of loading. When a load of 10 kg was applied to the joint, motion occurred at both bearings with friction coefficients 0.061 at the inner bearing and 0.026 at the outer bearing. With loads of over 20 kg, the outer bearing was the primary articulation. The inner bearing was the dominant articulation only when the acetabular cartilage had been removed.

Our results suggest that the motion of bipolar prostheses occurs mainly at the outer bearing during normal walking, and that this prosthesis cannot be expected to reduce wear of articular cartilage.