Wagner resurfacing arthroplasty of the canine hip

Twelve surface replacement arthroplasties were performed on the hips of ten mongrel dogs using scaled-down replicas of the Wagner prosthesis. The contralateral hips and two further animals served as nonoperated controls. Animals were killed 5 months postoperatively. Clinical, radiological, histological and fluorochrome-labelling studies were employed to assess the bony and soft tissue reaction to resurfacing arthroplasty. There was no clinical or radiographic evidence of prosthetic loosening. Histological examination disclosed a thick foreign body and chronic inflammatory membrane containing acrylic cement and polyethylene wear particles at the bone-cement interface of both components. Generally, the bone marrow and trabecula were viable. There was evidence of increased bony remodelling and new bone formation in the subchondral area. The similarity between the above findings and those of aseptic component loosening in man suggests a mechanism whereby wear debris initiate a biological foreign body reaction culminating in component loosening.     

Peripheral wear of Wagner resurfacing hip arthroplasty acetabular components

One hundred nine Wagner resurfacing arthroplasty acetabular components retrieved at revision surgery were examined for type, depth, and extent of wear at the periphery of the components. Ninety-two components were found to have evidence of peripheral wear caused by impingement of the femoral neck on the edge of the component. The thickness of the wall loss due to this impingement wear was found to be less the farther that measurements were taken from the edge of the component. Thus, when those components with any evidence of impingement wear were analyzed, it was found that significantly fewer components had evidence of impingement at depths of 3 mm and 5 mm in from the edge of the component. It is suggested that future designs of resurfacing hip arthroplasty acetabular components should be at least 3 mm and possibly 5 mm less than a hemisphere. This is likely to lead to less impingement on the femoral neck and therefore less cause for mechanical loosening and less production of wear debris.     

Metal-on-metal hip resurfacing arthroplasty

The main advantage of hip resurfacing is bone conservation for patients likely to outlive a primary conventional hip replacement. Previous attempts at hip resurfacing failed predominantly because of the consequences of a high amount of wear of thin polyethylene acetabular components and poor femoral component fixation. With correct patient selection, surgeon education, and operative technique, survivorship at five years is comparable with that of traditional hip replacements. Hip resurfacing has its own unique set of complications, including a fractured neck of the femur. It is necessary to understand the risk factors prior to performing the procedure.     

Revision of hip resurfacing arthroplasty

Metal-on-metal (MOM) hip resurfacing has become an increasingly popular treatment for young, active patients with degenerative disease of the hip, as bearing surfaces with better wear properties are now available. One proposed advantage of resurfacing is its ability to be successfully revised to total hip arthroplasty (THA). In addition, radiographic parameters that may predict failure in hip resurfacing have yet to be clearly defined. Seven MOM resurfacing arthroplasties were converted to conventional THAs because of aseptic failure. Using Harris Hip Scores (HHS) and Short Form 12 (SF-12) questionnaire scores, we compared the clinical outcomes of these patients with those of patients who underwent uncomplicated MOM hip resurfacing. In addition, all revisions were radiographically evaluated. Mean follow-up periods were 51 months (revision group) and 43 months (control group). There was no significant difference between the 2 groups' HHS or SF-12 scores. There was no dislocation or aseptic loosening after conversion of any resurfacing arthroplasty. Valgus neck-shaft angle (P < .03) was associated with aseptic failure of MOM hip resurfacing. Conversion of aseptic failure of hip resurfacing to conventional THA leads to clinical outcomes similar to those of patients who undergo uncomplicated hip resurfacing. The orientation of the femur and the components placed play a large role in implant survival in hip resurfacing. More work needs to be done to further elucidate these radiographic parameters.     

A study of implant failure in the Wagner resurfacing arthroplasty

Using clinical, radiographic, and pathological data, we investigated eighteen cases of early aseptic failure of an implant in patients who had undergone reconstruction of the hip with a Wagner resurfacing prosthesis. Sixteen patients required revision for loosening of the acetabular component, with eight of them also demonstrating loosening of the femoral component. One patient had loosening of the femoral component without failure of the acetabular component, and one patient sustained a femoral neck fracture that was associated with osteonecrosis. Six of the patients with loosening of the acetabular component had an associated significant loss of acetabular bone stock. Loosening was associated with the development of a membrane at the bone-cement interface in all patients. Histological examination of the membrane demonstrated a marked foreign-body response to wear products from the arthroplasty. Bone resorption appeared active at the bone-membrane interface. We concluded that the acetabular component of the Wagner prosthesis is prone to early loosening and that the early loosening is potentiated by a foreign-body response to debris resulting from arthroplastic wear.     

Biomechanics of the Birmingham hip resurfacing arthroplasty

The effects of the method of fixation and interface conditions on the biomechanics of the femoral component of the Birmingham hip resurfacing arthroplasty were examined using a highly detailed three-dimensional computer model of the hip. Stresses and strains in the proximal femur were compared for the natural femur and for the femur resurfaced with the Birmingham hip resurfacing. A comparison of cemented versus uncemented fixation showed no advantage of either with regard to bone loading. When the Birmingham hip resurfacing femoral component was fixed to bone, proximal femoral stresses and strains were non-physiological. Bone resorption was predicted in the inferomedial and superolateral bone within the Birmingham hip resurfacing shell. Resorption was limited to the superolateral region when the stem was not fixed. The increased bone strain observed adjacent to the distal stem should stimulate an increase in bone density at that location. The remodelling of bone seen during revision of failed Birmingham hip resurfacing implants appears to be consistent with the predictions of our finite element analysis.     

The evolution of hip resurfacing arthroplasty

Metal-on-metal hip resurfacing, a significant recent development in hip arthroplasty, preserves proximal femoral bone stock, optimizes stress transfer to the proximal femur, and offers inherent stability and optimal range of movement. The results of hip resurfacing in the 1970s and 1980s were disappointing, and the procedure was largely abandoned by the mid-1980s. The renaissance of metal-on-metal articulations for total hip arthroplasty has enabled the introduction of new hip resurfacings, and many implant manufacturers have introduced such systems. Early results are encouraging, and complications commonly seen in the 1970s and 1980s, such as early implant loosening and femoral neck fracture, are rare. Background research and better understanding of implant failure suggest that current hip resurfacing technology has developed beyond that of an experimental procedure.     

Total hip arthroplasty and hip resurfacing arthroplasty in the very young patient

Severe hip arthritis in an adolescent or very young adult can be a devastating disability that affects all aspects of a patient’s life. Newer treatment strategies in pediatric orthopedic surgery and hip preservation potentially could lessen the impact of this severe disorder in the future. Careful patient selection can lead to excellent outcomes for both THA and/or HRA in young patients. Further study will likely shed more light on whether HRA truly has more improved functional results than THA, and studies with longer follow-up that show definitive revision rates also should affect the future of HRA.     

Complications associated with hip resurfacing arthroplasty

Hip resurfacing arthroplasty is an old orthopedic concept that has undergone a resurgence of interest in the past decade. Because of the rapid increase in the number of procedures being performed, previously recognized complications have begun to recur. This article focuses on complications that are related to the hip resurfacing procedure such as femoral neck fractures, avascular necrosis, raised metal ion levels, and sound initial and durable long-term fixation of an all-metal monoblock cobalt/chrome acetabular component. Dislocation rates after resurfacing and other complications are briefly discussed.     

髋关节表面置换术的进展

随着对髋关节力学认识的加深和材料学的进展,表面置换重新受到重视,因其精确重建股骨近端和髋关节的正常解剖结构,术后具备良好的生物力学和关节稳定性,运动能力的恢复更接近于正常,降低了髋关节二次手术的难度等等优点,成为当今关节外科的最主要进展,具有广阔的临床应用前景。但尚存在如股骨颈骨折、缺血性坏死、金属离子水平升高等特殊而严重的并发症等需要解决的问题,除选择合适的适应症患者,不断改进假体材料和工艺、提高临床技术外,尚需进一步随访观察和验证。     

全髋表面置换术和传统全髋置换术术后生物力学结构恢复的比较研究

目的比较全髋表面置换术（HRA）和传统全髋置换术（THA）后的下肢长度、股骨偏心距和髋臼偏心距等恢复的情况,确定HRA是否更有利于恢复髋关节的生物力学结构。方法选择单侧施行HRA或THA的股骨头坏死患者各20例（对侧髋关节均健康）。术前、术后摄等比例X线正位片,测量患者双髋的下肢长度、股骨偏心距和髋臼偏心距指标,与对侧髋比较患髋术后的改变。将HRA和THA术后改变的结果进行比较。结果 HRA组各项生物力学参数差值恢复明显比THA组更接近正常。术后HRA组和THA组患侧和健侧比较下肢长度差分别为（-2.1±1.1）mm和（3.5±2.6）mm（P〈0.05）,HRA组为轻度短缩而THA组为轻度延长;股骨偏心距差分别为（-1.8±1.4）mm和（3.1±1.9）mm（P〈0.05）,HRA组股骨偏心距降低,而THA组偏心距增加;髋臼偏心距分别为（1.6±1.8）mm和（-2.3±2.1）mm（P〈0.05）,THA组髋臼偏心距增加较大。结论 HRA可以更加精确地恢复股骨近端解剖结构,大直径股骨头假体增加了髋关节的稳定性,避免了THA容易导致的下肢延长和偏心距增加,有利于改善软组织张力。但HRA还是有轻度缩短下肢长度和股骨偏心距的倾向。     

全髋关节表面置换术的研究进展

全髋关节表面置换术（resurfacing arthroplasty of the hip,HRA）采用人工髋臼帽和股骨头杯重建髋臼一股骨头关节面,恢复髋关节功能。 1 HRA的主要特点     

Complications after metal-on-metal hip resurfacing arthroplasty

This article determines the incidence and cause of the complications commonly associated with metal-on-metal hip resurfacing implants and the proposed methods to prevent these complications. The literature available in PubMed was reviewed. Complication rates after hip resurfacing are low, and the procedure has shown both safety and efficacy in the hands of surgeons trained in specialized centers. Proper surgical technique can further reduce the incidence of femoral neck fracture, component loosening, and abnormal wear of the prosthesis. A more systematic detection of adverse local tissue reactions is needed to provide accurate assessments of their prevalence.     

Wagner resurfacing hip arthroplasty. The results of one hundred consecutive arthroplasties after eight to ten years

In a prospective study of 100 consecutive Wagner resurfacing hip arthroplasties in ninety-three patients, the outcomes for all hips were determined for an eight to ten-year follow-up period. By survivorship analysis, the rate of survival of the arthroplasty was calculated to be 70 per cent at five years, but only 40 per cent at eight years. The major cause of failure was aseptic loosening of the acetabular or femoral component, or both. Fracture of the neck of the femur occurred in three hips. Although the medium-term results (at fifty-six to eighty-three months) were better than those in most comparable studies of resurfacing arthroplasty, the poor long-term results (at ninety-one to 118 months) show that meaningful studies of new prosthetic designs must continue for at least eight years, and, if at all possible, must include 100 per cent follow-up. The survival curve for the resurfacing arthroplasties in this study can serve as the basis for comparison of the early, medium, and long-term results of future designs of resurfacing hip prostheses.     

正确认识微创人工全髋关节置换术和髋关节表面置换术

近年来，人工髋关节外科的发展迅速，模型设计、假体材料、生物力学、部件可调换性、手术器械、手术技术等方面都有了很大进步，手术效果和假体存活率令人鼓舞，其中主要的进步之一就是微创全髋关节置换术的开展。微创全髋关节置换包含软组织的微创和骨的微创，而后者就是指髋关节的表面置换。     

重视金属对金属全髋关节置换及髋关节表面置换的临床评估——避免误读人工关节登记资料与临床研究报告

近年来针对采用金属对金属摩擦界面的全髋关节置换术以及同样是金属界面的髋关节表面置换术的临床研究报告,与来自不同国家和地区的人工关节登记资料的发表,在人工关节专业领域产生了极大的争议。某些品牌的假体由于来自人工关节登记系统的高失败率而实施了召回措施。这一切在非专业媒体和患者人群中甚至导致了对这一已有长期应用历史的摩擦界面的误解与恐慌。     

髋关节表面置换术的临床进展

髋关节疾病严重影响着患者的生活质量,尤其对于年轻、活动量大、预期寿命长、功能要求高的患者,由于传统的全髋关节置换术（total hip arthroplasty,THA）截除了正常的股骨颈而改变了生物力学关系,加上假体磨损相关并发症、股骨颈骨折等问题,使得THA术后可能需行多次翻修手术。     

The practical limitations of resurfacing hip arthroplasty

Resurfacing hip arthroplasty has recently experienced a resurgence in popularity, associated with an unprecedented amount of coverage in the media. This article assesses what proportion of a consecutive series of young adults presenting for total hip arthroplasty would have been suitable for resurfacing arthroplasty. Retrospective review of the preoperative radiographs was performed, with templating for the resurfacing prostheses. The hips were divided into those appropriate and those inappropriate for the procedure, and those in whom the procedure would be technically challenging. Sixty-one hips in 57 patients were reviewed, with ages ranging from 17 to 49 years. Twenty-eight hips were assessed as suitable, 26 as unsuitable, and 7 as technically challenging. Reasons for unsuitability included collapse and/or cystic degeneration of the femoral head.     

金属对金属髋关节表面置换术的短期随访研究

目的探讨金属对金属(MOM)混合固定型髋关节表面置换术(HRA)的近期疗效,分析手术技术要点。方法 2004年10月至2008年6月,对52例(58髋)股骨头缺血性坏死、骨关节炎、髋关节发育不良、强直性脊柱炎患者行MOM-HRA。其中男32例,女20例;年龄16～65岁,平均42.6岁。手术方法按照K.De.Smet标准方法进行,术后对Harris评分、关节活动度和X线片进行随访。结果失访7例(8髋),45例(50髋)获得随访,随访时间平均22个月(12～54个月)。术前平均Harris评分(37.0±1.2)分,术后22个月平均(93.0±1.0)分;术前屈髋度平均(25.3±1.6)°,术后22个月平均(105.0±1.8)°;术前外展度平均(18.8±0.8)°,术后22个月平均(40.6±1.0)°。评价:46髋优,3髋良,1髋差。无股骨颈骨折,无松动,无脱位,无感染,无翻修,1例异位骨化BrookerⅢ型。结论 HRA具有保留股骨头骨量、术后关节活动度恢复快、近期结果好等优点,对于获得优良的术后结果,严格的患者选择和精确的手术技术至关重要。