In vivo comparison of hip separation after metal-on-metal or metal-on-polyethylene total hip arthroplasty

BACKGROUND: Twenty subjects were analyzed in vivo with use of video fluoroscopy to determine if the femoral head separates from the acetabular component during normal gait and to determine if the amount of separation differs between metal-on-metal and metal-on-polyethylene total hip prostheses. METHODS: Ten subjects had been treated with a metal-on-metal total hip arthroplasty and ten, with a metal-on-polyethylene total hip arthroplasty. All of the prostheses were implanted by the same surgeon utilizing the same surgical technique, and all were judged to be clinically successful (a Harris hip score of >90 points). Each subject walked with a normal gait on a level treadmill while under fluoroscopic surveillance. The two-dimensional fluoroscopic videotapes were then converted into three-dimensional images with use of a computer-automated model-fitting technique. Each implant was analyzed at various flexion angles to assess the amount of femoral head sliding. RESULTS: No femoral head sliding was observed in the subjects with a metal-on-metal implant, whereas all ten subjects with a metal-on-polyethylene implant had sliding that was greater than our threshold value of 0.75 mm. The average amount of femoral head sliding in these subjects was 2.0 mm, and the sliding was observed during the swing phase of gait. The sliding was typically seen medially while the femoral head remained in contact with the acetabular component superolaterally. CONCLUSIONS: Femoral head sliding commonly occurred following traditional metal-on-polyethylene total hip arthroplasty but not after metal-on-metal arthroplasty. These kinematic data may be of value in future hip-simulation studies to better duplicate wear patterns observed in retrieval analyses, assist in the understanding of the lubrication and wear rates of metal-on-metal designs, and facilitate designing of prosthetic components that minimize wear and optimize hip kinematics.     

Large head metal-on-metal cementless total hip arthroplasty versus 28mm metal-on-polyethylene cementless total hip arthroplasty: design of a randomized controlled trial

Background  

Osteoarthritis of the hip is successfully treated by total hip arthroplasty with metal-on-polyethylene articulation. Polyethylene wear debris can however lead to osteolysis, aseptic loosening and failure of the implant. Large head metal-on-metal total hip arthroplasty may overcome polyethylene wear induced prosthetic failure, but can increase systemic cobalt and chromium ion concentrations. The objective of this study is to compare two cementless total hip arthroplasties: a conventional 28 mm metal-on-polyethylene articulation and a large head metal-on-metal articulation. We hypothesize that the latter arthroplasties show less bone density loss and higher serum metal ion concentrations. We expect equal functional scores, greater range of motion, fewer dislocations, fewer periprosthetic radiolucencies and increased prosthetic survival with the metal-on-metal articulation.     

金属对金属与金属对聚乙烯假体全髋关节置换术近期疗效比较研究

目的：比较大直径金属对金属（MOM）与金属对聚乙烯（MOP）假体全髋关节置换（THA）的近期疗效。方法回顾性分析2009年1月至2010年1月在苏州大学附属第一医院骨科行THA手术的44例（44髋）患者的临床资料,其中MOM组（22例22髋）采用大直径MOM承重界面假体,MOP组（22例22髋）采用MOP承重界面假体。对两组术中髋关节活动度,术后下床活动时间、Harris评分、影像学表现及并发症进行比较。结果两组术中髋关节屈曲、内收、外展、屈髋内旋、屈髋外旋活动度比较,差异有统计学意义（P＜0.05）。全部患者获得随访,MOM组术后平均随访30个月（18～37个月）,MOP组术后平均随访25个月（16～35个月）。MOM组和MOP组术后下床活动时间分别为（3±1）d和（7±2）d,两组比较,差异有统计学意义（P＜0.05）。术前,术后l、3、6、12个月及末次随访时,MOM组和MOP组Harris评分分别为（37.8±4.8）、（85.6±3.2）、（89.4±4.1）、（94.5±2.3）、（94.7±3.1）、（93.8±3.6）分和（38.5±5.5）、（80.2±4.4）、（83.6±2.9）、（90.8±2.7）、（91.6±3.6）、（89.6±6.3）分,术后各时相点与术前比较,差异有统计学意义（P＜0.05）;两组术后不同时相点比较,MOM组均高于MOP组（P ＜0.05）。术后12个月MOM组和MOP组髋关节总活动范围分别为（236±9）°和（203±10）°,与术前的（119±14）°和（112±15）°比较,差异有统计学意义（P＜0.05）;术后12个月MOM组髋关节活动度优于MOP组（P ＜0.05）。X线片检查示MOM组22髋股骨假体位于中立位,无内外翻,无股骨假体下沉;MOP组1髋轻度内翻位,术后6个月1髋出现＜1.5 mm的下沉,至末次随访股骨假体位置无明显改变。至末次随访,两组患者均未出现脱位、感染、神经损伤、深静脉血栓、假体无菌性松动、髋臼及股骨骨折或骨溶解等并发症。结论与MOP比较,采用大直径MOM行THA能够增加髋关节活动度,更为有效地恢复髋关节功能,术后可早期下床活动,临床效果明显。     

陶瓷对陶瓷与金属对聚乙烯全髋关节置换的10年随访研究

目的 比较陶瓷对陶瓷（ceramic-on-ceramic, COC）与金属对聚乙烯（metal-on-polyethylene, MOP）全髋关节置换的10年随访临床结果。 方法 对114例接受初次THA的患者进行回顾性研究,其中COC组48例（54髋）,MOP组66例（67髋）,比较COC与MOP两种不同摩擦界面假体的术后髋关节功能、翻修率以及不良事件发生率。 结果 末次随访时患者COC组与MOP组术后髋关节Harris评分分别为89.9±7.5和92.3±8.2,无显著性差异（P＞0.05）;COC组1例翻修（翻修时间术后3年）,MOP组4例翻修（翻修时间平均6年）。两者在翻修、脱位、假体破碎、关节异响、无菌性松动、假体周围骨溶解、深部感染、异化骨化发生率的比较,无显著性差异（P＞0.05）。结论 COC与MOP假体均能提供较好的临床疗效,两者在术后髋关节功能及并发症方面疗效相当。     

Comparison of metal ion concentrations and implant survival after total hip arthroplasty with metal-on-metal versus metal-on-polyethylene articulations

Background and purpose — Large metal-on-metal (MoM) articulations are associated with metal wear and corrosion, leading to increased metal ion concentrations and unacceptable revision rates. There are few comparative studies of 28-mm MoM articulations with conventional metal-on-polyethylene (MoP) couplings. We present a long-term follow-up of a randomized controlled trial comparing MoM versus MoP 28-mm articulations, focused on metal ions and implant survival.

Patients and methods — 85 patients with a mean age of 65 years at surgery were randomized to a MoM (Metasul) or a MoP (Protasul) bearing. After 16 years, 38 patients had died and 4 had undergone revision surgery. 13 patients were unavailable for clinical follow-up, leaving 30 patients (n = 14 MoM and n = 16 MoP) for analysis of metal ion concentrations and clinical outcome.

Results — 15-year implant survival was similar in both groups (MoM 96% [95% CI 88–100] versus MoP 97% [95% CI 91–100]). The mean serum cobalt concentration was 4-fold higher in the MoM (1.5?μg/L) compared with the MoP cohort (0.4?μg/L, p < 0.001) and the mean chromium concentration was double in the MoM (2.2?μg/L) compared with the MoP cohort (1.0?μg/L, p = 0.05). Mean creatinine levels were similar in both groups (MoM 93?μmol/L versus MoP 92?μmol/L). Harris hip scores differed only marginally between the MoM and MoP cohorts.

Interpretation — This is the longest follow-up of a randomized trial on 28-mm MoM articulations, and although implant survival in the 2 groups was similar, metal ion concentrations remained elevated in the MoM cohort even in the long term.     

Cushion bearings versus large diameter head metal-on-metal bearings in total hip arthroplasty: a short-term metal ion study

Introduction  

Metal-on-metal total hip arthroplasty (MOM THA) has the advantage of replicating the femoral head size, but the postoperative elevation of serum metal ion levels is a cause for concern. Metal-on-polycarbonate-urethane is a new cushion bearing featuring a large diameter metal head coupled with a polycarbonate-urethane liner.     

Metallosis after metal-on-polyethylene total hip arthroplasty

Metal debris should not be generated in a well-fixed, well-functioning metal-on-polyethylene total hip arthroplasty. However, surgeons sometimes encounter periprosthetic metallosis during revision hip surgery. Insert wear, fracture, or dislodgment in modular components may lead to articulation of the prosthetic head with the metallic shell and subsequent metallosis. Metallosis may occur with loose acetabular components as a consequence of fretting of the screws and shell screw holes or shedding of the ingrowth surface of the component. The femoral component can also be a source of metallosis: Wear of a titanium femoral head, loosening of rough surface finish from the femoral stem, and stem fracture all may result in metallic particles being deposited in periarticular tissues. Specific clinical and radiographic findings can help in differentiating these forms of failure and in planning surgery. When metallic debris-induced bone loss is recognized early, surgical intervention may limit its progression.     

Bearing surfaces for total disc arthroplasty: metal-on-metal versus metal-on-polyethylene and other biomaterials

Background contextConcerns about the effect of metallic wear debris from metal-on-metal bearing surfaces in total hip arthroplasty have increased. Some spinal arthroplasty devices include metal-on-metal bearing surfaces.PurposeTo review the literature for clinical reports of complications because of wear debris from metal-on-metal spinal arthroplasty devices. To review the biology of wear debris from metal-on-metal bearing surfaces drawn from the hip arthroplasty literature and place it in the context of global regulatory actions and clinical and laboratory studies.Study designLiterature review.MethodsTo identify clinical reports, the PubMed database from the United States National Library of Medicine was queried using Medical Subject Headings terms and additional keyword terms. In addition, experts from academia and regulatory agencies were questioned regarding their knowledge of reports, including experts who attended the US Food and Drug Administration roundtable in September 2010.ResultsThree case reports and one case series including seven total cases were identified in which abnormal inflammatory reactions and soft-tissue masses after metal-on-metal disc replacements were consistent with pseudotumor and metal hypersensitivity. Spinal cases are present as pain and neurologic symptoms. On plain radiography, there is no clear periprosthetic osteolysis or loosening. On magnetic resonance imaging, there is increased magnetic susceptibility artifact because of metallic debris that renders images inadequate. Computed tomography myelography demonstrates a soft-tissue mass, which exhibits epidural extension surgically. Histologically, large areas of necrotic debris and exudates are interspersed with chronic inflammatory cells. Lymphocyte or macrophage predominance is determined by the rate of wear and the presence of gross, microscopic, or submicron metallic wear debris. The metallurgy of the involved devices is cobalt-chromium-molybdenum (CoCrMo) alloy, and the bearing surface is CoCrMo-on-CoCrMo.ConclusionsMetal-on-metal spinal arthroplasty devices are subject to postoperative complications because of metallic wear debris with similar clinical, radiographic, histologic, gross anatomic, and device-related features to those found in metal-on-metal bearing surfaces in total hip arthroplasty.     

Painful metal-on-metal total hip arthroplasty

Two patients were evaluated for the possibility of hypersensitivity to a Metasul articulation (Centerpulse, Austin, Tex) coupled with total hip arthroplasty. Serum was tested with a lymphocyte proliferation assay, and the capsular tissues from the hip were examined for perivascular lymphocytes. The diagnosis of hypersensitivity to Metasul could not be confirmed in these patients, and ultimately, the painful hip arthroplasties were felt to be caused by a combination of musculoskeletal problems.     

金属-金属与金属-聚乙烯两种髋关节假体疗效比较的Meta分析

目的 系统评价金属-金属与金属-聚乙烯两种髋关节假体的临床疗效.方法计算机检索MEDLINE、EMBASE、Cochrane图书馆、Cochrane协作网肌骨创伤组试验数据库和中国生物医学文献数据库,手工检索相关骨科杂志及会议资料.收集所有比较金属-金属与金属-聚乙烯髋关节假体临床疗效的随机对照试验及半随机对照试验等,评价纳入研究的方法学质量,并使用 RewMan4.2.8统计学软件对结果进行Meta分析,比较金属-金属假体与金属-聚乙烯假体髋关节置换术后髋关节Harris评分、髋关节活动范围、假体周围透亮带、脱位及再手术的发生率、血液及尿液中金属离子的浓度.结果 共纳入9个研究,其中4篇随机对照试验,5篇临床对照研究.两组患者术后髋关节Harris评分、髋关节活动范围比较差异均无统计学意义(RR=-1.12,95%CI-2.91～0.66,P=0.22;RR=-0.10,95%CI-0.31～0.11,P=0.35).金属-金属组术后假体周围出现放射透亮带的例数较金属-聚乙烯组少,差异有统计学意义(RR=0.62,95%CI0.51～0.76,P<0.001);术后发生脱位及再次手术的例数较金属-聚乙烯组少,但差异无统计学意义(RR=0.42,95%CI0.11～1.57,P=0.20);术后血液中金属离子浓度高于金属-聚乙烯组,差异有统计学意义(RR=2.27,95%CI1.56～2.98,P<0.001);术后尿液中金属离子浓度也较金属-聚乙烯组高,但差异无统计学意义(RR=1.44,95%CI-0.27～3.14,P=0.10).结论两种髋关节假体术后髋关节功能无明显差异,但金属-金属假体术后假体周围出现放射透亮带的例数较金属-聚乙烯假体少,血液中金属离子浓度较金属-聚乙烯假体高.

Abstract：

Objective To evaluate clinical outcomes of primary cementless total hip arthroplasty with metal-on-metal versus metal-on-polyethylene prostheses. Methods We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialized Register, the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, and CBM, conference proceedings and reference lists of articles for randomised or quasi-randomised controlled trials comparing metal-on-polyethylene (MOP group) with metal-on-metal (MOM group) in cementless total hip arthroplasty. The Cochrane Collaboration's tool for assessing risk of bias and software RewMan 4. 2. 8 were used to evaluate methodological quality and to perform a system review. Results Altogether 4 randomised controlled trials and 5 clinical controlled trials were included in this study. Pooled results from all the 9 trials showed no statistical differences between the 2 groups in terms of functional status (Harris hip score) and range of motion ( RR = - 1. 12, 95% CI - 2. 91 to 0. 66, P = 0. 22;RR= -0. 10, 95% CI-0.31 to 0. 11, P = 0.35). However the cases of periprosthetic radiolucency in the MOP group were significantly more than in the MOM group ( RR = 0. 62, 95% CI 0. 51 to 0. 76, P < 0. 001) . Differences in the rate of postoperative dislocation or surgical revision were not statistically significant between the 2 groups( RR=0. 42, 95% CI 0. 11 to 1. 57, P =0. 20), although lower in the MOM group. Serum ion concentrations of cobalt and chromium were significantly higher in the MOM group (RR = 2. 27, 95% CI 1. 56 to 2.98, P <0.001), but differences in the urine ion concentrations were not statistically significant ( RR = 1. 44,95% CI -0. 27 to 3. 14, P = 0. 10) . Conclusions MOM implements may lead to higher serum metal ion concentrations and fewer cases of periprosthetic radiolucency than MOP ones. But both prostheses are similar in hip functional outcomes.     

Comparison of the risk of revision in cementless total hip arthroplasty with ceramic-on-ceramic and metal-on-polyethylene bearings

Background and purpose — Ceramic-on-ceramic (CoC) bearings were introduced in total hip arthroplasty (THA) to reduce problems related to polyethylene wear. We compared the 9-year revision risk for cementless CoC THA and for cementless metal-on-polyethylene (MoP) THA.

Patients and methods — In this prospective, population-based study from the Danish Hip Arthroplasty Registry, we identified all the primary cementless THAs that had been performed from 2002 through 2009 (n = 25,656). Of these, 1,773 THAs with CoC bearings and 9,323 THAs with MoP bearings were included in the study. To estimate the relative risk (RR) of revision, we used regression with the pseudo-value approach and treated death as a competing risk.

Results — 444 revisions were identified: 4.0% for CoC THA (71 of 1,773) and 4.0% for MoP THA (373 of 9,323). No statistically significant difference in the risk of revision for any reason was found for CoC and MoP bearings after 9 years of follow-up (adjusted RR = 1.3, 95% CI: 0.72–2.4). Revision rates due to component failure were 0.5% (n = 8) for CoC bearings and 0.1% (n = 6) for MoP bearings (p < 0.001). 6 patients with CoC bearings (0.34%) underwent revision due to ceramic fracture.

Interpretation — When compared to the “standard” MoP bearings, CoC THA had a 33% higher (though not statistically significantly higher) risk of revision for any reason at 9 years.     

Management of failed metal-on-metal total hip arthroplasty

The theoretical advantages of metal-on-metal (MOM) bearing couples in total hip arthroplasty (THA) have been recently balanced by concerns regarding adverse local and systemic effects. Higher than anticipated early revision rates have been reported by several joint registries. Failed MOM hips present with a spectrum of symptoms and findings and traditional methods of failure must be considered in addition to the failure modes that appear to be unique to the MOM bearing couple. Metal hypersensitivity and soft tissue immune reactions remain incompletely understood and require careful ongoing study. The tools available to evaluate MOM THAs and the indications for revision surgery remain to be defined. Outcomes following revision of MOM hips appear to depend on appropriate evaluation, early identification, and appropriate surgical management.     

Metallosis after contemporary metal-on-metal total hip arthroplasty. Five to nine-year follow-up

BACKGROUND: Authors of recent studies have reported early periprosthetic osteolysis in patients who have been treated with a contemporary metal-on-metal total hip arthroplasty and have suggested that metal hypersensitivity associated with an immunologic response to metal may be of etiologic importance. We evaluated the results and histologic findings in patients who had undergone revision of a failed contemporary metal-on-metal total hip arthroplasty. METHODS: Two hundred and seventeen total hip arthroplasties (SL-Plus stem and Bicon-Plus cup) with a Sikomet metal-on-metal articulation were implanted in 194 consecutive patients, and the results were retrospectively reviewed at a mean of seventy-seven months postoperatively. Clinical follow-up with the Harris hip score and plain radiographic evaluation were performed. Periprosthetic tissues from fourteen hips that had undergone revision arthroplasty were subjected to histologic analysis. RESULTS: The mean Harris hip score improved from 45 points preoperatively to 88 points at the final evaluation. Fourteen hips (6.5%) were revised: nine because of aseptic loosening, two because of technical failure, and three because of septic failure. Histologic examination of the retrieved periprosthetic tissues from the eleven patients who had undergone revision because of aseptic loosening or technical failure showed metallosis and extensive lymphocytic and plasma-cell infiltration around the metal debris. With removal of the component because of aseptic loosening as the end point, survivorship was 93% for the stem and 98% for the cup. CONCLUSIONS: Our findings are in agreement with those in recent publications and support the possibility that periprosthetic osteolysis and aseptic loosening in hips with a metal-on-metal articulation are possibly associated with hypersensitivity to metal debris. Prospective, comparative, randomized long-term studies are necessary to determine the cause(s) of loosening of prostheses with this particular articulation.     

Ceramic-on-ceramic bearings in total hip arthroplasty

The ideal bearing surface for total hip arthroplasty still is being sought. This bearing would be durable, cost-effective, easy to implant, inert, and produce minimal wear debris. Ceramic-on-ceramic bearings have continued to evolve and have enjoyed success in many European centers throughout the past 3 decades. A limited number of early reports from the United States discouraged widespread acceptance and use of ceramic-on-ceramic total hip arthroplasty. Once critically analyzed most of the failures from the early reports are attributable to design and material specific flaws. Vast improvements have been made in ceramic manufacturing leading to even more superior wear characteristics and higher burst strengths. The case for alumina-on-alumina ceramic bearings is becoming stronger as data accumulate clinically and in vitro. In a multicenter, prospective and randomized study, an alumina-on-alumina ceramic bearing is compared with a cobalt chrome-on-polyethylene bearing. After as many as 48 months there has been no significant difference in clinical performance between the two study groups. No ceramic head fracture or ceramic bearing failure has occurred. Therefore, this new alumina-on-alumina ceramic bearing is a safe option for total hip arthroplasty and may provide a more durable prosthesis especially in young and active patients.     

Revision total hip arthroplasty for metal-on-metal failure

Metal-on-metal (MoM) arthroplasty systems became popular in the early-2000s due to presumed advantages of improved wear characteristics and superior stability. However, subsequent reports of abnormal soft-tissue reactions to MoM implants and national registry data reporting high failure rates raised concerns. Early outcomes of revision total hip arthroplasty (THA) for adverse reaction to metal debris (ARMD) were poor, leading to development of surveillance programs and a trend towards early revision surgery. Patients with MoM arthroplasties require surveillance, comprehensive history and physical examination, imaging with ultrasound or magnetic resonance imaging (MRI), and laboratory evaluation including metal ion levels. Operative strategies for revision THA vary from exchange of modular components to extensive debridement and reconstruction with revision components. Surgeons should be aware of the increased risks of dislocation and infection following revision THA for ARMD. However, there is growing evidence that early revision surgery prior to extensive soft tissue destruction results in improved outcomes and decreased re-operation rates. It is estimated that >1 million MoM articulations have been implanted, with a large proportion still in situ. It is imperative to understand the aetiology, presentation, and management strategies for these patients to optimise their clinical outcomes.     

大直径金属对金属与金属对聚乙烯全髋关节置换初步疗效比较

目的 比较金属对金属(MOM)大直径全髋关节置换术后与金属对聚乙烯(MOP)全髋关节置换术后的近期疗效.方法 2007年6月至2008年12月采用髋关节后外侧入路对30例(30髋)进行MOM大直径全髋关节置换术(MOM组),男12例,女18例;平均年龄60.3岁;平均体质量指数23.7 kg/m2;术前Harris评分平均为(36±15)分.同期采用后外侧入路对30例(30髋)进行MOP全髋关节置换术(MOP组),男9例,女21例;平均年龄62.4岁;平均体质量指数23.4 kg/m2;术前Harris评分平均为(34±17)分.对两组患者的术后功能恢复及影像学进行比较.结果 术后随访12～18个月(平均14.4个月),两组患者均未发生感染、骨折脱位及神经损伤等并发症,MOP组有1例患者术后2个月形成深静脉血栓.术后1、3、6、12个月Harris评分MOM组平均分别为(86±3)、(90±3)、(95±4)、(92±4)分,MOP组平均分别为(78±4)、(84±3)、(90±4)、(92±4)分.术后1、3、6个月两组Harris评分比较差异均有统计学意义(P＜0.05).术后MOM组髋关节总活动范围平均为239.2°±21.9°,屈髋平均为135.4°±10.9°;MOP组髋关节总活动范围平均为190.1°±16.7°,屈髋平均为95.3°±11.3°,差异有统计学意义(P＜0.05).结论 MOM大直径全髋关节置换相比传统MOP全髋关节置换短期疗效好,其中远期疗效需进一步观察.     

Long-term follow-up and metal ion trend of patients with metal-on-metal total hip arthroplasty

Purpose

Long-term studies are required to support the use of metal-on-metal (MoM) bearings in total hip arthroplasty (THA) given the concern about systemic metal ion release and reports of adverse local soft tissue reactions. The purpose of this study was to report the seven to 13-year clinical, radiographic, and metal ion results in patients following MoM THA.

Methods

We studied 163 prostheses after second-generation MoM THA between July 1997 and November 2003. Cobalt and chromium metal ions were collected using whole and analysed by inductively-coupled plasma-mass spectrometry.

Results

The mean follow-up was 8.87 years (range, 7–13 years). Four hips (2.5 %) were revised. The Kaplan-Meier survivorship was 91.3 % for revision for all causes, and 97.5 % when excluding the hips revised for a manufacturer’s defect. Median whole blood cobalt levels peaked at a value of 2.87 μg/L at four years (p < 0.0001 vs. pre-operative) and subsequently decreased to 2.0 μg/L after nine years (p = 0.002 vs. four years). Median chromium levels maximally increased up to 0.75 μg/L after five years (p < 0.0001 vs. pre-operative) and tended to decrease thereafter to values of 0.56 μg/L after seven years.

Conclusions

This seven to 13-year follow-up study indicates that the clinical and radiological results following MoM THA are satisfactory with low revision rates. Cobalt and chromium ion levels peaked at four and five years, respectively, and gradually decreased thereafter.     

Metasul非骨水泥金属对金属全髋关节置换随访报告

[目的]探讨Metasul非骨水泥金属对金属全髋关节假体在人工全髋关节置换术中的应用效果.[方法]对本科于2003年8月-2005年12月行Metasul非骨水泥金属对金属人工全髋关节置换术25例(30髋)患者进行了随访.包括临床评估和放射学评估,并检测血铬浓度和肾功能情况.[结果]23例28髋获得随访,平均随访3.6年(2.5～4.8年).患者的平均Harris评分由术前的49.5分提高到末次随访时的93.4分.3髋(11.5%)形成透亮带;1髋股骨形成局灶性骨溶解.1例术中坐骨神经受损,2.5年后除趾背伸肌力较弱外其他均完全恢复.1例糖尿病患者血糖未控制理想,术后4年发生假体周围感染但X线检查未见松动迹象.无一术后发生脱位、股骨骨折等并发症.末次随访时平均血铬浓度为0.82 μg/L(0.020～0.140 μg/L),较正常参考值(0.007、0.109)无明显升高,未发现因血铬浓度升高导致的肾功能损害和癌症、白血病等恶性疾病.[结论]Metasul非骨水泥金属对金属全髋关节假体在人工全髋关节置换术中的效果令人满意,但有必要做进一步随访,以了解与金属对金属关节置换有关的任何不良反应.     

Midterm results of Metasul metal-on-metal total hip arthroplasty

We assessed 106 total hip arthroplasties performed with a new metal-on-metal hip system; the patients were monitored for at least 5 years. The average Harris Hip Score of the patients was 39.5 points before surgery and 87.8 points at final follow-up evaluation. Radiographically, the acetabular component was stable in 103 hips and possibly unstable in 3 hips. The femoral component was bone ingrown in 97 hips and stable and fibrous in 9. After surgery, 6 hips dislocated. The polyethylene liner dissociated in one patient. No patient exhibited clear signs of loosening, migration, or osteolysis. Distal femoral cortical hypertrophy was seen in 35.8% of the cases. Survival at the mean follow-up point (6.4 years) was 99.1%. There was no significant difference in serum chromium concentration between metal-on-metal bearings and polyethylene-on-metal bearings (control subjects). This study found that metal-on-metal total hip arthroplasty produces excellent midterm results.