膝盖置换缺乏长期的安全性和有效性资料


  【24drs.com】根据在线发表于Lancet期刊的一篇研究,膝盖置换术是现代医学的一个成功故事,但是还不知道病患的结果或各式植入物的效果,有关此手术的明确适应症也还缺乏共识。
  
  英国、瑞典和澳洲的作者写道,因为55岁以下膝盖跌伤者越来越多、矫正或追踪手术的比率越高,医师们需要改善决策方式,另一方面,有些人虽然功能性良好且只有轻微疼痛,仍接受了手术。
  
  这次的研究结果得自对1970年来的文献回顾,是近一周来、有关骨科关节置换术的安全性和有效性的疑虑的第二篇研究。一篇英国医学期刊发表的文献提出质疑,指出成千上万的髋关节金属置换术病患,对于可能曝露于有毒性的物质被蒙在鼓里。
  
  Lancet期刊这篇文章的第一作者Andrew Carr与共同作者们写道,美国进行全膝关节置换(TKRs)的人数,从1971-1976年的每100,000人年有31.2例,增加到2008年的每100,000人年220.9例,该年共超过650,000例手术,作者们预测,已开发国家之膝关节置换术的需要会持续增加,因为年长人口上升、肥胖比率增加,这两者也意味著骨关节炎比率更高,这也是该手术的主要适应症。
  
  虽然越来越多人的膝盖获得了新的「硬件」,到底有哪里些人是真正需要它呢?
  
  Carr博士等人写道,外科界对于实际适应症、术前症状的特定严重度、肥胖、年纪等并无明确共识,他们指出,国际骨关节炎协会与一个类风湿科组织组成的一个工作小组发现,疼痛、功能及X光片严重度和外科医师之膝关节置换建议无关。
  
  根据作者们表示,膝关节置换术的安全性和有效性资料也是依旧模糊。多数已发表的研究结果,是单一名医师或单一个中心的系列案例,这些报告大部分记载的是发明该植入物之医师的实务经验,因而会有偏见和可能的利益冲突。
  
  研究的关键结果是重做手术处置并发症的比率。植入物引起的无菌性松动是重做手术的最常见原因,是年轻和有活动力之病患的主要考量,第二个常见原因是感染,其它原因包括术后疼痛、失能、僵硬。
  
  作者们写道,植入物的设计对于需要重做手术之副作用的风险有相当大的关联,因此,需透过全国性的登记资料来监测这些植入物。不过,重做手术的其它原因可能是术前诊断、手术技术、经验、技巧;病患因素;手术室情况;术后照顾。
  
  如果依据TKR或部分膝关节置换(PKRs)区分术后结果,医师和病患有时候会因为感觉比较像正常膝盖、手术范围比较少、感染风险低而选择PKR,也知道他们在有需要时可以转换成TKR。不过,部分置换的重做手术风险高于全置换术,根据登记资料,转换成TKR者需要比一开始就进行TKR者追踪得更久。
  
  作者们呼吁,继续发展全国性登记资料,以监测膝关节置换术的长期结果,并使用电子化健康记录系统来辅助。他们指出,登记资料报告的膝关节置换术结果比发表的临床试验少,没有高质量、无偏见且可信赖的信息,医师们无法在每个临床状况做出可达到最佳结果的决定。
  
  除了建议做好病患筛选与完整结果报告之外,特别要注意和各个植入物的相关资料,作者们也期待有可以治疗初期骨关节炎年轻病患的新策略,而可避免重大手术。
  
  虽然作者们提出了膝关节置换状态的疑虑,仍对其有所好评。他们写道,关节置换术是新手术中最成功的范例之一,使末期关节炎患者的生活质量有所改善。
  
  资料来源:http://www.24drs.com/professional/list/content.asp?x_idno=6749&x_classno=0&x_chkdelpoint=Y
  

Knee Replacement Data Scarce for Long-Term Safety, Effectiveness

By Robert Lowes
Medscape Medical News

March 5, 2012 — Knee replacement surgery is a success story of modern medicine, yet not enough is known about patient outcomes or the effectiveness of various implants, and consensus is lacking about the precise indications for the procedure, according to a study published online March 6 in the Lancet.

The authors, based in the United Kingdom, Sweden, and Australia, write that surgeons need improved decision-making as more and more possible candidates for new knees fall are younger than 55 years — a group that has a higher rate of revision or follow-up surgery. On another problematic note, some patients undergo the operation despite having good functional ability and only mild pain beforehand.

The article, based on a literature review going back to 1970, is the second in less than a week raising doubts about the evidence on orthopaedic joint implant safety and effectiveness. On February 28, the British Medical Journal published an article charging that hundreds of thousands of patients with metal-on-metal hip replacements were kept in the dark about possible exposure to toxic substances.

Andrew Carr, FRCS FmedSci, lead author of the Lancet article, and coauthors write that the number of total knee replacements (TKRs) in the United States increased from 31.2 per 100,000 person-years in the period from 1971 to 1976 to 220.9 per 100,000 person-years in 2008, for a total that year of more than 650,000 procedures. The authors predict that the demand for knee replacement will continue to grow in developed countries, in light of aging populations and rising obesity rates, which both portend higher rates of osteoarthritis, the main clinical indication for the operation.

Although more and more people are getting new hardware for their knees, fuzzy thinking prevails as to who really needs it.

"No clear consensus exists within the surgical community about exact indications, particularly severity of preoperative symptoms, obesity, and age," Dr. Carr and coauthors write. They point to a task force organized by the Osteoarthritis Research Society International and a rheumatology organization that found that "pain, function, and radiographic severity are not associated with a surgeon's recommendation for knee replacement."

Improve Treatment of Early-Stage Osteoarthritis to Avoid Surgery

Outcomes data on the safety and effectiveness of knee-replacement surgery also are fuzzy, according to the authors. Most published reports of outcomes, they write, are single-surgeon or single-center case series. Many of these reports chronicle the practice of a surgeon who invented the implant, "which introduces bias and a potential conflict of interest."

The key outcome studied was the rate of revision surgery to deal with complications. Aseptic loosening, usually caused by implant wear, is the most common reason for revision surgery, and "is mainly a concern in young and active patients." The second most common reason is infection. Other major causes are postoperative pain, instability, and stiffness.

The authors write that an implant's design can make a big difference in minimizing or maximizing the risk for adverse events that require revision surgery, hence the need to monitor implants through national registries. However, revision surgery also can be blamed on preoperative diagnosis; surgical technique, experience, and skill; patient factors; operating room conditions; and postoperative care.

Outcomes data break down into those for TKRs vs those for partial-knee replacements (PKRs). Surgeons and their patients sometimes will choose a PKR for the sake of a more normal-feeling knee, less extensive surgery, and a lower risk for infection, knowing that they have the option of converting to a TKR if need be. However, partial replacement has a higher risk for revision surgery than total replacement, and a conversion TKR is more likely to require more follow-up than a primary TKR, according to registry data.

The authors urge the continued development of national registries to monitor the long-term outcomes of knee replacement surgery, as well as the use of electronic health record systems to facilitate this. They note that registries tend to report less glowing outcomes for knee replacement than published clinical trials. "Without high quality, unbiased, and reliable information, surgeons cannot make informed decisions about how to achieve the best outcome in each clinical situation," the authors write.

In addition to recommending better patient selection and better reporting of outcomes, particularly as it relates to individual implant devices, the authors also call for new strategies to treat early-stage osteoarthritis in younger patients that will "avoid the need for major surgery altogether."

Despite the misgivings they express about the state of knee replacement, the authors also render praise.

"Joint-replacement surgery," they write, "is one of the most successful examples of innovative surgery, and has resulted in substantial quality-of-life gains for people with end-stage arthritis."

One coauthor is paid by the Australian Orthopaedic Association as director of the National Joint Registry. One coauthor has received honoraria and support for travel from Biomet. One coauthor has received consultancy fees from Stryker and institutional research grants from Genzyme. The 4 remaining authors have disclosed no relevant financial relationships.

Lancet. Published online March 6, 2012.

    
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