骨科常見手術:膝關節置換術

1 患者教育：膝關節置換術(基礎篇)

什麼是膝關節置換術？膝關節置換術是一種用人造部件來替換患者部分膝關節的手術。

膝關節由大腿骨(股骨)下端、膝蓋骨(髕骨)和脛骨上端構成。

當膝關節出現問題時，膝部可出現疼痛、腫脹、僵硬或難以正常活動。膝關節問題的病因有很多，最常見的病因之一是骨關節炎，通常隨年齡增長而出現(圖 1)。

膝關節置換術能減輕膝部疼痛，改善膝關節功能。

何時需要通過膝關節置換術來治療膝關節問題？膝關節問題並非都需立即通過膝關節置換術來治療，醫生往往會建議先嘗試其他療法，比如減輕體重、藥物治療、使用膝關節支具或物理治療。若這些療法幫助不大，醫生才會建議行膝關節置換術。

這主要是因為替換的膝關節會逐漸磨損，尤其是對於年輕患者。替換的膝關節通常可使用至少10-15年，有的更久，具體取決於活動水平等多種因素。

膝關節置換術如何進行？膝關節置換術需在醫院的手術室中進行。首先，醫生會用藥物使您入睡、失去知覺，然後沿膝關節前方正中做一切口，用金屬、陶瓷或塑料製成的人工部件來替換部分膝關節(影像 1)。

術後如何恢復？多數患者術後需住院2-4日，在此期間使用：

●鎮痛藥

●預防感染的抗菌藥物

●預防下肢血栓的藥物

●預防下肢血栓的特殊靴子或筒襪

●物理治療–大多數患者術後1日內即可在輔助下站立和行走。理療師會教您如何通過鍛鍊強健腿部肌肉，並協助您彎曲關節、行走和爬樓梯，讓您能夠正常活動。

膝關節置換術可能引起哪些問題？患者術後短期內可能出現不同的問題(但嚴重問題罕見)，包括：

●下肢血栓–導致下肢疼痛和腫脹。

●感染–症狀包括發熱、寒戰、膝部疼痛逐漸加重或膝部腫脹。

出現上述症狀時請告知醫護人員。

有時，患者術後會感覺新的膝關節較僵硬，彎曲時不如原先靈活，爬樓梯或從矮椅子上起立有困難。

我出院後會去哪裡？許多患者可以回家，但部分患者需要短時間入住療養院或康復中心，待恢復一定程度後再回家。無論去哪兒，您都需要堅持鍛鍊並接受物理治療。

我何時能恢復日常活動？大多數患者可在膝關節置換術後4-6周內恢復日常活動。醫護人員會告訴您應該避免哪些活動。

我如何判斷自己是否適合接受膝關節置換術？請諮詢醫護人員：

●膝關節置換術有何優勢？

●膝關節置換術有何缺點？

●除了膝關節置換術外還有其他選擇嗎？

●如果我不接受膝關節置換術會怎樣？

2 全膝關節置換術（患者教育：高級篇）

全膝關節置換術，是一種用人工假肢部分替換膝關節的外科手術（圖1）。

一個正常的膝關節的功能是作為一個鉸鏈關節之間的大腿骨（股骨）和小腿骨（脛骨和腓骨）（圖1）。

隨著時間的推移，這些骨頭接觸的表面可能會變得磨損，這通常是由於關節炎或其他情況引起的，這可能會導致疼痛和腫脹。（參見「患者教育：骨關節炎症狀和診斷（超越基礎）」和「患者教育：骨關節炎治療（超越基礎）」

膝關節置換的原因

全膝關節置換術是緩解疼痛和恢復關節炎膝關節功能的一種選擇。膝關節置換最常見的原因是其他治療方法（減肥、運動/物理治療、藥物、注射和支撐）未能緩解關節炎相關的膝關節疼痛的治療方法。

膝關節置換術的目的是減輕疼痛，提高生活質量，維持或改善膝關節功能。這個手術適用於所有年齡段的人，除了骨骼還在生長的兒童。重要的是，在考慮這個手術之前，患者有明顯的疼痛和/或殘疾。因為關節置換的部件會隨著時間的推移而損壞，醫療保健提供者通常建議推遲膝關節置換，直到絕對必要。

膝關節置換術是最常用的關節置換術之一。

膝關節置換術

雖然全膝關節置換術在正確的情況下是有幫助的，但是你應該和醫生討論風險、好處和替代方案。全膝關節置換術的替代治療方案包括：

非手術治療-非手術治療最初推薦用於骨關節炎或炎性關節炎的患者。這可能包括：

●減肥——膝蓋承受每磅體重約4磅的壓力，因此即使是少量減肥（如10至15磅）也能減輕疼痛。

●運動/理療-加強膝蓋周圍的肌肉，幫助減輕膝蓋的壓力。關節的運動有助於防止關節僵硬。

●藥物，包括非處方藥和處方藥——包括止痛藥，如對乙醯氨基酚和消炎藥，如布洛芬或萘普生。患者應與他們的初級保健提供者和藥劑師討論這些藥物的使用，以確保副作用的風險是可接受的低。（參見「患者教育：非甾體抗炎藥（NSAIDs）（高級基礎知識）」。）

●膝蓋支撐或鞋墊-這些可能有助於對齊膝蓋並平衡關節上的重量。

●注射——這可能涉及類似可的松的藥物或透明質酸衍生物。（參見「患者教育：膝關節疼痛（高級基礎）」。）

關節鏡檢查-關節鏡是一種微創外科手術，醫生用一種叫做關節鏡的設備檢查關節的內部。醫生可以通過皮膚上的小切口修復任何損傷。關節鏡檢查只對某些類型的膝關節問題有幫助。關節鏡手術對骨關節炎患者沒有明顯的益處。

截骨術-截骨術是一種外科手術，包括切斷腿骨，使其重新排列，並使其癒合。它被用來將重量從膝蓋受損部位轉移到正常或受損較小的部位。對於60歲以上或患有炎症性關節炎（如類風溼性關節炎）的患者，不建議截骨術。

部分膝關節置換術-「部分」或「單關節」膝關節置換術只涉及更換膝關節的一部分。對於某些骨性關節炎僅限於膝蓋一個部分的人來說，這可能是一個選擇。你的醫生可以告訴你，你是否可能是這類手術的候選人，以及潛在的風險和好處。

膝關節置換術

膝關節置換術是在麻醉後在手術室進行的。手術需要兩到三個小時。手術後，你將在恢復區被監控數小時，直到麻醉效果消失。

大多數人在手術後會在醫院住一到三個晚上，儘管更短的住院時間越來越普遍，有些手術甚至是在門診部完成的（即，不需要住院）。

手術後，你將得到止痛藥，以幫助控制任何不適。

●如有可能，將使用非阿片類（非麻醉性）藥物，以減少疼痛。

●一些阿片類（麻醉）藥物可能需要用數周，尤其是在物理治療和睡眠前。

腿部血塊（稱為深靜脈血栓或「DVT」）是膝關節置換術後常見的問題。為了降低血栓風險，您可以：

●儘快起床和活動-與你的理療師合作，試著在手術當天或後天起床。在床上學習運動。

●服用抗凝血藥物-您將服用抗凝藥物（「血液稀釋劑」），可以是藥片，也可以是注射。大多數人手術後繼續服用這種藥幾個星期。

●躺下時穿上壓縮靴（腿周圍會定期充氣的裝置），一旦你能站起來走路，醫生可能會建議你穿上抗栓塞長襪。這些長襪緊貼腳、腳踝、小腿和膝蓋，有助於防止血凝塊。

感染是另一個主要問題，你將在手術後一小時內和術後24小時內服用抗生素。健康飲食、避免肥胖和戒菸都有助於降低感染風險。

康復-你會被鼓勵在手術後立即開始移動你的腳和腳踝。通常在手術的第二天或第二天開始物理治療。鼓勵膝關節主動運動。一些外科醫生可能會使用一種持續的被動運動裝置，當你躺在床上時，它會使你的腿抬起並緩慢移動。

物理治療是康復過程的重要組成部分。離開醫院後，一些人在家裡或診所接受物理治療，而另一些人則在康復機構或療養院呆幾天。

康復計劃通常包括改善活動範圍（你可以彎曲和伸直膝蓋的距離）和加強腿部肌肉的鍛鍊。你的外科醫生和理療師會幫助你在康復過程中設定目標。在恢復期避免過度勞累或使膝蓋勞累是很重要的。你通常可以在手術後三到六周內恢復正常的日常活動。經過幾個月的康復，你將能夠有一個更積極的生活方式。高衝擊性運動，如跑步和涉及大量接觸（足球）的運動是不推薦的，但你應該能夠參加像步行，自行車和遊泳這樣的活動。

潛在的併發症-嚴重的併發症在膝關節置換術後並不常見。然而，任何手術都會帶來風險，因此必須意識到這一點。你的醫生會和你詳細討論潛在的併發症。

研究表明，成功的關節置換術部分取決於外科醫生和醫院的經驗。找一位經驗豐富的外科醫生和一家常規進行關節置換的醫院，可能會提高手術成功的機率，同時改善膝關節功能，減少併發症。

以下是全膝關節置換術後可能出現的一些更常見的併發症：

血凝塊-全膝關節置換術增加了靜脈血凝塊形成的風險。膝關節手術後血栓形成的最常見部位是腿部深靜脈（稱為深靜脈血栓形成或DVT）。這是一個值得關注的問題，因為如果血塊進入肺部，它會致命（醫生稱之為肺栓塞）。如果你有跡象表明你患有深靜脈血栓，比如腿痛或腫脹，請打電話到你的醫生辦公室。（參見「患者教育：深靜脈血栓形成（DVT）（高級基礎知識）」。）

感染-膝關節置換術後感染是一種相對少見但嚴重的併發症。感染的症狀包括發燒、發冷、膝蓋疼痛突然加重、發紅或腫脹。如果你擔心會感染，請打電話給你的醫生辦公室。

傷口感染可以用抗生素治療，偶爾也可以從關節排出多餘的液體。如果感染變深或廣泛，可能需要在感染清除後移除假體關節並重新植入。（參見「患者教育：關節感染（高級基礎知識）」。）

僵硬-偶爾，儘管接受物理治療，患者的膝蓋可能會變得僵硬，可能無法正常彎曲或伸直。如果發生這種情況，患者可以回到手術室，在麻醉下彎曲和/或伸直膝蓋。

早期失敗-大多數膝關節置換術將持續15至20年。然而，由於各種原因，可能會發生早期故障。這些包括植入物鬆動、感染、植入物周圍骨骨折和不穩定。當早期失敗發生時，可能需要進行翻修手術。

因為膝關節植入物的使用壽命一般不會超過20年，所以在較年輕的時候接受膝關節置換術的人更可能需要翻修手術。年輕人的壽命可能比植入物的壽命長；他們的生活方式也可能更活躍，這會給植入物帶來壓力，隨著時間的推移，導致失敗。基於這些原因，醫生對50歲以下的人推薦膝關節置換術持謹慎態度。

持續性疼痛/不滿意-大約15%接受全膝關節置換術的患者可能有持續性疼痛或對手術結果不滿意。然而，大多數人都能顯著減輕或消除疼痛。

3 全膝關節置換術（醫生版）

Gregory M Martin, MD

翻譯:錢文偉

引言全膝關節置換術，是目前最常進行的骨科操作之一。截止2010年，美國每年有超過600,000例患者行全膝關節置換術，且該手術正越來越普遍[1]。在美國老年患者中，進行初次全膝關節置換術的人均數量從1991年到2010年翻了一番(年人均手術例數從31例/10,000醫保參保人數增至62例/10,000醫保參保人數)[2]。據預測，到2030年美國每年進行全膝關節置換術的總數將增長673%，達到3,480,000例[3]。各種影響膝關節的疾病都可以採用全膝關節置換術進行治療，達到緩解疼痛、恢復功能和活動。

正常膝關節像一個複雜的鉸鏈一樣發揮功能，主要是屈和伸運動，同時也可以旋轉和滑動。膝關節由3個間室組成：外側間室、內側間室和髕股關節間室。骨關節炎(osteoarthritis, OA)(特發性的或創傷後的)、炎症性關節炎(類風溼性關節炎、銀屑病性關節炎等)、缺血性骨壞死，腫瘤或者先天性畸形等疾病都可能導致一個或者多個間室的軟骨受損。在美國，超過95%的全膝關節置換術的原因是骨關節炎[1,4]。

普遍認為由Insall及其同事在1972年引入的「全髁型膝關節假體」是進入「現代」全膝關節置換術時代的標誌[5]。這種假體是最早用於替換膝關節所有3個間室的假體。現在的假體在初始設計的基礎上有了很多的改變，並且人們對膝關節部分置換(單髁置換)日益關注。(參見下文『假體的選擇和固定技術』和『全膝關節成形術的替代方案』)

現代全膝關節成形術包括切除膝關節表面的病變部分，然後用金屬和聚乙烯假體進行關節表面置換。對於經適當選擇的患者，該操作可顯著緩解疼痛，並改善功能和生活質量[6]。

儘管全膝關節成形術有潛在的好處，但這是一種擇期手術，只有在廣泛討論其風險、獲益和備選方案後再考慮進行。本專題總結了全膝關節成形術的各個方面，包括術前、術中和術後的注意事項。

與任何重大的外科操作一樣，全膝關節成形術的術中或術後均可能發生併發症。全膝關節成形術的併發症將單獨討論。(參見「全膝關節置換術的併發症」)

適應證全膝關節成形術的主要適應證是緩解非手術治療無效患者中膝關節炎相關的疼痛。對於膝骨關節炎患者的非手術治療包括改變活動方式、減輕體重(對於肥胖者)、使用手杖、使用鎮痛藥和/或使用非甾體類抗炎藥(nonsteroidal antiinflammatory agents, NSAIDs)。

對於一些骨壞死的患者，可能也有必要行全膝關節成形術。但是此類患者的結局可能比骨關節炎或炎症性關節炎患者差。(參見「骨質壞死(缺血性骨壞死)」，關於『全關節置換術』一節)

患者應該具有放射學檢查證實的晚期關節炎改變。如果膝關節的疼痛和放射學檢查表現不相稱，則在進行關節成形術前應排除其他原因。(參見「成人未分類膝關節疼痛的評估」)

畸形的矯正或功能的恢復應視作手術的次要結局，而不應視作手術的主要目標。各年齡組患者都可進行全膝關節成形術(除了骨骼未發育成熟者)。

假體關節具有有限的使用期，假體的耐用度取決於患者和關節成形術相關的因素。其中包括[7]：

●患者年齡–從1978年到2000年完成的11,606例初次(非翻修)全膝關節成形術中，55歲及以下患者假體的10年生存率低於70歲以上的患者(分別為83% vs 90%)。

●基礎疾病–骨關節炎患者的假體耐用度比類風溼性關節炎(rheumatoid arthritis, RA)患者低(10年假體生存率分別是90% vs 95%)。

●肥胖–肥胖對全膝關節置換術後的結局有負面影響。一項2012年的meta分析顯示，相比於不肥胖的患者，肥胖患者[體質指數(body mass index, BMI)≥30]感染的發生率(OR 1.90，95%CI 1.47-2.47)和翻修率(OR 1.30，95%CI 1.02-1.67)有所增加[8]。

禁忌證以下臨床情況不應該進行全膝關節置換術：

●膝關節或身體的任何部位有活動性感染

●伸膝系統沒有功能

●肢體循環或血供差

影響肢體的神經系統疾病是全膝關節置換術的相對禁忌證，取決於神經系統疾病對成功恢復和改善疼痛和功能可能性的影響。

死亡率全膝關節成形術和全髖關節成形術的總體死亡率相近，每年大約為0.5%-1%[4,9,10]。

術前評估必須進行仔細的術前評估以確定正確的診斷、鑑定是否需要手術、幫助制定手術計劃並防止圍手術期的併發症。術前評估相關的一般問題見其他專題。(參見「健康成年患者的術前醫療評估」和「非心臟手術前的心臟風險評估」和「術前肺部風險評估」)

全面的術前評估包括：

●病史(參見下文『病史』)

●體格檢查(參見下文『體格檢查』)

●影像學檢查(參見下文『影像學檢查』)

●實驗室檢查(參見下文『實驗室檢查』)

●對治療替代方案的審查(參見下文『對替代治療方案的評估』)

●對手術風險及收益、手術時機和替代治療方案進行討論(參見下文『對風險和獲益的討論』)

●考慮自體供血(參見下文『控制失血』)

病史

症狀 — 應記錄患者的症狀。記錄並檢查任何伴發的背部疼痛(患者經常表述為髖部的疼痛)、髖部疼痛(患者經常描述為腹股溝痛)或者是腿部的麻木、感覺異常或疼痛的病史是非常重要的。背部或髖部症狀的存在可能提示膝關節的疼痛來自於這些部位，而神經系統的主訴可能來自周圍神經、神經根或中樞神經系統的疾病。病史採集時也必須詢問關於小腿疼痛或跛行的問題，這些可能提示周圍血管疾病或者椎管狹窄。

●發病時間–如果患者有膝關節疼痛，記錄發病日期非常重要。應記錄疼痛是否是逐漸發作的或者是否存在特定的創傷性事件。

●疼痛位置–應該描述疼痛的部位(如內側疼痛、外側疼痛或髕股處的疼痛)。通常，患者會描述這些疼痛分別在膝關節內、膝關節外，或是膝蓋骨後面。也應記錄疼痛是單側的還是雙側的，如果是雙側的，哪一側更重。

●疼痛的嚴重程度和對功能的影響–應記錄疼痛的嚴重程度，以及疼痛對患者日常生活活動和生活質量的影響。應詢問出引起疼痛的活動(例如：爬樓梯，特別是下樓時的疼痛往往提示髕股疼痛)。

●關節交鎖、卡鎖、彈響–也應記錄其他症狀，如關節交鎖或卡鎖，因為這些症狀可能提示疼痛來自於半月板病變。膝關節的不穩定或者患者自己聽到彈響的病史可能提示韌帶的損傷或斷裂。

●既往治療–記錄患者既往因膝關節痛而進行的所有治療以及這些治療的療效(如NSAIDs、糖皮質激素注射劑、透明質酸注射劑、物理療法、替代治療及外科操作)。

內科共病/系統回顧 — 進行全膝關節成形術的患者必須能耐受麻醉，以及包括骨髓成分進入血液循環的手術應激和圍手術期失血等。因為適合進行全膝關節置換術的患者大部分年齡較大，所以應該特別注意患者的內科共病和對症狀的回顧。

●內科問題–患者的初級醫療保健人員和外科醫生或麻醉醫生之間的交流是至關重要的。應詳細詢問患者的任何心血管疾病(如心絞痛、心肌梗死、高血壓、充血性心力衰竭、心律失常)或肺部疾病(慢性阻塞性肺疾病、限制性肺疾病、呼吸系統感染、肺栓塞、睡眠呼吸暫停、哮喘)病史。

●系統回顧–系統回顧其他特別重要的部分包括：提示可能存在腦血管疾病(短暫性腦缺血發作、腦卒中、頸動脈狹窄)、周圍血管疾病(跛行、靜息痛、未癒合的潰瘍、深靜脈血栓形成)、血液系統疾病(貧血、凝血障礙、血液異常改變)、內分泌系統疾病(糖尿病、甲狀腺疾病、使用類固醇或糖皮質激素)、泌尿系統疾病(良性前列腺肥大、梗阻性尿路病、前列腺癌、泌尿道感染)和感染性疾病(HIV、肝炎、骨髓炎)的那些表現。還應篩查患者有無營養不良。根據需要，術前應進行適當的內科和外科會診。

藥物 — 應記錄患者目前的用藥，包括所有藥物的劑量。對於全膝關節成形術或全髖關節成形術的患者，應特別注意以下的藥物(參見「全髖關節成形術」)：

●阿司匹林和NSAIDs–考慮到這些藥物和圍手術期出血的相關性[11,12]，推薦在術前至少1周停用這些藥物。

●昔布類藥物–文獻中對於選擇性環氧化酶2(cyclooxygenase-2, COX-2)抑制劑(昔布類)是否對凝血系統具有臨床意義影響的意見不一致。一項對100例被隨機分配至接受羅非昔布或安慰劑組進行全膝關節成形術的患者的前瞻性研究顯示，兩組間的圍手術期出血或國際標準化比值(international normalized ratio, INR)的差異無統計學意義。隨後，羅非昔布因為嚴重心血管不良事件風險增加而撤出全球市場。

其他研究表明昔布類與華法林存在相互作用，雖然因具體藥物不同它們的相互作用程度可不相同[13-16]。最終的決定應由手術醫生定奪。一些外科醫生在術前處方昔布類藥物幫助管理患者術後的疼痛，因此，應該會有關於此專題的更多信息。

●抗凝藥–在進行全膝關節成形術前，患者應該有正常的凝血酶原時間(prothrombin time, PT)和INR。這通常需要患者在術前至少3-5日時停用華法林。高危患者(如有機械心臟瓣膜的患者)應該使用低分子量肝素作為過渡或術前應收入院並進行肝素化治療。術前6小時應停用肝素，並檢查部分凝血活酶時間。(參見「抗凝患者圍手術期處理」)

●抗生素–如前所述，活動性的膿毒性關節炎是全膝關節成形術的禁忌證。感染消退的患者應該在術前至少48小時停用抗生素。

●胰島素或口服降糖藥–應根據手術時間的安排減少胰島素的劑量。口服降糖藥應該在手術當日停用。(參見「成人糖尿病患者的圍手術期血糖管理」)

●糖皮質激素–為了減少對免疫系統的抑制和最小化幹擾傷口癒合的風險，理想的情況是糖皮質激素應逐漸減至可能的最低劑量。根據患者的正常劑量，為了避免可能的腎上腺功能不全的影響，有時候需要在圍手術期給患者「應激劑量」的糖皮質激素。(參見「成人腎上腺皮質功能減退症的治療」)

●甲氨蝶呤–對於疾病被藥物控制的腎功能正常並且沒有活動性感染的患者，我們在圍手術期繼續使用甲氨蝶呤(methotrexate, MTX)。MTX和其他改變病情的抗風溼藥物(disease-modifying antirheumatic drugs, DMARDs)在圍手術期的使用將單獨詳細總結。(參見「圍術期的用藥管理」，關於『風溼性疾病藥物』一節和「風溼性疾病患者術前評估及圍術期處理」，關於『非生物性DMARDs』一節)

●生物製劑–使用α-腫瘤壞死因子(tumor necrosis factor, TNF)抑制劑(如依那西普、英夫利西單抗、阿達木單抗)和其他用於治療RA和其他炎症性風溼性疾病的生物療法後，典型或非典型感染風險的增加。(參見「腫瘤壞死因子-α抑制劑：細菌、病毒和真菌感染」和「腫瘤壞死因子-α抑制劑與分枝桿菌感染」)

因此，在圍術期通常避免使用抗TNF藥物和其他生物類DMARDs。圍手術期中這些藥物的使用將單獨詳細總結。(參見「圍術期的用藥管理」，關於『風溼性疾病藥物』一節和「風溼性疾病患者術前評估及圍術期處理」，關於『生物性DMARDs』一節)

過敏史 — 應明確地記錄既往對抗生素的過敏史和反應類型(如皮疹、呼吸急促、全身性過敏反應)。同時也應弄清患者對阿片類鎮痛藥的使用和耐受(或不耐受)情況。恰當且重點突出的記錄將防止圍手術期的錯誤處理。

體格檢查 — 可能適合行全膝關節置換術的患者需要進行全面的肌肉骨骼檢查。對關節炎膝關節的適當檢查包括視診、觸診和使用特定的手法檢查評估。

視診 — 觀察患者的步態和皮膚是體格檢查的重要部分。

●步態–在膝關節疼痛的患者中可能觀察到的異常步態如下：

•減痛步態–膝關節炎患者通常表現出減痛步態。減痛步態患者因為疼痛受累側承重的時間較短。

•膝關節外擺–在行走(外擺)時膝關節的異常內側或外側運動可能表明韌帶不穩定。

•特倫德倫伯格步態–有特倫德倫伯格步態的患者，將軀幹移向患側髖關節從而減少為穩定骨盆而施加在髖關節的負重以減少疼痛。這種步態提示存在髖關節疾病和/或臀中肌無力。

●皮膚–應該徹底檢查整個雙側下肢的皮膚是否有任何擦傷、潰瘍、腫脹、發紅、血管變化或感染。活動性感染的存在是假體手術植入的禁忌證。應記錄下任何既往的膝關節瘢痕。膝關節周圍的皮膚癒合問題很常見，並且在手術時，需要考慮到既往的切口。應記錄所有的大體畸形(如內翻、外翻、反屈、屈曲攣縮)。這些畸形將採用放射學檢查進行明確地評估。

觸診 — 應觸診膝關節以檢查是否存在積液。將一隻手放在髕骨上，同時讓膝關節進行一定範圍的被動運動，能使臨床醫生檢查到患者是否有髕股關節捻發音。觸診時內側和外側關節接縫的壓痛通常見於關節炎，但也可能提示半月板病變。也應評估遠端動脈的搏動，包括足背動脈和脛後動脈。

其他手法檢查評估 — 多種手法可用於幫助術前評估，如下：

●關節的活動度–為了評估伸膝系統和記錄術前的關節活動度，應記錄膝關節最大的主動和被動的屈伸運動。應該記錄是否有關節攣縮。重要的是評估受累膝關節側的髖關節被動運動時的疼痛，特別是髖關節內旋時的疼痛。這一手法可以鑑定膝關節感知的疼痛是否實際上來源於髖關節。

●肌力檢查–應該對整個下肢的肌運動力量和緊張度進行評估，特別要注意股四頭肌或伸膝系統。

●神經檢查–除了檢查肌運動力量外，也應進行感覺和深部腱反射(膝反射和踝反射)檢查。

●韌帶檢查–外側副韌帶(lateral collateral ligament, LCL)和(特別是)內側副韌帶(medial collateral ligament, MCL)是在全膝關節置換術期間需要保護的非常重要的結構。術前需要對這些韌帶的穩定性或攣縮程度進行評估。

•側副韌帶–在屈膝30°的情況下，分別通過內翻和外翻應力來檢查LCL和MCL。膝內翻手術時，LCL通常是鬆弛的，而MCL則是攣縮的。在膝外翻時，LCL通常是攣縮的，而MCL是鬆弛的。MCL功能不全的證據可能提示需要一個更為限制性的假體。

•交叉韌帶–前交叉韌帶(anterior cruciate ligament, ACL)在大部分全膝關節置換術設計中是被切除的，所以對它的評估不是很重要。後交叉韌帶(posterior cruciate ligament, PCL)在手術時可能會被保留或切除。可通過屈膝90°時在脛骨上施加一個向後的力進行後抽屜試驗來評估PCL。

●半月板檢查–如果患者主要是有一個機械性症狀，比如膝關節交鎖或卡鎖，則可能是半月板撕裂引起的。此類患者可能獲益於侵入性更小的關節鏡檢查，但對於存在中度至重度骨關節炎的患者，關節鏡下半月板部分切除術似乎並不比非手術治療具有任何更好的效果[17,18](參見下文『對替代治療方案的評估』)。半月板的檢查採用McMurray試驗和Apley壓縮試驗進行。(參見「膝關節半月板損傷」)

●脊柱和髖關節檢查–重要的是排除脊柱或者髖關節來源的膝關節牽涉痛。直腿抬高或者髖關節運動(特別是內旋時)時引出的膝關節痛應引起懷疑，並需要進行進一步的檢查，包括對腰椎、髖關節或者兩者都進行的影像學檢查。

影像學檢查 — 很多可用於幫助處理膝關節疼痛的可用的成像模式包括：

●X線平片–X線平片是關節炎的診斷、全膝關節成形術術前規劃和術後評估的主要依據。至少應該進行3種位置的檢查(站立前後位、側位和髕骨切線位)。有時候也進行其他位置的檢查。例如，有時可能需要X線站立後前位45°以更準確地測定關節間隙內外側縮窄。全長、3個關節的站立位X線片可以確定下肢的解剖和機械力線(如內翻、外翻)，這對於術前計劃很有幫助。

在所有患者中都應進行以下三種基本位置的檢查：

•站立前後位–拍前後位片應該讓患者處於站立位以使關節正常負重。應評估內側關節間隙和外側關節間隙是否存在狹窄。

•側位片–側位片用於評估髕股關節和髕骨的位置(如低位髕骨、高位髕骨)。

•髕骨切線位片–應在髕骨切線位評估髕股關節間隙的情況(「日出位(sunrise)」、「天線位(skyline)」或Merchant位)。

●磁共振成像(magnetic resonance imaging, MRI)–對於大多數準備進行全膝關節置換術評估的患者不需要進行MRI。雖然對於早期骨關節炎改變的探測，MRI比X線平片更敏感，但全膝關節置換術的患者通常為更晚期的、X線表現明顯的疾病。MRI可觀察到幾乎普遍存在於晚期骨關節炎患者中且可能並不會引起症狀的半月板撕裂[19]。對於有膝關節疼痛且在X線平片上有輕度骨關節炎改變的患者，MRI可能有助於鑑別不適的其他根源，如半月板撕裂或骨壞死。

實驗室檢查 — 術前實驗室檢查需求根據患者的健康狀態和機構的政策的不同而有所不同，但是它們通常包括全血細胞計數、基本的生化檢查和凝血功能檢查(PT、INR和部分凝血活酶時間)。根據患者的年齡和麻醉策略通常要求進行心電圖和胸片檢查。也應該進行尿分析和尿培養。

對替代治療方案的評估 — 重要的是，將患者病史、體格檢查結果和放射學檢查結果考慮在內以確定患者是否可從侵入性較小的替代治療方案獲益。(參見下文『全膝關節成形術的替代方案』)

對風險和獲益的討論 — 患者必須充分了解手術相關的所有風險和結局。患者必須知道全膝關節置換術後的康復很艱苦。為考慮此手術的患者提供的手術相關信息的總結參見其他專題。(參見「Patient education: Total knee replacement (Beyond the Basics)」)

風險 — 全膝關節成形術併發症詳細的內容參見其他專題(參見「全膝關節置換術的併發症」)。以下是對手術潛在風險的簡要總結，包括：

●麻醉和術中事件–和其他重大手術一樣，全膝關節置換術存在麻醉給藥和術中意外相關的風險。

●血栓栓塞–深靜脈血栓形成和靜脈血栓栓塞是潛在的，且有時是致命的併發症。膝關節手術後的近端靜脈血栓形成風險可通過使用抗凝藥而降低，但是在使用預防性調整劑量的華法林或普通肝素或低分子量肝素的過程中仍可能發生。儘管使用了藥物預防抗凝，但在多達3%的全膝關節置換術後的患者中仍發生了症狀性的近端深靜脈血栓形成。肺栓塞的風險大約為1%。(參見「成人非骨科手術患者中靜脈血栓栓塞症的預防」)

●感染–感染性併發症並不常見，但是有可能很嚴重。假體關節感染可能導致住院時間延長、需要取出被感染的假體，以及延長抗生素的使用時間，隨後再植入假體。多達1%的全膝關節置換術接受者在術後第1年內出現假體感染。(參見「人工關節及其他骨科植入物感染的預防」和「人工關節感染的流行病學、臨床表現和診斷」和「人工關節感染的治療」)

●髕股關節疾病–各種髕股關節假體疾病和伸膝系統疾病都可能發生，包括髕骨半脫位、脫位、假體部件鬆動、骨折、髕骨活動受阻(「碰擊聲」現象)和伸膝系統的斷裂(股四頭肌或髕骨韌帶的斷裂)。

●神經損傷–可能發生術中或術後腓神經損傷，導致脛前肌肌無力(足下垂)和感覺喪失。

●動脈損傷–膕動脈或其他的動脈的損傷可能導致失血量增加，並需要進行動脈修補。可能發生動脈血栓形成和/或周圍栓塞。

●假體周圍骨折–可能發生股骨部件近端骨折(髁上骨折)或脛骨假體遠端骨折。

●傷口問題–傷口裂開會增加關節假體感染的風險，且可能需要額外的整形操作以充分覆蓋切口並獲得功能性的膝關節活動度。

●假體磨損和失敗–聚乙烯磨損可引起有時導致假體鬆動的炎症反應。如果因此導致假體膝關節功能障礙，則可能需要進行關節成形翻修術。

雙側同時進行膝關節成形術會增加併發症發生的風險，應該照這樣告知患者。2007年的一項meta分析顯示，相比於分期進行雙側手術或者單側手術，雙側同時進行全膝關節置換術會增加嚴重的心臟和肺臟併發症風險，以及增加死亡率。分期進行操作的最佳時段尚未明確[20]。

獲益 — 如引言中所提到的，全膝關節成形術的預期獲益包括疼痛緩解、功能和活動恢復。內翻或外翻畸形可能得到輕度改善。屈曲攣縮更難克服。

●疼痛緩解–一項系統評價表明，大約20%的全膝關節置換術接受者和10%的全髖關節置換術接受者在術後1年左右仍報導有持續性的或反覆性的疼痛。儘管一些患者對手術仍然是滿意的，但對於患者，重要的是記住不能完全緩解疼痛的風險並不是不重要的。確定次優結局風險因素的研究正在進行中[21]。

●功能改善–患者通常在日常活動和團體活動能力上有顯著的改善。術前功能狀態較差的患者在術後增加的功能往往最多，而術前功能最好的患者在術後往往能獲得最高水平的術後功能狀態[22]。雖然全膝關節成形術後，因為疼痛緩解，日常生活活動通常較容易進行，但是膝關節功能(如關節活動度)的客觀測量指標通常改善較少。在初次手術後平均隨訪的17年時，僅23%的膝關節被評定為具有極好的功能[23]。可預計的術後活動度高度取決於術前的活動度[24]。

●糾正畸形–外科技術能夠使膝外翻恢復正常或者接近正常。通過選擇合適的部件和軟組織松解可減輕大部分病例中的膝關節屈曲攣縮。例如，一項納入542例因膝關節屈曲攣縮進行膝關節成形術的患者的回顧性研究顯示，95%的患者有3°或者3°以下的殘餘屈曲畸形[25]。嚴重的畸形在全膝關節成形術期間可能不能得到糾正。

控制失血 — 進行全膝關節成形術的患者在圍手術期有大量失血的危險。全膝關節成形術的控制失血技術參見其他專題。(參見「全髖關節成形術」，關於『血液保護』一節)

全膝關節成形術的替代方案就像之前討論到的，對於骨關節炎或炎症性關節炎，在考慮外科治療之前，應該先嘗試非外科性治療。

除了全膝關節成形術之外的其他適當手術治療方案取決於幾個因素，包括：疾病的嚴重程度(如早期的軟骨改變伴發輕微關節間隙狹窄)；疾病的範圍和部位，包括是單間室的病變(外側、內側或髕股關節)還是2個或是3個間室的病變；引起關節病變的疾病過程(如骨關節炎、類風溼性關節炎、銀屑病關節炎等)；以及患者對每一種選擇相關的風險和優勢的偏好。

非手術治療 — 在因骨關節炎適應證而進行全膝關節成形術之前，應該嘗試多種非手術治療方案。兩項隨機對照臨床研究支持這些非手術幹預的有效性，即使對於晚期骨關節炎也如此[26,27]。雖然非手術幹預不如全膝關節成形術有效，但非手術幹預似乎能夠帶來顯著益處的同時風險較低，可能適用於期望避免或推遲手術幹預的患者或者不適合手術的患者。

類風溼性關節炎或者其他類型炎症性關節炎患者應該在內科治療無效後再進行全膝關節成形術。(參見「成人類風溼關節炎治療的一般原則」和「終末期類風溼關節炎的評估及藥物治療」)

關節鏡檢查 — 以下情況中可能考慮關節鏡檢查作為一種替代方案：

●關節軟骨仍然保留的類風溼性滑膜病變患者可能進行關節鏡下滑膜切除術。在一項納入41例患者的病例系列研究中，83%的患者在術後3年時具有良好的結局，但在術後8年時仍有良好結局的患者病例降至46%。

●多數情況下並不推薦在無機械症狀時對骨關節炎患者進行關節鏡下灌洗和清創術。此外，關節鏡手術無益於治療膝關節晚期骨關節炎。骨關節炎患者進行關節鏡下清創術的詳細討論參見其他專題。(參見「膝關節和髖關節骨關節炎手術治療概述」，關於『膝關節』一節)

●對於有單處或多處軟骨缺陷的較年輕患者，可能適合行包括軟骨下鑽孔、微骨折術、異體骨軟骨移植系統(osteochondral allograft transfer system, OATS)或自體軟骨細胞移植的軟骨保留或修復手術。(參見「膝關節和髖關節骨關節炎手術治療概述」，關於『自體軟骨細胞移植』一節)

截骨術 — 由Coventry推廣的截骨術[28,29]，對於那些非炎症性質以單側間室病變(不管是外側還是內側)為主的較年輕患者依然是一種治療選擇。膝關節截骨術的基本依據是通過將下肢的機械軸重新對線來對病變間室減壓。

內翻膝 — 對於內翻膝(更常見)，這是採用脛骨近端截骨術來完成，也被稱為脛骨高位截骨術，可以是開放楔形截骨術、閉合楔形截骨術或圓頂形截骨術。確定的適應證和禁忌證包括[30]：

●截骨術的適應證

•年齡小於60歲

•單側間室性關節炎

•在X線負重相上有10°-15°的內翻畸形

•術前活動度至少為90°

•屈曲攣縮少於15°

•具有安全有效地進行康復訓練的能力和動力

●截骨術的禁忌證

•外側間室關節間隙減小

•脛骨外側半脫位大於1cm

•內側骨丟失大於2-3mm

•韌帶不穩定

•炎症性關節炎

2005年一項納入11項研究(其中有6項研究被認為具有較高質量)的系統評價發現，接受脛骨高位外翻截骨術的患者術後有所改善，表現為疼痛減輕和功能改善[31]。比較對膝骨關節炎患者進行脛骨高位截骨術和其他外科操作(如膝骨關節炎內翻畸形的單髁關節成形術或其他截骨術)的數據有限(參見下文『單髁膝關節置換術』)

一項對102例因膝內翻而進行脛骨高位截骨術的患者長期(平均隨訪15年)回顧性研究闡明了可預期的結局[32]。在55%的患者中觀察到極好的或良好的結局，而45%的患者中觀察到一般的或差的結局。在術後10-15年，臨床結局往往出現惡化。

脛骨高位截骨術後可轉行全膝關節置換術。但是，關於脛骨高位截骨術後轉行全膝關節成形術的結局是否與最初即進行全膝關節成形術等效或較差，尚存爭議[33,34]。

外翻膝 — 對於外翻膝，截骨術通常在股骨遠端的髁上區域進行。適應證包括[30]：

●外翻畸形小於15°

●術前活動度至少為90°

●屈曲攣縮小於10°

21例行截骨術的外翻膝平均5年隨訪的結局90%為良好或極好[35]。另一項研究中， 49例膝外翻在平均隨訪7年時，87%沒有改行全膝關節成形術[36]。

截骨術可能具有嚴重的併發症，包括骨不連合、硬體故障、疼痛不能完全緩解而需要改行全膝關節成形術、神經血管損傷和骨筋膜室症候群。雖然如此，對於適當選擇的患者，截骨術仍是全膝關節成形術的一個極好的替代方案。

單髁膝關節置換術 — 隨著McKeever在20世紀50年代引入假體，人們開始進行單髁關節置換術[37,38]。從那時候開始，已出現了各種不同的設計以及不同的結局。因此，單髁關節置換術治療膝關節炎的作用是一個有爭議的話題。

反對者聲稱，只進行一個間室的表面置換通常會導致疼痛緩解不完全和較早期的假體故障，並且會讓翻修術更困難。支持者聲稱，單髁膝關節置換術能夠使正常的韌帶解剖學結構不受破壞，使膝關節更自然地運動，以及保留髕股關節和其他間室(為將來的翻修術保留了更多的骨組織)。支持者把單髁膝關節置換術相比於全膝關節成形術生存率更低的原因歸結為早期單間室假體設計缺陷。

對於單側間室病變的非炎性關節炎患者，將單髁膝關節置換術作為全膝關節置換術和截骨術的替代方案再度引起學者們的興趣。廣泛認可的單髁膝關節置換術的禁忌證包括：炎症性關節炎、屈曲小於90°、大於15°的屈曲攣縮畸形或是目前的單髁假體設計不能矯正的較大畸形。

對於適當選擇的患者，單髁膝關節置換術可能成功，如下所述：

●一項對28例單髁膝關節置換術(患者平均年齡為52歲)的研究發現，其早期結局(2-6年)優於截骨術的結局[39]。

●一項為期5年的回顧性研究在102例患者中比較了單髁膝關節置換術和全膝關節置換術[40]。相比接受全膝關節置換術的患者，進行單髁膝關節置換術的患者關節活動度增加、疼痛更少且恢復更快。

●一項對該間室的單純性病變患者使用Lubinus髕股假體的結局回顧性研究顯示，34例患者的45個關節成形中有64%的關節結局良好至極好，17%操作的結局不令人滿意[41]。以後研發的假體可能會有更好的結局。在平均隨訪3.75年的15例患者中，有14例患者(93%)具有良好或極好的結局[42]。

單髁膝關節成形術的耐用度可能和全膝關節置換術相似。例如，一項納入60例行單髁膝關節置換術患者的回顧性研究發現，在平均隨訪12年時，假體的存活率達到了93%[43]。另一項對63例單髁膝關節置換術進行長期隨訪的研究顯示10年時的假體存活率為84%，而15年的假體存活率為79%[44]。

關於單髁膝關節置換術後改行全膝關節置換術的結局是與初次即行全膝關節置換術[45]的結局更相近還是與翻修術結局更相近的報導不一致[46]。

單髁膝關節置換術後的併發症和全膝關節置換術後的併發症相似。(參見「全膝關節置換術的併發症」)

膝關節固定術 — 膝關節固定術或融合術，一般不考慮作為膝關節炎的初始手術。但在多發性假體感染、伸膝系統故障和其他複雜情況下它仍是一種可行的補救方法。

外科技術患者以仰臥位躺在手術臺上。可能使用全身麻醉、椎管內麻醉或硬膜外麻醉。皮膚切開前預防性應用抗生素。最常見地，要使用止血帶(但並不總是要使用)。

通常通過皮膚正中切口入路膝關節。如果存在舊瘢痕，則儘可能利用原有的皮膚切口。有多個瘢痕時，因為皮瓣血供的問題，通常選最外側的切口。偶爾地，對於有多個瘢痕的膝關節，術前應請整形外科會診。大部分外科醫生使用內側髕骨旁入路膝關節。採用這種方法，在上方的股四頭肌腱處作切口，切口沿著髕骨內側緣向下走，直到脛骨結節內側面。偶爾也使用外側髕骨旁入路。與「微創」技術結合使用的股內側肌下入路和經股內側肌中間入路正再次興起。

軟組織的平衡對於全膝關節成形術是一個關鍵部分。內翻膝往往內側緊張，而外側鬆弛。而外翻膝通常外側緊張，內側鬆弛。軟組織的平衡通常是通過松解緊張側的側副韌帶來達到的。一般首先行關節囊松解。在大部分全膝關節置換術中，應盡力保護LCL和(特別地)MCL的完整性。ACL幾乎總是被切除。正如下文討論的，PCL則可能被保留或被切除。

植入體的選擇取決於外科醫生。諸如微創膝關節置換術和手術計算機輔助導航等技術的作用仍有待明確[47]。

假體的選擇和固定技術植入體的選擇取決於外科醫生。所有的全膝關節成形術都由股骨部件、脛骨部件和髕骨部件組成(影像 1)。

現在有很多膝關節假體生產商和很多種假體設計。大多數可用的假體系統是帶聚乙烯襯墊的模塊化金屬脛骨託盤。設計上可以保留PCL(如PCL保留型)，也可以移除PCL(如PCL切除型)。PCL切除型也叫做後交叉韌帶替代型，因為脛骨部件需要一個額外的支柱來提供正常情況下由PCL提供的穩定性。固定技術包括骨水泥固定(股骨和脛骨假體都用骨水泥固定)，非骨水泥固定，或混合固定(一般股骨假體不用骨水泥固定，而脛骨假體用骨水泥固定)。

在假體選擇上沒有一致的意見，不同的國家、州、城市和外科醫生間存在很大的差異。這種在設計和技術上的差異使得分析和概括報導結果特別困難。全膝關節成形術在隨訪10年時的存活率預計約為90%-95%[48]。

PCL保留 vs PCL切除 — PCL保留型與PCL切除型均有強有力的理論依據。

●PCL保留的理論優點包括因能再現股骨後旋而獲得較大的關節活動度、減少作用在移植體上的應力而減少失敗率、改善爬樓梯時的本體感受以及保留骨組織[48]。

●PCL切除的理論優點包括能夠更可靠地糾正畸形、更容易平衡膝關節、消除股骨過度後旋，這可能使植入體更靈活地活動和增加假體的順應性，從而導致接觸應力降低和聚乙烯磨損的減少[48]。

然而，兩種方式的大部分推測的優點尚未在臨床研究中實現，且兩種設計都可能獲得極好的結局[49-55]。一項納入了17項隨機試驗(共計1810例患者)的系統評價評估了對骨關節炎患者進行全膝關節成形術中PCL保留型相比於PCL切除型的優點和缺點。結果發現，關節活動度、疼痛、臨床結局和放射學結局方面沒有臨床相關差異[56]。

固定技術 — 大部分的全膝關節成形術採用骨水泥來固定部件，並且可用的長期隨訪研究也是採用骨水泥固定植入體。總的來說，全膝關節成形術中非骨水泥植入體因脛骨鬆動、聚乙烯襯墊磨損和骨溶解的發生率較高而被認為效果不太令人滿意[48]。然而，一些外科醫生已在隨訪10年或以上時獲得了極好的結局(初次關節成形術的存活率>90%)[57,58]。

髕骨表面置換 — 髕骨表面置換(通常採用聚乙烯扣)在全膝關節成形術中依然是一個有爭議的主題[49]。進行髕骨表面置換的主要原因是認為這能減輕膝前疼痛，因此能夠減少髕骨表面置換二次手術的需要。這可能被不行髕骨表面置換的優勢所抵消，這些優勢包括保留骨組織以及減少諸如骨折和鬆動這樣的髕股關節併發症。(參見「全膝關節置換術的併發症」，關於『髕股異常』一節)

其他的設計 — 還有許多其他的假體設計可用，包括半月板負重假體和旋轉平臺假體，這些都是為減少聚乙烯的磨損和減少假體鬆動而研製。也有更限制性的設計(如鉸鏈植入物)可用於包括嚴重的膝關節不穩定和翻修手術在內的情況。一般來說，更限制性的植入物可將更多的力量轉移至假體部件，導致較高的失敗率。

新興技術 — 已經發明一些旨在使外科醫生能夠更準確地植入裝置的技術。這些技術包括機器人輔助和個體化截骨導板(基於患者自身解剖結構，需術前MRI或CT)[59,60]。當前證據仍不足以確定此類技術較現有技術的有用性。

術後管理術後管理包括預防感染和靜脈血栓栓塞，以及進行適當的物理治療以獲得可能的最佳膝關節活動度和可行的安全康復。

●術前給予預防性抗生素，術後繼續使用一小段時間。(參見「人工關節及其他骨科植入物感染的預防」，關於『植入過程中』一節)

●我們推薦術後常規使用藥物預防靜脈血栓栓塞。對於有較高出血風險的患者，使用間隙性充氣加壓(intermittent pneumatic compression, IPC)是預防性抗凝藥物的一種替代選擇，IPC也可聯合其他預防血栓的方法使用。外科手術患者中血栓栓塞性疾病預防的詳細討論參見其他專題。(參見「成人非骨科手術患者中靜脈血栓栓塞症的預防」)

●越來越多的患者採用神經阻滯和/或關節周圍注射進行處理，以便減少全身麻醉和留置硬膜外導管引起的併發症和康復延遲。患者自控鎮痛(patient-controlled analgesia, PCA)在患者關節成形術後很有幫助。隨後可能使用口服阿片類鎮痛藥(參見「圍術期急性疼痛管理」)。隨著越來越多地使用多模式鎮痛策略，全膝關節置換術後的疼痛控制已有了相當大的改善。這通常包括「預先」使用對乙醯氨基酚、選擇性COX-2 NSAIDs、股神經阻滯、區域麻醉和關節周圍注射[61-63]。加巴噴丁或普瑞巴林越來越多地被用於控制圍手術期間的疼痛[64]。止吐藥通常預先給予，胃腸外麻醉藥和PCA泵的使用正在逐漸減少。

●對於全膝關節成形術後的成功結局，需要患者配合進行術後康復計劃。試圖保護膝關節活動度的幹預包括使用膝關節固定器和臥床時在手術側足下墊一枕頭來保持膝關節的伸直及防止屈曲攣縮。應儘可能快地在理療師的監督下開始進行關節活動度的鍛鍊。術後康複目標應該符合現實。雖然屈曲畸形可能通過全膝關節成形術達到部分或完全矯正，但是膝關節的最大活動度可能並不會改善很多，而且術後的活動度主要是由術前活動度所決定[24]。

一個組織良好的物理治療計劃應該包括關節活動度的訓練、步態訓練、股四頭肌力量訓練，且日常生活活動的訓練是康復過程中的一個重要組成部分。2007年一項納入5項隨機試驗的meta分析總結認為，相比於常規治療，出院後參與物理治療師監督下的功能訓練計劃的患者能在短期內改善膝關節功能和活動範圍[65]。針對單純性全膝關節成形術患者的研究表明，住院康復獲得的活動度改善並不優於在家接受物理治療[66]。

●使用持續被動活動(continuous passive motion, CPM)裝置來改善膝關節活動度並防止靜脈血栓栓塞症，這是許多機構實施術後康復治療的常見做法。然而，CPM的獲益與它使用起來的不便利性及費用不成比例。2014年發表的兩項meta分析顯示，在標準治療基礎上加用CPM並未給關節活動度、疼痛、功能、生存質量或防止靜脈血栓栓塞事件帶來有臨床意義的影響[67,68]。

從長期來看，可能鼓勵患者進行低到中等強度的、低衝擊力的訓練，因為更多的活動似乎並不會增加其需要行翻修成形術的風險[69]。可用的有限證據提示，保持一定的活動量實際上可能減少手術的膝關節之後行置換術的需要。

患者教育UpToDate提供兩種類型的患者教育資料：「基礎篇」和「高級篇」。基礎篇通俗易懂，相當於5-6年級閱讀水平(美國)，可以解答關於某種疾病患者可能想了解的4-5個關鍵問題；基礎篇更適合想了解疾病概況且喜歡閱讀簡短易讀資料的患者。高級篇篇幅較長，內容更深入詳盡；相當於10-12年級閱讀水平(美國)，適合想深入了解並且能接受一些醫學術語的患者。

以下是與此專題相關的患者教育資料。我們建議您以列印或電子郵件的方式給予患者。(您也可以通過檢索「患者教育」和關鍵詞找到更多相關專題內容。)

●基礎篇(參見「患者教育：膝關節置換術(基礎篇)」)

●高級篇(參見「Patient education: Total knee replacement (Beyond the Basics)」)

總結與推薦

●現代全膝關節成形術包括切除膝關節表面的病變部分，然後採用金屬和聚乙烯假體部件進行表面置換。對於經適當選擇的患者，操作可顯著緩解疼痛，並改善功能和生活質量。儘管全膝關節成形術有潛在的益處，但這仍然是一個擇期手術，只有在廣泛討論其風險、獲益和備選方案後再考慮進行。(參見上文『引言』)

●全膝關節成形術的主要目的是為非手術治療無效患者緩解膝關節炎疼痛。畸形的糾正和功能的恢復應視作手術的次要結局，而不是主要目的。假體關節的使用壽命有限，影響假體耐用性的因素包括患者的年齡、基礎疾病、肥胖，以及假體本身和手術因素。(參見上文『適應證』)

●全膝關節置換術的禁忌證包括膝關節或者身體其他部位的活動性感染、伸膝系統無功能和肢體循環或血供差。影響肢體的神經系統疾病是相對禁忌證。全膝關節成形術和全髖關節成形術的30日總體死亡率相近。(參見上文『禁忌證』和『死亡率』)

●必須進行仔細的術前評估，以確定正確的診斷、確定是否需要手術、幫助制定手術計劃，以及防止圍手術期的併發症。全面的評估包括病史的某些部分、體格檢查、影像學檢查、實驗室檢查、替代治療方案的審查、討論其手術的風險和收益以及討論自體供血。(參見上文『術前評估』和「健康成年患者的術前醫療評估」和「非心臟手術前的心臟風險評估」和「術前肺部風險評估」)

●全膝關節成形術以外其他適當手術方法取決於若干因素，包括疾病的嚴重程度、受累間室數量和引起關節病變的疾病過程。替代方案包括非手術治療、關節鏡術、截骨術、單髁膝關節置換術和膝關節固定術。(參見上文『全膝關節成形術的替代方案』)

●患者以仰臥位躺在手術臺上，可能使用區域麻醉、全麻、椎管內麻醉或硬膜外麻醉。皮膚切開前預防性應用抗生素。常用止血帶。植入物的選擇取決於外科醫生。微創膝關節置換術和外科手術計算機輔助導航等技術缺乏長期隨訪，其作用尚未被充分確定。所有全膝關節成形術都是由股骨部件、脛骨部件和髕骨部件組成。(參見上文『外科技術』和『假體的選擇和固定技術』)

●術後管理包括預防感染和靜脈血栓栓塞，以及進行適當的物理療法以獲得最佳的可能關節活動度以及可行的安全康復。多模式疼痛控制技術已改善了患者在全膝關節成形術後的體驗。(參見上文『術後管理』)

英語版

1 Patient education: Total knee replacement (Beyond the Basics)

INTRODUCTION

Total knee replacement, also known as total knee arthroplasty, is a surgical procedure in which parts of the knee joint are replaced with artificial (prosthetic) parts (image 1).

A normal knee functions as a hinge joint between the upper leg bone (femur) and the lower leg bones (tibia and fibula) (figure 1). The surfaces where these bones meet can become worn out over time, often due to arthritis or other conditions, which can cause pain and swelling. (See "Patient education: Osteoarthritis symptoms and diagnosis (Beyond the Basics)" and "Patient education: Osteoarthritis treatment (Beyond the Basics)".)

More detailed information about knee replacement is available by subscription. (See 'Professional level information' below.)

REASONS FOR KNEE REPLACEMENTTotal knee replacement is one option to relieve pain and to restore function to an arthritic knee. The most common reason for knee replacement is that other treatments (weight loss, exercise/physical therapy, medicines, injections, and bracing) have failed to relieve arthritis-associated knee pain.

The goal of knee replacement is to relieve pain, improve quality of life, and maintain or improve knee function. The procedure is performed on people of all ages, with the exception of children, whose bones are still growing. It is important to have significant pain and/or disability prior to considering this procedure. Because the replacement parts can break down over time, healthcare providers generally recommend delaying knee replacement until it is absolutely necessary.

Knee replacements are one of the most commonly performed joint replacement procedures.

ALTERNATIVES TO KNEE REPLACEMENTWhile total knee replacement can be helpful under the right circumstances, you should discuss the risks, benefits, and alternatives with a doctor. Alternatives to total knee replacement include:

Nonsurgical treatment — Nonsurgical treatment methods are initially recommended for patients with osteoarthritis or inflammatory arthritis. This may include:

●Weight loss – The knee bears about four pounds of pressure for each pound of body weight, so even a small amount of weight loss (eg, 10 to 15 pounds) can reduce pain.

●Exercise/physical therapy – Strengthening the muscles around the knee help take pressure off the knee. Motion of the joint helps to keep it from getting stiff.

●Medications, including over-the-counter and prescription – These include pain relievers such as acetaminophen and antiinflammatory drugs such as ibuprofen or naproxen. Patients should discuss use of these medications with their primary care provider and pharmacist to be sure the risk of side effects is acceptably low. (See "Patient education: Nonsteroidal antiinflammatory drugs (NSAIDs) (Beyond the Basics)".)

●Knee bracing or shoe inserts – These may help align the knee and balance the weight on the joint.

●Injections – This might involve a cortisone-like drug or a hyaluronic acid derivative. (See "Patient education: Knee pain (Beyond the Basics)".)

Arthroscopy — Arthroscopy is a minimally invasive surgical procedure in which a doctor examines the inside of a joint with a device called an arthroscope. The doctor can repair any damage through small surgical incisions in the skin. Arthroscopy is only helpful for a certain type of knee problems. Arthroscopic surgery has not demonstrated significant benefit for patients with osteoarthritis.

Osteotomy — Osteotomy is a surgical procedure that involves cutting the leg bone, realigning it, and allowing it to heal. It is used to shift weight from a damaged part of the knee to a normal or less damaged one. Osteotomy is not recommended for patients older than 60 years of age or for those with inflammatory arthritis (such as rheumatoid arthritis).

Partial knee replacement — A "partial" or "unicompartmental" knee replacement involves replacing only one part of the knee joint. It may be an option for certain people whose osteoarthritis is limited to only one compartment of the knee. Your doctor can talk to you about whether you might be a candidate for this type of procedure, as well as the potential risks and benefits.

THE KNEE REPLACEMENT PROCEDUREKnee replacement is performed in an operating room after you are given anesthesia. The surgery takes two to three hours. After surgery, you will be monitored in a recovery area for several hours, until the effects of the anesthesia wear off.

Most people stay in the hospital for one to three nights after surgery, although shorter stays are becoming more common and some procedures are even done on an outpatient basis (ie, not requiring a hospital stay).

After surgery, you will be given pain medicines to help control any discomfort from the procedure.

●Whenever possible, non-opioid (non-narcotic) medicines will be used to help minimize pain.

●Some opioid (narcotic) medicines may be needed for a few weeks, particularly before physical therapy and sleep.

Blood clots in the legs (called deep vein thromboses or "DVT") are a common concern after knee replacement surgery. To reduce the risk of blood clots, you can:

●Get up and moving as soon as possible – Work with your physical therapist to try and get up the day of surgery or the day after. Learn exercises to do while in bed.

●Take an anti-clotting medication – You will take an anticoagulant medicine ("blood thinner"), either as a pill or a shot. Most people continue to take this medicine for a few weeks after surgery.

●Wear compression boots (devices that go around the legs and inflate periodically) while you are lying down – Once you are able to get up and walk, your doctor may suggest wearing antiembolism stockings. These stockings fit snugly around the foot, ankle, lower leg, and knee to help prevent blood clots.

Infection is another major concern, and you will be given antibiotics within an hour of the procedure and for up to 24 hours after. Eating a healthy diet, avoiding obesity, and smoking cessation all are helpful for minimizing infection risk.

Rehabilitation — You will be encouraged to start moving your feet and ankles immediately after surgery. It is common to begin physical therapy the day of or the day after surgery. Active motion of the knee is encouraged. Some surgeons may use a continuous passive motion device, which raises and slowly moves your leg while you are in bed.

Physical therapy is an important part of the recovery process. After leaving the hospital, some people have physical therapy in their home or at a clinic, while others stay in a rehabilitation facility or nursing home for a few days.

The rehabilitation program generally includes exercises to improve range of motion (how far you can bend and straighten your knee) and to strengthen your leg muscles. Your surgeon and physical therapist will help to set goals as you progress through rehabilitation. It is important to avoid overworking or straining the knee during the recovery period. You can usually resume your normal daily activities within three to six weeks after surgery. After several months of rehabilitation, you will be able to have a more active lifestyle. High-impact sports such as running and sports that involve heavy contact (football) are not recommended, but you should be able to participate in activities like walking, bicycling, and swimming.

Potential complications — Serious complications are not common after knee replacement. However, any surgery comes with risks, and it is important to be aware of this. Your doctor will discuss the potential complications with you in detail.

Studies have shown that a successful joint replacement partially depends upon the experience of the surgeon and the hospital. Finding an experienced surgeon and a hospital where joint replacements are routinely done will likely improve your chances of a successful procedure with improved knee function and minimal complications.

The following are some of the more common complications that may occur after total knee replacement:

Blood clot — Having total knee replacement increases the risk of a blood clot forming in a vein. The most common place for a clot to develop after knee surgery is in the deep veins of the leg (called a deep vein thrombosis or DVT). This is a concern because a clot can be deadly if it travels to the lungs (doctors call this a pulmonary embolism). Call your doctor's office if you have symptoms that could indicate a DVT, such as leg pain or swelling. (See "Patient education: Deep vein thrombosis (DVT) (Beyond the Basics)".)

Infection — Infection following knee replacement is a relatively uncommon but serious complication. Signs of infection include fever, chills, pain in the knee that gets worse suddenly, increasing redness, or swelling. Call your doctor's office if you are worried that you could have an infection.

Wound infections are treated with antibiotics and occasionally by draining excess fluid from the joint. If an infection becomes deep or extensive, the prosthetic joint may need to be removed and reimplanted later, after the infection has cleared. (See "Patient education: Joint infection (Beyond the Basics)".)

Stiffness — Occasionally, despite physical therapy, a patient's knee may get stiff and may not bend or straighten properly. If this occurs, then the patient may return to the operating room in order to bend and/or straighten the knee under anesthesia.

Early failure — The majority of knee replacements will last between 15 to 20 years. However, early failures may occur due to a variety of reasons. These include loosening of the implants, infection, fractures of the bone around the implants, and instability. When early failures occur, revision surgery may be necessary.

Because knee implants typically do not last much longer than 20 years, people who get a knee replacement at a younger age are more likely to require revision surgery. Younger people are more likely to live for longer than the lifespan of their implant; they may also have a more active lifestyle, which can put strain on the implant, contributing to failure over time. For these reasons, doctors are cautious about recommending knee replacement in people younger than 50.

Persistent pain/dissatisfaction — Approximately 15 percent of patients who undergo total knee replacement may have persistent pain or will not be satisfied with the outcome of the procedure. However, most people experience significant reduction or elimination of pain.

2 Total knee arthroplasty

INTRODUCTIONTotal knee arthroplasty (TKA), also known as total knee replacement, is one of the most commonly performed orthopedic procedures. As of 2010, over 600,000 TKAs were being performed annually in the United States and were increasingly common [1]. Among older patients in the United States, the per capita number of primary TKAs doubled from 1991 to 2010 (from 31 to 62 per 10,000 Medicare enrollees annually) [2]. The number of TKAs performed annually in the United States is expected to increase in volume by 143 percent by 2050 compared with 2012 [3,4].

TKA consists of resection of the diseased articular surfaces of the knee, followed by resurfacing with metal and polyethylene prosthetic components [5]. For the properly selected patient, the procedure results in significant pain relief, as well as improved function and quality of life. In spite of the potential benefits of TKA, TKA is usually performed on an elective basis and should only be considered after exhaustion of appropriate nonsurgical therapies and extensive discussion of the risks, benefits, and alternatives.

This topic reviews aspects of TKA including indications and perioperative considerations. As with any major surgical procedure, complications may result during or after TKA. Complications of this procedure are discussed separately. (See "Complications of total knee arthroplasty".)

PREOPERATIVE CONSIDERATIONS

Indications — Generally, total knee arthroplasty (TKA) is performed for destruction of joint cartilage either from osteoarthritis, rheumatoid arthritis/inflammatory arthritis, posttraumatic degenerative joint disease, or osteonecrosis/joint collapse with cartilage destruction. Damage to the synovial joint of one or more of the three compartments (lateral, medial, patellofemoral) may be the result of a variety of pathologic conditions. Such damage causes pain and impairs the normal functioning of the knee joint, which is a complex hinge, primarily allowing flexion and extension but also allowing rotation and gliding.

●Osteoarthritis – Osteoarthritis is the most common type of arthritis in adults, and can result in degenerative changes in the knee joint. Over 95 percent of TKAs in the United States are performed for osteoarthritis (picture 1) [1,6]. In patients with osteoarthritis, TKA is indicated for the relief of severe knee pain that is refractory to nonoperative treatments. Before proceeding to TKA, a multifaceted regimen of nonoperative treatment should be tried. Nonsurgical treatments offer significant benefit with lower risk. The efficacy of these nonsurgical interventions, even with advanced osteoarthritis, has been supported in clinical trials [7,8] and are appropriate, particularly in patients looking to avoid or postpone surgical intervention or for patients not fit for surgery. (See "Management of knee osteoarthritis", section on 'Moderate/severe knee osteoarthritis' and "Management of moderate to severe knee osteoarthritis", section on 'Surgery' and 'Medical risk assessment' below.)

●Inflammatory arthritis – Rheumatoid arthritis, gout, psoriatic arthritis, and spondyloarthritis, as well as other inflammatory arthritides, can all result in knee joint destruction and the need for TKA. However, the need for TKA due to inflammatory arthritis has declined due to the introduction of disease-modifying antirheumatic drugs [9,10]. (See "General principles of management of rheumatoid arthritis in adults" and "Evaluation and medical management of end-stage rheumatoid arthritis" and "Total joint replacement for severe rheumatoid arthritis", section on 'Total knee arthroplasty'.)

●Others – Other indications for TKA include posttraumatic arthritis (eg, following sports-related injuries, motor vehicle accidents), sequelae of infection, tumor, avascular necrosis (osteonecrosis), or congenital joint abnormalities.

Intraarticular infection resulting from bacterial, viral, or fungal organisms spreading through the bloodstream and depositing in the knee joint, penetrating trauma, or following knee surgery can cause septic arthritis. Subsequent damage to the articular cartilage can then result in debilitating joint pain and stiffness, which may require arthroplasty after proving infection has been eradicated with appropriate preoperative testing. (See "Septic arthritis in adults".)

Bone tumor involving the knee, either primary or metastatic, sometimes requires arthroplasty of the knee. Reconstruction can include the use of larger implants called megaprostheses (eg, total femur replacement, proximal tibia replacement) as part of limb salvage surgery.

Another possible indication for knee arthroplasty is avascular necrosis or spontaneous osteonecrosis of the knee (SONK), which is a condition of unknown etiology that results in an alteration to the blood supply of the knee, resulting in bone death and subchondral bone collapse and subsequent secondary osteoarthritis. (See "Osteonecrosis (avascular necrosis of bone)" and "Chronic complications and age-related comorbidities in people with hemophilia", section on 'Arthropathy' and "Overview of the musculoskeletal complications of diabetes mellitus".)

Contraindications — TKA should not be performed in the following clinical settings:

●Active infection – Active infection in the knee or anywhere in the body. TKA following infection that has been treated successfully must be undertaken with extreme caution. The risk of reactivation of quiescent infection or secondary infection following TKA is difficult to assess. Appropriate timing of arthroplasty after treatment of any infection is not well established, but it is prudent to delay until demonstrated to be infection-free off antibiotics. There may be up to a one-year delay between the treatment of septic arthritis and performance of TKA. Preoperative assessment may include evaluation of serum erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), joint aspiration, and imaging modalities such as magnetic resonance imaging (MRI) or bone scan to look for signs of persistent infection or osteomyelitis. (See "Osteomyelitis in adults: Clinical manifestations and diagnosis".)

●Nonfunctioning extensor mechanism – Neurologic disease affecting the lower extremity is a relative contraindication to TKA, depending upon the impact of the neurologic disorder on the potential for successful rehabilitation and for improvements in pain and function.

●Chronic lower extremity ischemia – In a patient with chronic lower-extremity ischemia, a thorough vascular assessment should be performed before undergoing TKA. The extent of large- or small-vessel disease, as well as the presence or absence of collateral flow, will influence the decision to proceed with revascularization procedures before TKA.

●Skeletal immaturity – Given that the physes near the knee are the major source of growth for the lower extremity, TKA is delayed until skeletal maturity is achieved.

It is important to note that patient participation in any type of postoperative rehabilitation program (eg, monitored or independent) is essential for a successful outcome following TKA, and an inability to participate may constitute a relative contraindication to this form of treatment. (See 'Rehabilitation' below.)

Surgical alternatives to total knee arthroplasty — The suitability of surgical approaches other than TKA, such as osteotomy, joint resurfacing, and unicompartmental arthroplasty, should be discussed with the patient. The various options depend on several factors, including the severity of the disease (eg, early chondral changes with minimal loss of joint space); the extent and location of disease, including whether it is unicompartmental (lateral, medial, or patellofemoral) versus bi- or tricompartmental; the disease process causing joint pathology (eg, osteoarthritis, rheumatoid arthritis, psoriatic arthritis, etc); and the patient's preferences for the risks and advantages associated with each option. (See "Overview of surgical therapy of knee and hip osteoarthritis", section on 'Alternatives to total knee arthroplasty'.)

PREOPERATIVE EVALUATIONAssessment of operative risk prior to total knee arthroplasty (TKA) includes verifying the severity of the underlying knee pathology and the failure of nonsurgical treatments, as well as identifying any medical comorbidities that might impact the choice of anesthesia, the conduct of the operation, and possible complications. The majority of TKAs are performed under elective circumstances for which there is adequate time to consider alternative treatments, assess surgical risk, and to make any necessary adjustments to medications.

Physical assessment — The patient's symptoms should be documented. It is critical to document and investigate any history of concomitant back pain (often described as hip pain by the patient), hip pain (often described as groin pain by the patient), or numbness, paresthesia, or pain in the leg. The presence of back or hip symptoms may indicate that knee pain is referred from these sites; neurologic complaints can arise from peripheral nerve, root, or central nervous system disorders. The clinician must also inquire about calf pain or claudication, which could indicate peripheral vascular disease or spinal stenosis.

The location of the pain (eg, medial, lateral, or patellofemoral) and the severity of the pain and the effect of the pain on the patient's activities of daily living and quality of life should be documented. Aggravating and relieving factors should be elicited.

Previous interventions for the knee pain and their effectiveness (eg, weight loss, nonsteroidal antiinflammatory drugs [NSAIDs], glucocorticoid injections, hyaluronan injections, physical therapy [PT], alternative treatments, surgery) should be noted. Identifying patients with higher levels of pain, anxiety, and depression on validated pain scales and psychological health testing has been advocated. Patients who used opioids prior to TKA can experience less pain relief from the operation and may need more pain medication after surgery [11]. As such, preoperative optimization should target opioid reduction using multimodal strategies. (See 'Perioperative pain control' below.)

The physical examination should include the following:

●Comprehensive knee examination – The knee exam involves assessment of the extensor mechanism, range of motion, and stability/integrity of ligaments and should document the following preoperatively, which serve as a baseline to judge the success of the procedure and for comparison in the event of complications (see "Physical examination of the knee"):

•Range of motion – Maximal active and passive knee flexion and extension should be recorded and any joint contracture noted.

•Presence of crepitus and pain on loading of compartments – In addition to the detection of crepitus, pain in the patellofemoral, medial, or lateral joint with passive flexion/extension can also help the clinician determine the extent of the disease in each compartment.

•Ligament examination – Preoperative assessment of the stability or degree of contracture of the knee ligaments, including the collateral and cruciate ligaments, is important (figure 1 and picture 2). Evidence of collateral ligament incompetence may indicate the need for a more constrained prosthesis. The posterior cruciate ligament (PCL) may be retained or sacrificed at the time of surgery. The anterior cruciate ligament (ACL) is sacrificed in the majority of total knee replacement designs, and therefore its assessment is not considered to be important for most implants.

●Spine and hip examination – It is important to exclude referred pain to the knee originating from the spine or hip. Elicitation of the knee pain with straight leg raising or with hip motion (especially internal rotation) should raise suspicion and warrants further study including imaging of the lumbar spine, hip, or both.

●Neuromuscular evaluation – Motor strength and tone should be tested in the entire lower extremity with special attention devoted to the quadriceps or extensor mechanism. In addition to checking motor strength, sensory and deep tendon reflex assessments (patella and ankle jerks) should be performed.

●Gait – Observing the patient's gait pattern is an important part of the physical examination. Among the abnormal gaits that may be observed in patients with knee pain are the following.

•Antalgic gait – Patients with knee arthritis will often have an antalgic gait. The patient with an antalgic gait spends a shorter time bearing weight on the affected side because of pain.

•Knee thrust – An abnormal medial or lateral movement of the knee while walking (thrust) is usually associated with a varus or valgus (picture 3) deformity.

•Trendelenburg gait – With a Trendelenburg gait, the patient shifts the torso over the affected hip, reducing the load on the hip that is imposed by stabilizing the pelvis and thereby decreasing pain. This suggests the presence of hip joint disease and/or weakness of the gluteus medius muscle. In a patient with a Trendelenburg gait or test that is positive, hip or back pathology must be excluded before TKA is considered.

●Pulses – Distal pulses, including the dorsalis pedis and posterior tibialis, should also be assessed.

●Skin – The skin over both of the entire lower extremities should be thoroughly inspected for any abrasions, ulcerations, swelling, redness, vascular changes, or infections. TKA is contraindicated in the presence of an active infection. Any previous scars over the knee should be noted. Wound healing problems are common around the knee, and previous incisions need to be taken into account at the time of surgery. Any gross deformities (eg, varus, valgus, recurvatum, flexion contracture) should be noted. Deformities will be definitively assessed with radiographs.

Medical risk assessment — The patient undergoing TKA must be able to tolerate anesthesia, associated operative stress, and perioperative blood loss, as well as the rehabilitation process involved following TKA. Since most patients presenting as candidates for total knee replacement are older, specific attention should be paid to the patient's comorbid medical problems and symptoms that may reflect underlying comorbidities that need to be considered prior to undergoing TKA.

●Medical problems – Communication between the patient's primary medical provider and the surgeon or anesthesiologist is paramount. Any history of cardiovascular disease (eg, angina, myocardial infarction, hypertension, congestive heart failure, arrhythmia) or pulmonary disease (chronic obstructive pulmonary disease, restrictive lung disease, respiratory infection, pulmonary embolus, sleep apnea, asthma) should be investigated thoroughly. (See "Evaluation of cardiac risk prior to noncardiac surgery" and "Evaluation of preoperative pulmonary risk".)

●Review of systems – Other particularly important components of the review of systems include those indicating the possible presence of cerebrovascular disease (transient ischemic attacks, stroke, carotid stenosis), thromboembolic disease (deep vein thrombosis [DVT]/pulmonary embolism), peripheral vascular disease (claudication, rest pain, nonhealing ulcers), hematologic disorders (anemia, coagulopathies, blood dyscrasias), endocrine disorders (diabetes mellitus, thyroid disorders, steroid or glucocorticoid use), urologic disorders (benign prostatic hypertrophy, obstructive uropathy, prostate cancer, urinary tract infections), and infectious disease (HIV, hepatitis, osteomyelitis). Patients should also be screened for malnutrition. Appropriate medical and surgical consults should be obtained preoperatively as needed.

●Obesity – While there is no weight limit for performing TKA, most surgeons would be concerned about performing a procedure in any patient with a body mass index (BMI) ≥40 kg/m2 (severely obese). Obese and morbidly obese patients may be at a higher risk for perioperative and long-term complications; however, such patients are not denied surgical options, given their often debilitating osteoarthritis [12-15]. Weight loss prior to surgery may help to reduce the risk of infection and other perioperative complications (eg, anesthesia-related complications) and reduce the risk of surgical revision [16]. (See 'Reoperation' below.)

●Smoking – Smoking cessation is advised at least six weeks prior to surgery to at least six weeks postoperatively, although lifelong cessation is preferred. Smokers are at risk for developing surgical complications. In a review of 8776 patients who underwent TKA, 11.6 percent were current smokers. Compared with nonsmokers, smokers had increased rates of any wound complication (3.8 versus 1.8 percent), deep infection (2.5 versus 1.0 percent), pneumonia (1.3 versus 0.4 percent), and reoperation (5 versus 3.1 percent) [17-19]. (See "Risk factors for impaired wound healing and wound complications", section on 'Smoking and nicotine replacement therapy' and "Pharmacotherapy for smoking cessation in adults".)

Medications should be reviewed prior to surgery, with special attention to the degree of opioid use, which can impact outcomes, as well as antithrombotic therapies, such as aspirin and other antiplatelet therapies, anticoagulants (warfarin), and antiinflammatory agents (eg, NSAIDs, biologic agents) that may affect hemostasis during and after surgery or impair wound healing. Nutritional supplements such as vitamins and fish oil should be reviewed, some of which may have anticoagulation properties as well. (See "Perioperative medication management" and "Risk factors for impaired wound healing and wound complications" and "Preoperative evaluation and perioperative management of patients with rheumatic diseases".)

The overall success and durability of the TKA also depends upon several patient-related factors [20]. Prior to proceeding with TKA, it is important to consider patient age, the underlying disease leading to TKA, and the presence of comorbidities that may influence the perioperative management of the patient undergoing TKA. (See 'Reoperation' below.)

Knee imaging — Patients should have plain radiographs documenting advanced arthritic changes (ie, verifying bone-on-bone contact (image 1 and image 2)). If knee pain appears to be out of proportion to the radiographic appearance, other causes, such as spine and hip pathology and referred pain, should be excluded before arthroplasty is pursued. (See "Imaging techniques for evaluation of the painful joint".)

Plain radiographs are the mainstay imaging modality for preoperative planning and postoperative assessment following TKA. The three basic views that should be obtained in all patients include the following:

●Standing anteroposterior view – The anteroposterior view should be obtained with the patient standing in order to normally load the joint. The medial and lateral joint spaces should both be assessed for narrowing.

●Lateral view – The lateral view is used to assess the patellofemoral joint and the position of the patella (eg, patella baja, patella alta). It is also beneficial to obtain this image while the patient is standing.

●Tangential patellar view – The patellofemoral joint space should be assessed on a tangential patellar view ("sunrise," "skyline," or Merchant view).

Other views are sometimes used. As an example, a standing 45-degree posteroanterior radiograph may be ordered to more accurately determine joint space narrowing of the medial and lateral sides. A long-length standing film containing the hip, knee, and ankle joints is obtained to determine the anatomic and mechanical alignment of the limb (eg, varus, valgus), which is helpful for preoperative planning.

Magnetic resonance imaging (MRI) and/or computed tomography (CT) scanning are generally not needed for patients being assessed for a routine TKA; however, these are sometimes used for preoperative planning, creation of patient-specific instrumentations, and templates for robotic surgery. In cases where standard radiographs do not demonstrate the expected advanced degenerative changes, MRI may be useful to detect other pathology (eg, osteonecrosis, large chondral lesions) if the indication for surgery is uncertain.

Laboratory studies — Preoperative laboratory requirements vary depending upon the patient's health and institutional policy, but they typically include a complete blood count, basic chemistry panel, and coagulation studies (prothrombin time, international normalized ratio [INR], and partial thromboplastin time). An electrocardiogram and a chest radiograph are usually required depending upon patient age and anesthesia policy. For patients with a history of infection, surveillance cultures (eg, blood, urine, tissue) following treatment must be negative (see "Preoperative medical evaluation of the healthy adult patient" and "Preoperative evaluation and perioperative management of patients with rheumatic diseases" and "Preoperative assessment of hemostasis"). Issues related to performing a urinalysis in patients without urinary symptoms prior to TKA are discussed in detail separately. (See "Preoperative evaluation and perioperative management of patients with rheumatic diseases" and "Preoperative assessment of hemostasis" and "Asymptomatic bacteriuria in adults", section on 'Joint arthroplasty'.)

Expected outcomes and informed consent — The patient must thoroughly understand the benefits and risks associated with TKA. While the primarily sought-after benefit of TKA is pain relief, improvement in function and quality of life is often reported to be higher compared with pain relief. In spite of a good surgical outcome, up to 25 percent of patients may remain dissatisfied [21-23]. Dissatisfaction following TKA surgery can be reduced as a result of extensive discussion and explanation before surgery [24].

●Pain relief – A systematic review documented that approximately 20 percent of recipients of total knee replacement report persistent or recurrent pain in the year or so following surgery [21,22]. Some of these patients are nonetheless satisfied, but it is important for patients to bear in mind that the risk of less than complete pain relief is not trivial. Research is ongoing to identify risk factors for a suboptimal outcome [23].

●Functional improvement – Patients generally experience dramatic improvements in the capacity to perform daily and community activities. Patients with worse functional status preoperatively tend to gain the most function following surgery, while patients with the best preoperative function tend to achieve the highest level of postoperative functional status [25]. While activities of daily living are generally easier to perform due to decreased knee pain following TKA, objective measures of knee function (eg, range of motion) typically improve less. The postoperative motion that can be expected is highly dependent on the preoperative motion [26].

●Correction of deformities – Patients with preoperative range of motion deficiencies should be counseled that the best predictor of their postoperative range of motion is their preoperative range of motion. Knee flexion contractures can be reduced in most cases by appropriate component selection and by soft tissue release [27]. Improvement in varus or valgus deformities is typically achieved.

The patient must also be aware of, and be fully able and willing to cooperate with, the rigors of the rehabilitation process following TKA. (See 'Contraindications' above and 'Rehabilitation' below.)

Timing of surgery for bilateral disease — The optimal period of time to stage bilateral procedures has not been well established [28,29]. Bilateral simultaneous knee arthroplasty has been associated with an increased risk for complications, and patients should be counseled as such. A meta-analysis demonstrated that simultaneous bilateral knee replacement increased risk of serious cardiac and pulmonary complications, as well as increased mortality, compared with staged bilateral or unilateral surgery [28]. Patients who are of younger age with symmetrical end-stage knee osteoarthritis and who are willing to undergo bilateral simultaneous TKA should be counseled regarding the slightly increased mortality risk. The advantages, however, of a shorter recovery and return to an improved quality of life should not be denied. Bilateral simultaneous TKA should only be performed in well-selected patients, using specialized anesthetic techniques, at an institution that is experienced in this type of surgery.

PERIOPERATIVE CARE

Antimicrobial prophylaxis — To reduce the risk for SSI, prophylactic antibiotics are given preoperatively. Infectious complications are uncommon but potentially serious. Wound dehiscence and surgical site infection (SSI) increase the risk for implant infection and may require additional surgical procedures to achieve eradication of infection and adequate coverage of the incision (picture 4). A more detailed discussion regarding antimicrobial prophylaxis in the setting of joint arthroplasty can be found elsewhere. Whether Staphylococcus aureus decolonization is beneficial for preventing infection is also discussed separately. (See "Prevention of prosthetic joint and other types of orthopedic hardware infection", section on 'Antimicrobial prophylaxis' and "Overview of control measures for prevention of surgical site infection in adults", section on 'S. aureus decolonization'.)

Thromboprophylaxis — Patients undergoing total knee arthroplasty (TKA) are considered to be at high risk for venous thromboembolism (VTE; deep vein thrombosis [DVT], pulmonary embolism [PE]). VTE is a potentially lethal complication of knee surgery. The reported incidence of DVT following TKA without prophylaxis ranges from 40 to 88 percent [30]. The incidences of asymptomatic PE, symptomatic PE, and mortality are 10 to 20 percent, 0.5 to 3 percent, and up to 2 percent, respectively. By contrast, the incidence of symptomatic VTE is reduced significantly to approximately 1 percent with prophylactic anticoagulation; however, VTE is not prevented altogether.

We recommend postoperative thromboprophylaxis in patients undergoing TKA; the method used is chosen based upon balancing the risk of VTE and the risk of bleeding associated with a particular strategy. There is considerable variability in practice among orthopedic surgeons. Our practice is generally consistent with guidelines from the American College of Chest Physicians (ACCP), the American Society of Hematology (ASH), and the American Academy of Orthopaedic Surgeons (AAOS). The approach to prevent thromboembolic disease in patients undergoing TKA is discussed in detail separately. (See "Prevention of venous thromboembolism in adult orthopedic surgical patients".)

Anesthetic considerations — TKA can be performed with general anesthesia (GA) or neuraxial anesthesia (ie, spinal, epidural, or combined spinal epidural [CSE]). The choice of anesthetic technique should be based on patient comorbidities and patient choice and is discussed in detail separately. (See "Anesthesia for total knee arthroplasty", section on 'General versus regional anesthesia'.)

Perioperative pain control — The goal for pain management after TKA is to provide effective analgesia that allows immediate rehabilitation and early mobilization. Multimodal strategies for postoperative pain control after TKA have reduced the need for intravenous opioids and may include acetaminophen, nonsteroidal antiinflammatory drugs (NSAIDs), gabapentinoids, regional anesthesia techniques, and periarticular local anesthetic infiltration. (See "Anesthesia for total knee arthroplasty", section on 'Plan for perioperative multimodal pain control'.)

●Peripheral nerve block – Single-injection and continuous peripheral nerve blocks are widely used for postoperative analgesia after TKA. Multiple studies have reported reduced perioperative complications and enhanced patient satisfaction with the use of peripheral nerve blocks compared with traditional opioid therapy [31-34].

Sensory innervation of the knee includes the femoral, sciatic, and obturator nerves. These nerves can be individually blocked, but, more commonly, a single block of the femoral nerve or its distal sensory branches (ie, the saphenous nerve and nerve to vastus medialis at the adductor canal) is performed to provide partial, usually adequate, analgesia (since the vast majority of the innervation of the knee is from the femoral nerve). The adductor canal block is increasingly used because it is associated with less quadriceps weakness [35-37], which may therefore facilitate early mobilization and rehabilitation and may reduce the risk of patient falls while the block is in effect. (See "Anesthesia for total knee arthroplasty", section on 'Peripheral nerve blocks'.)

●Periarticular infiltration – Periarticular wound infiltration by the surgeon is an emerging technique for postoperative pain control after TKA. This technique has not been standardized; solutions including long-acting local anesthetics and adjuvants (eg, NSAIDs, opioids) or liposomal local anesthetic solutions are often used [34,38-45]. (See "Anesthesia for total knee arthroplasty", section on 'Periarticular injection (PAI)/local infiltration analgesia (LIA)'.)

●Lumbar epidural analgesia – Postoperative continuous epidural analgesia is often used if epidural or combined spinal and epidural anesthesia is used for surgery. (See "Management of acute perioperative pain", section on 'Epidural analgesia with local anesthetics and opioids'.)

TOTAL KNEE ARTHROPLASTY PROCEDURETotal knee arthroplasty (TKA) consists of resecting the diseased articular surfaces of the knee, followed by resurfacing with metal and polyethylene prosthetic components (image 3) [5]. Patients are positioned supine on the operating table.

Total knee arthroplasty implant design — The introduction of the "total condylar prosthesis" by Insall and colleagues in 1972 is generally considered to mark the era of "modern" knee replacement. This prosthesis was the first to replace all three compartments of the knee. There are many variations of the original design, with the modern-day prosthesis representing a modular evolution of Insall's original design [46].

All TKAs consist of a femoral component, a tibial component, and a patellar component. There are a large number of manufacturers and designs of knee prostheses. Most available systems are modular with a metal tibia tray with polyethylene spacers that articulate with the femoral component. Designs can either retain the posterior cruciate ligament (PCL; eg, PCL retention/cruciate retaining [CR]) or remove the PCL (eg, PCL sacrificing/posterior stabilized [PS], cruciate substituting [CS]). Most currently used designs involve resection of the anterior cruciate ligament (ACL). More constrained designs are also available (eg, hinged implants) for situations including severe deformity, instability, and revision surgery. In general, a more constrained implant shifts more force onto the components, potentially leading to higher failure rates.

Fixation techniques involve either using cement to fix the prosthesis to the bone or relying on bone growth into and onto the prosthesis surface (cementless). This is often assisted by the use of hydroxyapatite and other surface changes on the prosthesis to enhance fixation.

Implant selection is surgeon-dependent. There is no consensus on implant choice, and there is wide variation among nations, states, cities, and individual surgeons. The variability of implant design and technique makes it difficult to analyze and generalize reported results. National joint replacement registries are enabling the analysis of the survival rates of joint replacements to be calculated based on revision surgery, if it is performed. The Australian National Joint Replacement Registry publishes its results every year in great detail, and the 2019 report was based on the results of 782,600 knee replacement procedures [47].

Minimizing perioperative blood loss — Perioperative blood loss for TKA can be minimized by using blood-saving techniques (tourniquet, topical agents, systemic agents). Other general measures to reduce blood loss are discussed separately. (See "Perioperative blood management: Strategies to minimize transfusions".)

Tourniquet use — To control bleeding from the cancellous bone and intramedullary cavity during drilling, a blood pressure cuff (tourniquet) is commonly (although not always) placed on the thigh during the initial setup. It is not typically inflated until after prepping and draping the patient to reduce the amount of inflation time, and it is typically deflated just prior to closing the wound. The total tourniquet time for the majority of knee specialist surgeons is approximately 60 to 90 minutes. The benefit of tourniquet use is a clean operative field not complicated by blood, less intraoperative blood loss, reduced operative time, and possibly better fixation of cement given a drier bony surface [48]. However, the use of a tourniquet may increase the risk for postoperative venous thrombosis, increased pain thereby increasing medication requirements, and reduced early range of motion and potentially a delay in early rehabilitation. Whether blood loss is reportedly reduced depends on how blood loss is measured and possibly on the timing of tourniquet release [49]. In a meta-analysis of randomized trials, reported intraoperative blood loss was less in the group using a tourniquet; however, in studies where visible blood loss or calculated blood loss was reported, the results were similar between the groups, and transfusion requirements were also similar [50]. Nevertheless, the overall rate of complications was higher when a tourniquet was used, and it was concluded that TKA without a tourniquet led to overall better outcomes.

Tranexamic acid — Topical, systemic (oral, intravenous), and combinations of administration routes of tranexamic acid have been used increasingly in conjunction with knee arthroplasty [51-57]. Regardless of route of administration, in randomized trials [58-69], tranexamic acid has reduced the need for perioperative transfusion compared with controls (ie, no drug; with or without tourniquet). While tranexamic acid appears to reduce blood loss to a greater extent compared with epsilon aminocaproic acid (EACA), whether this results in the need for transfusion more often has not been firmly established [70,71]. Prophylactic systemic tranexamic acid administration may be more effective than topical application, but this finding has not been universal [72,73]. The optimal route and timing of administration is still under study [62,74]. For patients undergoing TKA, we agree with major orthopedic societies that recommend tranexamic acid unless contraindicated. The dosing and timing of administration have not been standardized. We give 1 gram of tranexamic acid intravenously before incision and 1 gram of tranexamic acid intravenously during closure. Tranexamic acid can also be given in the postoperative period, as needed.

There is a paucity of evidence regarding the use of tranexamic acid in patients with a known history of a venous thromboembolism (VTE), myocardial infarction, cerebrovascular accident, transient ischemic attack, or vascular stent placement, as these patients have generally been excluded from clinical trials. The available data have not shown an increased risk of adverse perioperative thromboembolic events when using tranexamic acid in patients with comorbidities, and suggest that this population is likely to benefit more from reduced transfusion [75].

Arthroplasty technique — The knee is typically approached via a midline skin incision (figure 2). When previous knee scars are present, all attempts are made to incorporate the prior skin incisions. With multiple knee scars, the most lateral is usually used to optimize the blood supply to the skin flap. On occasion, preoperative plastic surgery consult is needed to aid with planning in knees with multiple scars.

The majority of surgeons use a medial parapatellar approach to enter the knee for initial TKA. With this approach, an incision is made in the quadriceps tendon above, down along the medial side of the patella, down to the medial aspect of the tibial tubercle. The medial parapatellar approach allows for lateral eversion or subluxation of the patella. Occasionally, the lateral parapatellar approach is used for a valgus knee. Other approaches include subvastus and midvastus approaches.

Once the knee joint is entered, the soft tissue is removed from the joint (menisci and ACL, possibly PCL, depending on prosthesis type), and osteophytes are removed from the edges of the bone.

Several technologies have been developed to enable the surgeon to implant the TKA implant more accurately. Manual instruments referencing the bony alignment and surfaces, navigation systems, and patient-specific guides are used to assist surgeons in making the required bony cuts to facilitate the placement of the prosthetic components. Individualized cutting guides are based directly on the patient's anatomy using a preoperative magnetic resonance imaging (MRI) or computed tomography (CT) scan (see 'Knee imaging' above) [76-78]. Robotic systems are also being used to assist with bone preparation and the placement of implants in TKA. Trial implants are also used to assess for balance prior to putting in the final implant.

The patella may or may not be resurfaced. Patella resurfacing, typically with a polyethylene button, remains a controversial topic in TKA [79]. There is some evidence that resurfacing the patella might lessen anterior knee pain postoperatively and therefore reduce the need for a second operation to resurface the patella. However, the advantage of not resurfacing, which includes preserving bone stock and reducing patellofemoral complications such as fractures and loosening, may offset the potential reduction in pain. (See "Complications of total knee arthroplasty", section on 'Patellofemoral disorders'.)

Ligamentous releases may be required for adequate soft tissue balance, particularly if the knee had a significant preoperative deformity. Varus knees are usually tight medially and lax laterally. Valgus knees are usually tight laterally and lax medially. Soft tissue balance is typically achieved by performing releases on the capsuloligamentous structures on the tight side. The PCL may be retained or sacrificed. (See 'Handling the posterior cruciate ligament' below.)

The bony surfaces can be cleaned of blood and fat via pulse lavage and dried with fresh sponge. The femoral and tibial components are prepared with balance in flexion/extension, varus/valgus, and rotation; cementless or cemented implants may be used. At this stage, the cement is mixed if it is to be used. The cement is applied to the tibia, femur, and the prosthesis and impacted to the bone with the excess removed carefully. Cement is also applied to the patella, and the patella button is applied. After approximately 10 minutes, the cement will have hardened, and the joint is irrigated again with pulse lavage to remove any debris.

The wound is closed in layers starting with the retinaculum, then fat, subcutaneous tissue, and finally skin. The tourniquet is deflated prior to closure to assess for any bleeding and achieve hemostasis [80].

Handling the posterior cruciate ligament — Whether to retain or sacrifice the PCL is controversial. PCL sacrificing is also called substitution because the tibial polyethylene component requires the addition of a post to provide the stability normally provided by the PCL. Both PCL retention and PCL sacrificing designs have compelling theoretical reasons for their existence.

●Theoretical advantages of PCL retention include greater range of motion due to reproduction of femoral rollback, decreased stress on the implant leading to lower rates of failure, improved proprioception in stair climbing, and preservation of bone stock [30].

●Theoretical advantages of PCL sacrificing include more reliable correction of deformity; easier balancing of the knee; and elimination of excessive femoral rollback, which may compromise implant fixation and which may increase conformity of the prosthesis, thus leading to decreased contact stresses and to decreased polyethylene wear [30].

However, most of the purported advantages for either approach have not been realized in clinical studies, and excellent results may be obtained with either design [79,81-87]. A systematic review of 17 randomized trials with 1810 patients assessed the benefits and harms of retention compared with sacrifice of the PCL in TKA in osteoarthritis patients. It found no clinically relevant differences with respect to range of motion, pain, and clinical and radiologic outcomes [88].

POSTOPERATIVE COURSE AND FOLLOW-UPPostoperative management includes pain management, prophylaxis against venous thromboembolism (VTE), minimization of postoperative morbidity, and appropriate physical therapy (PT) to achieve the best possible knee motion and return to full function as safely as possible.

Patients are generally mobilized the day of surgery and, with the aid of the physiotherapist, can usually walk with assistive devices on postoperative day 1. The length of hospitalization varies from zero to five days, depending on comorbidities and local practice. Total knee arthroplasty (TKA) is trending toward being performed on an outpatient basis in selected low-risk patients and with discharge to home directly rather than to a rehabilitation unit.

The first signs of clinical improvement compared with preoperative status generally occur between 6 and 12 weeks postoperatively with full recovery occurring between one and two years postoperatively.

Postoperative care potentially includes pain management utilizing the acute pain services, postoperative knee radiography, complete blood test (particularly hemoglobin) and electrolytes on day one; and ongoing thromboprophylaxis and antimicrobial prophylaxis.

Rehabilitation — There is no clear consensus regarding the optimal frequency, duration, or intensity of physical rehabilitation protocols for TKA patients [89]. However, participation by the patient in a postoperative rehabilitation program is required for a successful outcome following TKA. A well-structured PT program that includes range of motion exercises, gait training, quadriceps strengthening, and training in activities of daily living is an important component of the rehabilitation process. Rehabilitation goals should be realistic.

Interventions that attempt to preserve knee motion include the use of pillows under the operative foot while in bed to maintain extension and to avoid flexion contracture. Active and passive exercises to achieve maximal flexion should be instituted early with appropriate use of analgesia to minimize pain. Realistic expectations on flexion range should be based on preoperative flexion and average flexion of total knee replacements around the world being around 115 degrees [90].

Range of motion exercises should be started as soon as possible. A 2007 meta-analysis of five randomized trials concluded that participation after discharge from the hospital in a functional exercise program supervised by a physical therapist improves knee function and range of motion in the short term when compared with routine care [91]. Inpatient rehabilitation has not been shown to result in improved mobility compared with home-based PT in patients who have undergone an uncomplicated TKA [92].

Follow-up and activity level — Following the surgery, depending on the indication for the surgery and the conduct of the operation, the patient may follow up with their provider.

The typical follow-up schedule starts with wound review within two weeks of surgery. This can be done by an internist, nurse practitioner, rehabilitation doctor, physiotherapist, or the surgeon. The patient typically sees the surgeon at six to eight weeks with or without a repeat knee radiograph. Subsequent follow-up is highly variable.

In the long term, patients are encouraged to pursue low- to moderate-intensity, low-impact exercises, as patients who are more active do appear to increase their risk of needing revision arthroplasty [93]. Walking, swimming, and moderate activity are always encouraged for maintaining strength and physical and mental well-being. This level of activity should be expected following TKA. The role of a total knee replacement is to alleviate pain so that patients can return to their daily activities. Sports can be allowed within reason after appropriate rehabilitation. If the patient had a moderate level of sport prior to surgery, then it may be continued with advice that the joint will have higher load and possible wear. (See 'Reoperation' below.)

OUTCOMES

Morbidity and mortality — Mortality following total knee arthroplasty (TKA) is overall low, ranging from 0.5 to 1 percent per year, and is primarily related to preexisting medical comorbidities [6,94-96]. Surgeon volume impacts surgical outcomes as there is evidence that low-volume surgeons and hospitals are associated with worse outcomes compared with high-volume surgeons and hospitals [97,98].

Complications — Complications associated with TKA include those in common with other surgeries, such as those related to anesthesia or blood transfusion, venous thromboembolism (VTE), and surgical site infection (SSI), as well as complications specific to operations involving the knee joint, including neurovascular injury, prosthetic joint infection, peri-implant fractures, patellofemoral disorders, and issues related to wear and tear of the prosthetic. These specific complications are discussed separately. (See "Complications of total knee arthroplasty".)

Reoperation — Reoperation may be needed for a variety of problems related to TKA (eg, implant wear, aseptic loosening, implant infection, patellofemoral disorders, peri-implant fracture). (See "Complications of total knee arthroplasty".)

Loosening of the prosthesis is the main reason for revision [99]. Males have a higher revision rate, mostly secondary to higher rates of infection. For patients with primary osteoarthritis, the revision rate in Australia is 5.3 percent in 10 years and 8.6 percent at 18 years. Revision rates in patients with rheumatoid arthritis is slightly lower, and for patients with osteonecrosis or other inflammatory arthritis, the revision rate is slightly higher [47].

A large meta-analysis including data from national registries estimated that approximately 82 percent of total knee replacements last 25 years [100]. The longevity of the implant largely reflects the total load that the implant bears over time. In general, younger TKA recipients use their implants at a more active time in their lives. Thus, the devices are much more likely to fail in their lifetime compared with the implant in older TKA recipients. The impact of patient age on the likelihood of needing revision surgery was evaluated in a large population-based study including 54,276 patients aged 50 or older who had undergone a TKA between 1991 and 2011 [101]. The lifetime risk of revision surgery in patients who had a TKA over the age of 70 years was approximately 5 percent, with no difference between men and women. However, the lifetime risk of revision increased with decreasing age, with the highest risk of 35 percent observed in men between the ages of 50 and 54. The risk of surgical revision appears to be even higher in patients under the age of 50, suggesting that TKA should be undertaken cautiously in these patients. In another population-based study that included 120,538 patients who had undergone TKAs, almost 5 percent of patients under 50 years old required revision surgery at one year [102].

As with age, underlying disease also plays a role in the longevity of the prosthesis. Rheumatoid arthritis patients are generally less active, placing less of a load on the joint compared with osteoarthritis patients. A survivorship analysis of 11,606 TKAs found that the durability of the prosthesis was shorter in patients with osteoarthritis compared with those with inflammatory arthritis (10-year prosthesis survival of 90 versus 95 percent, respectively) [20].

Obesity also has a negative effect on outcome after TKA [12,103]. In a 2012 meta-analysis, patients who were obese (body mass index [BMI] ≥30 kg/m2) had increased rates of infection (odds ratio [OR] 1.90, 95% CI 1.47-2.47) and revision for any reason (OR 1.30, 95% CI 1.02-1.67) compared with patients who were not obese [103].

Implant infection may result in prolonged hospitalization, the need to remove the infected implant, and an extended course of antibiotic treatment, followed by reimplantation. Up to 1 percent of total knee replacement recipients experience an infected prosthesis over the course of the first postoperative year. Prolonged infection treatment may lead to multiple surgeries, fusion, or even amputation. (See "Prosthetic joint infection: Epidemiology, microbiology, clinical manifestations, and diagnosis" and "Prevention of prosthetic joint and other types of orthopedic hardware infection" and "Prosthetic joint infection: Treatment".)

SOCIETY GUIDELINE LINKSLinks to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Total knee arthroplasty".)

INFORMATION FOR PATIENTSUpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6thgrade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Knee replacement (The Basics)")

●Beyond the Basics topics (see "Patient education: Total knee replacement (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Total knee arthroplasty (TKA), also known as total knee replacement, consists of resection of the diseased articular surfaces of the knee, followed by resurfacing with metal and polyethylene prosthetic components. For the properly selected patient, the procedure results in significant pain relief, as well as improved function and quality of life. In spite of the potential benefits of TKA, it is an elective procedure and should only be considered after thorough discussion of the risks, benefits, and alternatives. (See 'Introduction' above.)

●The most common indication for TKA is for the relief of pain associated with osteoarthritis of the knee in patients who have failed nonoperative treatments. Other conditions that cause pain resulting in the need for TKA include inflammatory arthritides (eg, rheumatoid arthritis, psoriatic arthritis, spondyloarthritis), crystal-induced arthritis (eg, gout), posttraumatic arthritis, sequelae of infection, tumor, avascular necrosis (osteonecrosis), or congenital joint abnormalities. Loss of function and deformity are less common but clinically important indications as well. (See 'Indications' above.)

●Contraindications to TKA include active infection in the knee or anywhere in the body, a nonfunctioning extensor mechanism, chronic lower extremity ischemia not amenable to revascularization, and skeletal immaturity. Patient participation in a postoperative rehabilitation program is essential for a successful outcome following TKA, and an inability to participate may constitute a relative contraindication to this form of treatment. (See 'Contraindications' above.)

●A careful preoperative evaluation must be performed to verify the severity of the underlying knee pathology and the failure of conservative treatments, as well as identify any medical comorbidities that might impact the choice of anesthesia, the conduct of the operation, and possible complications. A thorough evaluation includes particular elements of the history, a physical examination, imaging and laboratory studies, a review of treatment alternatives, and discussions of the benefits and risks of the procedure. (See 'Preoperative evaluation' above.)

●Prophylactic antibiotics (table 1) are given preoperatively to reduce the risk for surgical site infection (SSI) and prosthetic joint infection. Postoperative thromboprophylaxis should also be administered in patients undergoing TKA. The approach to thromboprophylaxis in adult orthopedic surgery as well as the use of antimicrobial prophylaxis are discussed in detail separately. (See "Prevention of venous thromboembolism in adult orthopedic surgical patients" and "Prevention of prosthetic joint and other types of orthopedic hardware infection".)

●TKA can be performed with general or neuraxial (ie, spinal, epidural, or combined spinal epidural [CSE]) anesthesia. Regional anesthesia techniques and/or periarticular local anesthetic infiltration are increasingly used as part of multimodal opioid-sparing strategies for postoperative pain management. (See 'Anesthetic considerations' above and 'Perioperative pain control' above and "Anesthesia for total knee arthroplasty".)

●All TKAs consist of a femoral component, a tibial component, and a patellar component (figure 2). There are a large number of manufacturers and designs of knee prostheses. Most available systems are modular with a metal tibia tray with polyethylene spacers. Designs can either retain or remove the posterior cruciate ligament (PCL). (See 'Total knee arthroplasty procedure' above.)

●Postoperative care can include pain management, prophylaxis against infection, venous thromboembolism (VTE) prophylaxis, and minimization of postoperative morbidity, as well as appropriate physical therapy (PT) to achieve the best possible knee motion and return to full function as quickly and safely as possible. The first signs of clinical improvement compared with preoperative status generally occur between 6 and 12 weeks postoperatively with full recovery occurring between one and two years postoperatively. (See 'Postoperative course and follow-up' above.)

●Mortality following TKA is overall low, ranging from 0.5 to 1 percent per year, and is primarily related to preexisting medical comorbidities. Complications associated with TKA include those in common with other surgeries (eg, SSI), as well as those specific to operations involving the knee joint (eg, prosthetic joint infection). Reoperation may be needed for a variety of problems related to TKA (eg, implant wear, aseptic loosening, implant infection, patellofemoral disorders, peri-implant fracture) that may lead to implant/joint failure or patient dissatisfaction. Loosening of the prosthesis is the main reason for revision. Complications specific to knee arthroplasty are discussed in detail separately. (See 'Morbidity and mortality' above and "Complications of total knee arthroplasty".)

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連結

骨科常見損傷：踝關節扭傷

新型冠狀病毒的發生發展轉歸-中醫五運六氣學說一點看法

骨腫瘤疾病：軟骨肉瘤

患者教育：腕管症候群(基礎篇)

骨科常見疾病：痛風