대한정형외과학회지 : 제 39 권제 1 호 2004 J. of Korean Orthop. Assoc. 2004; 39: 108-14 슬관절부분치환술 중앙대학교의과대학정형외과학교실 슬관절부분치환술은 1970 년초기에소개된이후최근까지그치료결과에대하여이론이많았다. 환자에대한선택, 수술수기의발달과보철기구설계의개선으로그결과가많이향상되었다. 수술후 10 년생존율에서인공관절전치환술보다다소떨어지는것이일반적인보고이나, 최근몇몇보고는전치환술과비슷한결과를보고하고있으며 15 년이상생존율에서는전치환술보다다소떨어지나많이개선된상태이다. 부분치환술이절골술이나전치환술에비해이점이있으므로한쪽부분에골성관절염환자특히중년부인에서이점이있는좋은수술방법으로사료된다. 최근에수술수기의발달로수술후회복이빠르고입원기간의단축및기능상정상에가까운기능회복등으로최근에다시각광을받고있는실정이다. 그러나, 수술전에술자는다음과같은점을신중히고려해야한다. 첫째, 퇴행성관절염이한쪽관절부분에만국한된것인지확인해야되며이를임상적, 방사선사진및스트레스방사선검사등으로만할것인지아니면다른정밀검사즉동위원소검사, 관절경검사등을할것인지고려해야한다. 둘째, 한쪽부분에만퇴행성관절염이있을경우에수술의금기사항은아닌지잘검토해야된다. 셋째, 고정된내반및외반또는굴곡변형이부분치환술후교정이가능한것인지, 넷째, 변형을과도하게교정을하면정상측관절면이퇴행성변화가촉진되므로어느정도교정하는것이좋을것인지또한폴리에틸렌의두께는최소한어느정도이상되어야하는지등을잘검토하여야된다. Principles of Unicompartmental Knee Arthroplasty Young Bok Jung, M.D., and Yong Seuk Lee, M.D. Department of Orthopedic Surgery, Yong-San Hospital, Chung-Ang University, Seoul, Korea Unicompartmental knee arthroplasty has been controversial since its introduction in the early 1970s. Refinements were made in patient selection, surgical technique, and prosthetic design. Ten-year follow up studies were reported that showed survivorship was slightly less than that reported for total knee arthroplasty but acceptable considering the theoretically conservative nature of unicompartmental surgery. Unicondylar knee arthroplasty can be an attractive alternative to osteotomy or total knee arthroplasty especially some middle-aged women. Approximately all studies with followups of 10 years or greater show that unicompartmental knee arthroplasty will have inferior survivorship to total knee arthroplasty whether from loosening, prosthetic wear, or secondary degeneration of the opposite compartment in the second decade. Recently there has been a resurgence of interest in doing unicompartmental knee arthroplasty, which was encouraged by easier recuperation, decreased hospital stays, and good functional results. Before doing a unicompartmental arthroplasty, the surgeon should answer four important questions: Is the disease truly unicompartmental? Can this be determined on a clinical examination and standard radiographs, or are more sophisticated studies such as a bone scan or an arthroscopy required? Second, if the patient does have unicompartmental disease are there any specific contraindications to the surgery? What are the limits of fixed deformity in varus or flexion that can be corrected by a unicompartmental replacement? Overcorrection of angular deformities has in the past led to increased wear of the opposite compartment. Therefore, how much should the knee be corrected? What is the minimal polyethylene thickness that is permissible? 통신저자 : 정영복서울시용산구한강로 3 가 65-207 중앙대학교의과대학부속용산병원정형외과 TEL: 02-748-9963 FAX: 02-793-6634 E-mail: jungyb2000@hanmir.com Address reprint requests to Young-Bok Jung, M.D. Department of Orthopaedic Surgery, Yong-San Hospital, Chung-Ang University 65-207 Hangangro 3 ga, Yongsan-gu, Seoul 140-757, Korea Tel: +82.2-748-9963, Fax: +82.2-793-6634 E-mail: jungyb2000@hanmir.com 108
슬관절부분치환술 109 무릎관절의부분치환술은 MacIntoshi (1958) 가경골면에바이탈이움 (vitallium) 으로만든한쪽면만갈아끼는것으로시작해서최근에다시시도하는 unispacer는다시개조해서시도되고있으나그사용에대한결과는아직도추시관찰과보다더많은연구가필요한상태이다 39). 최근에많이사용되고있는부분치환술은 1975년에서 1983년까지성공률이 37-92%, 합병증발병률이 7% 에서 38% 까지다양하게보고되었다 2,3,12,14,22). 주된합병증으로 polyethylene tibial component 의이완 (loosening) 과내려앉음 (subsidence) 이었다. 1976년부터 1세대옥스포드부분치환술이사용되었고 12), 1986 년전까지는인공관절에사용하는폴리에틸렌을기계로깍아서사용하였다. 폴리에틸렌을압축해서만들고, 소독을가스로하고난후부터최근에부분치환보철의디자인개발과수술기술의향상으로그결과가많이좋아진것으로보고되고있다. 1990년초반까지도그결과의보고가다양하였고만족할만한결과가거의없어서한동안슬관절부분치환술을하지않다가유럽에서좋은결과를보고함으로써다시북미에서최근에활발하게시행되고있는실정이다. 최근 Murray (1998) 는 10년생존율을 98% 로보고했다 11,28,29). 그러나, 아직도부분치환술에대해서는수술자에따라서상반되는견해가많다. 최근에는슬관절부분치환술을해야할경우에도근위경골절골술을하든지아니면슬관절전치환술을시행하는편이좋다고생각하는학자와슬관절의부분치환술이근위경골절골술보다는통증완화등의효과및성공률이높고합병증이적다고주장하는학자가있다. 또한슬관절전치환술에대해서는전방십자인대및외측부분관절연골의보존및소절개 (minimal incision) 등으로회복기간도빠르고기능도보다정상에가까우므로환자선택과수술술기가정확하다면보다좋은결과를보고하고있다 4,6,7,11,15,20,28-30,32,34). 이에부분치환술환자의선택즉적응증, 비적응증및장단점등을문헌고찰과함께살펴보고자한다. 환자선택 ( 부분치환술의적응증 ) 환자의선택은임상적, 방사선및최종적으로수술방에서의육안적또는관절경적검사로써결정되어진다. 임상적으로는퇴행성관절염, 외상성관절염환자에서심한통증이있으며 (disabling pain) 일상생활에기능적제한 이있는경우, 15-20 미만의내반및외반변형이외래에서시행하는내 외반스트레스검사로써쉽게교정이가능하며굴곡구축이 20 이내이어야되고, 슬개대퇴관절및반대측구획에이상소견이거의없거나아주경미하여야된다 6,15,17,18,20,29,38,44,46,47). 또한비수술적치료즉치료적근육운동, 무릎관절침범부위에체중이적게받도록하는생활의양식변경 (activity modification), 진통소염제사용, glucosamine과 chodroitin sulfate 사용을해본경우뿐만아니라보조기착용등의비수술적치료를시도해서효과가없는경우에수술의적응증이된다. 방사선적으로는기립성전후및측면방사선사진과무릎을 45 굴곡상태에서촬영한후전면사진상중등도내지는고도로관절연골손상이예상되며관절간격이아주좁아졌을때, 대퇴골및경골의연골하골의경화가있으며전내측퇴행성관절염이중등도이상일때, 전방십자인대가임상적으로정상적이고외측관절연골이정상적두께로유지될때, 즉 20 굴곡상태에서외반스트레스사진상외측관절간격이정상적으로유지된다고판단될때, 대퇴슬개골관절면의관절연골손상이아주경미하며관절간격이비교적잘유지되고슬개골압통이없을때좋은적응증이된다. 다음과같은경우에는부분치환술의적응증이되며경골근위부절골술은결과가좋지않다. 1) 보행시한쪽부분에통증이국한되고이로인해서일상생활에지장을받을때, 2) 무릎관절을완전신전또는 45 굴곡위치의기립상태 (standing) 방사선사진에서내측또는외측의한쪽관절간격이매우좁아져있을때 (Grade II Ahlback 방사선변화 ), 3) 관절경적수술 (debridement or abrasion arthroplasty) 에실패한 Grade I Ahlback 방사선변화가한쪽부분에있을때, 4) 15-20 이하의슬관절내반변형이있으면서수동적으로교정이가능하고, 90 이상굴곡이가능할때, 5) 골성관절염또는외상후관절염이한쪽부분에만국한된경우, 6) 나이가 55-60세이상 ( 옥스포드그룹에서는나이와비만은상관하지않고있다.), 7) 주로앉아서일하는직업 (sedentary), 8) 슬관절외반변형이있으면서외측에국한된관절염이있을때. 또한, 경한슬개골연골연화증이있으며통증이없을때는부분치환술의금기증이되지않는다. 방사선변화가없으나심한통증이있는경우에는대퇴골또는경골
110 부위골괴사를의심해야되며골괴사로대퇴골한쪽이침범된경우자기공명 (MRI) 촬영이나동위원소검사를시행하여서진단후보존적요법에실패했을때부분치환술의적응증이될수있다. 그러나, 그침범범위가너무깊고클때는부분치환술이좋지않으며이러한경우에는전치환술을고려해야한다. 그리고, 무엇보다도부분치환술을할것인지아닌지의최종결정은수술장에서결정되어진다 33,37,42,44,46,48). 부분치환술의금기증다음과같은경우에서는일반적으로부분치환술의금기증으로받아들여지고있다. 1) 방사선상무릎관절의내측및외측모두또는세구획모두에중등도이상관절염의변화가있을경우, 2) 통증이무릎관절의내측, 외측또는슬개대퇴관절에있을때, 즉무릎의두관절이상통증및압통이심할때 ( 슬개대퇴관절연골의변화및슬개대퇴활차의이상 (patellofemoral mal-tracking) 은일반적으로무릎의내측퇴행성관절염으로내반변형이생길때생기나슬관절부분치환술후에슬개대퇴활차가교정되며부분치환술의최종결과와슬개대퇴관절의상태와는임상적으로상관관계가없다고한다 11,28,29,46). 슬개대퇴관절의퇴행성변화로인해서부분치환술을전치환술로다시수술한경우는없다고보고한논문도있다 36). 그러나, 슬개대퇴관절의심한관절염 ( 관절연골이없는경우 ) 이있을경우에는전치환술을하는것이좋을것으로사료되며금기증으로보고한저자들이많다 17,18,20,24,25,34). 3) 불안정성이있을때 ( 전방십자인대가없거나내외측전위 (subluxation) 가 3 mm 이상될때 ), 4) 무릎관절이 15-20 이상의내반또는외반변형이있을때, 굴곡구축 (flexion contracture) 이 15-20 이상일때, 5) 활동력이아주많은환자, 6) 전신성염증성질환으로인한무릎관절염이생겼을때 ( 통풍성관절염, 류마티스관절염 ), 7) 최근에화농성염증이있었던경우, 8) 상대적금기증으로는 1 환자나이가 55-60세이하, 2 체중이많은비만증환자 ( 관절치환부분의폴리에틸렌의마모가빨리생길수있으므로상대적으로금기증으로보는저자가있는가하면옥스포드그룹들은환자의나이와비만증은비적응이되지않는다고보고하고있다 11,28, 29).) 수술수기및기구선택의주의점 1. 수술수기보철기구는적합한크기를선택하는것이중요하다. 경골부위보철기구 (component) 는가능한한경골관절면을충분히덮을수있는넓은것이좋고, 특히내측피질골 (medial cortical bone) 위에보철기구가덮어야되나, 2 mm 이상나오지않도록하는것이좋다 30,32,41,42). 보철기구가내려앉는 (subsidence) 것은주로해면골에서생긴다. 대퇴골보철기구가정상관절면보다튀어나오지않도록해야하며특히앞쪽 (anterior) 으로튀어나올경우슬개골과충돌 (impingement) 이생기므로무릎관절굴곡시통증의원인이될수있다. 최근에설계된부분치환술은대퇴전방부분이가라앉게되어있다. 대퇴골보철기구는대퇴과골의내 외측중앙에경골의장축과일직선이되게하며내반및외반이되지않게하는것이좋다. Mobile bearing에서는접촉면적이넓으며접촉성 (congruency) 이좋으므로내반및외반이 10 까지는허용된다고한다. 경골보철기구는경골의장축에대하여 90 로골절제를하고, 3-5 후방경사를정상적으로유지해야되며전 후방십자인대-특히후방십자인대-의과도한긴장이초래되지않게주의를요한다. 보철기구를너무두꺼운 (thick) 것을사용해서내측변형을과도교정 (overcorrection) 을할경우반대측, 즉외측부에서조기에관절연골의퇴행성변화로인한통증이발생해서실패하게되므로과도교정을해서는안된다. 부분치환술시무릎관절의내반변형이있을경우에는중립위치, 즉, 대퇴경골각이 0 이하로교정하고, 무릎관절이외반변형이있을경우에는해부학적축 (anatomic alignment) 5-6 외반정도로 undercorrection 하는것이좋으며해부학적축이 2 내반에서 6 외반이내로교정하는것이바람직하다고했다 17-19,22,24). Kennedy와 White는역학적축이내측부분치환술시는무릎관절의중심을지나거나약간내측을지나는것이좋으며외측부분치환술시는약간외측으로지나는것이좋다고하였다 19). 즉, 변형을절골술시와같이과도교정을하는것은허용이되지않으며중립위치의교정이바람직할것이다. 수술후부분치환 ( 내측또는외측 ) 을한부분에서인대이완의정도는무릎을완전신전상태에서외반또는내반스트레스를줄때 1-2 mm 정도의내측또는외측관절간격이있는것
슬관절부분치환술 111 이좋다 28,32-34,38,44,48). 수술수기상인대절개를통한축의교정은하지않아야되며 (no ligaments release) 연부조직의균형은골절제정도로조절해야한다 19,28,29,33,35). 보철기구의크기는대퇴골의경우에는중간정도의크기일경우에는큰것으로사용하는것이골보존을많이할수가있으므로권장되고, 경골의경우에는피질골을덮을수있는크기를사용해야되며대퇴골과의후방부분은골절제를적게해서굴곡간격이너무협소한것 (tight) 보다는다소많이절제하는것이좋다. 2. 보철기구의선택 (Choice of implant) 환자의여명이 10 년이내로예상될때는경골부분에폴리에틸렌으로된기구를사용해도좋을것으로사료된다. 경골부분의폴리에틸렌으로된기구를사용할때는최소한폴리에틸렌의두께가 6.5 mm 이상되어야한다 6). 여명이 15-20년이상예상될때는 mobile bearing이좋을것으로생각된다. 수술후 15-20년의결과는무릎전치환술보다결과가떨어지므로환자의여명이 15-20년정도로예상되면부분치환술을할것인지전치환술을할것인지신중히고려해서결정하는것이좋을것이다 1,3,41, 48). 80대전후에내측퇴행성관절염의경우에적응증이될때는부분치환술이아주좋을것으로예상된다. 그이유로회복이빠르고수술로인한손상이적으므로합병증도적고 (less medical morbidity) 무릎의기능도거의정상적이기때문이다 6,38,42). 부분치환술의장단점및실패원인 1. 부분치환술의장단점부분치환술의장점으로는 bone stock 을가능한한보존할수있고, 수술의출혈이적으며전 후방십자인대및슬개골을그대로유지하므로써보다빠른회복과운동범위가관절전치환술시보다좋고, 거의정상에가까운기능을할수있다는데있다. 또한부분치환술의실패후슬관절전치환술로재치환시전치환술후에재치환술보다용이하다 27). 부분치환술의단점으로는최근에는개선되었으나 instrumentation 이정교하게되어있지않다 8,18, 34,37,38,41). Modular capability가적고수술수기가슬관절전치환술보다어렵다 3,8,18,21,27). 2. 부분치환술의실패원인부분치환술의임상적실패원인으로는가장많았던것이첫째, 환자선택의잘못 2,3,18,38,41), 둘째, 수술수기의문제점, 셋째, 보철기구의문제점과기구의설계상 (design) 문제로 loosening, 폴리에틸렌의마모및 porous coating 의파괴등이주된원인이다. 즉, 세구획 ( 내, 외대퇴경골관절과슬개대퇴관절 ) 의퇴행성관절염의진행으로부분치환술이실패하는주된원인으로는 1) 무릎변형의과도교정 (overcorrection), 2) 이차적전방십자인대의손상또는약화로관절의아탈구 ( 진행되는퇴행성관절염에서전방십자인대의마모는관절경수술때가끔볼수있는소견이다 18).), 3) 보철기구의편평한관절면 ( 경골보철기구관절면이완전히편평한경우 (completely nonconforming) 는경골대퇴관절의아탈구가잘생길수있고전방십자인대에과도한스트레스가전달되어서전방십자인대가약화되기쉽다. 또한스트레스가일부분에집중되어서플리에틸렌의마모가증가된다.), 4) 반대측관절연골의퇴행성변화의자연적과정, 5) 골극에의한경골과대퇴골사이에충돌 (osteophyte impingement) 등이그원인이될수있다. 부분치환술의수술수기는전치환술보다정확성을요하며더욱까다롭고어렵다 18,19,31). 보철기구로써는최근에는금속판받침대를사용하므로스트레스분배 (distribution) 가잘되어폴리에틸렌의 creep 변형을줄일수있고, modular 형을 ( 플라스틱두께를조절해서삽입할수있으므로 ) 사용하므로수술수기상안정성을보다좋게할수있으며시간이많이경과된후에폴리에틸렌부분만교환할수있다는이점이있다. 경골부분이금속받침대 (metalback) 로된 fixed bearing을사용할때는폴리에틸렌의두께가최소한 6 mm 가될려면적어도 8-9 mm 정도의두께가되는것이좋을것이다 2,4-6). 옥스포드그룹에서는경골부분의폴리에틸렌두께가 3.5 mm 이상되면문제가없다고한다 11,28,29). 그러나, 경골보철부분의두께는적어도 8-9 mm 정도를사용하는것이바람직하다고한다. 실제전체두께가 8 mm인경우폴리에틸렌부분의두께는 5 mm 정도이며 design에따라서는경골보철의변연부의폴리에칠렌부분은약 2 mm 정도밖에안되므로문제가될수있다. 따라서금속받침대보철기구에대한견해는무릎관절전치환술의경우폴리에칠렌부분이적어도 6-8 mm 정도쓰는것이좋다
112 고했다 40). 경골부분이 8 mm 이상폴리에틸렌으로만된경골보철기구가회사에따라서만들어지고있다. 금속받침보철기구를사용하는경우전체두께가 8-10 mm가되게사용해야되므로골절제를많이해야하는문제가있다. 이상열거한문제때문에다소상반되는견해를갖고있다. Emerson 등 8) 에의하면 11 년추시관찰에서 meniscal bearing에서 99%, fixed bearing에서는 93% 의생존율을보고하고있다. 부분치환술의수명및전치환술과의비교부분치환술의수명은다양하게보고되어왔다. Scott 등 40) 이 100 명을추시관찰한결과수술후 9년에 90%, 10 년에 85%, 11년에 82% 의생존율을보고했고, Marmor 26) 는 60예에서 10-13년추시결과 70% 에서만족스럽고, 87% 에서통증이없었다고보고했다. Heck 등 13) 은경골부분이금속받침대가없이폴리에틸렌으로된시멘트형에서여러센터조사결과수술후 5년에 97.9%, 10년에 91.4%, 12년에 81.6% 에서생존율의좋은결과를보고하므로경골보철기구의금속받침대사용에대한재연구가필요하다고생각된다. 반면에, 재치환술이필요한경우 (revision rate) 는 Insall 등 14) 은 6년추시에서 28% 로보고했으며, Laskin 22) 은최소 2년추시에서 25% 로보고하였다. 최근에발표되는논문에서는 10 년생존율이 Engh 등 9) 은 80%, Cartier 등 4) 은 13년생존율이 93% 에서 98% 까지보고되고있으며 15년생존율은 89% 42), 수술후 10년까지는전치환술과비슷하게보고되고있는경우가많으나 10 년이후에는전치환술보다생존율이다소떨어지는것으로보는것이일반적인경향이다. 그러므로환자의여명기간이 15-20 년이상예상될때는보다신중을기하는것이좋을것이다. 슬관절부분치환술과전치환술을비교분석한논문들의결과를보면 Laurencin 등 23) 의보고에의하면, 환자자신들의주관적평가로부분치환술이전치환술보다각각 50%, 44% 에서기능이좋다고했고, 21%, 12% 에서는전치환술이더좋다고했다. 또한 29%, 44% 에서양측의차이가없었다고했다. 저자가과거임상분석한결과는처음 6-12개월까지는부분치환술이좋다고했으나 2년이지나면서는별차이가없다고했으며부분치환술이합병증발생률이높았다. 이는환자선택과수술수기 의잘못으로인한결과였다 2,3). 최근 31예의옥스포드부분치환술과 130 예의전치환술을비교한결과통증완화나기능점수및재치환술비율등에서두군간비슷한결과를보고했으나병원입원기간은부분치환술에서짧았다고보고했다 45) 일반적으로슬관절부분치환술이그기능면에서환자의만족도가전치환술보다좋은것으로인정되고있다. Robertsson 등 36) 이스웨덴에서무릎의부분또는전치환술을 1981년에서 1995년사이에받은 27,372명환자에서시행한설문조사에서전치환술, 내측부분치환술과외측부분치환술사이에환자의만족도에서는차이점은없었고, 수술후 2년에서 17년사이의환자에서 8% 환자에서불만족을나타냈다. 같은무릎에서양측즉내 외측에부분치환술을받은환자에서는현저하게만족도가떨어졌으며무릎관절의부분치환술후재치환술을받은환자에서전치환술후재치환술을받은환자에서보다만족도가높았다고했다 36). 부분치환술실패후전치환술로의재치환술이보다쉽다고인정되고있으나, Padgett 등 31) 은부분치환술후전치환술로의재치환술시큰골결손이경골부위에생긴경우가 16예 (76%) 로결코간단하지는않다고했다. -소절개수술 (Minimal invasive surgery)- 소절개수술은기존의슬개골을탈구시켜서하는수술보다손상이적고출혈도적으며수술후회복기간도빠르다는제반이점이있다. 1999년 Repicci 34) 가무릎내측에 3인치길이의소절개에대한수술술기에대한상세한보고를한후에현재에는모두가소절개를통한부분치환술을하고있는실정이다. Price 등 33) 은소절개와기존의슬개골을탈구시키는절개방법과전치환술과의비교연구에서하지직거상, 계단올라가는기능, 70 까지굴곡등을비교한결과소절개에서기존의절개방법에서보다 2배, 전치환술보다 3배가빠르며방사선분석결과는 -보철기구의위치, 고정등- 차이가나지않았다고보고했다 10,33). 결론결론적으로부분치환술의성공의열쇠는환자를잘선택해서해야되고수술수기가정확하고적절한보철기기를사용하면기능면이나통증완화면에서경골근위절골술보다이점이있는좋은수술방법이며기능면에서전치
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