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Original Article J Korean Knee Soc, Vol. 23, No. 1, March 2011 PS-TKA with more than 10 o of Preoperative Posterior Tibial Slope Jong-Heon Kim, M.D. and Soon-Myung Kim, M.D. Department of Orthopedic Surgery, Guri Hospital, Hanyang University Colledge of Medicine, Guri, Korea Purpose: We wanted to evaluate the effects of a preoperative posterior tibial slope of more than 10 o on the extension gap and patellar height during posterior substituted total knee arthroplasty. Materials and Methods: One hundred ten posterior substituted total knee arthroplasties were divided into group I (more than 10 o of preoperative posterior tibial slope, n=56) and group II (less than 10 o of slope, n=54). Each group was evaluated to compare the frequency of additional distal femoral resections due to an insufficient extension gap and the correlation with the decrease of the patellar bone height. Results: In each group, the preoperative tibial slope was 12.77 o (±3.22 o ) vs. 6.72 o (±2.58 o ), respectively (p=0.000) and the decrease of the posterior slope was 10.74 o (±3.54 o ) vs. 4.78 o (±2.66 o ), respectively, (p=0.000). The frequencies of additional distal femoral resection were 54.5% vs. 46.1%, respectively, (p=0.448) with flexion contracture and 11.8% vs. 34.1%, respectively, (p=0.022) without flexion contracture. The decrease of the patellar bone height was 0.35 (±4.79) mm vs. 1.99 (±4.78) mm, respectively, (p=0.075). There was weak correlation between the decrease of the patellar bone height and the decrease of the posterior tibial slope (r= 0.253, p=0.016). Conclusion: In the group having more than 10 o of preoperative posterior tibial slope without flexion contracture, the decrease of the posterior tibial slope had to be considered as one of the factors that affected making the extension gap significantly greater during the gap technique and to preserve the patellar bone height. Key Words: Knee, Degenerative osteoarthritis, Posterior Substituting Total Knee Arthroplasty, Posterior tibial slope, Extension gap, Patellar height 서 정상적인슬관절의경골후방경사각은평균 5 10 o 로다양한값을보고하고있으며 7,22-24,26), 슬관절전치환술후의후방경사각은술후관절운동범위등을포함한수술의결과에영향을미치는중요한요소이다 12,17,18). 최소 Received: October 28, 2010 Revised: (1st) November 24, 2010, (2nd) December 15, 2010 Accepted: February 4, 2011 Corresponding author: Jong-Heon Kim, M.D. Department of Orthopaedic Surgery, Guri Hospital, Hanyang University College of Medicine, 249-1, Gyomun-dong, Guri 471-701, Korea TEL: 82-31-560-2316, FAX: 82-31-557-8781 E-mail: jhkim111@hanyang.ac.kr 론 5 o 이상의경골후방경사각을유지하는것이후방십자인대의긴장을줄이고, 굴곡에유리하다는후방십자인대보존형에비해 2,15,21,23), 후방십자인대대치형은경골대치물의불안정성 1), 후방굴곡불안정성 20), 캠-포스트충돌 (cam-post impingement) 6,16) 등의이유로평균 0 3 o 의경골후방경사각을추천한다 1,6,20). 이로인해술전후방경사각이큰경우후방십자인대보존형에비하여경골고평부의전방부에서더많은양의골절제가이루어지므로 19), 수술의성패에중요한신전및굴곡간격을일치시키는과정과시상면에서의관절선의변화에영향이있을것으로생각된다. 저자들은 10 o 이상의술전경골후방경사각을가진환자에서후방십자인대대치형슬관절전치환술시경골후 7

8 대한슬관절학회지 : 제 23 권제 1 호 2011 Volume 23, Number 1, March 2011 방경사각의감소가신전간격및슬개골의높이에미치는영향에대하여알아보고자하였다. 1. 연구대상 대상및방법 2003 년 2월부터 2005 년 3월까지동일술자가시행한후방십자인대대치형슬관절전치환술 110 예를대상으로하였다. 환자들의수술당시연령은 51세에서 77세까지로평균 65세이었고여자는 68명, 105 예였으며남자는 5명, 5예였으며선행질환은전례에서퇴행성골관절염이었다. 사용된기구는 NexGen R (Zimmer, Warsaw, IN, USA) 79예, PFC Sigma R (Johnson & Johnson, Raynham, MA, USA) 16예, Scorpio R (Stryker, Mahwah, NJ, USA) 12 예, Genesis II R (Smith & nephew, Richards, Memphis, TN, USA) 3예였다. 신전간격에영향을줄수있는술전굴곡구축 23) 에대해서는수술직전마취상태에서각도계 (goniometer) 를이용하여슬관절의최대신전각을측정하였다. 2. 방법 1) 수술방법수술시대퇴골절골술과정에서기본적으로는각대퇴골삽입물의원위부두께만큼을절제하려하였고, 전후절제는모든증례에서 anterior referencing system 을이용하여측정한대퇴골의전후크기에가장근접한삽입물에대한절제를시행하였다. 대퇴골회전정렬은화이트사이드선 (Whiteside's line) 25), 과상간축 (transepicondylar axis) 3), 후과축 (posterior condylar axis) 10) 을참고하여 3 o 외회전을하여대퇴후방골절제를시행하였다. 경골절제는 0 3 o 의후방경사를목표로하여시행하였다. 폴리에틸렌은경골절제된크기만큼의두께를삽입하는것을원칙으로하였으며의도하지않은내외측불안정성 (mediolateral laxity) 에의해과도한두께의폴리에틸렌이삽입된증례는없었다. 원칙적으로굴곡 -신전간격을일치시키고자하였으며원위대퇴골추가절제는치환물의크기를결정한후대퇴골및경골절골술과표준화된술식에따라가능한연부조직의균형을맞춘후가치환물 (trial component) 과스페이서 (spacer) 를이용한골곡- 신전간격의일치화과정에 Fig. 1. The picture shows methods of determining posterior slope of tibia. PTC: posterior tibial cortex. 서굴곡간격에대하여신전간격이부족한경우에대퇴부절제기구 (femoral cutting zig) 를이용하여 2 mm 단위로시행하였다. 최종적으로굴곡 -신전간격이일치되지않은증례는대상에서제외하였다. 2) 측정방법수술전후의경골후방경사각의측정은 Brazier 등 5) 이제시한 6가지방법중경골의후방피질을기준으로술전은경골의내측고평부, 술후는경골절단면의경사를측정하였으며 (Fig. 1) 10 o 이상의술전경골후방경사각을가진 56예 (group I) 와 10 o 미만인 54예 (group II) 로분류하여술전경사에서술후경사를뺀각도를후방경사각의감소 (difference of slope) 로정의하였다. 슬개골높이의측정은 Blackburne-Peel ratio 4) 를응용하여수술전후의일치성을고려하여, 슬개골의하첨부를기준으로하였다. 슬관절측면사진은앙와위에서 30 o 굴곡상태에서촬영되었으며, 계측은술전및술후측면방사선사진에서대퇴경골간관절선으로부터슬개골높이 (patella bone height, PBH) 를측정하였는데, 술전에는슬개골하첨부에서경골상단의관절면까지수직으로내린선의길이 (preo. PBH) 로정의하였으며이때관절면은연골면의두께를고려하여대퇴골과경골간격의중간지점으로설정하였고, 술후에는슬개골하첨부에서인공슬관절경골삽입물관절면까지수직으로내린선의길이 (postop. PBH)

김종헌외 :10 o 이상의경골후방경사각에서의 PS-TKA 9 Fig. 2. The picture shows radiologic measurements of patellar bone height (PBH). 로정의하였다 (Fig. 2). 방사선촬영의확대비율에따른길이의보정을위해, 슬개골의상단과하단간의길이는골극을제외한상태에서측정하였으며술전후의길이의비를이용하여확대비율을보정하여, 보정후술후관절선으로부터의슬개골높이를구하고술전수치에서보정한술후수치를빼관절선으로부터의슬개골높이감소 (dpbh) 를얻었다. 모든수치는단일관찰자에의해 2회반복하여측정되었으며측정치의평균을내어최종수치를결정하였다. 3) 통계방법 Cut-off value의값을구하기위해 R for Windows 2.11.1 (The R Foundation for Statistical Computing, University of Auckland, Auckland, New Zealand) 을이용하여 maximally selected log rank Chi-square analysis 로계산하였으며술전, 술후계측치간의상호유의성은 SPSS for windows 17.0 (SPSS Inc., Chicago, IL, USA) 을이용하여 paired t-test, chi-square test 방법을사용하였다. 계측치간의상관관계는 Pearson correlation analysis를사용하였다. 유의수준은 p<0.05 로하였다. Table 1. Preoperative/Postoperative Posterior Tibial Slope and Change of Patellar Bone Height (n=110) Group A Group B (n=56) (n=54) p-value Preop. slope ( o ) 12.77±3.22 6.72±2.58 0.000 Postop. slope ( o ) 2.03±1.77 1.94±1.59 0.78 dslope 10.74±3.54 4.78±2.66 0.000 dpbh (mm) 0.35±4.79 1.99±4.78 0.075 Flexion 39.3% (n=22) 24.1% (n=13) 0.065 contracture dslope: decrease of posterior tibial slope, dpbh: decrease of patellar bone height. 결 Group I, II에서술전경골후방경사각은평균 12.77 o (±3.22 o ) 와 6.72 o (±2.58 o ) (p=0.000), 술후후방경사각은평균 2.03 o (±1.77 o ) 와 1.94 o (±1.59 o ) (p=0.78), 경골각감소는 10.74 o (±3.54 o ) 와 4.78 o (±2.66 o ) (p=0.000) 이었다. 술전굴곡구축은 39.3% (22/56예) 와 24.1% (13/54 예 ) (p=0.065) 에서있었으며 (Table 1), 굴곡구축의평균은 20.71 o (±8.23 o ) 이었다. 과

10 대한슬관절학회지 : 제 23 권제 1 호 2011 Volume 23, Number 1, March 2011 로측정되었으며통계적으로유의한차이를보이지않았다. 고 찰 Fig. 3. The graph shows the correlation between decrease of posterior slope and difference of patella bone height (Pearson correlation coefficient r= 0.253, p=0.016). 수술중원위대퇴골추가절제빈도는 28.6% (16/56 예 ) 와 37.0% (20/54 예 ) (p=0.229) 이었고, 술전굴곡구축이있는경우에서 54.5% (12/22예) 와 46.1% (6/13예) (p=0.448) 로통계적으로유의한상관관계를보이지않았으나굴곡구축이없는경우에서는 11.8% (4/34 예 ) 와 34.1% (14/41 예 ) (p=0.022) 로통계적으로유의한차이를보였다. 대퇴- 경골관절선을기준으로하여측정한술전슬개골높이는 41.52 (±2.96) mm와 40.36 (±2.99) mm로통계적으로유의한차이를보였으며 (p=0.042), 술후슬개골높이는 45.11 (±3.67) mm와 44.24 (±3.35) mm로유의한차이를보이지않았다 (p=0.199). 슬개골높이감소는 0.35 (±4.79) mm와 1.99 (±4.78) mm (p=0.075) 로두군간의차이를보이지않았으며경골후방경사각감소와슬개골높이감소간에는약한음의상관관계 (r= 0.253, p=0.016) 를보였으나 (Fig. 3), group I, II로나누어경골후방경사각감소와슬개골높이감소를각각비교했을때에는양군모두유의한상관관계를보이지않았다 (group I: r= 0.213, p=0.117, group II: r= 0.120, p=0.387). 원위대퇴골의추가절제로인한관절선의변화를알아보기위해원위대퇴골추가절제가있었던경우와없었던경우에서의 group I, II 간의슬개골높이감소를비교하였으며, 원위대퇴골추가절제가있었던군에서의슬개골높이감소는 1.731 (±5.576) mm와 1.190 (±5.06) mm (p=0.109) 로, 원위대퇴골추가절제가없는군에서는 1.181 (±4.232) mm와 2.459 (±4.62) mm (p=0.219) 저자는이전연구를통해후방십자인대대치형슬관절전치환술에서슬관절전치환술시경골후방경사각의감소는술후슬개골높이에영향을주는요소중하나가될수있으며 14), 또한상대적으로경골전방부의절제를증가시키는효과를보여신전간격을증가시킴을보고한바있다 13). 앞서의고찰에서저자는술전방사선검사를통해후방경사각의감소정도를미리예측하는것이수술중동일한신전-굴곡간격을얻는것과슬개골높이를유지함에도움이될것으로결론지었으며이에본연구에서는술전방사선검사상경골후방경사각의감소정도에대해특히고려해야할술전경골후방경사각의크기에대한구체적인기준을제시해보고자하였다. 정상적으로는경골의후방경사각은측정방법에따라그값이달라지지만평균 5 10 o 의다양한값이보고되고있다 7,22-24,26). 이에저자들은 10 o 의경골후방경사각을기준으로그이상인 group I과미만인 group II를비교하였으며, 실제로가장적절한 cut-off value 를구할수있는통계분석방법인 maximally selected log rank chisquare analysis 11) 를이용하여계산된값역시 10.36 o 로측정되었다. 수술중원위대퇴골추가절제빈도에대해 group I과 group II에서유의한차이가없었으나굴곡구축이없는경우에서는통계적으로유의한차이를보여이는 group I 에서술전경골후방경사각의감소가슬관절전치환술중유의한신전간격을유발할수있는인자가될수있을것으로생각되며술전방사선검사를통해 10 o 이상의경골후방경사각을갖는환자에서의슬관절전치환술의수술시굴곡-신전간격을일치시킬시에충분히고려되어야할것으로생각된다. 슬관절전치환술후슬개골높이에대하여술후대퇴경골간관절선으로부터슬개골높이가증가할수록, 즉슬개골이수술후상부로이동할수록 Hospital for Special Surgery 점수, 관절운동범위가증가하고, 슬관절동통은감소하는연구결과 8) 가이미보고되었으며, 슬관절전치환술의우수한결과를위해서는인공슬개골의하단부가

김종헌외 :10 o 이상의경골후방경사각에서의 PS-TKA 11 관절선에서 1 3 cm 범위에유지되어야함 9) 이보고된바있다. 수술전후의경골후방경사각감소량과슬개골높이감소는유의한음의상관관계가있었음에도불구하고, 슬개골의높이감소는 group I과 group II 간에유의한차이를보이지않았는데 (p=0.075), 이는슬개골의높이가술전의경골후방경사각의크기의절대량이아닌술후와비교하였을때의경골후방경사각의감소량에영향을받기때문으로, 곧경골고평부의전방부위의골절제의정도가슬개골의높이를결정하는민감한인자로써적용되는것으로생각된다. 따라서술전계획수립시슬개골의높이에대해방사선검사상의계측에있어술후예상되는경골후방경사각까지고려된세심한관찰이필요할것으로생각되었다. 전체적으로경골후방경사각과슬개골높이감소에약하지만유의한상관관계가있었음에도불구하고, group I, II로나누었을때는모두슬개골높이감소와의상관관계가유의하게나타나지않은점, 원위대퇴골추가절제의유무에따라각각 group I, II의슬개골높이감소를비교한결과에서평균값의양군간의차이는보였으나통계적으로유의하지않았던점에대해서는군을세분화함에따라통계적의미를가질수있는최소한의개체수가부족해졌기때문으로생각된다. 본연구의제한점으로굴곡및신전간격의크기를수치화하지않은점을들수있으나본연구는굴곡및신전간격의불일치에대해일치화시키는과정에있어서영향을줄수있는인자에대한것이므로절대적인수치는결과에있어서큰의미가없을것으로생각되었다. 단일기구가아닌다양한기구가사용되어생길수있는오차에대해서이론적으로는폴리에틸렌에의한후방경사각에의한차이가있을수있으나술후경골후방경사각이일정하도록표준화된수술술기를동일하게적용하였으며, 또한이는어디까지나임상적인결과의문제로생각되며골절제및그에대한술전후의방사선적측정치에대한본연구의결과에서의영향은미미할것으로생각되었다. 단, 수술전후의임상적결과에대한연구가실행되지않아이에대한추가적인연구가필요할것으로생각된다. 그럼에도불구하고본연구는비교적간편하게술전에검사할수있는측면방사선사진을통해 10 o 이상의경골후방경사각을가진환자의경우에서는근위경골의절제만으로도어느정도의신전간격이유발되므로, 잔존골질 의양을줄이고관절선을상승시키며대퇴골후과의길이가상대적으로짧아지며이로인해고정이불안정해지는등의영향을줄수있는원위대퇴골의추가적인절제가불필요하다는기준을설정한것에의미가있다고생각된다. 결 후방십자인대대치형슬관절전치환술에서술전측면방사선검사소견상 10 o 이상의경골후방경사각을가진환자에서술후경골후방경사각의감소는굴곡구축이없는경우, 10 o 미만의경골후방경사각을가진환자에비교하여상대적인신전간격의증가를초래하여, 수술중굴곡및신전간격을일치시키는과정에고려되어야할요소이며, 또한수술전후의슬개골의높이유지에영향을주는요소로생각되었다. 론 CONFLICT OF INTEREST No potential conflict of interest relevant to this article was reported. REFERENCES 1. Bai B, Baez J, Testa N, Kummer FJ: Effect of posterior cut angle on tibial component loading. J Arthroplasty, 15; 916-920: 2000. 2. Bellemans J, Robijns F, Duerinckx J, Banks S, Vandenneucker H: The influence of tibial slope on maximal flexion after total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc, 13; 193-196: 2005. 3. Berger RA, Rubash HE, Seel MJ, Thompson WH, Crossett LS: Determining the rotational alignment of the femoral component in total knee arthroplasty using the epicondylar axis. Clin Orthop Relat Res, (286); 40-47: 1993. 4. Blackburne JS, Peel TE: A new method of measuring patellar height. J Bone Joint Surg Br, 59; 241-242: 1977. 5. Brazier J, Migaud H, Gougeon F, Cotten A, Fontaine C, Duquennoy A: Evaluation of methods for radiographic measurement of the tibial slope. A study of 83 healthy knees. Rev Chir Orthop Reparatrice Appar Mot,

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김종헌외 :10 o 이상의경골후방경사각에서의 PS-TKA 13 10 o 이상의술전경골후방경사각을가진후방십자인대대치형슬관절전치환술 한양대학교의과대학구리병원정형외과 김종헌ㆍ김순명 목적 : 10 o 이상의술전경골후방경사각을가진환자의후방십자인대대치형슬관절전치환술에서경골후방경사각이신전간격및슬개골의높이변화에미치는영향을알아보고자하였다. 대상및방법 : 후방십자인대대치형슬관절전치환술 110 예를대상으로, 술전경골후방경사각이 10 o 이상인 group I; 56 예와 10 o 미만인 group II; 54 예로분류하여수술중상대적인신전간격의부족에따른원위대퇴골추가절제의시행빈도와슬개골높이감소를비교분석하였다. 결과 : Group I, II 에서의술전경골후방경사각은평균 12.77 o (±3.22 o ) 와 6.72 o (±2.58 o )(p=0.000), 경골후방경사각감소는 10.74 o (±3.54 o ) 와 4.78 o (±2.66 o )(p=0.000) 이었다. 굴곡구축이있는경우수술중원위대퇴골추가절제빈도는 54.5% 와 46.1% (p=0.448) 이었으나, 굴곡구축이없는경우는 11.8% (4 예 ) 와 34.1% (14 예 )(p=0.022) 이었다. 슬개골높이감소는 0.35 (±4.79) mm 와 1.99 (±4.78) mm (p=0.075) 의차이를보였다. 경골후방경사각감소와슬개골높이감소는약한상관관계가있었다 (r= 0.253, p=0.016). 결론 : 후방십자인대대치형슬관절전치환술시 10 o 이상의경골후방경사각을가진환자에서술후경골후방경사각의감소는굴곡구축이없는경우, 10 o 미만의경골후방경사각을가진환자에비교하여상대적인신전간격의증가를초래하여, 수술중굴곡및신전간격을일치시키는과정에고려되어야할요소이며, 또한수술전후의슬개골의높이유지에영향을주는요소로생각되었다. 색인단어 : 슬관절, 퇴행성골관절염, 후방십자인대대치형슬관절전치환술, 경골후방경사각, 신전간격, 슬개골높이