Journal of Korean Society of Spine Surgery Survival Rate and Risk Factor Analysis in Patients Who Experience a New Fracture after Kyphoplasty Jung-Hoo

Journal of Korean Society of Spine Surgery Survival Rate and Risk Factor Analysis in Patients Who Experience a New Fracture after Kyphoplasty Jung-Hoon Kim, M.D., Dong-Hyok Kim, M.D. J Korean Soc Spine Surg 2018 Sep;25(3):99-107. Originally published online September 30, 2018; https://doi.org/10.4184/jkss.2018.25.3.99 Korean Society of Spine Surgery Asan Medical Center 88, Olympic-ro 43 Gil, Songpa-gu, Seoul, 055, Korea Tel: +82-2-483-3413 Fax: +82-2-483-3414 Copyright 2017 Korean Society of Spine Surgery pissn 2093-4378 eissn 2093-4386 The online version of this article, along with updated information and services, is located on the World Wide Web at: http://www.krspine.org/doix.php?id=10.4184/jkss.2018.25.3.99 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http:// creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. www.krspine.org

Original Article J Korean Soc Spine Surg. 2018 Sep;25(3):99-107. https://doi.org/10.4184/jkss.2018.25.3.99 Survival Rate and Risk Factor Analysis in Patients Who Experience a New Fracture after Kyphoplasty Jung-Hoon Kim, M.D., Dong-Hyok Kim, M.D. Department of Orthopedic Surgery, Inje University Ilsan Paik Hospital, Goyang. Korea Study Design: Retrospective study. Objectives: To evaluate the factors related to the incidence of a new fracture in an adjacent vertebra after kyphoplasty for single vertebral body fracture due to osteoporosis and to assess the impact of such factors on patients survival rate. Summary of Literature Review: It is controversial whether fracture of an adjacent vertebra after kyphoplasty is due to the natural course of osteoporosis or as a complication of kyphoplasty. Materials and Methods: From December 2006 to December 2016, among 490 cases of kyphoplasty for single vertebral body fracture due to osteoporosis, 153 cases were analyzed retrospectively. The survival rate was analyzed based on age, gender, body mass index (BMI), fracture level, leakage of cement, amount of cement, compression rate, recovery rate, bone density, osteoporotic medication rate and compliance, existence of a compression fracture, hypertension, diabetes, and smoking habit. The average follow-up duration was 15.1 months (range, 1 month to 8 years and 8 months) and the mean age was 74.4 years (range, 54-93 years). Results: A new fracture in an adjacent vertebral body occurred in 27 cases (17.3%). The 1-year survival rate was 82.6%, the 2-year survival rate was 72.5%, and the 6-year survival rate was 53.7%. The survival rate was significantly higher in patients younger than 75 years (p=0.0495). The survival rate was also significantly higher in patients with a preoperative vertebral bone density greater than 3.7 and hip bone density greater than 2.2 (p<0.0001, p=0.0114). The survival rate was significantly higher in patients with a BMI greater than 18.1 kg/m2 at the time of surgery (p=0.0014). Furthermore, the survival rate was significantly higher in patients with a postoperative recovery of vertebral height of 14% or less (p=0.0031). In addition, the survival rate was higher in patients without a compression fracture before surgery (p=0.0297). In multiple factor analysis, vertebral bone density (p=0.0049) and age (p=0.0408) were identified as statistically significant factors. Conclusions: The survival rate was significantly lower at 1, 2, and 6 years in patients with an adjacent vertebral fracture. The most crucial factors affecting the survival rate were age and vertebral bone density. Key Words: Osteoporosis, Vertebral compression fracture, Kyphoplasty, Survival rate analysis 서론 고령화사회로의진입으로골다공증성추체압박골절이증가함에따라 1) 이에대한보존적치료로침상안정, 약물에의한통증조절, 보조기착용등을시행하지만골량감소및보조기착용의어려움등의단점 2,3) 이발생할수있다. Tosteson 등 4) 의연구에서는척추압박골절후삶의질이 1년뒤에는 20%, 2년뒤는 15% 감소한다고보고하고있고, Meltone 등 5) 의연구에서도추체압박골절환자에서 30% 의사망률증가를보고하고있어이에대한적극적인치료로근래에는추체성형술이개발되어시행되어지고있는데추체성형술후에는골절부안정성증가, 동통의감소및조기거동에있어괄목할만한치료효과가보고되고있어시술의빈도또한증가하고있는추세이다. 6,7) 하지만경피적추체성형술은통증의호전및추체의안정성 이라는점에서효과적인치료방법으로고려되고있으나골절 의정복이나추체높이의회복의효과는미약하다는단점도가 지고있다. 또한시술빈도가증가함에따라추체성형술의합 병증도발생하는데이는골시멘트의강제적주입에의한추체 Received: February 15, 2018 Revised: April 19, 2018 Accepted: July 10, 2018 Published Online: September 30, 2018 Corresponding author: Jung-Hoon Kim, M.D. Department of Orthopedic Surgery, Ilsan Paik Hospital, Inje University College of Medicine, #1, Juhwaro, Ilsanseogu, Goyang, Gyeonggido, Korea ORCID ID: Jung-Hoon Kim: https://orcid.org/0000-0002-9997-0263 Dong-Hyok Kim: https://orcid.org/0000-0002-6181-8x TEL: +82-31-910-7968, FAX: +82-31-910-7967 E-mail: jhkim@paik.ac.kr Copyright 2018 Korean Society of Spine Surgery Journal of Korean Society of Spine Surgery. www.krspine.org. pissn 2093-4378 eissn 2093-4386 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 99

Jung-Hoon Kim et al Volume 25 Number 3 September 30 2018 외, 척수강내및혈관내로의시멘트유출, 이로인한신경마비, 폐색전및감염, 출혈및기흉등이발생할수있다. 8,9) 이런추체성형술의단점및시멘트유출로인한합병증을피하기위해서풍선추체성형술이개발되었으며이는추체내공동을형성하여골절정복을시도할수있고척추후만증을교정하고추체높이를회복하는효과가있으며추체성형술보다상대적으로낮은압력으로시멘트를주입하므로추체외로의시멘트유출가능성도추체성형술보다낮출수있다는보고들이있어몇몇술자들에서는선호되어시행되어지고있다. 10,11) 하지만 Liebschner 등 12) 의연구및여러다른연구에서는추체회복율이높을수록인접추체골절을발생시킬수있다는것을보여주고있으며이는추체성형술과비교하여추체높이를더회복시킬수있는풍선추체성형술이시술자체로인접추체골절의위험요인이될수있다는것을의미한다. 이에저자들은단일척추체에골다공증성압박골절로경피적풍선추체성형술을시행한후인접척추체에발생된새로운골절에따른생존율을분석하고그에관여하는요인을알아보고자하였다. 대상및방법 1. 대상 2006년 12월부터 2016년 12월까지본교실에서골다공증으로인한단일척추체압박골절에대해경피적척추체풍선성형술을시행받은총 490예중추적가능했던 153예를대상으로후향적으로분석하여인접척추체에새로운골절발생에대한생존분석을시행하였다. 경미한충격이나반복적인일상생활등에서골절이발생하는골다공증으로인한압박골절환자에서골주사검사나자기공명영상검사를통해급성압박골절환자중에서단일압박골절환자를대상으로하였으며감염이나종양등의이차성질환이있는환자들은제외하였다. 시술시나이, 성별, 체질량지수, 추간판내로의시멘트유출, 시술시주입된시멘트양, 시술전압박율, 시술후추체높이회복율, 술전골밀도, 술후골다공증약물복용여부및순응도, 고혈압, 당뇨및흡연여부등에따른단일인자및다중인자생존분석을시행하였다. 추시기간 ( 생존기간 ) 은평균 15.1개월 (1개월 ~8년 8개월 ) 로마지막방문했을시까지의기간, 또는인접분절에새로운골절이발생할때까지의기간으로하였으며 1년이상추시는 118 예, 2년이상 29예, 5년이상은 6예였다. 시술시평균나이는 74.4세 (54~93세) 였으며남자는 35명이었고여자는 118명이었고풍선추체성형술을시행하였던부위는제 1요추가 51명 (33.3%), 제 12흉추가 40명 (26.1%), 제 2요추가 17명 (11.1%), 제 11 흉추가 11 명 (7.2%), 제 3 요추가 11 명 (7.2%), 제 8 흉추가 7 명 (4.6%), 제 9 흉추가 3 명 (2.0%), 제 4 요추가 4 명 (2.6%), 기 타부위가 9 명 (5.9%) 으로제 1 요추와제 12 흉추의흉요추부가 전체의 59.5% 였다. 환자들의평균체질량지수는 22.6(13.6 33.3) 이었고평균척추골밀도수치는 -2.1(+0.7-4.9) 이었으 며평균고관절골밀도수치는 -2.7(+0.5-5.1) 이었다. 흡연 자는 13 명, 비흡연자는 140 명이었고당뇨가있었던환자는 28 명, 없었던환자는 125 명이었으며고혈압이있었던환자는 89 명, 없었던환자는 64 명이었다 (Table 1). 2. 연구방법 수술당시나이, 수술당시체질량지수, 술전척추골밀도, 술전고관절골밀도, 술전전방추체압박률및술후추체높 이회복율은 ROC (receive operating characteristic) 곡선을근 거하여기준을정하여분석하였다. 수술당시나이는 75 세를 기준으로하였고 (75 세초과 명, 75 세이하 83 명 ) 수술당 시체질량지수는 18.1 을기준으로하였으며 (18.1 초과 46 명, 18.1 이하 107 명 ) 술전척추골밀도는 -3.7 을기준으로하였고 (-3.7 초과 136 명, -3.7 이하 17 명 ) 술전고관절골밀도는 -2.2 를기준으로하였으며 (-2.2 초과 46 명, -2.2 이하 107 명 ) 시술 시주입된시멘트양은 4cc 를기준으로하였고 (4cc 초과 명, 4cc 이하 83 명 ) 술전전방추체압박율은 22.9% (22.9% 초과 117 명, 22.9% 이하 36 명 ) 를기준으로하였다. 또한, 술후추체 높이회복율은수술전단순방사선사진에서측정한추체전방 높이와수술후단순방사선사진에서측정한추체전방높이의 차이를백분율로나타냈으며 14%(14% 초과 30 명, 14% 이하 Table 1. Demographic and clinical data obtained in patients Parameter Value No. patient 153 Gender (M:F) 35:118 Mean age 74.4(54~93) Mean BMI 22.6(13.6~33.3) Mean BMD Spine -2.1(-4.9~0.7) Hip -2.7(-5.1~0.5) HTN 89 DM 28 Smoking 13 Follow up period(months) 15.2 M: Male, F: Female, BMI: Body mass index, BMD: Bone mineral density, HTN: Hypertension, DM: Diabete. www.krspine.org

Journal of Korean Society of Spine Surgery Survival Rate of new Fracture in Adjacent Vertebral Body After Kyphoplasty Table 2. ROC (receive operating characteristic) curves Parameter Criterion Sensitivity Specificty Age >75 56.0 57.5 Hip BMD 2.2 92.6 34.9 Spine BMD -3.7 29.6 94.4 BMI 18.02 33.3 95.2 Cement amount >4 59.3 57.1 Compression rate 22.9071 37.0 78.6 Reductino rate >14 37.0 84.1 123 명 ) 를기준으로구분하였고시술부위는제 12 흉추와제 1 요추의흉요추부위와이외의부위를나누어구분하여분석하 였다 (Table 2). 골다공증약물복용율과순응도 (compliance) 를알아보았는 데, 약물복용율은 MPR (medication possession rate) 을아래와 같이계산하여 % 미만인경우복용하지않은것으로, % 이상인경우는복용한것으로정의하였다. 1년중처방받은약의일수 MPR (Medication possestion rate)= 365 그리고순응도 (compliance) 는 MPR % 를기준으로 % 미만인경우에는나쁜순응도 (poor compliance) 를, % 이상 인경우좋은순응도 (good compliance) 를가진것으로판단하 여분석하였다. 통계적처리는 MedCalc version 14.8.1 (MedCalc Software, Mariakerke, Belgium) 를이용하여생존율은 Kaplan-Meier 법 으로분석하였고, 새롭게발생한척추골절에대한위험인자를 찾기위해앞에서언급한여러인자들로단일인자및다중인자 분석을시행하였으며단일인자분석은 Log-rank 법을이용하 였고, 다중인자분석은 Cox proportional hazard regression 법을 이용하였다. P 값이 0.05 보다작은경우에유의한것으로판단 하였다. IRB FILE No: 2018-03-008. 결과 연구대상총 156 예중풍선추체성형술시행후인접분절에 새로운골절이발생한예는 27 예 (17.3%) 였으며그중근위부 인접분절에골절이발생한경우는 14 예 (52%) 였고, 원위부인 접분절에골절이발생하였던경우는 13 예 (48%) 였고 (Table 3) 인접분절에새로운골절발생시까지평균기간은 11 개월 (1 Table 3. New fracture at adjacent vertebra Kyphoplasty level Number of new fracture Proximal djacent new fracture Distal adjacent new fracture T8 2 1 1 T9 1 1 T10 T11 3 1 2 T12 8 2 6 L1 7 4 3 L2 2 2 L3 4 3 1 Total 27/156 (17.3%) 14 (52%) 13 (48%) Table 4. Result Parameter Value Postop. Adjacent fx. rate 27 Proximal 14 Distal 13 Preop. Compression fx. 46 Cement leakage Proximal 40 Distal 11 Proximal&distal 2 Average amount of cement(cc) 4.4 Average preop. compression rate(%) 35.3 Average postop. reduction rate(%) 9.0 71 개월 ) 이었다. 기존에골다공증성압박골절이있었던경우는 46 예였고인접추간판으로시멘트유출이있었던경우는총 49 예였으며이중에서근위부추간판으로유출은 40 예, 원위부추 간판으로유출은 11 예였고근위부와원위부의추간판으로동 시에유출된경우는 2 예가있었다 (Table 3). 시술시주입된평 균시멘트양은 4.4(2.0 9.0)cc 이었고술전평균전방추체압 박율은 35.3% (0.5 87%) 였으며술후평균추체높이회복율 은 9.0% (0.1 67.9%) 였다 (Table 4). 골다공증성척추체압박 골절환자에서경피적척추체풍선성형술을시행하고인접척 추체에새로운골절발생이없었던 1 년생존율은 82.6% 였으 며 2 년생존율은 72.5% 였고, 6 년생존율은 53.7% 였다 (Fig. 1). 수술당시나이 75 세를기준으로나누어분석한결과 75 세이 하의생존율이유의하게높게분석되었고 (p=0.0495, Hazard ratio=0.4953, CI=0.2279 1.0763) (Fig. 2A) 술전척추골밀도 www.krspine.org 101

Jung-Hoon Kim et al Volume 25 Number 3 September 30 2018 90 0 20 40 120 Fig. 1. Graph of the survival rate. -3.7을기준으로나누어분석한결과 -3.7 초과에서생존율이유의하게높게분석되었으며 (p<0.0001, Hazard ratio=0.16, CI=0.036 0.7639) (Fig. 2B) 술전고관절골밀도 -2.2를기준으로나누어분석한결과 -2.2 초과에서생존율이유의하게높게분석되었다 (p=0.0114, Hazard ratio=0.1932, CI=0.08434 0.4426) (Fig. 2C) (Table 5). 또한, 수술당시체질량지수 18.1을기준으로 18.1 초과인환자에서생존율이유의하게높게분석되었고 (p=0.0014, Hazard ratio=0.2873, CI=0.08519 0.9690) 술후추체높이회복율 14% 를기준으로나누어분석한결과 14% 이하일경우생존율이유의하게높게분석되었으며 (p=0.0031, Hazard ratio=0.3239, CI=0.1090 0.9625) (Fig. 2D) 이전압박골절의존재유무에따른차이는이전압박골절이없었던경우에생존율이유의하게높게분석되었다 (p=0.0297, Hazard ratio=0.4462, CI=0.1994 0.9987) (Fig. 2E) (Table 5). 성별에따른차이 (p=0.3777), 흡연여부에따른차이 (p=0.5772), 당뇨병유무에따른차이 (p=0.8551), 고혈압유무에따른차이 (p=0.3244), 술전압박율에따른차이 (p=0.78), 인접추간판내로시멘트유출유무에따른차이 (p=0.1230), 시술시주입된시멘트양에따른차이 (p=0.0968), 시술부위에따른차이 (p=0.53), 골다공증약물복용도에따른차이 (p=0.1815), 골다공증약물순응도에따른차이 (p=0.0573), 인접척추체에새로운골절발생생존율에유의한차이를보이지않았다. 이를바탕으로한다중인자분석에서는수술당시나이 (p=0.0408, Hazard ratio=0.4535, CI=0.1985 1.0364) 와술전척추골밀도 (p=0.0049, Hazard ratio=0.2454, CI=0.0923 0.6523) 에서통계적으로의미있는요인으로분석되었다 (Table 6). 그러나, 수술당시체질량지수 (p=0.3962, Hazard ratio=0.67, CI=0.2666 1.6875), 술전고관절골밀도 (p=0.0742, Hazard ratio=0.2582, CI=0.0584 1.1414), A C D Age 90 >75 75 술후추체높이회복율 (p=0.2846, Hazard ratio=1.6526, CI=0.6586 4.14) 및이전압박골절의존재유무에따른차 이 (p=0.3373, Hazard ratio=1.4924, CI=0.6587 3.3813) 는 p 값이 0.05 이상으로유의한의미를가지지못했다. 고찰 0 20 40 120 90 hip BMD >-2.2-2.2 40 0 20 40 120 90 40 Reduction-rate >14 14 0 20 40 120 Spine BMD 90 >-3.7-3.7 40 30 0 20 40 120 BMD >18.1 18.1 골다공증성척추골절로인한즉각적인통증의완화와척추 의안정성유지를위해경피적추체성형술이널리시행되고있 다. 이런추체성형술은골절의정복및추체높이의회복이라 40 20 0 20 0 20 40 120 Previous-fractures No fracture 90 Previous-fractures 40 30 0 20 40 120 Fig. 2. Univariate analysis: (A) age, (B) preoperative spine bone mineral density, (C) preoperative hip bone mineral density, (D) body mass index, (E) reduction rate, (F) previous fractures. B D E 102 www.krspine.org

Journal of Korean Society of Spine Surgery Survival Rate of new Fracture in Adjacent Vertebral Body After Kyphoplasty Table 5. Risk factors (Univariate analysis) Risk factors p Hazard ratio CI Age: 75 vs>75 0.0495 0.4953 0.2279~1.0763 Preop spine BMD: -3.7 vs >-3.7 <0.0001 0.16 0.036~0.7639 Preop hip BMD: -2.2 vs >-2.2 0.0114 0.1932 0.08434~0.4426 Preop BMI: 18.1 vs >18.1 0.0014 0.2873 0.08519~0.9690 Postop reduction: 14 vs >14 0.0031 0.3239 0.1090~0.9625 No preop compression fx. 0.0297 0.4462 0.1994~0.9987 BMD: Bone mineral density, CI: Confidence interval, BMI: Body mass index. Table 6. Risk factors (Multivariate analysis) Variables Hazard ratio CI p Age 75 0.4535 0.1985~1.0364 0.0408 >75 1.00 Preop spine BMD >-3.7 0.2454 0.0923~0.6523 0.0049-3.7 1.00 BMD: Bone mineral density, CI: Confidence interval. 는점에서한계점을가지고있으며시멘트의유출이라는합병증및이로인해유발되는폐색전증, 신경학적손상, 감염, 출혈및기흉등의추가적인합병증도보고되고있다. 8,9) 이러한추체성형술의한계점을극복하고시멘트유출및다른합병증의발생률을낮추고자풍선추체성형술이개발되었는데이는추체내공동을형성해추체성형술보다상대적으로시멘트주입압력을낮게하여시멘트주입을원활하게함으로써추체후만및높이의회복, 시멘트유출의낮은발생률을기대할수있게한다. 하지만풍선추체성형술후새롭게발생하는추체의골절에대한연구가보고되고있는데특히, 인접추체골절발생률은많은문헌에서 6.5~25% 로보고되고있으며 13-16) Pflugmacher 등 17) 은풍선추체성형술후 18.3% 에서 3주 ~22개월사이에인접추체골절이발생한다고보고하고있다. 본연구에서도풍선추체성형술후추가골절발생률은 17.3% 로비슷한연구결과를보이고있음을알수있다. 많은연구에서생역학적으로추체회복율의증가가인접추체의새로운골절의위험인자가될수있다고보고하고있는데 Baroud 등 18) 은시멘트주입으로인하여인접추간판으로의압력이증가하고이것이다시인접추체의추체판 (endplate) 으로전달되어추체판의팽윤 (bulging) 을초래하고인접부위골 절위험을증가시키는지지효과 (pillar effect) 를설명하였다. Berleman 등 19) 은시멘트주입으로인한추체의 stiffness 의증가로인해인접추체로의부하장애를증가시켜골절을유발시킬수있다고보고하고있다. 이를종합해보았을때추체높이회복율이높을수록인접추체골절발생율이증가하는것으로볼수있으며본연구에서도술후회복율 14% 기준으로기준이하일때생존율이유의하게높은것으로분석되었다. 여러연구및결과들을종합하였을때술후추체높이회복에유리한풍선추체성형술에서인접추체골절가능성이높을것으로예상되나 Jensen 등과 Gardos 등 20,21) 의다른여러연구들에서추체성형술후다른인접추체골절가능성은 12~58% 로보고하며이는풍선추체성형술후인접추체골절발생률과비교했을때두시술사이에큰차이가없음을알수있고김등 22) 의연구에서도풍선추체성형술과추체성형술간의생존율에유의한차이를보이지않으며시술방법과상관없이 3% 초과회복율을보인군에서골절발생률이높은결과를보고하였다. 이러한결과로보았을때시술방법에따라인접추체골절발생의위험도가결정되는것이아니라술후추체높이의회복율그자체가새로운골절의위험인자가될수있다고생각할수있다. 본연구에서는경피적풍선추체성형술을시행하고인접척추체에새로운골절발생이없었던 1년생존율은 83% 이며실제새로운골절발생시까지평균기간은 11개월 (1~71 개월 ) 로다른년수에비하여생존율감소가큰것을알수있었으며술후 2년, 6년째에도역시생존율감소가크게나타나전반적으로생존율은점점감소하는양상을보였다. 본연구에서사용된생존분석은기본적으로모든환자가동일한날동일시점에수술을받았다는전제하에시간에따른생존율의변화를보여줌으로써장기추시의결과를시간적추이에따라살펴보는데에의의가있다. 추시중지속적인추적관찰이불가능한경우나추가골절이있었으나본원에서치료받지않은경우또한있을수있어생존율감소나추가골절발생빈도는더높을것이라 www.krspine.org 103

Jung-Hoon Kim et al Volume 25 Number 3 September 30 2018 추정된다. 단순한시멘트주입뿐만아니라주입한시멘트의양에따라서도인접추체의골절을유발할수있다는연구결과도보고되고있다. 특히, Liebschner 등은골시멘트의과다한주입은인접운동분절의정상적물리역학의변화를초래하여이경우과부하가발생하여추체성형술이후압박골절의발생은인접된추체에밀집되어서나타나는경향이있다고하였다. 12) 그러나, 본연구에서는평균시멘트주입량이 4.4 cc로이는다른연구결과들과비교하였을때평균적인시멘트양이었으며 23) 주입된시멘트양에따른생존율에는차이가없었다. Uppin 등 10) 은골다공증이심할수록골절의가능성은증가한다하였으며 Shaofeng Yang 등 11) 은골밀도가높을수록인접추체의골절가능성은낮다고보고하고있다. Zang 등 24) 의연구에서도인접추체골절의발생은낮은골밀도로인한것이라는메타연구또한보고되고있다. 본연구에서도단변량분석에서술전척추골밀도가 -3.7 초과일때, 고관절골밀도가 -2.2 초과일때높은생존율값을또한, 다변량분석에서도술전척추골밀도가 -3.7 초과일때높은생존율을보였다. Siris 등 25) 은골다공증약물복용력과골절율의연관관계를연구한논문들을비교분석하여대체적으로 MPR % 이상의순응도에서골절율이유의하게감소한양상을보인연구결과를보고하였다. 본연구에서는이를기반으로골다공증약물의복용여부와순응도에대해복용여부는 MPR % 이상일때, 순응도가좋은경우는 MPR % 이상일때를기준으로분석을시행하였지만통계적으로유의한값을갖지못했다. 이는복용여부와순응도를단순히처방받은약의일수를이용한통계적인수치로변환하였기때문에임상과통계적수치에대한차이로인한결과일가능성이있으며이미골다공증성골절이발생한환자군에있어시술후골다공증의약물투여가환자의골다공증의호전에크게기여하지못했을것이라는점에서이런연구결과가나온것으로사료된다. 본연구에서는낮은 BMI가인접추체골절의위험인자로분석되었는데낮은 BMI를가지고있는환자군은골다공증이더쉽게발병할수있고추체골절이유발될가능성이높은군에비해서높은것으로알려져있다. 26) 또한 Lin 등 27) 의연구에서는 BMI가 22 미만의군에서인접추체골절발생의위험인자가될수있다고보고하고있는데 BMI는에스트로겐과양의상관관계에있어, 낮은 BMI는지방양과에스트로겐의감소를의미하며이는에스트로겐에의해방지되는골소실및추체골절발생이유발되는것을의미한다. 또한, 본연구에서는술전압박골절이있던군에서생존율이낮은결과를보였는데이는이전의압박골절로인한후만각의변형및추체의생역학적인변화로인해거동이불편해지고 이로인한낙상의위험도가높아질수있으며다른추체에많은하중이걸려인접추체골절을유발할수있을것으로사료된다. 28) Evans AJ 등 29) 의연구에따르면이전추체성형술을받은경우술후환자의동통감소와활동범위의증가로인해추가골절의발생율이높을수있다는연구결과또한보고되고있다. 본연구의단일인자분석에서성별, 흡연, 당뇨병, 술전추체압박율, 인접추간판내로시멘트유출, 시술부위는인접척추체에새로운골절발생생존율에유의한차이를보이지않았으나나이, 술후추체높이회복율, 이전압박골절의존재유무및술전골밀도에대한결과가의미를가지는것으로나타났다. 또한, 이를바탕으로다중인자분석을시행한결과나이와술전척추골밀도가의미를가지는것으로분석되었다. 위의결과를토대로보았을때경피적풍선추체성형술을시행한경우에나이가 75세초과인경우, 술전척추골밀도가 -3.7 이하일경우, 술후 1년, 2년, 6년때에인접분절에재골절이발생할가능성이높을것이라사료된다. 또한, 본연구에서는추체성형술후인접분절의척추체에골절발생에관여하리라생각되는여러인자들에대한분석이자료가충실히갖추어시행하지못한한계가있으며특히추체성형술부위와인접상하추체간의생역학적측면을고려하지않았고임상적평가및장기적인골다공증약물치료및약물제제에따른차이에대한평가가첨가되지못한제한이있어향후이에대한연구가필요하리라사료된다. 결론 골다공증성압박골절로추체성형술후인접분절추체에새로운골절발생에대한생존율은 1년, 2년, 6년째에의미있는감소가있었고생존분석결과가장중요한인자는나이와술전척추골밀도임을알수있었다. REFERENCES 1. Charles H. Osteroporosis, an Underdiagnosed disease. JAMA. 2001;286(22):2865-6. DOI:10.1/ jama.286.22.2865. 2. Hall SE, Criddel ra, Comito TL, et al. A case-control study of quality of life and functional impairment in women with long-standing vertebral osteoporotic fracture. Osteoporosis Int. 1999;9(6):8-15. DOI: 10.7/s001901. 3. Pradhan BB, Bae HW, Patel VV, et al. Kyphoplasty reduction of osteoporotic vertebra compression fractures: Cor- 104 www.krspine.org

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Original Article J Korean Soc Spine Surg. 2018 Sep;25(3):99-107. https://doi.org/10.4184/jkss.2018.25.3.107 풍선추체성형술후새로운골절발생에대한생존율및위험인자분석 김정훈 김동혁인제대학교일산백병원정형외과학교실연구계획 : 후향적연구목적 : 골다공증으로인한단일추체압박골절에서풍선추체성형술후인접추체골절발생에대한생존율을분석하고그에관여하는요인을알아보고자하였다. 선행연구문헌의요약 : 풍선추체성형술후인접추체에새로운골절발생이수술에의한것인지골다공증의자연경과인지에대해논란이많다. 대상및방법 : 2006년 12월부터 2016년 12월까지본교실에서골다공증으로인한단일추체압박골절에대해풍선추체성형술을시행받은총 490예중추적가능했던 153예를대상으로후향적으로인접추체에새로운골절발생에대한생존분석을시행하였다. 시술시나이, 성별, 체질량지수, 골절부위, 추간판내로의시멘트유출, 시멘트양, 시술전압박율, 시술후추체높이회복율, 술전골밀도, 술후골다공증약물복용여부및순응도, 술전압박골절유무, 고혈압, 당뇨및흡연여부등에따른생존분석을시행하였다. 평균추시기간은 15.1개월 (1개월 ~8년 8개월 ), 시술시평균나이는 74.4세 (54~93 세 ) 였다. 결과 : 총 153예중인접추체에새로운골절이발생한경우는 27예 (17.3%) 였으며추체압박골절환자에서풍선추체성형술후인접추체에새로운골절발생이없었던 1년생존율은 82.6%, 2년생존율은 72.5%, 6년생존율은 53.7% 였다. 수술당시나이 75세를기준으로 75세이하의생존율이유의하게높게분석되었으며 (p=0.0495) 술전척추골밀도 -3.7을기준으로 -3.7 초과, 술전고관절골밀도 -2.2를기준으로 -2.2 초과인환자에서생존율이유의하게높게분석되었다 (p<0.0001, p=0.0114). 또한, 수술당시체질량지수 18.1을기준으로 18.1 초과인환자에서생존율이유의하게높게분석되었고 (p=0.0014) 술후추체높이회복율 14% 를기준으로 14% 이하일경우생존율이유의하게높게분석되었으며 (p=0.0031). 술전압박골절이없는경우에도생존율이유의하게높게분석되었다 (p=0.297). 다중인자분석에서는수술당시나이 (p=0.0408) 와술전척추골밀도 (p=0.0049) 가통계적으로의미있는요인으로분석되었다. 결론 : 골다공증성압박골절로풍선추체성형술후인접분절추체에새로운골절발생에대한생존율은 1년, 2년, 6년째에의미있는감소가있었고생존분석결과가장중요한인자는나이와술전척추골밀도로볼수있다. 색인단어 : 골다공증, 척추압박골절, 풍선추체성형술, 생존분석 약칭제목 : 풍선성형술후인접추체골절생존율 접수일 : 2018년 2월 15일 수정일 : 2018년 4월 19일 게재확정일 : 2018년 7월 10일 교신저자 : 김정훈 경기도고양시일산서구주화로 1 인제대학교일산백병원정형외과교실 TEL: 031-910-7968 FAX: 031-910-7967 E-mail: jhkim@paik.ac.kr Copyright 2018 Korean Society of Spine Surgery Journal of Korean Society of Spine Surgery. www.krspine.org. pissn 2093-4378 eissn 2093-4386 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 107