메뉴 건너뛰기




Volumn 469, Issue 1, 2011, Pages 180-187

Do ion levels in hip resurfacing differ from metal-on-metal THA at midterm?

Author keywords

[No Author keywords available]

Indexed keywords

CHROMIUM; COBALT; MOLYBDENUM;

EID: 78951485750     PISSN: 0009921X     EISSN: 15281132     Source Type: Journal    
DOI: 10.1007/s11999-010-1424-3     Document Type: Conference Paper
Times cited : (46)

References (40)
  • 1
    • 33645217473 scopus 로고    scopus 로고
    • Background of metal-on-metal resurfacing
    • 1:STN:280:DC%2BD283ksFKlsA%3D%3D 16669378
    • HC Amstutz MJ Le Duff 2006 Background of metal-on-metal resurfacing Proc Inst Mech Eng H 220 85 94 1:STN:280:DC%2BD283ksFKlsA%3D%3D 16669378
    • (2006) Proc Inst Mech Eng H , vol.220 , pp. 85-94
    • Amstutz, H.C.1    Le Duff, M.J.2
  • 2
    • 0035184881 scopus 로고    scopus 로고
    • The wear pattern in metal-on-metal hip prostheses
    • 1:CAS:528:DC%2BD3MXos1aqtL4%3D 10.1002/jbm.1068 11745520
    • HL Anissian A Stark V Good H Dahlstrand IC Clarke 2001 The wear pattern in metal-on-metal hip prostheses J Biomed Mater Res 58 673 678 1:CAS:528:DC%2BD3MXos1aqtL4%3D 10.1002/jbm.1068 11745520
    • (2001) J Biomed Mater Res , vol.58 , pp. 673-678
    • Anissian, H.L.1    Stark, A.2    Good, V.3    Dahlstrand, H.4    Clarke, I.C.5
  • 3
    • 24344495778 scopus 로고    scopus 로고
    • How do serum cobalt and chromium levels change after metal-on-metal hip resurfacing?
    • 10.1097/01.blo.0000166901.84323.5d 16131888
    • DL Back DA Young AJ Shimmin 2005 How do serum cobalt and chromium levels change after metal-on-metal hip resurfacing? Clin Orthop Relat Res 438 177 181 10.1097/01.blo.0000166901.84323.5d 16131888
    • (2005) Clin Orthop Relat Res , vol.438 , pp. 177-181
    • Back, D.L.1    Young, D.A.2    Shimmin, A.J.3
  • 4
    • 0142252192 scopus 로고
    • In vivo corrosion of a cobalt-base and its biological consequences
    • Hildebrand HF, Champy M eds NATO ASI Series. New York, NY: Plenum Press
    • Black J. In vivo corrosion of a cobalt-base and its biological consequences. In: Hildebrand HF, Champy M eds. Biocompatibility of Co-Cr-Ni Alloys. NATO ASI Series. New York, NY: Plenum Press; 1988;83-100.
    • (1988) Biocompatibility of Co-Cr-Ni Alloys , pp. 83-100
    • Black, J.1
  • 5
    • 0041527157 scopus 로고    scopus 로고
    • Levels of metal ions after small-and large-diameter metal-on-metal hip arthroplasty
    • 1:STN:280:DC%2BD3szpsVGhsA%3D%3D 12931818
    • MT Clarke PT Lee A Arora RN Villar 2003 Levels of metal ions after small-and large-diameter metal-on-metal hip arthroplasty J Bone Joint Surg Br 85 913 917 1:STN:280:DC%2BD3szpsVGhsA%3D%3D 12931818
    • (2003) J Bone Joint Surg Br , vol.85 , pp. 913-917
    • Clarke, M.T.1    Lee, P.T.2    Arora, A.3    Villar, R.N.4
  • 6
    • 59949104219 scopus 로고    scopus 로고
    • Six-year results of a prospective study of metal ion levels in young patients with metal-on-metal hip resurfacings
    • 1:STN:280:DC%2BD1M7hslGntQ%3D%3D 19190049
    • J Daniel H Ziaee C Pradhan DJ McMinn 2009 Six-year results of a prospective study of metal ion levels in young patients with metal-on-metal hip resurfacings J Bone Joint Surg Br 91 176 179 1:STN:280:DC%2BD1M7hslGntQ%3D%3D 19190049
    • (2009) J Bone Joint Surg Br , vol.91 , pp. 176-179
    • Daniel, J.1    Ziaee, H.2    Pradhan, C.3    McMinn, D.J.4
  • 7
    • 58249088819 scopus 로고    scopus 로고
    • Initial American experience with hip resurfacing following FDA approval
    • 10.1007/s11999-008-0563-2 18949528
    • CJ Della Valle RM Nunley SJ Raterman RL Barrack 2009 Initial American experience with hip resurfacing following FDA approval Clin Orthop Relat Res 467 72 78 10.1007/s11999-008-0563-2 18949528
    • (2009) Clin Orthop Relat Res , vol.467 , pp. 72-78
    • Della Valle, C.J.1    Nunley, R.M.2    Raterman, S.J.3    Barrack, R.L.4
  • 8
    • 0032190304 scopus 로고    scopus 로고
    • Metal wear particle characterization from metal on metal total hip replacements: Transmission electron microscopy study of periprosthetic tissues and isolated particles
    • 1:CAS:528:DyaK1cXlvVCjsLc%3D 10.1002/(SICI)1097-4636(199810)42:1<103: AID-JBM13>3.0.CO;2-M 9740012
    • PF Doorn PA Campbell J Worrall PD Benya HA McKellop HC Amstutz 1998 Metal wear particle characterization from metal on metal total hip replacements: transmission electron microscopy study of periprosthetic tissues and isolated particles J Biomed Mater Res 42 103 111 1:CAS:528:DyaK1cXlvVCjsLc%3D 10.1002/(SICI)1097-4636(199810)42:1<103:AID-JBM13>3.0.CO;2-M 9740012
    • (1998) J Biomed Mater Res , vol.42 , pp. 103-111
    • Doorn, P.F.1    Campbell, P.A.2    Worrall, J.3    Benya, P.D.4    McKellop, H.A.5    Amstutz, H.C.6
  • 9
    • 9444289847 scopus 로고    scopus 로고
    • Tissue reaction to metal on metal total hip prostheses
    • 10.1097/00003086-199608001-00017 8769334
    • PF Doorn JM Mirra PA Campbell HC Amstutz 1996 Tissue reaction to metal on metal total hip prostheses Clin Orthop Relat Res 329 suppl S187 S205 10.1097/00003086-199608001-00017 8769334
    • (1996) Clin Orthop Relat Res , vol.329 , Issue.SUPPL.
    • Doorn, P.F.1    Mirra, J.M.2    Campbell, P.A.3    Amstutz, H.C.4
  • 10
    • 14844286982 scopus 로고    scopus 로고
    • Metal-on-metal total hip replacement: What does the literature say?
    • 10.1016/j.arth.2004.08.011 15902856
    • JH Dumbleton MT Manley 2005 Metal-on-metal total hip replacement: what does the literature say? J Arthroplasty 20 174 188 10.1016/j.arth.2004.08.011 15902856
    • (2005) J Arthroplasty , vol.20 , pp. 174-188
    • Dumbleton, J.H.1    Manley, M.T.2
  • 11
    • 76249133477 scopus 로고    scopus 로고
    • The John Charnley Award: Metal-on-metal hip resurfacing versus large-diameter head metal-on-metal total hip arthroplasty: A randomized clinical trial
    • 10.1007/s11999-009-1029-x 19697090
    • DS Garbuz M Tanzer NV Greidanus BA Masri CP Duncan 2010 The John Charnley Award: Metal-on-metal hip resurfacing versus large-diameter head metal-on-metal total hip arthroplasty: a randomized clinical trial Clin Orthop Relat Res 468 318 325 10.1007/s11999-009-1029-x 19697090
    • (2010) Clin Orthop Relat Res , vol.468 , pp. 318-325
    • Garbuz, D.S.1    Tanzer, M.2    Greidanus, N.V.3    Masri, B.A.4    Duncan, C.P.5
  • 14
    • 43549083291 scopus 로고    scopus 로고
    • Th1 type lymphocyte reactivity to metals in patients with total hip arthroplasty
    • February 13. doi: 10.1186/1749-799X-3-6
    • Hallab NJ, Caicedo M, Finnegan A, Jacobs JJ. Th1 type lymphocyte reactivity to metals in patients with total hip arthroplasty. J Orthop Surg Res. 2008;3:6. February 13. doi: 10.1186/1749-799X-3-6.
    • (2008) J Orthop Surg Res. , vol.3 , pp. 6
    • Hallab, N.J.1    Caicedo, M.2    Finnegan, A.3    Jacobs, J.J.4
  • 15
    • 0035108321 scopus 로고    scopus 로고
    • Metal sensitivity in patients with orthopaedic implants
    • 10.1302/0301-620X.83B3.9674 11263649
    • N Hallab K Merritt JJ Jacobs 2001 Metal sensitivity in patients with orthopaedic implants J Bone Joint Surg Am 83 428 436 10.1302/0301-620X.83B3.9674 11263649
    • (2001) J Bone Joint Surg Am , vol.83 , pp. 428-436
    • Hallab, N.1    Merritt, K.2    Jacobs, J.J.3
  • 16
    • 0014525462 scopus 로고
    • Traumatic arthritis of the hip after dislocation and acetabular fractures: Treatment by mold arthroplasty. An end-result study using a new method of result evaluation
    • 1:STN:280:DyaF1M3gtlWltQ%3D%3D 5783851
    • WH Harris 1969 Traumatic arthritis of the hip after dislocation and acetabular fractures: treatment by mold arthroplasty. An end-result study using a new method of result evaluation J Bone Joint Surg Am 51 737 755 1:STN:280:DyaF1M3gtlWltQ%3D%3D 5783851
    • (1969) J Bone Joint Surg Am , vol.51 , pp. 737-755
    • Harris, W.H.1
  • 18
    • 16844377563 scopus 로고    scopus 로고
    • The relationship between activity and ions in patients with metal-on-metal bearing hip prostheses
    • 10.2106/JBJS.D.01820 15805207
    • C Heisel M Silva AK Skipor JJ Jacobs TP Schmalzried 2005 The relationship between activity and ions in patients with metal-on-metal bearing hip prostheses J Bone Joint Surg Am 87 781 787 10.2106/JBJS.D.01820 15805207
    • (2005) J Bone Joint Surg Am , vol.87 , pp. 781-787
    • Heisel, C.1    Silva, M.2    Skipor, A.K.3    Jacobs, J.J.4    Schmalzried, T.P.5
  • 19
    • 0031727764 scopus 로고    scopus 로고
    • Metal release in patients who have had a primary total hip arthroplasty: A prospective, controlled, longitudinal study
    • 1:STN:280:DyaK1M%2FhsFygsA%3D%3D 9801213
    • JJ Jacobs AK Skipor LM Patterson NJ Hallab WG Paprosky J Black JO Galante 1998 Metal release in patients who have had a primary total hip arthroplasty: a prospective, controlled, longitudinal study J Bone Joint Surg Am 80 1447 1458 1:STN:280:DyaK1M%2FhsFygsA%3D%3D 9801213
    • (1998) J Bone Joint Surg Am , vol.80 , pp. 1447-1458
    • Jacobs, J.J.1    Skipor, A.K.2    Patterson, L.M.3    Hallab, N.J.4    Paprosky, W.G.5    Black, J.6    Galante, J.O.7
  • 21
    • 0032112143 scopus 로고    scopus 로고
    • Alternative bearing surfaces for total joint arthroplasty
    • 1:STN:280:DyaK1czkvVGjtQ%3D%3D 9682082
    • LM Jazrawi FJ Kummer PE DiCesare 1998 Alternative bearing surfaces for total joint arthroplasty J Am Acad Orthop Surg 6 198 203 1:STN:280: DyaK1czkvVGjtQ%3D%3D 9682082
    • (1998) J Am Acad Orthop Surg , vol.6 , pp. 198-203
    • Jazrawi, L.M.1    Kummer, F.J.2    Dicesare, P.E.3
  • 22
    • 33749340043 scopus 로고    scopus 로고
    • Importance of head diameter, clearance, and cup wall thickness in elastohydrodynamic lubrication analysis of metal-on-metal hip resurfacing prostheses
    • 16961189
    • F Liu Z Jin P Roberts P Grigoris 2006 Importance of head diameter, clearance, and cup wall thickness in elastohydrodynamic lubrication analysis of metal-on-metal hip resurfacing prostheses Proc Inst Mech Eng H 220 695 704 16961189
    • (2006) Proc Inst Mech Eng H , vol.220 , pp. 695-704
    • Liu, F.1    Jin, Z.2    Roberts, P.3    Grigoris, P.4
  • 23
    • 9644295677 scopus 로고    scopus 로고
    • Can a safe level for metal ions in patients with metal-on-metal total hip arthroplasties be determined?
    • 10.1016/j.arth.2004.09.008 15578557
    • SJ MacDonald 2004 Can a safe level for metal ions in patients with metal-on-metal total hip arthroplasties be determined? J Arthroplasty 19 8 suppl 3 71 10.1016/j.arth.2004.09.008 15578557
    • (2004) J Arthroplasty , vol.19 , Issue.8 SUPPL. 3 , pp. 71
    • MacDonald, S.J.1
  • 24
    • 9644270292 scopus 로고    scopus 로고
    • A consensus paper on metal ions in metal-on-metal hip arthroplasties
    • 10.1016/j.arth.2004.09.009 15578546
    • SJ MacDonald W Brodner JJ Jacobs 2004 A consensus paper on metal ions in metal-on-metal hip arthroplasties J Arthroplasty 19 8 suppl 3 12 10.1016/j.arth.2004.09.009 15578546
    • (2004) J Arthroplasty , vol.19 , Issue.8 SUPPL. 3 , pp. 12
    • MacDonald, S.J.1    Brodner, W.2    Jacobs, J.J.3
  • 25
    • 77549088281 scopus 로고    scopus 로고
    • Contact mechanics and elastohydrodynamic lubrication in a novel metal-on-metal hip implant with an aspherical bearing surface
    • 10.1016/j.jbiomech.2009.11.018 20003978
    • Q Meng L Gao F Liu P Yang J Fisher Z Jin 2010 Contact mechanics and elastohydrodynamic lubrication in a novel metal-on-metal hip implant with an aspherical bearing surface J Biomech 43 849 857 10.1016/j.jbiomech.2009.11.018 20003978
    • (2010) J Biomech , vol.43 , pp. 849-857
    • Meng, Q.1    Gao, L.2    Liu, F.3    Yang, P.4    Fisher, J.5    Jin, Z.6
  • 26
    • 0030990581 scopus 로고    scopus 로고
    • The biological exposure indices: A key component in protecting workers from toxic chemicals
    • 1:CAS:528:DyaK2sXktVCnsb4%3D 10.2307/3433400 9114280
    • MS Morgan 1997 The biological exposure indices: a key component in protecting workers from toxic chemicals Environ Health Perspect 105 suppl 1 105 115 1:CAS:528:DyaK2sXktVCnsb4%3D 10.2307/3433400 9114280
    • (1997) Environ Health Perspect , vol.105 , Issue.SUPPL. 1 , pp. 105-115
    • Morgan, M.S.1
  • 27
    • 42449094638 scopus 로고    scopus 로고
    • Does ion release differ between hip resurfacing and metal-on-metal THA?
    • 10.1007/s11999-007-0106-2 18196364
    • A Moroni L Savarino M Cadossi N Baldini S Giannini 2008 Does ion release differ between hip resurfacing and metal-on-metal THA? Clin Orthop Relat Res 466 700 707 10.1007/s11999-007-0106-2 18196364
    • (2008) Clin Orthop Relat Res , vol.466 , pp. 700-707
    • Moroni, A.1    Savarino, L.2    Cadossi, M.3    Baldini, N.4    Giannini, S.5
  • 28
    • 33748368667 scopus 로고    scopus 로고
    • Ion concentrations from hip implants
    • 16919205
    • A Sargeant T Goswami M Swank 2006 Ion concentrations from hip implants J Surg Orthop Adv 15 113 114 16919205
    • (2006) J Surg Orthop Adv , vol.15 , pp. 113-114
    • Sargeant, A.1    Goswami, T.2    Swank, M.3
  • 29
    • 0036380582 scopus 로고    scopus 로고
    • Ion release in patients with metal-on-metal hip bearings in total joint replacement: A comparison with metal-on-polyethylene bearings
    • 1:CAS:528:DC%2BD38XnsFKmtrg%3D 10.1002/jbm.10299 12209889
    • L Savarino D Granchi G Ciapetti E Cenni A Nardi Pantoli R Rotini CA Veronesi N Baldini A Giunti 2002 Ion release in patients with metal-on-metal hip bearings in total joint replacement: a comparison with metal-on-polyethylene bearings J Biomed Mater Res. 63 467 474 1:CAS:528:DC%2BD38XnsFKmtrg%3D 10.1002/jbm.10299 12209889
    • (2002) J Biomed Mater Res. , vol.63 , pp. 467-474
    • Savarino, L.1    Granchi, D.2    Ciapetti, G.3    Cenni, E.4    Nardi Pantoli, A.5    Rotini, R.6    Veronesi, C.A.7    Baldini, N.8    Giunti, A.9
  • 30
    • 18344406592 scopus 로고    scopus 로고
    • Sister chromatid exchanges and ion release in patients wearing fracture fixation devices
    • 1:CAS:528:DC%2BD3cXntFegsw%3D%3D 10.1002/(SICI)1097-4636(200004)50: 1<21:AID-JBM4>3.0.CO;2-R 10644959
    • L Savarino S Stea D Granchi M Visentin G Ciapetti ME Donati G Rollo G Zinghi A Pizzoferrato L Montanaro A Toni 2000 Sister chromatid exchanges and ion release in patients wearing fracture fixation devices J Biomed Mater Res. 50 21 26 1:CAS:528:DC%2BD3cXntFegsw%3D%3D 10.1002/(SICI)1097-4636(200004)50:1<21: AID-JBM4>3.0.CO;2-R 10644959
    • (2000) J Biomed Mater Res. , vol.50 , pp. 21-26
    • Savarino, L.1    Stea, S.2    Granchi, D.3    Visentin, M.4    Ciapetti, G.5    Donati, M.E.6    Rollo, G.7    Zinghi, G.8    Pizzoferrato, A.9    Montanaro, L.10    Toni, A.11
  • 31
    • 0033372378 scopus 로고    scopus 로고
    • Increased blood cobalt and chromium after total hip replacement
    • 1:CAS:528:DC%2BD3cXlsVCqtA%3D%3D 10.1081/CLT-100102463 10630267
    • AW Schaffer A Pilger C Engelhardt K Zweymueller HW Ruediger 1999 Increased blood cobalt and chromium after total hip replacement J Toxicol Clin Toxicol. 37 839 844 1:CAS:528:DC%2BD3cXlsVCqtA%3D%3D 10.1081/CLT-100102463 10630267
    • (1999) J Toxicol Clin Toxicol. , vol.37 , pp. 839-844
    • Schaffer, A.W.1    Pilger, A.2    Engelhardt, C.3    Zweymueller, K.4    Ruediger, H.W.5
  • 33
    • 11844297258 scopus 로고    scopus 로고
    • Metal-on-metal total hip replacement
    • 10.1097/01.blo.0000149995.84350.d7 15662304
    • M Silva C Heisel TP Schmalzried 2005 Metal-on-metal total hip replacement Clin Orthop Relat Res. 430 53 61 10.1097/01.blo.0000149995.84350.d7 15662304
    • (2005) Clin Orthop Relat Res. , vol.430 , pp. 53-61
    • Silva, M.1    Heisel, C.2    Schmalzried, T.P.3
  • 34
    • 0346037224 scopus 로고    scopus 로고
    • Serum and urine metal levels in patients with metal-on-metal surface arthroplasty
    • 1:CAS:528:DC%2BD38XoslGmt7Y%3D 10.1023/A:1021179029640 15348670
    • AK Skipor PA Campbell LM Patterson HC Amstutz TP Schmalzried JJ Jacobs 2002 Serum and urine metal levels in patients with metal-on-metal surface arthroplasty J Mater Sci Mater Med. 13 1227 1234 1:CAS:528:DC%2BD38XoslGmt7Y%3D 10.1023/A:1021179029640 15348670
    • (2002) J Mater Sci Mater Med. , vol.13 , pp. 1227-1234
    • Skipor, A.K.1    Campbell, P.A.2    Patterson, L.M.3    Amstutz, H.C.4    Schmalzried, T.P.5    Jacobs, J.J.6
  • 35
    • 0035229408 scopus 로고    scopus 로고
    • The effect of femoral head diameter upon lubrication and wear of metal-on-metal total hip replacements
    • 1:STN:280:DC%2BD3M3ptlOqtw%3D%3D 11382075
    • SL Smith D Dowson AA Goldsmith 2001 The effect of femoral head diameter upon lubrication and wear of metal-on-metal total hip replacements Proc Inst Mech Eng H. 215 161 170 1:STN:280:DC%2BD3M3ptlOqtw%3D%3D 11382075
    • (2001) Proc Inst Mech Eng H. , vol.215 , pp. 161-170
    • Smith, S.L.1    Dowson, D.2    Goldsmith, A.A.3
  • 36
    • 0025336472 scopus 로고
    • Tribologic behavior of metal/metal combinations for artificial hip joints [in German]
    • 1:STN:280:DyaK3czivFCltQ%3D%3D 10.1515/bmte.1990.35.5.107
    • RM Streicher R Schon MF Semlitsch 1990 [Tribologic behavior of metal/metal combinations for artificial hip joints] [in German] Biomed Tech (Berl) 35 107 111 1:STN:280:DyaK3czivFCltQ%3D%3D 10.1515/bmte.1990.35.5.107
    • (1990) Biomed Tech (Berl) , vol.35 , pp. 107-111
    • Streicher, R.M.1    Schon, R.2    Semlitsch, M.F.3
  • 37
    • 9644263984 scopus 로고    scopus 로고
    • Accumulation in liver and spleen of metal particles generated at nonbearing surfaces in hip arthroplasty
    • 10.1016/j.arth.2004.09.013 15578561
    • RM Urban MJ Tomlinson DJ Hall JJ Jacobs 2004 Accumulation in liver and spleen of metal particles generated at nonbearing surfaces in hip arthroplasty J Arthroplasty 19 8 suppl 3 94 101 10.1016/j.arth.2004.09.013 15578561
    • (2004) J Arthroplasty , vol.19 , Issue.8 SUPPL. 3 , pp. 94-101
    • Urban, R.M.1    Tomlinson, M.J.2    Hall, D.J.3    Jacobs, J.J.4
  • 38
    • 34249789255 scopus 로고    scopus 로고
    • Chromium and cobalt ion release following the Durom high carbon content, forged metal-on-metal surface replacement of the hip
    • 10.1302/0301-620X.89B4.18054 17463109
    • PA Vendittoli S Mottard AG Roy C Dupont M Lavigne 2007 Chromium and cobalt ion release following the Durom high carbon content, forged metal-on-metal surface replacement of the hip J Bone Joint Surg Br. 89 441 448 10.1302/0301-620X.89B4.18054 17463109
    • (2007) J Bone Joint Surg Br. , vol.89 , pp. 441-448
    • Vendittoli, P.A.1    Mottard, S.2    Roy, A.G.3    Dupont, C.4    Lavigne, M.5
  • 39
    • 33749477485 scopus 로고    scopus 로고
    • Exposure to chromium, cobalt and molybdenum from metal-on-metal total hip replacement and hip resurfacing arthroplasty
    • 10.1080/17453670610012863 17068698
    • WC Witzleb J Ziegler F Krummenauer V Neumeister KP Guenther 2006 Exposure to chromium, cobalt and molybdenum from metal-on-metal total hip replacement and hip resurfacing arthroplasty Acta Orthop. 77 697 705 10.1080/ 17453670610012863 17068698
    • (2006) Acta Orthop. , vol.77 , pp. 697-705
    • Witzleb, W.C.1    Ziegler, J.2    Krummenauer, F.3    Neumeister, V.4    Guenther, K.P.5
  • 40
    • 33645219513 scopus 로고    scopus 로고
    • Understanding the role of corrosion in the degradation of metal-on-metal implants
    • 1:CAS:528:DC%2BD28Xksl2gs7Y%3D 10.1243/095441105X63246 16669385
    • Y Yan A Neville D Dowson 2006 Understanding the role of corrosion in the degradation of metal-on-metal implants Proc Inst Mech Eng H. 220 173 181 1:CAS:528:DC%2BD28Xksl2gs7Y%3D 10.1243/095441105X63246 16669385
    • (2006) Proc Inst Mech Eng H. , vol.220 , pp. 173-181
    • Yan, Y.1    Neville, A.2    Dowson, D.3


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.