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Introduction Methods Results Conclusion Metal on Metal Metal on

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Introduction Methods Results Conclusion Metal on Metal Metal on Powered By Docstoc
					                             Outcome of Metal on Metal articulation in Primary Conventional THA: Analysis of 17,833 procedures
                                                                                                                                Disclosure: No potential conflicts of interest of listed authors

                                                                                     Stephen Graves1, Richard de Steiger1, David Davidson1, Philip Ryan2, Lisa Miller2, Kara Cashman2
                                                                                     1Australian   Orthopaedic Association National Joint Replacement Registry; 2Data Management & Analysis Centre, Discipline of Public Health, University of Adelaide, Australia


Australian Orthopaedic Association National Joint Replacement Registry
www.dmac.adelaide.edu.au/aoanjrr/index.jsp                                                                                                                                                                                                                   Metal on Metal                                                                                                                Metal on Polyethylene
Introduction                                                                                                                                                                                        Head Size
                                                                                                                                                                                                                                     12%
                                                                                                                                                                                                                                                                                                                                                 Head Size
                                                                                                                                                                                                                                                                                                                                                                               12%
                                                                                                                                                                                                                                               ≤32mm                                                                                                                                   ≤32mm
 There is limited information on the outcome of metal on metal articulation in           Both females and males have a higher rate of revision when a MoM                                                                                      >32mm                                                                                                                                   >32mm
                                                                                                                                                                                                                                     10%                                                                                                                                       10%
 conventional total hip arthroplasty (THA).       This study presents Australian         articulation is used compared to MoP. When a MoM articulation is used




                                                                                                                                                                                                       Cumulative Percent Revision




                                                                                                                                                                                                                                                                                                                                                 Cumulative Percent Revision
 Orthopaedic Association National Joint Replacement Registry data on the                 females have a higher rate of revision compared to males. This contrasts to                                                                  8%                                                                                                                                        8%


 outcome of metal on metal (MoM) and metal on polyethylene (MoP)                         MoP articulation where males have a higher rate of revision.                                                                                 6%                                                                                                                                        6%

 articulations in primary conventional THA.          The survivorship of MoM
                                                                                                                                                                                                                                      4%                                                                                                                                        4%
 articulations when used in conventional THA is presented and compared to                   Females (MoM vs MoP)
 MoP articulations reported to the Registry during the same time period.                           0-1.5 years:            HR=1.4 (1.2, 1.6)       p<0.001                                                                            2%                                                                                                                                        2%


                                                                                                   1.5-3 years:            HR=3.7 (2.9, 4.8)       p<0.001                                                                            0%                                                                                                                                        0%
                                                                                                                                                                                                                                       0.0       1.0       2.0      3.0      4.0      5.0       6.0   7.0   8.0   9.0                                                            0.0     1.0     2.0     3.0      4.0       5.0      6.0   7.0   8.0   9.0
Methods                                                                                            3-5 years:              HR=2.1 (1.5, 2.9)       p<0.001                                                                                                           Years Since Primary Procedure                                                                                                        Years Since Primary Procedure


 The Registry commenced data collection in September 1999 and this analysis                        >5 years:               HR=0.7 (0.4, 1.5)       p=0.355
                                                                                                                                                                                                    Gender                                                                                                                                       Gender
 includes all primary conventional THA using MoM or MoP articulation with a                 Males (MoM vs MoP)                                                                                                                       12%
                                                                                                                                                                                                                                               Male
                                                                                                                                                                                                                                                                                                                                                                               12%
                                                                                                                                                                                                                                                                                                                                                                                       Male
                                                                                                                                                                                                                                               Female                                                                                                                                  Female
 diagnosis of osteoarthritis performed up to and including 31 December 2009 in                     Entire Period:          HR=1.3 (1.1, 1.4)       p<0.001                                                                           10%                                                                                                                                       10%

 all Australian hospitals (both public and private). There were 17,833 primary




                                                                                                                                                                                                       Cumulative Percent Revision




                                                                                                                                                                                                                                                                                                                                                 Cumulative Percent Revision
                                                                                                                                                                                                                                      8%                                                                                                                                       8%
 MoM THA and 83,945 primary MoP THA analysed. The outcome was time to
                                                                                         MoM has a higher risk of revision compared to MoP regardless of age.                                                                         6%                                                                                                                                       6%
 first revision following the primary procedure. Unadjusted cumulative percent
 revision (CPR) with 95% confidence intervals were reported using the                                                                                                                                                                 4%                                                                                                                                       4%

 Kaplan-Meier method, and deaths were right censored. The impact of age,                    Age <55 (MoM vs MoP)
                                                                                                                                                                                                                                      2%                                                                                                                                       2%
 gender, femoral head size and reason for revision were examined.                                  Entire Period:          HR=1.4 (1.1, 1.8)       p=0.002
                                                                                            Age 55-64 (MoM vs MoP)                                                                                                                    0%                                                                                                                                       0%
                                                                                                                                                                                                                                       0.0       1.0       2.0      3.0      4.0      5.0       6.0   7.0   8.0   9.0                                                            0.0     1.0     2.0     3.0      4.0       5.0      6.0   7.0   8.0   9.0
 Cox proportional hazards models, adjusting for age and gender where                               0-1.5 years:            HR=1.1 (0.9, 1.4)       p=0.548                                                                                                           Years Since Primary Procedure                                                                                                        Years Since Primary Procedure

 appropriate, were used to compare revision rates.              Cox time-varying                   1.5-2 years:            HR=3.1 (1.8, 5.1)       p<0.001
                                                                                                                                                                                                    Age                                                                                                                                          Age
 proportional hazards models were used where the predictor variable(s) did not                     2-3 years:              HR=2.6 (1.7, 4.2)       p<0.001                                                                           12%                                                                                                                                       12%
                                                                                                                                                                                                                                                                                                                                                                                       <55
                                                                                                                                                                                                                                               <55
                                                                                                                                                                                                                                               55-64                                                                                                                                   55-64
 satisfy the assumption of proportionality over the entire survivorship. All tests                 >3 years:               HR=1.4 (1.0, 2.0)       p=0.046                                                                                     65-74
                                                                                                                                                                                                                                                                                                                                                                               10%
                                                                                                                                                                                                                                                                                                                                                                                       65-74
                                                                                                                                                                                                                                     10%       ≥75                                                                                                                                     ≥75
 were two-tailed at the 5% level of significance. Statistical analysis was per-             Age 65-74 (MoM vs MoP)




                                                                                                                                                                                                                                                                                                                                                 Cumulative Percent Revision
                                                                                                                                                                                                     Cumulative Percent Revision
                                                                                                                                                                                                                                     8%                                                                                                                                        8%
 formed using SAS software version 9.2 (SAS Institute Inc., Cary, NC).                             Entire Period:          HR=1.5 (1.3, 1.8)       p<0.001
                                                                                            Age ≥75 (MoM vs MoP)                                                                                                                     6%                                                                                                                                        6%



Results                                                                                            Entire Period:          HR=1.6 (1.3, 1.9)       p<0.001                                                                           4%                                                                                                                                        4%


 MoM articulations have a higher rate of revision compared to MoP and this                                                                                                                                                           2%                                                                                                                                        2%

 difference increases as time progresses. At nine years the CPR is 7.7 for MoM
                                                                                         MoM has a higher rate of revision due to loosening and metal sensitivity                                                                    0%                                                                                                                                        0%
 and 4.9 for MoP.                                                                                                                                                                                                                      0.0       1.0       2.0      3.0      4.0      5.0       6.0   7.0   8.0   9.0                                                            0.0     1.0    2.0      3.0      4.0      5.0       6.0   7.0   8.0   9.0
                                                                                         compared to MoP.                                                                                                                                                            Years Since Primary Procedure                                                                                                        Years Since Primary Procedure


 There is no difference in the revision rate between MoM and MoP when using                                                                                                                                                                                                 MoM
                                                                                                                                                                                                                                                                           MoM                                                                                                                                   MoP
                                                                                                                                                                                                                                                                                                                                                                                                               MoP
                                                                                                                                                                                                    Revision Diagnosis                                                                                                                           Revision Diagnosis
 head sizes 32mm or less. After two years, there is over three times the rate of                                                                                                                                                         3.5%
                                                                                                                                                                                                                                      3.5%                                                                                                                         3.5%
                                                                                                                                                                                                                                                                                                                                                                3.5%
                                                                                                                                                                                                                                                           Loosening/Lysis
                                                                                                                                                                                                                                                       Loosening/Lysis                                                                                                                       Loosening/Lysis
                                                                                                                                                                                                                                                                                                                                                                                        Loosening/Lysis
                                                                                                                                                                                                                                                           Prosthesis Dislocation
                                                                                                                                                                                                                                                       Prosthesis Dislocation                                                                                                                Prosthesis Dislocation
                                                                                                                                                                                                                                                                                                                                                                                        Prosthesis Dislocation
 revision for head sizes greater than 32mm for MoM articulations. There is no          Conclusion                                                                                                                                        3.0%
                                                                                                                                                                                                                                      3.0%                 Fracture
                                                                                                                                                                                                                                                       Fracture                                                                                                    3.0%
                                                                                                                                                                                                                                                                                                                                                                3.0%                         Fracture
                                                                                                                                                                                                                                                                                                                                                                                        Fracture
                                                                                                                                                                                                                                                           Infection
                                                                                                                                                                                                                                                       Infection                                                                                                                             Infection
                                                                                                                                                                                                                                                                                                                                                                                        Infection
 difference in the revision rate for MoP articulations with respect to head size.                                                                                                                                                                          Metal Sensitivity
                                                                                                                                                                                                                                                       Metal Sensitivity                                                                                                                     Metal Sensitivity
                                                                                                                                                                                                                                                                                                                                                                                        Metal Sensitivity




                                                                                                                                                                                                     Cumulative Incidence
                                                                                                                                                                                                     Cumulative Incidence




                                                                                                                                                                                                                                                                                                                          Cumulative Incidence
                                                                                                                                                                                                                                                                                                                                                  Cumulative Incidence
                                                                                                                                                                                                                                         2.5%
                                                                                                                                                                                                                                      2.5%                                                                                                                         2.5%
                                                                                                                                                                                                                                                                                                                                                                2.5%
                                                                                         MoM has a higher rate of revision compared to MoP for all
                                                                                                                                                                                                                                         2.0%
                                                                                                                                                                                                                                      2.0%                                                                                                                         2.0%
                                                                                                                                                                                                                                                                                                                                                                2.0%

   Head Size ≤32mm (MoM vs MoP)                                                          age groups and both females and males when head sizes                                                                                           1.5%
                                                                                                                                                                                                                                      1.5%                                                                                                                         1.5%
                                                                                                                                                                                                                                                                                                                                                                1.5%
       Entire Period:       HR=1.1 (0.9 1.3)     p=0.304                                 greater than 32mm are used. The increased rate of revision                                                                                      1.0%
                                                                                                                                                                                                                                      1.0%                                                                                                                         1.0%
                                                                                                                                                                                                                                                                                                                                                                1.0%
   Head Size >32mm (MoM vs MoP)
                                                                                         for MOM is due to a higher incidence of loosening and metal                                                                                     0.5%
                                                                                                                                                                                                                                      0.5%                                                                                                                         0.5%
                                                                                                                                                                                                                                                                                                                                                                0.5%
       0-2 years:           HR=1.3 (1.1, 1.6)    p=0.015                                                                                                                                                                                 0.0%
                                                                                                                                                                                                                                      0.0%                                                                                                                         0.0%
                                                                                                                                                                                                                                                                                                                                                                0.0%
       >2 years:            HR=3.3 (2.0, 5.2)    p<0.001
                                                                                         sensitivity.                                                                                                                                        0.00.0 1.01.0 2.02.0 3.03.0 4.04.0 5.0 5.0 6.0 6.0 7.0 7.0 8.0 8.0 9.0 9.0                                                          0.0 0.01.0 1.02.0 2.03.0 3.04.0 4.0      6.0 6.0
                                                                                                                                                                                                                                                                                                                                                                                                                    5.0 5.0           8.0 8.0
                                                                                                                                                                                                                                                                                                                                                                                                                                7.0 7.0     9.0 9.0

                                                                                                                                                                                                                                                                             Years Since Primary
                                                                                                                                                                                                                                                                          Years Since Primary                                                                                                                Years Since Primary
                                                                                                                                                                                                                                                                                                                                                                                                         Years Since Primary

				
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