human
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Introduction The causes for revision of primary total hip arthroplasty ( THA ) are various and quite well known . The developing use of dual-mobility THA ( DM-THA ) seems a relevant option to decrease the risk of instability . Due to lack of long-term follow-up , this innovative retentive concept is suspected to increase the risk of polyethylene ( PE ) wear . the aim of the study was to analyse the causes for  DM-THA revision and assess whether or not its occurrence is different from that of fixed-st and ard ( FS ) THA , particularly for aseptic loosening or wear and /or osteolysis . Material s and methods The SoFCOT group conducted an observational prospect i ve multicentre study from 1 January 2010 to 31 December 2011 . Inclusion criteria comprised an exhaustive collection of 2044 first-revision THAs with 251 DM-THAs and 1793 FS-THAs . After excluding complications linked to patient factors ( infection and periprosthetic fractures ) , we performed a matched case – control study ( matching ratio 1:1 ) comparing two groups of 133 THAs . Results Revisions for aseptic loosening or osteolysis/wear were as frequent in DM-THA ( 58.7 % ) as in FS-THA ( 57.1 % ) ( p 0.32 ) ; 7.5 % of DM-THA were revised for dislocation versus 19.5 % of FS-THA ( p 0.007 ) . Discussion Revision for osteolysis/wear and aseptic loosening were as frequent in DM-THA as in FS-THA ;  revision for dislocation was less frequent in DM-THA . This confirms the efficiency of the DM concept regarding the risk of dislocation . Causes for revision were different between groups , and revisions for dislocation were less frequent in DM-THA . Only prospect i ve comparative studies could provide reliable information that may support broader use of the DM concept Background and purpose — Revision total hip arthroplasty ( THA ) is associated with higher dislocation rates than primary THA . We compared the risk of dislocation within 6 months and all-cause re-revision during the whole study period using either the dual-mobility cup or the unipolar cup . Methods — We used a prospect i ve hospital registry-based cohort including all total and cup-only revision THAs performed between 2003 and 2013 . The cups used were either dual-mobility or unipolar ; the choice was made according to the preference of the surgeon . 316 revision THAs were included . The mean age of the cohort was 69 ( 25–98 ) years and 160 THAs ( 51 % ) were performed in women . The dual-mobility group ( group 1 ) included 150 THAs ( 48 % ) and the mean length of follow-up was 31 ( 0–128 ) months . The unipolar group ( group 2 ) included 166 THAs ( 53 % ) and the mean length of follow-up was 52 ( 0–136 ) months . Results — The incidence of dislocation within 6 months was significantly lower with the dual-mobility cup than with the unipolar cup ( 2.7 % vs. 7.8 % ) . The unadjusted risk ratio ( RR ) was 0.34 ( 95 % CI : 0.11–1.02 ) and the adjusted RR was 0.28 ( 95 % CI : 0.09–0.87 ) . The number of patients needed to treat with a  dual-mobility cup in order to prevent 1 case of dislocation was 19 . The unadjusted incidence rate ratio for all-cause re-revision in the dual-mobility group compared to the unipolar group was 0.6 ( 95 % CI : 0.3–1.4 ) . Interpretation — Use of a dual-mobility rather than a unipolar cup in revision THA reduced the risk of dislocation within 6 months Purpose To evaluate early performance of contemporary dual mobility acetabular systems with second generation annealed highly cross-linked polyethylene for primary hip arthroplasty of patients under 55 years of age . Methods A prospect i ve observational five years study across five centers in Europe and the USA of 321 patients with a mean age of 48.1 years was performed . Patients were assessed for  causes of revision , hip instability , intra-prosthetic dissociation , Harris hip score and radiological signs of osteolysis .  Results There were no dislocations and no intra-prosthetic dissociations . Kaplan Meier analysis demonstrated 97.51 % survivorship for all cause revision and 99.68 % survivorship for acetabular component revision at five years . Mean Harris hip score was 93.6 . Two acetabular shells were revised for neck-rim implant impingement without dislocation and ten femoral stems were revised for causes unrelated to dual mobility implants . Conclusion Contemporary highly cross-linked polyethylene dual mobility systems demonstrate excellent early clinical , radiological , and survivorship results in a cohort of patients that dem and high performance from their implants . It is envisaged that DM and second generation annealed HXLPE may reduce THA instability and wear , the two most common causes of THA revision in hip arthroplasty We evaluated all revisions performed from March 1996 to December 2008 and compared complications , mortality , and clinical outcomes between patients 80 years and older and patients younger than 80 years . Data were collected prospect ively . There were 325 revisions , 84 ( 25.8 % ) in patients 80 years and older and 241 in patients younger than 80 years ( 62 % revision for aseptic loosening in both groups ) . The mean follow-up was 4.3 years . The results , 80 years and older vs younger than 80 years , revealed the following : mortality , 5 % vs 0 % 3 months postoperatively ; medical complications in 23.8 % vs 6.2 % ; postoperative fractures , 9.5 % vs 2.5 % ; and improved Merle d'Aubigné scores from 9.6 to 13.0 vs 10.4 to 14.3 . Revision total hip arthroplasty in patients 80 years and older was associated with substantial clinical improvement and patient satisfaction . However , medical complications and 90-day mortality were higher , and postoperative fractures occurred more frequently BACKGROUND Constrained acetabular components have been used to treat hips with recurrent instability following total hip arthroplasty and hips that demonstrate instability during revision surgery . In such hips , when a secure cementless acetabular shell is present , the surgeon can cement a constrained liner into the existing shell . The purpose of this study was to evaluate the clinical and radiographic outcome of this technique with use of a tripolar constrained liner that was cemented into a well-fixed cementless acetabular shell . METHODS Between 1988 and 2000 , constrained liners were cemented into thirty-one well-fixed cementless acetabular shells  at three centers . The average age of the patients at the time of the index surgery was 72.1 years , and the indications for the procedure were recurrent hip instability in sixteen hips and intraoperative instability in fifteen hips . The patients were evaluated with respect to the clinical outcome and radiographic evidence of shell loosening and osteolysis . RESULTS At an average duration of follow-up of 3.9 years , twenty-nine liners ( 94 % ) were securely fixed in the cementless shells and two constrained liners had failed . One liner failed because it separated from the cement , and one failed because of fracture of the capturing mechanism . Both hips were successfully revised with another cemented tripolar constrained liner . No acetabular component demonstrated radiographic evidence of progressive loosening or osteolysis . CONCLUSIONS A constrained tripolar liner cemented into a secure , well-positioned cementless acetabular shell provides stability and durability at short-term follow-up . Careful attention to the preparation of the liner , the sizing of the component , and the cementing technique are likely to reduce the failure of this construct , which can be used for difficult cases of total hip instability BACKGROUND Constrained liners are used as part of a salvage procedure to provide stability for patients at high risk for dislocation after a total hip arthroplasty . However , no recent studies exist highlighting their effectiveness and /or limitations . METHOD This prospect i ve review included 166 consecutive hip arthroplasties , either primary ( 27 % ) or revision ( 73 % ) , with a unique design of a constrained liner : Lefèvre retentive cup . There were 113 females ( 69 % ) , and the average age at index surgery was 75.9 years ( range , 35 - 94 ) . The mean follow-up was 6.2 years ( range , 0.3 - 11 ) . RESULTS Twenty patients had a reoperation ; 10 for infection ( 4 acute and 6 chronic joint infection ) and 10 for cup failure ( 5 fixation failure , 3 aseptic loosening , and 2 dislocation ) . Ten-year survivals for cup revision were 89 % ( CI , 83 - 94 ) and 92 % ( CI , 89 - 97 ) for all revision and revision for noninfectious reasons , respectively . When solely evaluating for dislocation , the survival at 10 years was 99 % ( CI , 97 - 100 ) . Considering primary and revision cases , 10-year survivals cup revision for aseptic reasons were 92.4 % ( CI , 84 - 100 ) and 92.5 % ( CI , 87 - 98 ) , respectively . CONCLUSIONS The Lefèvre retentive cup demonstrated excellent 10-year 's survivorship . With the rate of aseptic loosening around 2 % and a dislocation rate around 1 % , the cup is as effective as other available devices and is therefore a cost-effective tool to reduce the risk of dislocation in at-risk patients undergoing hip arthroplasty BACKGROUND  Total hip arthroplasty ( THA )  using dual-mobility ( DM ) design permits larger hip range of motion . However , it is unclear how it benefits the patients during activities of daily living . The purpose was to compare kinematic variables of the operated limb between  THA patients using either DM or single-bearing ( SB ) implants during a squat task . METHODS Twenty-four THA patients were r and omly assigned to either a DM or SB implant and matched to 12 healthy controls ( CTRLs ) . They underwent 3-dimensional squat motion analysis  before and 9 months after surgery . Sagittal and frontal plane angles of the pelvis and the hip were analyzed using statistical parametric mapping . Paired analyses compared presurgery and postsurgery squat depth . RESULTS Peak sagittal pelvis angle of DM was closer to normal compared with that of SB . Both implant groups had similar hip angle patterns and magnitude but significantly lower than the CTRLs . SB reached a much large hip abduction compared with the other groups . Both surgical groups had significantly worst squat depth than the CTRLs . CONCLUSION Neither THA implant groups were able to return pelvis and hip kinematics to the level of CTRLs . The deficit of DM implants at the pelvis combined with the poorer functional scores should caution clinicians to use this implant design in active patients . SB design causes a larger hip abduction to reach their maximum squat depth . Post-THA rehabilitation should focus on improving joint range of motion and strength 
    Output:
    
agent
In short-term outcomes ( 5 years or less , with follow-up of 0–5 years ) , the best implant of choice that has lowest risk of revision and dislocation after THA is DMTHA follow by BTHA .
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Introduction The causes for revision of primary total hip arthroplasty ( THA ) are various and quite well known . The developing use of dual-mobility THA ( DM-THA ) seems a relevant option to decrease the risk of instability . Due to lack of long-term follow-up , this innovative retentive concept is suspected to increase the risk of polyethylene ( PE ) wear . the aim of the study was to analyse the causes for  DM-THA revision and assess whether or not its occurrence is different from that of fixed-st and ard ( FS ) THA , particularly for aseptic loosening or wear and /or osteolysis . Material s and methods The SoFCOT group conducted an observational prospect i ve multicentre study from 1 January 2010 to 31 December 2011 . Inclusion criteria comprised an exhaustive collection of 2044 first-revision THAs with 251 DM-THAs and 1793 FS-THAs . After excluding complications linked to patient factors ( infection and periprosthetic fractures ) , we performed a matched case – control study ( matching ratio 1:1 ) comparing two groups of 133 THAs . Results Revisions for aseptic loosening or osteolysis/wear were as frequent in DM-THA ( 58.7 % ) as in FS-THA ( 57.1 % ) ( p 0.32 ) ; 7.5 % of DM-THA were revised for dislocation versus 19.5 % of FS-THA ( p 0.007 ) . Discussion Revision for osteolysis/wear and aseptic loosening were as frequent in DM-THA as in FS-THA ;  revision for dislocation was less frequent in DM-THA . This confirms the efficiency of the DM concept regarding the risk of dislocation . Causes for revision were different between groups , and revisions for dislocation were less frequent in DM-THA . Only prospect i ve comparative studies could provide reliable information that may support broader use of the DM concept Background and purpose — Revision total hip arthroplasty ( THA ) is associated with higher dislocation rates than primary THA . We compared the risk of dislocation within 6 months and all-cause re-revision during the whole study period using either the dual-mobility cup or the unipolar cup . Methods — We used a prospect i ve hospital registry-based cohort including all total and cup-only revision THAs performed between 2003 and 2013 . The cups used were either dual-mobility or unipolar ; the choice was made according to the preference of the surgeon . 316 revision THAs were included . The mean age of the cohort was 69 ( 25–98 ) years and 160 THAs ( 51 % ) were performed in women . The dual-mobility group ( group 1 ) included 150 THAs ( 48 % ) and the mean length of follow-up was 31 ( 0–128 ) months . The unipolar group ( group 2 ) included 166 THAs ( 53 % ) and the mean length of follow-up was 52 ( 0–136 ) months . Results — The incidence of dislocation within 6 months was significantly lower with the dual-mobility cup than with the unipolar cup ( 2.7 % vs. 7.8 % ) . The unadjusted risk ratio ( RR ) was 0.34 ( 95 % CI : 0.11–1.02 ) and the adjusted RR was 0.28 ( 95 % CI : 0.09–0.87 ) . The number of patients needed to treat with a  dual-mobility cup in order to prevent 1 case of dislocation was 19 . The unadjusted incidence rate ratio for all-cause re-revision in the dual-mobility group compared to the unipolar group was 0.6 ( 95 % CI : 0.3–1.4 ) . Interpretation — Use of a dual-mobility rather than a unipolar cup in revision THA reduced the risk of dislocation within 6 months Purpose To evaluate early performance of contemporary dual mobility acetabular systems with second generation annealed highly cross-linked polyethylene for primary hip arthroplasty of patients under 55 years of age . Methods A prospect i ve observational five years study across five centers in Europe and the USA of 321 patients with a mean age of 48.1 years was performed . Patients were assessed for  causes of revision , hip instability , intra-prosthetic dissociation , Harris hip score and radiological signs of osteolysis .  Results There were no dislocations and no intra-prosthetic dissociations . Kaplan Meier analysis demonstrated 97.51 % survivorship for all cause revision and 99.68 % survivorship for acetabular component revision at five years . Mean Harris hip score was 93.6 . Two acetabular shells were revised for neck-rim implant impingement without dislocation and ten femoral stems were revised for causes unrelated to dual mobility implants . Conclusion Contemporary highly cross-linked polyethylene dual mobility systems demonstrate excellent early clinical , radiological , and survivorship results in a cohort of patients that dem and high performance from their implants . It is envisaged that DM and second generation annealed HXLPE may reduce THA instability and wear , the two most common causes of THA revision in hip arthroplasty We evaluated all revisions performed from March 1996 to December 2008 and compared complications , mortality , and clinical outcomes between patients 80 years and older and patients younger than 80 years . Data were collected prospect ively . There were 325 revisions , 84 ( 25.8 % ) in patients 80 years and older and 241 in patients younger than 80 years ( 62 % revision for aseptic loosening in both groups ) . The mean follow-up was 4.3 years . The results , 80 years and older vs younger than 80 years , revealed the following : mortality , 5 % vs 0 % 3 months postoperatively ; medical complications in 23.8 % vs 6.2 % ; postoperative fractures , 9.5 % vs 2.5 % ; and improved Merle d'Aubigné scores from 9.6 to 13.0 vs 10.4 to 14.3 . Revision total hip arthroplasty in patients 80 years and older was associated with substantial clinical improvement and patient satisfaction . However , medical complications and 90-day mortality were higher , and postoperative fractures occurred more frequently BACKGROUND Constrained acetabular components have been used to treat hips with recurrent instability following total hip arthroplasty and hips that demonstrate instability during revision surgery . In such hips , when a secure cementless acetabular shell is present , the surgeon can cement a constrained liner into the existing shell . The purpose of this study was to evaluate the clinical and radiographic outcome of this technique with use of a tripolar constrained liner that was cemented into a well-fixed cementless acetabular shell . METHODS Between 1988 and 2000 , constrained liners were cemented into thirty-one well-fixed cementless acetabular shells  at three centers . The average age of the patients at the time of the index surgery was 72.1 years , and the indications for the procedure were recurrent hip instability in sixteen hips and intraoperative instability in fifteen hips . The patients were evaluated with respect to the clinical outcome and radiographic evidence of shell loosening and osteolysis . RESULTS At an average duration of follow-up of 3.9 years , twenty-nine liners ( 94 % ) were securely fixed in the cementless shells and two constrained liners had failed . One liner failed because it separated from the cement , and one failed because of fracture of the capturing mechanism . Both hips were successfully revised with another cemented tripolar constrained liner . No acetabular component demonstrated radiographic evidence of progressive loosening or osteolysis . CONCLUSIONS A constrained tripolar liner cemented into a secure , well-positioned cementless acetabular shell provides stability and durability at short-term follow-up . Careful attention to the preparation of the liner , the sizing of the component , and the cementing technique are likely to reduce the failure of this construct , which can be used for difficult cases of total hip instability BACKGROUND Constrained liners are used as part of a salvage procedure to provide stability for patients at high risk for dislocation after a total hip arthroplasty . However , no recent studies exist highlighting their effectiveness and /or limitations . METHOD This prospect i ve review included 166 consecutive hip arthroplasties , either primary ( 27 % ) or revision ( 73 % ) , with a unique design of a constrained liner : Lefèvre retentive cup . There were 113 females ( 69 % ) , and the average age at index surgery was 75.9 years ( range , 35 - 94 ) . The mean follow-up was 6.2 years ( range , 0.3 - 11 ) . RESULTS Twenty patients had a reoperation ; 10 for infection ( 4 acute and 6 chronic joint infection ) and 10 for cup failure ( 5 fixation failure , 3 aseptic loosening , and 2 dislocation ) . Ten-year survivals for cup revision were 89 % ( CI , 83 - 94 ) and 92 % ( CI , 89 - 97 ) for all revision and revision for noninfectious reasons , respectively . When solely evaluating for dislocation , the survival at 10 years was 99 % ( CI , 97 - 100 ) . Considering primary and revision cases , 10-year survivals cup revision for aseptic reasons were 92.4 % ( CI , 84 - 100 ) and 92.5 % ( CI , 87 - 98 ) , respectively . CONCLUSIONS The Lefèvre retentive cup demonstrated excellent 10-year 's survivorship . With the rate of aseptic loosening around 2 % and a dislocation rate around 1 % , the cup is as effective as other available devices and is therefore a cost-effective tool to reduce the risk of dislocation in at-risk patients undergoing hip arthroplasty BACKGROUND  Total hip arthroplasty ( THA )  using dual-mobility ( DM ) design permits larger hip range of motion . However , it is unclear how it benefits the patients during activities of daily living . The purpose was to compare kinematic variables of the operated limb between  THA patients using either DM or single-bearing ( SB ) implants during a squat task . METHODS Twenty-four THA patients were r and omly assigned to either a DM or SB implant and matched to 12 healthy controls ( CTRLs ) . They underwent 3-dimensional squat motion analysis  before and 9 months after surgery . Sagittal and frontal plane angles of the pelvis and the hip were analyzed using statistical parametric mapping . Paired analyses compared presurgery and postsurgery squat depth . RESULTS Peak sagittal pelvis angle of DM was closer to normal compared with that of SB . Both implant groups had similar hip angle patterns and magnitude but significantly lower than the CTRLs . SB reached a much large hip abduction compared with the other groups . Both surgical groups had significantly worst squat depth than the CTRLs . CONCLUSION Neither THA implant groups were able to return pelvis and hip kinematics to the level of CTRLs . The deficit of DM implants at the pelvis combined with the poorer functional scores should caution clinicians to use this implant design in active patients . SB design causes a larger hip abduction to reach their maximum squat depth . Post-THA rehabilitation should focus on improving joint range of motion and strength 
    Output:
    