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: The two senior authors ( PMP , RP ) independently began using an identical enhanced posterior soft tissue repair after total hip replacement  through a posterior approach . In the first author 's experience , a  dislocation rate  of 4 % in 395 patients before using the enhanced closure  was reduced to 0 % in 395 patients in whom the enhanced closure was performed . In the second author 's experience , 160 total hip replacements had a dislocation rate of 6.2 % before the enhanced closure whereas 124 total hip replacements had a dislocation rate of 0.8 % after the enhanced closure . These results are highly statistically significant 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 The current study aim ed to evaluate the outcome of a continuous and prospect i ve series of 61 revision THAs with AAOS grade III and IV acetabular bone defect reconstruction using a Kerboull cross-plate , structural allograft and cemented dual mobility cup ( Saturne , Amplitude , Valence , France ) . At a 7.5-year mean follow-up , no instability was reported after revision . In addition , no failure of the acetabular reconstruction was observed in 98 % of the patients with complete allograft osseointegration and no evidence of mechanical rupture of the Kerboull cross-plate and /or loosening of the cemented dual mobility cup . In conclusion , such reconstruction technique demonstrated excellent results at mid-term follow-up in terms of prevention of instability after revision , restoration of the acetabular bone stock , and stable cemented fixation of the dual mobility cup BACKGROUND The use of larger femoral heads has been proposed to reduce the risk of dislocation after total hip arthroplasty , but there is a lack of evidence to support this proposal . The aim of this multicenter r and omized controlled trial was to determine whether the incidence of dislocation one year after total hip arthroplasty is significantly lower in association with the use of a 36-mm femoral head articulation as compared with a 28-mm articulation . METHODS Six hundred and forty-four middle-aged and elderly patients undergoing primary or revision arthroplasty were r and omized intraoperatively to receive either a 36 or 28-mm metal femoral head on highly cross-linked polyethylene .  Patients who were at high risk of dislocation ( including those with dementia and neuromuscular disease ) and those undergoing revision for the treatment of recurrent hip dislocation or infection were excluded . Patients were stratified according to other potential risk factors for dislocation , including diagnosis and age . Diagnosis of hip dislocation required confirmation by a physician and radiographic evidence of a dislocation . RESULTS Overall , at one year of follow-up , hips with a 36-mm femoral head articulation had a significantly lower incidence of dislocation than did those with a 28-mm articulation ( 1.3 % [ four of 299 ] compared with 5.4 % [ seventeen of 316 ] ; difference , 4.1 % [ 95 % confidence interval , 1.2 % to 7.2 % ] ) when controlling for the type of procedure ( primary or revision ) ( p = 0.012 ) . The incidence of dislocation following primary arthroplasty was also significantly lower for hips with a 36-mm femoral head articulation than for those with a 28-mm articulation ( 0.8 % [ two of 258 ] compared with 4.4 % [ twelve of 275 ] ; difference , 3.6 % [ 95 % confidence interval , 0.9 % to 6.8 % ] ) ( p = 0.024 ) . The incidence of dislocation following revision arthroplasty was 4.9 % ( two of forty-one ) for hips with a 36-mm articulation and 12.2 % ( five of forty-one ) for hips with a 28-mm articulation ; this difference was not significant with the relatively small sample size of the revision group ( difference , 7.3 % [ 95 % confidence interval , -5.9 % to 21.1 % ] ) ( p = 0.273 ) . CONCLUSIONS Compared with a 28-mm femoral head articulation , a larger 36-mm articulation result ed in a significantly decreased incidence of dislocation in the first year following primary total hip arthroplasty . However , before a 36-mm metal-on-highly cross-linked polyethylene articulation is widely recommended , the incidence of late dislocation , wear , periprosthetic osteolysis , and liner fracture should be established Dislocation is a leading cause of revision after  total hip arthroplasty ( THA ) . To address this risk , dual-mobility technology was developed , which features a mobile polyethylene liner locked onto a femoral head and articulating in a metallic acetabular shell . This study reports clinical outcome data after implantation of the third-generation POLARCUP Dual-Mobility System ( Smith & Nephew Orthopaedics AG , Rotkreuz , Switzerl and ) .  Primary THA procedures were performed in 150 patients . At 7.1 years , cumulative cup survival according to Kaplan-Meier was 97.4 % . The mean Postel-Merle d'Aubigne score improved from 8.9 to 17.1 during the investigation . Two cups were revised at 5.4 and 6.4 years because of aseptic loosening . No dislocations were observed during follow-up . The current results confirm excellent early to midterm clinical outcomes for the POLARCUP Dual-Mobility System Use of a dual-mobility acetabular cup is associated with a lower risk of dislocation compared with conventional hip implants . The seleXys ® DS acetabular cup combines the advantages of Charnley low-friction arthroplasty with those of dual mobility . We performed a non-r and omised , prospect i ve study of patients receiving primary hip arthroplasty , including an uncemented seleXys ® DS dual-mobility acetabular cup with hydroxyapatite coating ( Mathys AG , Bettlach , Switzerl and ) and a cemented femoral component ( Stallion femoral stem Groupe Lepine , Lyon , France ) . The objective of the study was to evaluate longevity of the implant and the risk of dislocation . All operations were performed by a single surgeon using a posterior approach , with patients lying in the lateral decubitus position . The stem had a modular head diameter of 22.2 mm and was cemented in all patients . A total of 53 patients were studied , and the median duration of follow-up was 78.9 months . Implant survival 6 years after surgery was 98.4 % ( n=47 ; 95 % CI : 89.3–99.8 ) . There was one revision for sepsis 29 months after surgery , and one dislocation . The results of this study appear to demonstrate excellent implant survival and a low rate of dislocation using the chosen implants INTRODUCTION Displaced fractures of the femoral neck in the elderly are best treated with arthroplasty . The type of arthroplasty to be used , either hemi- or total hip arthroplasty , remains controversial as total hip replacements potentially have a higher rate of dislocation . HYPOTHESIS Dual mobility cups have a low dislocation rate when used to manage acute fractures of the femoral neck . PATIENTS AND METHODS In a multicenter prospect i ve study conducted in France over an inclusion time of 3 months , all displaced fractures of the femoral neck treated with arthroplasty  were operated on with insertion of a dual mobility cup . Patients had clinical and radiological assessment at 3 , 6 , and 9 months postoperative . RESULTS Two hundred and fourteen hips in 214 patients with a mean age of 83 years ( range , 70 - 103 years ) were included . None of the patients was lost to follow-up . The mortality rate after 9 months was 19 % . Two patients ( 1 % ) had early postoperative infection successfully treated with lavage and antibiotics . Three patients ( 1.4 % ) , operated through a posterior approach , presented one postoperative dislocation , all of which were posterior . Reduction was performed through closed external manipulation under general anesthesia . There was no recurrence of dislocation . DISCUSSION This low rate of dislocation after acute total hip replacement using dual mobility design cups favorably compares with hemiarthroplasties . Dual mobility cups might therefore be considered a valuable option to prevent postoperative dislocation when treating displaced intracapsular fractures of the proximal femur in elderly patients if a total hip replacement is recommended . Further study is needed before extending the indications for total hip arthroplasty following a fracture of the femoral neck , to assess the potential cost and complications of a longer procedure with its potential acetabular complication , and weigh them against the potential benefits UNLABELLED The outcome of a single design of dual mobility cup was prospect ively evaluated in a continuous series of 994 revision THAs with respect to dislocation and intra-prosthetic dislocation ( IPD ) . At a 7.3-year mean follow-up , the dislocation rate was 1.5 % and the IPD rate was 0.2 % . The 2 IPD occurred in acetabular-only revisions and were related to a poor head-to-neck ratio with early impingement and wear at the polyethylene mobile component chamfer . Dual mobility cups demonstrated a low dislocation rate in revision THA but did not compensate for potential perioperative technical errors . In addition , IPD did not appear to be a concern with respect to the benefit in term of instability prevention though caution is advised in acetabular-only revision associated with a poor head-to-neck ratio . LEVEL OF EVIDENCE Therapeutic study -Level IV Background Dislocation after revision THA is a common complication . Large heads have the potential to decrease dislocation rate , but it is unclear whether they do so in revision THA . Questions / purpose sWe therefore determined whether a large femoral head ( 36 and 40 mm ) result ed in a decreased dislocation rate compared to a st and ard head ( 32 mm ) . Methods We r and omized 184 patients undergoing revision THA to receive either a 32-mm head ( 92 patients ) or 36- and 40-mm head ( 92 patients ) and stratified patients by surgeon . The two groups had similar baseline demographics . The primary end point was dislocation . Quality -of-life ( QOL ) measures were WOMAC and SF-36 . The mean followup for dislocation was 5 years ( range , 2–7 years ) ; the mean followup for QOL was 2.2 years ( range , 1.6–4 years ) . Results In the 36- and 40-mm head group , the dislocation rate was 1.1 % ( one of 92 ) versus 8.7 % ( eight of 92 ) for the 32-mm head . There was no difference in QOL outcomes between the two groups . Conclusions Our observations confirm a large femoral head ( 36 or 40 mm ) reduces dislocation rates in patients undergoing revision THA at short-term followup . We now routinely use large heads with a highly crosslinked polyethylene acetabular liner in all revision THAs . Level of Evidence Level I , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence Background Isolated acetabular revisions using st and ard cups are at risk of dislocation . The introduction of a nonconstrained dual-mobility cup was design ed to improve prosthetic stability without increasing loosening rates , but it is unclear whether the risk of dislocation is reduced . Questions / purpose sWe therefore determined : ( 1 ) if the rate of dislocation in isolated acetabular revisions is lower with a dual-mobility cup , ( 2 ) implant survival , ( 3 ) patient function , and ( 4 ) radiographic incidence of migration , loosening , and osteolysis . Methods We prospect ively followed 33 selected patients who underw 
    Output:
    
agent
Conclusion Based on the current data , the use of DM acetabular components are effective in minimising the risk of instability after both primary and revision THA .
This benefit must be balanced against continuing concerns about the additional modularity , and the new mode of failure of intraprosthetic dislocation .
***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: The two senior authors ( PMP , RP ) independently began using an identical enhanced posterior soft tissue repair after total hip replacement  through a posterior approach . In the first author 's experience , a  dislocation rate  of 4 % in 395 patients before using the enhanced closure  was reduced to 0 % in 395 patients in whom the enhanced closure was performed . In the second author 's experience , 160 total hip replacements had a dislocation rate of 6.2 % before the enhanced closure whereas 124 total hip replacements had a dislocation rate of 0.8 % after the enhanced closure . These results are highly statistically significant 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 The current study aim ed to evaluate the outcome of a continuous and prospect i ve series of 61 revision THAs with AAOS grade III and IV acetabular bone defect reconstruction using a Kerboull cross-plate , structural allograft and cemented dual mobility cup ( Saturne , Amplitude , Valence , France ) . At a 7.5-year mean follow-up , no instability was reported after revision . In addition , no failure of the acetabular reconstruction was observed in 98 % of the patients with complete allograft osseointegration and no evidence of mechanical rupture of the Kerboull cross-plate and /or loosening of the cemented dual mobility cup . In conclusion , such reconstruction technique demonstrated excellent results at mid-term follow-up in terms of prevention of instability after revision , restoration of the acetabular bone stock , and stable cemented fixation of the dual mobility cup BACKGROUND The use of larger femoral heads has been proposed to reduce the risk of dislocation after total hip arthroplasty , but there is a lack of evidence to support this proposal . The aim of this multicenter r and omized controlled trial was to determine whether the incidence of dislocation one year after total hip arthroplasty is significantly lower in association with the use of a 36-mm femoral head articulation as compared with a 28-mm articulation . METHODS Six hundred and forty-four middle-aged and elderly patients undergoing primary or revision arthroplasty were r and omized intraoperatively to receive either a 36 or 28-mm metal femoral head on highly cross-linked polyethylene .  Patients who were at high risk of dislocation ( including those with dementia and neuromuscular disease ) and those undergoing revision for the treatment of recurrent hip dislocation or infection were excluded . Patients were stratified according to other potential risk factors for dislocation , including diagnosis and age . Diagnosis of hip dislocation required confirmation by a physician and radiographic evidence of a dislocation . RESULTS Overall , at one year of follow-up , hips with a 36-mm femoral head articulation had a significantly lower incidence of dislocation than did those with a 28-mm articulation ( 1.3 % [ four of 299 ] compared with 5.4 % [ seventeen of 316 ] ; difference , 4.1 % [ 95 % confidence interval , 1.2 % to 7.2 % ] ) when controlling for the type of procedure ( primary or revision ) ( p = 0.012 ) . The incidence of dislocation following primary arthroplasty was also significantly lower for hips with a 36-mm femoral head articulation than for those with a 28-mm articulation ( 0.8 % [ two of 258 ] compared with 4.4 % [ twelve of 275 ] ; difference , 3.6 % [ 95 % confidence interval , 0.9 % to 6.8 % ] ) ( p = 0.024 ) . The incidence of dislocation following revision arthroplasty was 4.9 % ( two of forty-one ) for hips with a 36-mm articulation and 12.2 % ( five of forty-one ) for hips with a 28-mm articulation ; this difference was not significant with the relatively small sample size of the revision group ( difference , 7.3 % [ 95 % confidence interval , -5.9 % to 21.1 % ] ) ( p = 0.273 ) . CONCLUSIONS Compared with a 28-mm femoral head articulation , a larger 36-mm articulation result ed in a significantly decreased incidence of dislocation in the first year following primary total hip arthroplasty . However , before a 36-mm metal-on-highly cross-linked polyethylene articulation is widely recommended , the incidence of late dislocation , wear , periprosthetic osteolysis , and liner fracture should be established Dislocation is a leading cause of revision after  total hip arthroplasty ( THA ) . To address this risk , dual-mobility technology was developed , which features a mobile polyethylene liner locked onto a femoral head and articulating in a metallic acetabular shell . This study reports clinical outcome data after implantation of the third-generation POLARCUP Dual-Mobility System ( Smith & Nephew Orthopaedics AG , Rotkreuz , Switzerl and ) .  Primary THA procedures were performed in 150 patients . At 7.1 years , cumulative cup survival according to Kaplan-Meier was 97.4 % . The mean Postel-Merle d'Aubigne score improved from 8.9 to 17.1 during the investigation . Two cups were revised at 5.4 and 6.4 years because of aseptic loosening . No dislocations were observed during follow-up . The current results confirm excellent early to midterm clinical outcomes for the POLARCUP Dual-Mobility System Use of a dual-mobility acetabular cup is associated with a lower risk of dislocation compared with conventional hip implants . The seleXys ® DS acetabular cup combines the advantages of Charnley low-friction arthroplasty with those of dual mobility . We performed a non-r and omised , prospect i ve study of patients receiving primary hip arthroplasty , including an uncemented seleXys ® DS dual-mobility acetabular cup with hydroxyapatite coating ( Mathys AG , Bettlach , Switzerl and ) and a cemented femoral component ( Stallion femoral stem Groupe Lepine , Lyon , France ) . The objective of the study was to evaluate longevity of the implant and the risk of dislocation . All operations were performed by a single surgeon using a posterior approach , with patients lying in the lateral decubitus position . The stem had a modular head diameter of 22.2 mm and was cemented in all patients . A total of 53 patients were studied , and the median duration of follow-up was 78.9 months . Implant survival 6 years after surgery was 98.4 % ( n=47 ; 95 % CI : 89.3–99.8 ) . There was one revision for sepsis 29 months after surgery , and one dislocation . The results of this study appear to demonstrate excellent implant survival and a low rate of dislocation using the chosen implants INTRODUCTION Displaced fractures of the femoral neck in the elderly are best treated with arthroplasty . The type of arthroplasty to be used , either hemi- or total hip arthroplasty , remains controversial as total hip replacements potentially have a higher rate of dislocation . HYPOTHESIS Dual mobility cups have a low dislocation rate when used to manage acute fractures of the femoral neck . PATIENTS AND METHODS In a multicenter prospect i ve study conducted in France over an inclusion time of 3 months , all displaced fractures of the femoral neck treated with arthroplasty  were operated on with insertion of a dual mobility cup . Patients had clinical and radiological assessment at 3 , 6 , and 9 months postoperative . RESULTS Two hundred and fourteen hips in 214 patients with a mean age of 83 years ( range , 70 - 103 years ) were included . None of the patients was lost to follow-up . The mortality rate after 9 months was 19 % . Two patients ( 1 % ) had early postoperative infection successfully treated with lavage and antibiotics . Three patients ( 1.4 % ) , operated through a posterior approach , presented one postoperative dislocation , all of which were posterior . Reduction was performed through closed external manipulation under general anesthesia . There was no recurrence of dislocation . DISCUSSION This low rate of dislocation after acute total hip replacement using dual mobility design cups favorably compares with hemiarthroplasties . Dual mobility cups might therefore be considered a valuable option to prevent postoperative dislocation when treating displaced intracapsular fractures of the proximal femur in elderly patients if a total hip replacement is recommended . Further study is needed before extending the indications for total hip arthroplasty following a fracture of the femoral neck , to assess the potential cost and complications of a longer procedure with its potential acetabular complication , and weigh them against the potential benefits UNLABELLED The outcome of a single design of dual mobility cup was prospect ively evaluated in a continuous series of 994 revision THAs with respect to dislocation and intra-prosthetic dislocation ( IPD ) . At a 7.3-year mean follow-up , the dislocation rate was 1.5 % and the IPD rate was 0.2 % . The 2 IPD occurred in acetabular-only revisions and were related to a poor head-to-neck ratio with early impingement and wear at the polyethylene mobile component chamfer . Dual mobility cups demonstrated a low dislocation rate in revision THA but did not compensate for potential perioperative technical errors . In addition , IPD did not appear to be a concern with respect to the benefit in term of instability prevention though caution is advised in acetabular-only revision associated with a poor head-to-neck ratio . LEVEL OF EVIDENCE Therapeutic study -Level IV Background Dislocation after revision THA is a common complication . Large heads have the potential to decrease dislocation rate , but it is unclear whether they do so in revision THA . Questions / purpose sWe therefore determined whether a large femoral head ( 36 and 40 mm ) result ed in a decreased dislocation rate compared to a st and ard head ( 32 mm ) . Methods We r and omized 184 patients undergoing revision THA to receive either a 32-mm head ( 92 patients ) or 36- and 40-mm head ( 92 patients ) and stratified patients by surgeon . The two groups had similar baseline demographics . The primary end point was dislocation . Quality -of-life ( QOL ) measures were WOMAC and SF-36 . The mean followup for dislocation was 5 years ( range , 2–7 years ) ; the mean followup for QOL was 2.2 years ( range , 1.6–4 years ) . Results In the 36- and 40-mm head group , the dislocation rate was 1.1 % ( one of 92 ) versus 8.7 % ( eight of 92 ) for the 32-mm head . There was no difference in QOL outcomes between the two groups . Conclusions Our observations confirm a large femoral head ( 36 or 40 mm ) reduces dislocation rates in patients undergoing revision THA at short-term followup . We now routinely use large heads with a highly crosslinked polyethylene acetabular liner in all revision THAs . Level of Evidence Level I , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence Background Isolated acetabular revisions using st and ard cups are at risk of dislocation . The introduction of a nonconstrained dual-mobility cup was design ed to improve prosthetic stability without increasing loosening rates , but it is unclear whether the risk of dislocation is reduced . Questions / purpose sWe therefore determined : ( 1 ) if the rate of dislocation in isolated acetabular revisions is lower with a dual-mobility cup , ( 2 ) implant survival , ( 3 ) patient function , and ( 4 ) radiographic incidence of migration , loosening , and osteolysis . Methods We prospect ively followed 33 selected patients who underw 
    Output:
    