title: Posterior Approach to Total Hip Replacement Using Enhanced Posterior Soft Tissue Repair Causes for revision of dual-mobility and standard primary total hip arthroplasty Acetabular reconstruction using a Kerboull cross-plate, structural allograft and cemented dual-mobility cup in revision THA at a minimum 5-year follow-up. Large femoral heads decrease the incidence of dislocation after total hip arthroplasty: a randomized controlled trial. The dual-mobility POLARCUP: first results from a multicenter study. Dual-Mobility Cup and Cemented Femoral Component: 6 Year Follow-Up Results Dual mobility cups hip arthroplasty as a treatment for displaced fracture of the femoral neck in the elderly. A prospective, systematic, multicenter study with specific focus on postoperative dislocation. Can Dual Mobility Cups prevent Dislocation in All Situations After Revision Total Hip Arthroplasty? The Frank Stinchfield Award: Dislocation in Revision THA: Do Large Heads (36 and 40 mm) Result in Reduced Dislocation Rates in a Randomized Clinical Trial? A Dual-mobility Cup Reduces Risk of Dislocation in Isolated Acetabular Revisions Cementless dual-mobility cup in total hip arthroplasty revision Hospital cost of dislocation after primary total hip arthroplasty. Posterior Soft Tissue Repair After Primary THA is Durable at Mid-term Followup: A Prospective MRI Study Relationship of Femoral Head and Acetabular Size to the Prevalence of Dislocation Are modern dual mobility cups a valuable option in reducing instability after primary hip arthroplasty, even in younger patients? Clinical outcomes, survivorship and adverse events with mobile-bearings versus fixed-bearings in hip arthroplasty-a prospective comparative cohort study of 143 ADM versus 130 trident cups at 2 to 6-year follow-up.
abstract: 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 underwent isolated acetabular revisions with a minimum of 2 years ’ followup ( mean , 3 years ; range , 2–5 years ) . In 24 patients a stainless steel dual-mobility cup was cemented into an antiprotrusio cage , whereas in nine we used a hyaluronan dual-mobility revision cup with a foramen hook and superior and posterior flanges screw fixations . We determined Harris hip ( HHS ) and WOMAC scores and examined radiographs for migration , loosening , and osteolysis . Results There were no dislocations . Survivorship rates of the femoral and acetabular components were 97 % at 5 years ; the rerevision rate for any reason was 3 % . At last followup , the mean HHS increased from 48 points preoperatively to 86 points . No patients had progressive osteolysis , component migration , or loosening on radiographs . Conclusion In this select group of isolated acetabular revisions , our data suggest the use of a dual-mobility cup reduced the risk of dislocation without increasing loosening from 2 to 5 years . Level of Evidence Level IV , therapeutic study . See the Guidelines for Authors for a complete description of levels of evidence Purpose Dislocation is a frequent complication in total hip arthroplasty ( THA ) revision . Cup fixation is the second concern . In order to know outcomes at two years , we prospect ively followed a continuous series of 78 patients to demonstrate that  cementless dual-mobility cup ( DMC ) used in revision THA  is safe as regards dislocation risk and bone fixation . Method We enrolled 78 consecutive patients ( 79 cases ) in a prospect i ve study . Mean interval between index surgery and revision was 12.9 years . Mean age at revision was 75.5 years . Two types of cementless DMC were used : a st and ard DMC in 68 cases with low- grade bone defect ( Paprosky grade 1 and 2 ) , and a specific design reconstruction DMC in 11 cases with severe bone loss ( Paprosky grade 3 ) . Results At two years of follow-up , 68 patients were review ed ; four were lost to follow-up . , and six patients were deceased . We identified three types of situations at risk : st and ard risk ( 33 cases ) , Paprosky grade 1 or 2 ; medium risk ( 37 cases ) , revision for recurrent instability ( 21 ) , periprosthetic fractures ( 14 ) or severe loosening Paprosky grade 3 without femorotomy ( 2 ) ; high risk ( nine cases ) , revision for severe loosening with a femorotomy . One ( 1.3 % ) patient dislocated her hip at one month without recurrence . Revision rate for dislocation was 0 % ; two ( 2.7 % ) early mechanical failures occurred . Conclusion Considering outcomes of this series , cementless DMC can be suggested in THA revision surgery BACKGROUND The treatment of dislocation following primary total hip arthroplasty usually requires the use of expensive hospital re sources and sometimes requires revision surgery . The hospital costs associated with treating this complication have not been previously analyzed , to our knowledge . The purpose of this study was to assess the financial impact of treating dislocations at our institution . METHODS Between 1997 and 2001 , 3671 patients underwent a total of 4054 consecutive primary total hip arthroplasties at our institution . The patients were prospect ively followed at regular intervals , and their follow-up data were recorded in an institutional total joint registry . Ninety-nine hips ( 2.4 % ) in ninety-nine patients dislocated . The costs to our institution to treat these dislocations were evaluated by determining the cost of each treatment episode required to reestablish hip stability and were expressed as the percent increase in cost compared with that of an uncomplicated primary total hip replacement . RESULTS Of the ninety-nine hips that dislocated , sixty-two ( 63 % ) remained stable after one or more closed reductions and thirty-seven ( 37 % ) ultimately required revision surgery . The hospital cost of each closed reduction episode represented 19 % of the hospital cost of an uncomplicated total hip replacement . When revision surgery was eventually needed , the average hospital costs of one or more closed reductions and the subsequent revisions represented 148 % of the hospital cost of an uncomplicated primary total hip replacement . CONCLUSIONS Dislocation after primary hip replacement continues to be a prevalent and costly complication that diminishes the cost-effectiveness of an otherwise very successful surgical procedure Background The enhanced posterior soft tissue repair has reduced the frequency of dislocation after primary THA performed through the posterolateral approach . However , the long-term integrity of the repair is unknown and could influence surgeon choice regarding surgical technique and THA approach . Questions / Purpose sWe asked : ( 1 ) What is the durability of the enhanced posterior soft tissue repair at a minimum of 49 months using MRI to evaluate soft tissue to bone integrity ? ( 2 ) How does the appearance of the posterior soft tissues change during this time ? ( 3 ) Are there patient characteristics associated with the long-term imaging appearance of the posterior repair ? Methods All patients without a contraindication for MRI who were undergoing unilateral primary uncemented THA through a posterior approach between February and May 2005 were eligible for inclusion . Ninety percent consented to participate ( 36 of 40 patients ) , and 30 patients were followed prospect ively with MRI postoperatively and again at 3 months ; of those , 22 ( 73 % ; 12 men , 10 women ) completed the study by having another MRI study at a minimum of 49 months ( mean , 51 months ; range , 49–59 months ) . Each patient underwent metal-artifact – reduction sequence MRI to evaluate the integrity of the posterior soft tissues , which had been repaired anatomically during primary THA at a minimum of 4 years earlier . The results were compared with those of prior MR images obtained immediately after surgery and at 3 months postoperatively . All patients were given a self-reported modified Harris hip score at the time of the most recent MRI study ( maximum score = 81 ) . Results At latest followup , 21 of 22 ( 96 % ) patients had a posterior capsule in contact with bone , and 21 of 22 ( 96 % ) had an intact quadratus femoris . Twenty-one patients ( 96 % ) had soft tissue or a scar from the piriformis and conjoined tendons in continuity with bone . In these cases , the interface between the piriformis and conjoined tendons and the greater trochanter observed immediately postoperatively and at 3 months postoperatively became filled with hypointense tissue , with signal characteristics similar to tendon . Time from surgery was most associated with changes in native tendon-to-bone distances ( p < 0.001 ) and MRI signal intensity of the repair ( p < 0.001 ) . Conclusions At followup of just more than 4 years , the posterior capsule and quadratus femoris most often were healed to bone . In the majority of patients , scar tissue between the piriformis and conjoined tendons and bone matured to achieve orientation and signal intensity resembling native tendon . We believe the enhanced posterior soft tissue repair facilitates this process . Our results provide a plausible explanation for improved postoperative stability observed in patients receiving an enhanced soft tissue repair compared with those in whom a repair is not performed . Level of Evidence Level IV , therapeutic study Two clinical studies , one prospect i ve r and omized and one retrospective , were performed to evaluate the relationship of femoral head size and acetabular component outer diameter to the prevalence of dislocation of the  modular total hip replacement . Between October 1995 and April 1996 , 31 primary total hip arthroplasties in 30 patients were r and omized to a femoral head diameter of 22 mm or 28 mm , for two groups of acetabular components of outer diameters of 56 mm or larger and 54 mm or smaller . Head size ( 22 mm ) and acetabular component outer diameter ( ≥ 56 mm ) were found to increase the risk of dislocation . From December 1984 to January 1994 , 308 primary total hip arthroplasties were performed through a posterior approach by one surgeon using a modular 28 mm femoral head and one type of uncemented acetabular component .  The rate of dislocation for acetabular components with an outer diameter of 62 mm or larger was increased significantly ( five of 36 hips , 14 % ) compared with those with an outer diameter of 60 mm or smaller ( 11 of 272 hips , 4 % ) Hip instability after total hip replacement has been shown to be a critical cause of failure . The use of dual mobility has been classically restricted to patients " at risk " , over 70 years of age . The question rises up about extended indications of so-called " modern " second generation dual mobility cups . This prospect i ve multicenter study reports on first results at 2 - 5 years of the HA anatomical ADM cup  upon two comparative groups of patients under 70 years ( 112 hips ) vs. over 70 years of age ( 325 hips ) . No dislocation , migration , tilting , wear , or intra-prosthetic dislocation was recorded within each of the two cohorts . Survivorship for cup failures at this 4-year period was ideal at 100 % in the younger patients , and 99.7 % in the older group of patients The principle of dual mobility cups , often called " tripolar " , has been developed to overcome the problem of instability following primary hip arthroplasty . We prospect ively compared two cohorts which differed only by the type of bearings , i.e. " mobile bearing hip " ( MBH ) in a 143- study cohort of ADM cups versus " fixed bearing hip " ( FBH ) of 130 Trident PSL cups  , at a follow-up at 2 - 6years . The survival rates at 4.13-years , with instability as endpoint was significantly ( P=0.0176 ) in favor of mobile bearings at 100 % with no dislocation reported , versus 94.8 % with fixed bearings . These mobile bearings , matching both " modern " dual mobility cups and annealed highly crossed polyethylene , would appear to offer at longer follow-up a valuable solution to clinical outcomes in acetabular arthroplasty
target: 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 .
background: Aims The aim of this systematic review was to report the rate of dislocation following the use of dual mobility ( DM ) acetabular components in primary and revision total hip arthroplasty ( THA ) .