title: A double-blind, prospective, randomized controlled trial comparing highly cross-linked and conventional polyethylene in primary total hip arthroplasty. Combination of direct and indirect evidence in mixed treatment comparisons. New polyethylenes in total hip replacement: a prospective, comparative clinical study of two types of liner. Highly Crosslinked Polyethylene Reduces Wear in Total Hip Arthroplasty at 5 Years Cross-linked Compared with Historical Polyethylene in THA: An 8-year Clinical Study Comparison of surgical outcomes and implant wear between ceramic-ceramic and ceramic-polyethylene articulations in total hip arthroplasty. A randomised prospective evaluation of ceramic-on-ceramic and ceramic-on-highly cross-linked polyethylene bearings in the same patients with primary cementless total hip arthroplasty Large-diameter Delta ceramic-on-ceramic versus common-sized ceramic-on-polyethylene bearings in THA. A randomized trial of ceramic-on-ceramic bearing versus ceramic-on-crossfire-polyethylene bearing in total hip arthroplasty: five-year outcomes. Crosslinked polyethylene compared to conventional polyethylene in total hip replacement: Pre-clinical evaluation, in-vitro testing and prospective clinical follow-up study The squeaking hip: a phenomenon of ceramic-on-ceramic total hip arthroplasty. A prospective randomised controlled trial comparing three alternative bearing surfaces in primary total hip replacement. A randomized prospective evaluation of outcomes after total hip arthroplasty using cross-linked marathon and non-cross-linked Enduron polyethylene liners. THA With Delta Ceramic on Ceramic: Results of a Multicenter Investigational Device Exemption Trial
abstract: Highly cross-linked polyethylene was developed to reduce articular bearing wear in total hip arthroplasty . In vitro studies have shown reduced wear in comparison with conventional polyethylene . A double-blind , prospect i ve , r and omized trial was performed comparing highly cross-linked and conventional polyethylene  in 119 patients . The primary outcome variables were linear , 3-dimensional , and volumetric wear as determined by analysis of digitized radiographs using vali date d wear measurement software . Linear , 3-dimensional , and volumetric wear rates were significantly less in the highly cross-linked polyethylene group between 6 months and 4 years postoperatively ( P < .05 ) . The data presented here show that highly cross-linked polyethylene reduces short-term polyethylene wear . The intermediate and long-term clinical results of highly cross-linked polyethylene remain unknown pending further follow-up Mixed treatment comparison ( MTC ) meta- analysis is a generalization of st and ard pairwise meta- analysis for A vs B trials , to data structures that include , for example , A vs B , B vs C , and A vs C trials . There are two roles for MTC : one is to strengthen inference concerning the relative efficacy of two treatments , by including both ' direct ' and ' indirect ' comparisons . The other is to facilitate simultaneous inference regarding all treatments , in order for example to select the best treatment . In this paper , we present a range of Bayesian hierarchical models using the Markov chain Monte Carlo software WinBUGS . These are multivariate r and om effects models that allow for variation in true treatment effects across trials . We consider models where the between-trials variance is homogeneous across treatment comparisons as well as heterogeneous variance models . We also compare models with fixed ( unconstrained ) baseline study effects with models with r and om baselines drawn from a common distribution . These models are applied to an illustrative data set and posterior parameter distributions are compared . We discuss model critique and model selection , illustrating the role of Bayesian deviance analysis , and node-based model criticism . The assumptions underlying the MTC models and their parameterization are also discussed Ultra-high-molecular-weight polyethylene sterilised in the absence of air and highly cross-linked polyethylene have been used to avoid osteolysis and loosening in total hip replacement . Our prospect i ve r and omised study has assessed the results using two different polyethylenes associated with the same prosthetic design . We assessed 45 Allofit acetabular components with a Sulene-polyethylene liner of conventional polyethylene gamma sterilised with nitrogen and 45 Allofit acetabular components with a Durasul-polyethylene liner sterilised in ethylene oxide , both matched with an Alloclassic stem  with a 28 mm modular femoral head . The prostheses were implanted between May 1999 and December 2001 . The mean follow-up was for 66.3 months ( 60 to 92 ) . The linear penetration of the femoral head was estimated at 6 weeks , at 6 and 12 months and annually thereafter from st and ardised digitised radiographs using image- analysis software . There was no loosening of any prosthetic component . There were no radiolucent lines or osteolysis . The mean rate of penetration calculated from regression analysis during the first five years was 38 microm/year ( SD 2 ) for the Sulene group and 6 microm/year ( SD 1 ) for the Durasul group ( p = 0.00002 ) . The rate of penetration of the Durasul group was 15.7 % of that of the Sulene group Background Although hip arthroplasty reliably relieves pain and improves function , problems have arisen with wear and osteolysis .  Highly crosslinked polyethylene has been developed to address this problem although at present there is limited clinical evidence it does so longer term . Questions / purpose sWe compared the in vivo wear of st and ard versus highly crosslinked polyethylene ( HXLP ) in primary total hip arthroplasty at a minimum of 5-year followup . Methods We enrolled 122 patients in a prospect i ve , double-blinded , r and omized trial and followed them annually to assess their progress . Annual radiographs were analyzed using previously vali date d edge detection software to assess for two-dimensional , three-dimensional , and volumetric wear . The mean follow up was 5.5 years ( range , 4.1 to 7 years ) . Results The two-dimensional wear measurements for HXLP showed lower wear compared to the conventional group ( 0.05 mm/year versus 0.26 mm/year , respectively ) . Three-dimensional and volumetric wear were similarly lower in the HXLP group . Conclusions Highly crosslinked polyethylene undergoes substantially less wear than conventional polyethylene at medium term . The effect of hip arthroplasty longevity will need to be assessed with longer-term studies , but this may lead to a decreased need for revision as a result of less wear and osteolysis . Level of Evidence Level I , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence Abstract Wear particle-induced osteolysis is a major cause of aseptic loosening in THA . Increasing wear resistance of polyethylene ( PE ) occurs by increasing the cross-link density and early reports document low wear rates with such implants . To confirm longer-term reductions in wear we compared cross-linked polyethylene ( irradiation in nitrogen , annealing ) with historical polyethylene ( irradiation in air ) in a prospect i ve , r and omized clinical study involving 48 patients who underwent THAs with a minimum followup of 7 years ( mean , 8 years ; range , 7–9 years ) . The insert material was the only variable . The Harris hip score , radiographic signs of osteolysis , and polyethylene wear were recorded annually . Twenty-three historical and 17 moderately cross-linked polyethylene inserts were analyzed ( five patients died , three were lost to followup ) . At 8 years , the wear rate was lower for cross-linked polyethylene ( 0.088 ± 0.03 mm/year ) than for the historical polyethylene ( 0.142 ± 0.07 mm/year ) . This reduction ( 38 % ) did not diminish with time ( 33 % at 5 years ) . Acetabular cyst formation was less frequent ( 39 % versus 12 % ) , affected fewer DeLee and Charnley zones ( 17 % versus 4 % ) , and was less severe for the cross-linked polyethylene . The only revision was for an aseptically loose cup in the historical polyethylene group . Moderately cross-linked polyethylene maintained its wear advantage with time and produced less osteolysis , showing no signs of aging at mid-term followup . Level of Evidence : Level I , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence The results of a prospect i ve multicenter trial comparing 357 hips r and omized to total hip arthroplasty with either ceramic-ceramic or ceramic-polyethylene couplings  are presented . No statistically significant difference in clinical outcomes scores between the ceramic-ceramic and ceramic-polyethylene groups was observed at any time interval . The mean linear rate was statistically lower ( P < .001 ) in the ceramic-ceramic group ( 30.5 μm/year ) when compared with the ceramic-polyethylene group ( 218.2 μm/year ) . The rates of ceramic implant fracture ( 2.6 % ) and audible component-related noise ( 3.1 % ) were statistically higher in the ceramic-ceramic group when compared with the ceramic-polyethylene group ( P < .05 ) . Lastly , there was no statistically significant difference in the dislocation or revision rate between the groups at the time of last clinical follow-up Purpose Very few studies have compared alumina-on-alumina ceramic and alumina-on-highly cross-linked polyethylene bearings in the same patient . The purpose of this prospect i ve r and omised study was to compare the clinical and radiographic results and the prevalence of osteolysis in cementless total hip arthroplasty using an alumina-on-alumina and alumina-on-highly cross-linked polyethylene bearings in young active patients . Methods We prospect ively compared the results of 100 patients ( 200 hips ) who had undergone a cementless total hip arthroplasty with an alumina-on-alumina ceramic bearing in one hip and an alumina-on-highly cross-linked polyethylene in the other . There were 66 men and 34 women with a mean age of 45.3 years ( range , 21–49 years ) at the time of surgery . The mean follow-up was 12.4 years ( range , 11–13 years ) . The patients were assessed clinical ly and radiographically at three months , one year , and annually thereafter . Results Harris hip , Western Ontario and McMaster Universities Osteoarthritis Index , and University of California , Los Angeles activity scores did not show statistically significant differences between the two groups of bearings preoperatively or at the time of final follow-up . Radiographic findings of the component were not significantly different between the two groups . The mean polyethylene linear penetration was 0.031 ± 0.004 mm per year . No hips in either group displayed osteolysis . The Kaplan-Meier survivorship with revision as the end point at 12.4 years was 100 % ( 95 % confidence interval [ CI ] , 94–100 % ) for the femoral component in both groups and 99 % ( 95 % CI , 93–100 % ) for the acetabular component . Conclusion The clinical and radiographic results of using an alumina-on-alumina ceramic and alumina-on-highly cross-linked polyethylene bearings were similar The higher failure rate of total hip arthroplasty ( THA ) in young , active patients remains a challenge for surgeons . Recently , larger-diameter femoral heads combined with an alumina matrix composite ceramic ( BIOLOX Delta ; CeramTec AG , Plochingen , Germany ) articulation was developed to improve implant longevity and meet patients ' activity dem and s while reducing the risk of component-related complications . The purpose of this study was to determine whether this new device may provide advantages for young , active patients . A prospect i ve , r and omized , controlled trial was conducted on 93 patients ( 113 THAs ) with more than 3 years of follow-up . Patients were r and omly divided into a study group ( 51 THAs ) with a 36-mm Delta ceramic-on-ceramic ( COC ) articulation and a control group ( 62 THAs ) with a common-sized alumina ceramic head on polyethylene liner ( COP ) articulation .  Clinical and radiographic results were collected to compare the outcomes and complications , including implant-related failures , osteolysis , and noises . The large-diameter Delta COC articulation provided greater range of motion improvement ( 6.1 ° more ) , similar Harris Hip Scores , and similar complication rates compared with the alumina COP articulation . This study suggests that in the short term , the large-diameter Delta COC articulation results in better range of motion with no higher complication rates ; however , mid-term ( 8 - 10 years ) or longer follow-up is necessary to determine its superiority in young , active patients This study determined how ceramic-on-ceramic bearing THA affected joint-specific pain , function and stiffness in the first five postoperative years compared with ceramic-on-highly-crosslinked-polyethylene bearing THA .  Subjects less than 61 years of age were r and omized  to ceramic-on-ceramic ( CERAMIC ) [ n = 48 ] or ceramic-on-highly-crosslinked-polyethylene ( POLYETHYLENE ) [ n = 44 ] bearing THA . Subjects were assessed using the Western Ontario McMaster Osteoarthritis Index ( WOMAC ) and the R AND 12-Item Health Survey ( R AND -12 ) preoperatively , and at one and five years postoperatively . 92 subjects(50 ( 54 % ) males ; average age = 52 ( SD 6.6 ) years ) were enrolled . 78 ( 85 % ) subjects returned five years postoperatively . All subjects reported improvements at one and five years in all measured indices with no group differences detected . Seven ( 8 % ) subjects experienced postoperative THA complications , none related to bearing surfaces ; two subjects ( POLYETHYLENE ) required revision for instability . Both bearing surfaces provided excellent short-term results in younger subjects Background Polyethylene wear-induced osteolysis is a major cause of implant loosening in total hip arthroplasty . New crosslinked polyethylenes are presumed to give lower wear rates , but no long-term clinical results are available yet . Patients and methods We compared basic material characteristics and MTS hip joint simulator wear rates of a crosslinked polyethylene ( Duration ) to those of conventional polyethylene . In a r and omized double-blind 5-year clinical follow-up study , 133 hips ( 67 conventional , 66 Duration ) in 127 patients were followed-up for an average of 5 ( 3–6 ) years .  Wear rates were measured using a computer-based edge detection method . The radiographic appearances of wear-related phenomena were recorded . Results The Duration polyethylene showed a significantly lower in-vitro wear rate in the simulator study ( mean 22 ( SD 2.3 ) vs. 40 ( SD 1.5 ) mm3/106 cycles ) . Also , the in-vivo wear was lower for Duration ( mean 0.083 ( SD 0.056 ) mm/year ) than for conventional polyethylene ( mean 0.123 ( SD 0.082 ) mm/year ) . All radiographic signs of osteolysis were less frequent in the Duration group . Interpretation Our study has given a substantial body of evidence —from lower wear rates , less frequent signs of osteolysis , and higher survival rates after a mean follow-up of 5 years — that Duration provides better clinical outcomes than conventional polyethylene BACKGROUND Early reports on modern  ceramic-on-ceramic total hip replacements  have demonstrated excellent clinical and radiographic results with few cases of catastrophic failure , which , in the case of earlier design s , often had been caused by implant fracture . Several reports , however , have noted the presence of audible squeaking . The purpose of the present study was to determine the incidence of squeaking in association with the use of this bearing couple . METHODS During the period from March 2003 to May 2005 , three surgeons performed 159 total hip arthroplasties in 143 patients with use of a ceramic-on-ceramic bearing . One hundred and forty-nine hips ( 131 patients ) were available for review after at least one year of follow-up . These patients were followed prospect ively with use of the modified Hospital for Special Surgery hip score and a patient-administered question naire . Additionally , a control group of sixty hips ( forty-eight patients ) with a metal-on-polyethylene bearing  was matched to the ceramic group on the basis of age , sex , and body mass index to compare the incidence of squeaking and other noises . Radiographic evaluations were performed according to previously established criteria . RESULTS Fourteen ( 10.7 % ) of 131 patients described an audible squeak during normal activities . However , squeaking was reproducible clinical ly in only four patients , and only one patient complained of squeaking before being presented with the question naire . The average Hospital for Special Surgery score improved from 19.8 preoperatively to 38.4 at the time of the latest follow-up , indicating excellent clinical results . Ninety-five percent of the patients had a satisfaction score of > or = 8 of 10 . Three hips dislocated . One of those three hips squeaked and was revised because of recurrent dislocations . One patient was considering revision because of squeaking . In the matched metal-on-polyethylene cohort , there were no cases of squeaking . CONCLUSIONS The squeaking hip is a phenomenon that is unique to total hip replacements with hard-on-hard bearings . The incidence of squeaking in association with ceramic-on-ceramic bearings may be higher than previously reported as < 1 % of the patients in the present study reported this finding before being queried . The causes and implication s of squeaking are yet to be determined . The use of hard-on-hard bearings offers many advantages in terms of wear reduction , especially for young and active patients . Nonetheless , patients considering ceramic-on-ceramic bearings should be counseled with regard to this phenomenon The ideal bearing surface for young patients undergoing total hip replacement ( THR ) remains controversial . We report the five-year results of a r and omised controlled trial comparing the clinical and radiological outcomes of 102 THRs in 91 patients who were < 65 years of age . These patients were r and omised to receive a cobalt-chrome on ultra-high-molecular-weight polyethylene , cobalt-chrome on highly cross-linked polyethylene , or a ceramic-on-ceramic bearing . In all , 97 hip replacements in 87 patients were available for review at five years . Two hips had been revised , one for infection and one for peri-prosthetic fracture . At the final follow-up there were no significant differences between the groups for the mean Western Ontario and McMaster Universities osteoarthritis index ( pain , p = 0.543 ; function , p = 0.10 ; stiffness , p = 0.99 ) , Short Form-12 ( physical component , p = 0.878 ; mental component , p = 0.818 ) or Harris hip scores ( p = 0.22 ) . Radiological outcomes revealed no significant wear in the ceramic group . Comparison of st and ard and highly cross-linked polyethylene , however , revealed an almost threefold difference in the mean annual linear wear rates ( 0.151 mm/year versus 0.059 mm/year , respectively ) ( p < 0.001 ) Cross-linked liners were introduced with the promise that they would substantially reduce polyethylene wear . In 1999 , our institution initiated a prospect i ve study to compare the outcome of total hip arthroplasty patients who were r and omized to non-cross-linked Enduron liners  with that of total hip arthroplasty patients who were r and omized to Marathon polyethylene liners that had been cross-linked with 5 Mrad ( 50 kGy ) of gamma-irradiation and heat-treated to eliminate free radicals . At a mean follow-up of 5.7 years , the clinical outcomes among the Marathon and Enduron liners were similar . However , the mean wear rate was 0.01 + /- 0.07 mm/y for the Marathon group , which represents a 95 % reduction compared with the mean wear rate of 0.19 + /- 0.12 mm/y for the Enduron group . In addition , the incidence of osteolysis was lower in the Marathon group Although the published studies on the outcomes of  total hip arthroplasty (  THA ) performed with currently available ceramic components show high survivorship and low bearing wear at midterm followup , concern over ceramic fracture and squeaking persist . For these reasons , the use of ceramic is limited . Recently , a new alumina matrix composite material ( Delta ceramic ) with improved material properties was developed to address these concerns . We report the early outcomes and complications of a prospect i ve , r and omized , multicenter trial of 263 patients ( 264 hips ) at eight centers , comparing a Delta ceramic-on-ceramic ( COC ) articulation with a Delta ceramic head-crosslinked polyethylene bearing combination ( COP ) . There were 177 COC hips and 87 COP hips . Complications  were reported for all patients , whereas  clinical and radiographic results were provided for the 233 patients with minimum 2-year followup ( average , 31.2 months ; range , 21–49 months ) . The Harris hip scores and clinical , radiographic , and survivorship outcomes were similar in both groups . There were four ( 2 % ) revisions in the COC group and two ( 2 % ) in the COP group . We encountered three intraoperative ceramic liner-related events . In addition , one patient receiving the COC underwent revision for chipping of the ceramic liner , and a second had ceramic fragmentation on followup radiographs but has not undergone revision . These liner related complications remain a concern . No patient reported squeaking in either group ; this leaves us hopeful the new material will lessen the frequency of squeaking . In the short term , the Delta COC articulation provided similar functional scores and survivorship and complication rates with the ceramic head mated with crosslinked polyethylene . Level of Evidence : Level I , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence
target: Conclusions Current published evidence does not support survivorship differences among commonly used bearing surfaces in patients younger than age 65 years undergoing THA at short- to mid-term followup .
background: Background  Total hip arthroplasty ( THA )  is increasingly being performed in patients with long life expectancies and active lifestyles .
  Newer implant bearing surfaces , with superior wear characteristics , often are used in this cohort with the goal of improving longevity of the prosthesis , but comparisons across the numerous available bearing surfaces are limited , so the surgeon and patient may have difficulty deciding which implants to use .
  Questions / purpose sThe purpose of this study was to answer the following question : Is there a short- to mid-term survivorship difference between common THA bearings used in patients younger than age 65 years ?