title: A double-blind, prospective, randomized controlled trial comparing highly cross-linked and conventional polyethylene in primary total hip arthroplasty. Prospective randomized trial comparing alumina ceramic-on-ceramic with ceramic-on-conventional polyethylene bearings in total hip arthroplasty. Delta Ceramic-on-Alumina Ceramic Articulation in Primary THA: Prospective, Randomized FDA-IDE Study and Retrieval Analysis 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 A comparison of the penetration rate of two polyethylene acetabular liners of different levels of cross-linking. A prospective randomised trial. The seven-year wear of highly cross-linked polyethylene in total hip arthroplasty: a double-blind, randomized controlled trial using radiostereometric analysis. 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 Use of an alumina-on-alumina bearing system in total hip arthroplasty for osteonecrosis of the hip. The creep and wear of highly cross-linked polyethylene: a three-year randomised, controlled trial using radiostereometric analysis. Excellent results with cementless total hip arthroplasty and alumina-on-alumina pairing: minimum ten-year follow-up EBRA migration patterns of the Plasmacup with ceramic or polyethylene inserts: a randomised study. Large-diameter Delta ceramic-on-ceramic versus common-sized ceramic-on-polyethylene bearings in THA. Zirconia versus Co-Cr Femoral Heads in Total Hip Arthroplasty: Early Assessment of Wear A randomized controlled trial comparing Oxinium and cobalt-chrome on standard and cross-linked polyethylene. A randomized trial of ceramic-on-ceramic bearing versus ceramic-on-crossfire-polyethylene bearing in total hip arthroplasty: five-year outcomes. A prospective randomised controlled trial comparing three alternative bearing surfaces in primary total hip replacement. Highly Crosslinked Polyethylene Does Not Reduce Aseptic Loosening in Cemented THA 10-year Findings of a Randomized Study New polyethylenes in total hip replacement: A ten- to 12-year follow-up study. THA With Delta Ceramic on Ceramic: Results of a Multicenter Investigational Device Exemption Trial Minimum five-year follow-up wear measurement of longevity highly cross-linked polyethylene cup against cobalt-chromium or zirconia heads. High Incidence of Squeaking in THAs with Alumina Ceramic-on-ceramic Bearings Differences in highly cross-linked polyethylene wear between zirconia and cobalt-chromium femoral heads in Japanese patients: a prospective, randomized study. Comparison of polyethylene wear associated with cobalt-chromium and zirconia heads after total hip replacement. A prospective, randomized study. The Effect of Femoral Head Size on Functional Outcome in Primary Total Hip Arthroplasty: A Single-Blinded Randomised Controlled 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 This prospect i ve r and omized study aims to compare the outcome between an alumina ceramic-on-ceramic ( CC ) articulation with a ceramic on ultra-high-molecular-weight polyethylene articulation ( CP ) .  Fifty-six hips in 55 patients with mean age 42.2 ( range , 19 - 56 ) each received uncemented components , a 28-mm alumina head with r and omization of acetabular liner .  Mean St Michael 's outcome score for each group with up to 10 years follow-up ( median , 8 years ; range , 1 - 10 ) was 22.8 and 22.9 , respectively ( P = .819 ) . Wear was identified in all but 1 CP replacement , but only 12 of the 23 CC . Mean wear in the CP group was 0.11 mm/y and 0.02 mm/yr in the CC group ( P < .001 ) . Other than significantly greater wear in the polyethylene group , there was no significant difference in midterm outcome between the 2 groups Wear and osteolysis continue to be major reasons for revision surgery in THA .  Ceramic-on-ceramic bearings eliminate polyethylene wear debris . The newest generation of these bearings incorporate nanosized , yttria-stabilized tetragonal zirconia particles producing an alumina matrix composite . We asked whether this new material would perform as well as a conventional bearing in terms of functional hip scores , radiographic migration and osteolysis , complications and survival . As part of a US FDA investigational device exemption study ( G000075 ) , we conducted an initial prospect i ve safety study of 21 alumina matrix composite femoral heads articulating on alumina liners followed by a prospect i ve , r and omized study with 44 more of these articulations and 45 zirconia femoral heads on polyethylene liners .  The minimum followup for all patients was 26 months ( mean , 73 months ; range , 26–108 months ) . Harris hip scores and radiographic findings were similar in the two groups as was survivorship ( trial 95 % versus control 93 % ) . There were three reoperations in the trial group and three in the control group . A fractured head retrieval showed a 33 % monoclinic transformation with an increase in surface roughness from 3 to 5 nm at the main wear zone . While our numbers were insufficient to compare device-related complications , the trial device performed as well as the control device in terms of reoperation , and clinical and radiographic outcome . The alumina matrix composite femoral head on an alumina liner provided high survivorship . Level of Evidence : Level II , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence 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 We carried out a prospect i ve r and omised study design ed to compare the penetration rate of acetabular polyethylene inserts of identical design but different levels of cross-linking at a minimum of four years follow-up . A total of 102 patients ( 102 hips ) were r and omised to receive either highly cross-linked Durasul , or contemporary Sulene polyethylene inserts at total hip replacement .  A single blinded observer used the Martell system to assess penetration of the femoral head . At a mean follow-up of 4.9 years ( 4.2 to 6.1 ) the mean femoral head penetration rate was 0.025 mm/year ( SD 0.128 ) in the Durasul group compared with 0.106 mm/year ( SD 0.109 ) in the Sulene group ( Mann-Whitney test , p = 0.0027 ) . The mean volumetric penetration rate was 29.24 mm(3)/year ( SD 44.08 ) in the Durasul group compared with 53.32 mm(3)/year ( SD 48.68 ) in the Sulene group . The yearly volumetric penetration rate was 55 % lower in the Durasul group ( Mann-Whitney test , p = 0.0058 ) . Longer term results are needed to investigate whether less osteolysis will occur BACKGROUND The use of highly cross-linked polyethylene is now commonplace in total hip arthroplasty . Hip simulator studies and short-term in vivo measurements have suggested that the wear rate of highly cross-linked polyethylene is significantly less than that of conventional ultra-high molecular weight polyethylene . However , long-term data to support its use are limited . The aim of this study was to compare the intermediate-term steady-state wear of highly cross-linked polyethylene compared with that of conventional ultra-high molecular weight polyethylene acetabular liners in a prospect i ve , double-blind , r and omized controlled trial with use of radiostereometric analysis . METHODS Fifty-four patients were r and omized to receive hip replacements with either conventional ultra-high molecular weight polyethylene acetabular liners ( Zimmer ) or highly cross-linked polyethylene liners ( Longevity ; Zimmer ) . All patients received a cemented , collarless , polished , tapered femoral component ( CPT ; Zimmer ) and an uncemented acetabular component ( Trilogy ; Zimmer ) . Clinical outcomes were assessed and the three-dimensional penetration of the head into the socket was determined for a minimum of seven years . Linear regression was used to calculate the steady-state wear rate following the creep-dominated penetration seen during the first year . RESULTS At a minimum of seven years postoperatively , the mean total femoral head penetration was significantly lower in the highly cross-linked polyethylene group ( 0.33 mm ; 95 % confidence interval [ CI ] , ±0.10 mm ) than it was in the ultra-high molecular weight polyethylene group ( 0.55 mm ; 95 % CI , ±0.10 mm ) ( p = 0.005 ) . The mean steady-state wear rate  of highly cross-linked polyethylene was 0.005 mm/yr ( 95 % CI , ±0.015 mm/yr ) , compared with 0.037 mm/yr ( 95 % CI , ±0.019 mm/yr ) for conventional ultra-high molecular weight polyethylene ( p = 0.007 ) . No patient in the highly cross-linked polyethylene group had a wear rate above the osteolysis threshold of 0.1 mm/yr , compared with 9 % of patients in the ultra-high molecular weight polyethylene group . CONCLUSIONS This study demonstrates that highly cross-linked polyethylene has a significantly lower steady-state wear rate compared with that of conventional ultra-high molecular weight polyethylene . Longer-term follow-up is required to determine if this will translate into improved clinical performance and longevity of these implants 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 BACKGROUND The results of total hip arthroplasty in patients with osteonecrosis of the femoral head are not always optimal . The use of alumina-on-alumina interfaces in young and active patients may decrease wear and lower the rate of aseptic loosening of the implant and appears to be an attractive alternative to the use of conventional cobalt-chromium-on-polyethylene bearings . The purpose of this study was to evaluate the safety and efficacy of the alumina-on-alumina bearing in patients with osteonecrosis and to compare this group of patients to a group of similarly treated patients with osteoarthritis and a group of patients who received conventional cobalt-chromium-on-polyethylene bearings . METHODS Patients were selected from a United States Investigational Device Exemption multicenter prospect i ve r and omized clinical study that was initiated in 1996 . Seventy patients with osteonecrosis of the femoral head ( seventy-nine hips ) received a cementless alumina-on-alumina bearing system and were directly matched to seventy-six patients with osteoarthritis of the hip ( seventy-nine hips ) who were managed with the same implant . Both groups were compared with twenty-five patients ( twenty-six hips ) with osteonecrosis and twenty-five patients ( twenty-six hips ) with osteoarthritis who were managed with a cementless cobalt-chromium-on-polyethylene bearing system . All patients received a cementless hydroxyapatite-coated femoral stem and were followed both clinical ly and radiographically . RESULTS The clinical outcomes for alumina-on-alumina bearings were similar for both osteonecrotic and osteoarthritic hips . The seven-year survival probability was 95.5 % for the osteonecrotic hips and 89.4 % for the osteoarthritic hips in the alumina-on-alumina bearing group and 92.3 % for the osteonecrotic hips and 92.9 % for the osteoarthritic hips in the cobalt-chromium-on-polyethylene bearing group . At the time of the most recent follow-up , the mean Harris hip score was 96 points for both the osteonecrotic and the osteoarthritic hips in the alumina-on-alumina group and 96 points for the osteonecrotic hips and 97 points for the osteoarthritic hips in the cobalt-chromium-on-polyethylene bearing group . CONCLUSIONS The results of the use of alumina-on-alumina and cobalt-chromium-on-polyethylene bearings in cementless st and ard total hip implants in patients with osteonecrosis and osteoarthritis were comparable . The low revision rate for the alumina-on-alumina bearing is encouraging and offers a promising option for younger , more active patients who have this challenging disease . LEVEL OF EVIDENCE Therapeutic Level III . See Instructions to Authors on jbjs.org for a complete description of levels of evidence The creep and wear behaviour of highly cross-linked polyethylene and st and ard polyethylene liners were examined in a prospect i ve , double-blind r and omised , controlled trial using radiostereometric analysis . We r and omised 54 patients to receive hip replacements with either highly cross-linked polyethylene or st and ard liners  and determined the three-dimensional penetration of the liners over three years . After three years the mean total penetration was 0.35 mm ( SD 0.14 ) for the highly cross-linked polyethylene group and 0.45 mm ( SD 0.19 ) for the st and ard group . The difference was statistically significant ( p = 0.0184 ) . From the pattern of penetration it was possible to discriminate creep from wear . Most ( 95 % ) of the creep occurred within six months of implantation and nearly all within the first year . There was no difference in the mean degree of creep between the two types of polyethylene ( highly cross-linked polyethylene 0.26 mm , SD 0.17 ; st and ard 0.27 mm , SD 0.2 ; p = 0.83 ) . There was , however , a significant difference ( p = 0.012 ) in the mean wear rate ( highly cross-linked polyethylene 0.03 mm/yr , SD 0.06 ; st and ard 0.07 mm/yr , SD 0.05 ) . Creep and wear occurred in significantly different directions ( p = 0.01 ) ; creep was predominantly proximal whereas wear was anterior , proximal and medial . We conclude that penetration in the first six months is creep-dominated , but after one year virtually all penetration is due to wear . Highly cross-linked polyethylene has a 60 % lower rate of wear than st and ard polyethylene and therefore will probably perform better in the long term Ceramic-on-ceramic coupling is thought to be a durable alternative to metal- or alumina-on-polyethylene pairing . No evidence exists suggesting superior clinical and radiological results for hydroxyapatite-coated stems versus uncoated stems . The aim of this study is to report the performance of an alumina-on-alumina bearing  cementless total hip arthroplasty and to compare stems with a tapered design with and without hydroxyapatite coating . We prospect ively analysed the results of  cementless tapered femoral stems ( 40 hydroxyapatite-coated versus 22 uncoated stems ) , a metal-backed fibre mesh hydroxyapatite-coated socket and alumina-on-alumina pairing .  Of 75 hips studied , 62 were available for follow-up ( mean of 10.5 years after surgery ) . The average Harris hip score was 90 . Only one hydroxyapatite-coated stem was revised for aseptic loosening . One instance of non-progressive osteolysis was detected around a screw of a cup . All other components showed radiographic signs of stable ingrowth .  Hydroxyapatite coating of the stem had no significant impact on the clinical or radiological results . Total hip arthroplasty with the presented implant and pairing provides a durable st and ard for all patients requiring hip joint replacement against which all newer generations of cementless implants should be judged AIM In this prospect i ve r and omised study , the influence of different bearing material s on migration and wear was measured and their effect on the function of the artificial joint and the patient outcome was investigated . Mid-term results were recorded so that recommendations can be made on the use of certain bearings , which minimise wear and thus the danger of subsequent aseptic loosening . METHOD Sixty-six patients met the inclusion criteria and were willing to take part in the study . These patients were r and omised to 2 groups . All of them had total hip arthroplasty with implantation of a cementless Bicontact stem and Plasmacup using a cementless press-fit technique . Thirty-five of these patients were given a ceramic-ceramic bearing and 31 patients a ceramic-polyethylene bearing ( gamma sterilised/nitrogen environment ) . At the most recent follow-up , they underwent detailed clinical and radiological examination and evaluation by means of the Harris Hip Score , Hannover function question naire and single-film X-ray analysis ( EBRA ) . RESULTS The overall follow-up rate was 65.2 % ( 43 of 66 ) and the mean follow-up period was 8.1 ( 7.1 - 9.2 ) years . The median Harris Hip Score at the time of follow-up was 90.1 ( 58.7 - 99.9 ) points . The average Hannover function score was 87.14 % ( 63.9 - 100 ) . In 4 of 66 cases ( 6.1 % ) there was a tendency for the Plasmacup to subsidence in the first postoperative months that was slight but detectable by EBRA ; however , this stopped subsequently . This primary subsidence was independent of the chosen bearing material . No significant difference in the clinical and radiological parameters was found between the two groups . CONCLUSION The very good results with regard to the rate of loosening confirm the press-fit cup fixation concept . The study shows a similar medium-term result for the ceramic-ceramic and ceramic-polyethylene bearing so that use of both bearings can continue to be recommended . Only long-term studies with sufficiently large numbers of patients will be able to show whether significant differences can be detected between the two slide bearings with regard to wear and migration behaviour and so that a recommendation can be given to the surgeon 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 Polyethylene wear and associated osteolysis are major limitations to the long-term success of total hip arthroplasty . In vitro laboratory studies suggest polyethylene wear in THA may be substantially reduced with ceramic femoral heads . We evaluated the potential value of zirconia ceramic on conventional polyethylene as an “ alternative bearing ” for total hip arthroplasty in a prospect i ve , r and omized clinical trial in comparison with femoral heads made of Co-Cr-Mo . Patients were evaluated with st and ardized clinical outcome instruments , and measurement of head penetration was performed with computerized wear measurement software .  Study enrollment was halted because of a recall of the zirconia heads .  At that time , 30 total hip arthroplasties with Co-Cr-Mo heads and 30 total hip arthroplasties with zirconia heads had been performed . Mean followup was similar for both groups ( Co-Cr-Mo = 51.7 months ; zirconia = 51.2 months ) . The mean annual head penetration rate was low and similar for both groups ( Co-Cr-Mo = 0.060 mm/year ; and zirconia = 0.055 mm/year ) . In view of the recently reported potential for zirconia ceramics to undergo monoclinic phase transformation in vivo , with result ant increased fracture risk and degradation of wear properties , we do not recommend use of zirconia femoral heads as an “ alternative bearing ” for total hip arthroplasty . Level of Evidence : Level II , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence The purpose of the investigation was to assess the clinical and radiographic outcomes in four bearing surfaces . Eighty patients ( 91 hips ) undergoing total hip arthroplasty between 2004 and 2007 were r and omized to one of four bearing surfaces : ( 1 ) cobalt-chrome ( CoCr ) and ultra-high molecular weight polyethylene ( UHMWPE ) ; ( 2 ) CoCr and XLPE ; ( 3 ) Oxinium and UHMWPE ; and ( 4 ) Oxinium and XLPE . The mean follow-up for this study was 6.8 years . There were no significant differences in clinical outcomes . The linear wear rates for the four groups were 0.241 mm/year , 0.076 mm/year , 0.238 mm/year and 0.061 mm/year respectively . HXLPE results in significantly less wear than UHMWPE . However , we found no significant reduction in wear rate by using Oxinium in place of CoCr femoral heads at early follow-up 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 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 ) Background Polyethylene ( PE ) wear particles are believed to cause aseptic loosening and thereby impair function in hip arthroplasty .  Highly crosslinked polyethylene ( XLPE ) has low short- and medium-term wear rates . However , the long-term wear characteristics are unknown and it is unclear whether reduced wear particle burden improves function and survival of cemented hip arthroplasty . Questions / purpose sWe asked whether XLPE wear rates remain low up to 10 years and whether this leads to improved implant fixation , periprosthetic bone quality , and clinical function compared to conventional PE . Methods We r and omized 60 patients ( 61 hips ) to receive either PE or XLPE cemented cups combined with a cemented stem .  At 10 years postoperatively , 51 patients ( 52 hips ) were evaluated for polyethylene wear and component migration estimation by radiostereometry , for radiolucent lines , bone densitometry , and Harris hip and pain scores . Revisions were recorded . Results XLPE cups had a lower mean three-dimensional wear rate between 2 and 10 years compared to conventional PE hips : 0.005 mm/year versus 0.056 mm/year . We found no differences in cup migration , bone mineral density , radiolucencies , functional scores , and revision rate . There was a trend toward improved stem fixation in the XLPE group . The overall stem failure rate was comparably high , without influencing wear rate in XLPE hips . Conclusions XLPE displayed a low wear rate up to 10 years when used in cemented THA , but we found no clear benefits in any other parameters . Further research is needed to determine whether cemented THA design s with XLPE are less prone to stem loosening . Level of Evidence Level I , therapeutic study . See the Instructions for Authors for a complete description of levels of evidence Between 1999 and 2001 , 90 patients underwent total hip replacement using the same uncemented acetabular and femoral components  with a 28 mm metallic femoral head but with prospect i ve r and omisation of the acetabular liner to either Durasul highly cross-linked polyethylene or nitrogen-sterilised Sulene polyethylene . We assessed 83 patients at a minimum follow-up of ten years .  Linear penetration of the femoral head was estimated at six weeks , six and 12 months and annually thereafter , using the Dorr method , given the non-spherical shape of the acetabular component . There was no loosening of any component ; only one hip in the Sulene group showed proximal femoral osteolysis . The mean penetration of the femoral head at six weeks was 0.08 mm ( 0.02 to 0.15 ) for the Durasul group and 0.16 mm ( 0.05 to 0.28 ) for the Sulene group ( p = 0.001 ) . The mean yearly linear penetration was 64.8 % lower for the Durasul group at 0.05 mm/year ( sd 0.035 ) for the Sulene group and 0.02 mm/year ( sd 0.016 ) for the Durasul ( p < 0.001 ) . Mean linear femoral head penetration at ten years was 61 % less in the Durasul than Sulene group . Highly cross-linked polyethylene gives excellent results at ten years 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 We investigated the efficacy of combining highly cross-linked polyethylene with ceramic heads on further reduction in polyethylene wear compared with the combination with cobalt-chromium heads via PolyWare computer-assisted method . A prospect i ve cohort study was performed on 102 cementless total hip arthroplasties using Longevity ( Zimmer , Warsaw , Ind ) highly cross-linked polyethylene liners . Either  26-mm zirconia heads or 26-mm cobalt-chromium heads were r and omly used in 51 hips each . At a mean follow-up of 6.7 years , no significant differences were identified between the groups for total penetration rate and steady-state wear rate . Osteolysis was not observed in any hips in either group . In conclusion , no advantage was seen for the 26-mm zirconia head compared with the 26-mm cobalt-chromium head in this period Abstract Ceramic-on-ceramic bearings in THA are a popular alternative to overcome wear concerns in traditional metal-polyethylene bearings . However , squeaking is a potentially worrisome phenomenon in ceramic-on-ceramic THAs which we observed in some of our patients . We review ed all 42 patients who underwent 43 ceramic-on-ceramic noncemented THAs during the time of the study .  Squeaking , defined as a reproducible sound of squeaking , clicking , or grating , occurred in nine of 43 implants ( 20.9 % ) . St and ard radiographs were normal . We used CT imaging to determine cup anteversion and inclination angles , comparing the squeaking hips with those of a r and omly selected control group , but found no differences . We then hypothesized specific design features ( stem size , cup size , head size , and neck length of the head ) would be risk factors for squeaking . We found a difference in neck length between squeaking and nonsqueaking implants . A neck length of −4 mm or shorter result ed in a relative risk of 5.56 ( 95 % confidence interval , 1.14–27.01 ) for squeaking . We found a high incidence of squeaking in our population , and we believe this phenomenon is an underreported side effect of these types of bearings . A short neck length of the femoral implant was a risk factor for squeaking in ceramic-on-ceramic THA . Level of Evidence : Level III , therapeutic study The purpose of this study was to compare highly cross-linked polyethylene wear between the zirconia head and the cobalt-chromium head in Japanese patients . A prospect i ve , r and omized study was performed to evaluate the outcomes in 32 hips that had zirconia heads and in 30 hips that had cobalt-chromium heads .  The mean follow-up periods of both groups were same ( 5 years ) . There were no significant differences between the zirconia head and the cobalt-chromium head in the mean polyethylene linear wear per year and the mean volumetric polyethylene wear per year in the steady phase . This study indicates that zirconia head offers no benefits over metal head in terms of wear reduction at 5 years in Japanese patients who have lightweight and thin polyethylene liners BACKGROUND A ceramic femoral head is an alternative to a metal femoral head for the bearing surface of total hip arthroplasty . The purpose of this study was to compare polyethylene wear in patients who had undergone bilateral total hip arthroplasty with implants that differed only with regard to the material used for the femoral head : a zirconia head was used on one side , and a cobalt-chromium head was inserted on the contralateral side . METHODS A prospect i ve , r and omized study was performed to evaluate the outcomes in fifty-two patients who had undergone sequential bilateral primary total hip replacement . A zirconia head was used in one hip , and a cobalt-chromium head was used in the other . There were forty-eight men and four women ; the mean age at the time of surgery was 44.2 years . The mean duration of follow-up was 7.1 years . Clinical and radiographic evaluations were performed preoperatively and at six weeks ; three , six , and twelve months ; and yearly postoperatively . Linear wear of the polyethylene liner was measured radiographically . Two femoral components with a zirconia head had aseptic loosening and were revised . The explanted heads were evaluated with use of interferometry , environmental scanning electron microscopy , and x-ray diffraction studies . RESULTS The mean polyethylene wear rate was 0.08 mm/yr in association with the zirconia heads and 0.17 mm/yr in association with the cobalt-chromium heads ( p = 0.004 ) . The mean amount of volumetric polyethylene wear was 350.8 mm3 in association with the zirconia heads and 744.7 mm3 in association with the cobalt-chromium heads ( p = 0.004 ) . With regard to surface roughness , the Ra values of the two explanted zirconia heads were 15.87 and 17.35 nm and the Rpm values were 153.86 and 156.18 nm . Two identical zirconia heads that had not been implanted had Ra values of 5.31 and 5.48 nm and Rpm values of 65.27 and 66.35 nm . Four unimplanted cobalt-chromium heads that were identical to the ones implanted in this study had Ra values ranging between 25 and 50 nm and Rpm values ranging between 262.6 and 525.2 nm . Little phase transformation was noted in the two revised zirconia heads . CONCLUSIONS The mean amount and rate of polyethylene wear were significantly lower in the hips with a zirconia head than they were in the hips with a cobalt-chromium head , presumably because the zirconia heads had a smoother articulating surface We conducted a prospect i ve single-blinded r and omised controlled trial to compare the functional and quality of life outcomes in two groups of patients between 60 and 80 years of age undergoing THR ; the first receiving a small head ( 28–32 mm ) metal on polyethylene ( MoP ) articulation , and the second receiving a large head ( 44–54 mm ) metal on metal ( MoM ) articulation .  We recruited 49 patients and r and omised them into one of the two groups ( 22 MoP and 27 MoM ) . The results demonstrated no statistical difference in any of the assessed functional outcomes at any follow-up point ( p>0.05 ) . There were no dislocations or revisions in either group . Although it has been suggested that large head MoM articulations in THA offer superior stability and function , our results suggest that small head MoP articulations can achieve comparable ROM , function and quality of life at short-term follow-up
target: The present evidence indicated the similar performance in survivorship among CoC , CoPc , CoPxl and MoPxl bearing implants , and that all likely have superiority compared with the MoM and MoPc bearing implants in THA procedures .
background: PURPOSE Although many  total hip bearing implants  are widely used all over the world , simultaneous comparisons across the numerous available bearing surfaces are rare .
  The purpose of this study was to compare the survivorship of total hip arthroplasty ( THA ) with six available bearing implants .