The effects of different weight-bearing regimes on press-fit cup stability: a randomised study with five years of follow-up using radiostereometry Does the Dual-Mobility Hip Prosthesis Produce Better Joint Kinematics During Extreme Hip Flexion Task? Use of an alumina-on-alumina bearing system in total hip arthroplasty for osteonecrosis of the hip. A randomized trial of ceramic-on-ceramic bearing versus ceramic-on-crossfire-polyethylene bearing in total hip arthroplasty: five-year outcomes. Periprosthetic bone mineral density and fixation of the uncemented CLS stem related to different weight bearing regimes 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 Comparison of Fixed-Bearing and Mobile-Bearing Total Knee Arthroplasties No adverse effects of early weight bearing after uncemented total hip arthroplastyA randomized study of 20 patients The squeaking hip: a phenomenon of ceramic-on-ceramic total hip arthroplasty. THA With Delta Ceramic on Ceramic: Results of a Multicenter Investigational Device Exemption Trial Early experience with dual mobility acetabular systems featuring highly cross-linked polyethylene liners for primary hip arthroplasty in patients under fifty five years of age: an international multi-centre preliminary study Long-term comparison of fixed-bearing and mobile-bearing total knee replacements in patients younger than fifty-one years of age with osteoarthritis. 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. Large-diameter Delta ceramic-on-ceramic versus common-sized ceramic-on-polyethylene bearings in THA. High Incidence of Squeaking in THAs with Alumina Ceramic-on-ceramic Bearings Antero-lateral minimal invasive (ALMI) approach for total hip arthroplasty technique and early results Early clinical results of a high-flexion, posterior-stabilized, mobile-bearing total knee arthroplasty: a US investigational device exemption trial. Zirconia versus Co-Cr Femoral Heads in Total Hip Arthroplasty: Early Assessment of Wear Delta Ceramic-on-Alumina Ceramic Articulation in Primary THA: Prospective, Randomized FDA-IDE Study and Retrieval Analysis Comparison of polyethylene wear associated with cobalt-chromium and zirconia heads after total hip replacement. A prospective, randomized study. One Year After Navigated Total Knee Replacement, No Clinically Relevant Difference Found Between Fixed Bearing and Mobile Bearing Knee Replacement in a Double-Blind Randomized Controlled Trial A randomized controlled trial comparing Oxinium and cobalt-chrome on standard and cross-linked polyethylene. Immediate weight bearing after uncemented total hip arthroplasty with an anteverted stem: A prospective randomized comparison using radiostereometry Mobile Bearings Do Not Improve Fixation in Cemented Total Knee Arthroplasty [Fixed-bearing versus mobile-bearing total knee arthroplasty: a prospective randomized clinical and radiological study]. Alumina Ceramic Bearings for Total Hip Arthroplasty: Five-year Results of a Prospective Randomized Study
Purpose There is little evidence to support immediate weight bearing after uncemented total hip arthroplasty ( THA ) . Methods Thirty-seven patients with unilateral osteoarthritis of the hip received a press-fit cup . Cup stability was assessed with radiostereometry ( RSA ) over five years . Patients were r and omised to immediate full weight bearing , or partial weight bearing for three months . Results At five years , we found no difference in micromotion as assessed with radiostereometry . Numerically , there was more proximal translation and increased inclination with immediate weight bearing , but these values barely exceeded the precision limit for the method . Pooled data for the two groups revealed translations of 0.1 - 0.3 mm and rotations of 0.2 - 0.3 ° over the five year follow-up period . Conclusions We found no adverse effects of immediate weight bearing after THA in relation to stability of these press-fit cups . Early mobilisation might have other advantages BACKGROUND  Total hip arthroplasty ( THA )  using dual-mobility ( DM ) design permits larger hip range of motion . However , it is unclear how it benefits the patients during activities of daily living . The purpose was to compare kinematic variables of the operated limb between  THA patients using either DM or single-bearing ( SB ) implants during a squat task . METHODS Twenty-four THA patients were r and omly assigned to either a DM or SB implant and matched to 12 healthy controls ( CTRLs ) . They underwent 3-dimensional squat motion analysis  before and 9 months after surgery . Sagittal and frontal plane angles of the pelvis and the hip were analyzed using statistical parametric mapping . Paired analyses compared presurgery and postsurgery squat depth . RESULTS Peak sagittal pelvis angle of DM was closer to normal compared with that of SB . Both implant groups had similar hip angle patterns and magnitude but significantly lower than the CTRLs . SB reached a much large hip abduction compared with the other groups . Both surgical groups had significantly worst squat depth than the CTRLs . CONCLUSION Neither THA implant groups were able to return pelvis and hip kinematics to the level of CTRLs . The deficit of DM implants at the pelvis combined with the poorer functional scores should caution clinicians to use this implant design in active patients . SB design causes a larger hip abduction to reach their maximum squat depth . Post-THA rehabilitation should focus on improving joint range of motion and strength 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 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 and purpose There is no consensus on the best rehabilitation regime after uncemented total hip arthroplasty . Theoretically , bone ingrowth into the implant should benefit from initial partial weight bearing . We investigated whether the degree of postoperative weight bearing influences the periprosthetic bone mineral density ( BMD ) and /or the stability of the CLS stem . Patients and methods 38 patients received an uncemented CLS stem  and were  r and omized  to either unrestricted postoperative weight bearing or to partial weight bearing for 3 months .  Periprosthetic BMD was measured in the 7 Gruen zones with DXA and the stability of the femoral stem was assessed by radiostereometric analysis ( RSA ) after surgery and at 3 , 12 , 24 , and 60 months . Results Periprosthetic BMD was not influenced by the type of postoperative weight bearing . BMD was reduced by 8–15 % in all Gruen zones at 3 months . Restoration toward initial BMD was observed in all zones except in zone 7 ( calcar region ) , where BMD was reduced by 22 % at 5 years . Immediate weight bearing after surgery had no influence on the stability of the CLS stem , as assessed by RSA . Interpretation Immediate full weight bearing after uncemented total hip arthroplasty is safe . There is no difference in the periprosthetic BMD or in stability of the stem as measured by RSA compared to partial weight bearing for 3 months . BMD is reduced by more than 20 % in the calcar region around a CLS stem after 5 years 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 purpose of the current study was to directly compare the results of fixed-bearing and mobile-bearing total knee arthroplasties in the same patient who had bilateral simultaneous total knee replacements . A fixed-bearing total knee prosthesis ( AMK ) was implanted in one knee and a mobile-bearing total knee prosthesis ( LCS ) was implanted in the other knee in 116 patients . The average age of the patients was 65 years ( range , 33–70 years ) . The average followup was 7.4 years ( range , 6–8 years ) .  Clinical and radiographic followup was done using Knee Society and Hospital for Special Surgery knee rating systems at 6 weeks , 3 months , 6 months , 1 year after surgery , and yearly thereafter . Total knee score , pain score , mean functional score , and range of motion were comparable in both groups . Two knee replacements ( 2 % ) in one patient with AMK prostheses were revised because of complete wear of tibial bearing polyethylene . One knee replacement ( 1 % ) in one patient with an LCS prosthesis was revised because of dislocation of the medial tibial bearing polyethylene and one knee replacement ( 1 % ) in one patient with an LCS prosthesis was revised because of complete wear of the medial tibial bearing polyethylene . No knee had aseptic loosening or osteolysis in either group . After a minimum followup of 6 years , the results of fixed- and mobile-bearing total knee prostheses in the current series are favorable . However , there is no evidence to prove the superiority of the mobile-bearing total knee design BACKGROUND Few guidelines are available whether early weight-bearing after an  uncemented total hip arthroplasty ( THA ) can be recommended or not . Stability and ingrowth may be jeopardized by immediate loading of the implant while functional recovery may be promoted and periprosthetic demineralization reduced . PATIENTS AND METHODS We did a prospect i ve study of 20 patients who were operated on with a hydroxyapatite-coated ( HA ) , uncemented total hip arthroplasty with a tapered stem because of unilateral arthrosis , and r and omized the patients to the immediate ( I ) or late ( L ) weight-bearing ( after 3 months ) group . The shoe on the operated side was equipped with an auditory device signaling when the patient placed a load on the extremity . The clinical assessment was done with the Harris hip score at the time of the operation and after 12 and 24 months . Radiographs and dual-energy x-ray absorptiometry ( DEXA ) were evaluated for migration , femoral remodeling and bone mineral density ( BMD ) after 3 , 6 , 12 and 24 months .  Tc-scintigraphy  was done after 6 , 12 and 24 months . RESULTS Postoperatively , the Harris hip score showed no group difference . After 3 months , we noted a large reduction in BMD around the stem prosthesis . This was most marked in the proximal regions and the bone loss was significantly larger in zone 1 , 4 and 5 in the L group . Distally , the BMD normalized with time , but the loss of bone persisted in the proximal zones after 24 months . An initial increase in the scintigraphic uptake ratio in all zones in both groups declined with time , but it was still increased on the operated side after 24 months . Several radiographic signs of bone remodeling were seen , but the patterns were similar in both groups . INTERPRETATION We found no adverse effect of immediate weight bearing with this prosthesis 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 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 Purpose To evaluate early performance of contemporary dual mobility acetabular systems with second generation annealed highly cross-linked polyethylene for primary hip arthroplasty of patients under 55 years of age . Methods A prospect i ve observational five years study across five centers in Europe and the USA of 321 patients with a mean age of 48.1 years was performed . Patients were assessed for  causes of revision , hip instability , intra-prosthetic dissociation , Harris hip score and radiological signs of osteolysis .  Results There were no dislocations and no intra-prosthetic dissociations . Kaplan Meier analysis demonstrated 97.51 % survivorship for all cause revision and 99.68 % survivorship for acetabular component revision at five years . Mean Harris hip score was 93.6 . Two acetabular shells were revised for neck-rim implant impingement without dislocation and ten femoral stems were revised for causes unrelated to dual mobility implants . Conclusion Contemporary highly cross-linked polyethylene dual mobility systems demonstrate excellent early clinical , radiological , and survivorship results in a cohort of patients that dem and high performance from their implants . It is envisaged that DM and second generation annealed HXLPE may reduce THA instability and wear , the two most common causes of THA revision in hip arthroplasty BACKGROUND There is limited information comparing the results of fixed-bearing total knee replacement and mobile-bearing total knee replacement in patients with osteoarthritis who are younger than fifty-one years and who have a fixed-bearing implant in one knee and a mobile-bearing implant  in the other . The purpose of this study was to compare our long-term clinical and radiographic results of fixed-bearing total knee replacement and mobile-bearing total knee replacement in a group of patients from this population . METHODS We prospect ively compared the results of 108 patients with osteoarthritis who were younger than fifty-one years ( mean age , forty-five years ) who had received a fixed-bearing prosthesis in one knee and a rotating platform mobile-bearing prosthesis in the other .  The mean follow-up was 16.8 years ( range , fifteen to eighteen years ) . The patients were assessed clinical ly and radiographically . Knee motion and function were assessed as a primary outcome . Patients were assessed with question naires , and each knee was assessed separately . RESULTS Although there was significant improvement in both groups of knees , there was no significant difference between the groups ( i.e. , fixed-bearing and mobile-bearing knees ) with regard to the mean postoperative knee motion ( 126 ° and 128 ° , respectively ; p = 0.79 ) , the mean Knee Society knee clinical score ( 95 and 94 points , respectively ; p = 0.79 ) , or the Knee Society knee functional score ( 84 and 85 points , respectively ; p = 0.19 ) at the latest follow-up . In the fixed-bearing group , one knee was revised because of infection , two for aseptic loosening of the tibial component , and two because of wear of the tibial polyethylene insert . In the rotating platform mobile-bearing group , two knees were revised because of instability and one because of infection . The Kaplan-Meier survivorship for revision at 16.8 years of follow-up was 95 % ( 95 % confidence interval , 91 to 100 ) for the fixed-bearing prosthesis and 97 % ( 95 % confidence interval , 93 to 100 ) for the rotating platform mobile-bearing prosthesis . CONCLUSIONS Long-term results of both fixed and mobile-bearing total knee arthroplasties were encouraging in patients who were younger than fifty-one years of age with osteoarthritis . However , we found no superiority of the mobile-bearing total knee prosthesis over the fixed-bearing total knee prosthesis 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 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 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 Introduction : Minimally invasive surgery represents one of the most recent techniques to have emerged within THA . In conventional THA , the incision typically measures 15–20 cm . Minimal invasive approach defined as less invasive to the skin , muscles , or bone may reduce complications and improve recovery time . A number of different approaches and methods have been described in literature . Purpose : This is a prospect i ve study describing the technique and early results of the modified antero-lateral minimal invasive ( ALMI ) approach and comparing our results to the results of other investigators interested in minimal invasive THA . Material s and methods : Seventy-five consecutive primary total hip arthroplasties ( cemented and cementless ) were done through a modified ALMI approach ( 6–8 cm ) , in which we kept the hip abductors intact . Neither special instruments nor specially design ed prostheses were needed . Minimum follow-up was 12 months . Results : The mean Harris hip score for patients after 12-month follow-up was 90 while the mean Merle d’Abugine mean score was 16.5 . Both scores reached almost the maximum values within 3 months after surgery . The cup abduction angle for 70 % patients was between 35 ° and 45 ° . No femoral stem mal-alignment was recorded . The mean operative time of cemented prosthesis was 65 min while that of the cementless prosthesis was 55 min . No wound complications or dislocations were recorded . All the patients were allowed to weight bear in the second post-operative day and involved in an early rehabilitation program . Conclusion : ALMI hip approach with sparing of hip abductors is safe and gives excellent orientation for positioning of prosthesis components . It also allows early and smooth post-operative rehabilitation with fast recovery of the patient in terms of weight bearing Between May 2001 and June 2004 , 388 total knee arthroplasty cases were enrolled in a prospect i ve , r and omized , multicenter investigational device exemption trial . Patients received either the investigational high-flexion mobile-bearing knee or a fixed-bearing control . At 2 to 4 years of follow-up , results in 293 patients with degenerative joint disease were compared using Knee Society Assessment and Function scores , radiographic results , complications analysis , and survival estimates . The mobile-bearing and fixed-bearing groups demonstrated similar , significant improvement over preoperative assessment s in Knee Scores , maximum flexion , and range of motion . One mobile-bearing arthroplasty required revision . Radiographic results were unremarkable , and implant-related complications were rare in both groups . At this early follow-up , the investigational high-flexion mobile-bearing knee and its fixed-bearing counterpart demonstrated comparable , effective performance 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 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 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 Background : The mobile bearing design s have not yet been shown to improve clinical outcome of total knee arthroplasty ( TKA ) . In this prospect i ve r and omized study , we compared the short-term clinical results of a mobile bearing implant with those of the fixed bearing version of the same implant . Methods : We r and omized 100 knees into two double-blind groups who received either the fixed ( FB , 52 knees ) or the mobile bearing ( MB , 48 knees ) version of the same implant .  We used navigation to st and ardize the surgical technique . For up to one year , we recorded the Knee Society ( KSS ) and Oxford ( OXF ) scores . We performed an exploratory analysis of variance ( ANOVA ) to determine the influence of baseline scores as covariate and the extent of improvement in clinical outcome over time . Results : After one year , we did not detect any statistically significant difference between the two groups . The KSS scores differed by 2 points , the OXF scores by 1.1 points . Conclusion : Even with identical geometry of implant surfaces and a navigated surgical technique , first-year results do not support a preference for either a fixed or a mobile design 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 Background In uncemented total hip arthroplasty with hydroxyapatite coating , early weight bearing is frequently practice d but there is still not much evidence to support this recommendation . Method In a prospect i ve r and omized study we evaluated the effect of partial and full weight bearing after  cementless total hip arthroplasty ( ABG ; Stryker-Howmedica ) using radiostereometric analysis ( RSA ) . Between February 1996 and February 2000 , 43 consecutive patients ( mean age 53 ( 41–63 ) years , 23 women ) with hip osteoarthrosis received an uncemented and hydroxyapatite-coated prosthesis with an anteverted stem . All patients were operated in a st and ardized way by three experienced surgeons and they were r and omized to partial ( P ) or full ( F ) weight bearing during the first 6 weeks after surgery . The patients in the partial weight bearing group were equipped with a pressuresensitive insole signaling when their load exceeded the prescribed weight limit . Results At 3-month follow-up , the mean proximal (+)/ distal ( - ) migration of the stem was -0.14 mm ( -1.93– 0.11 ) in group P and -0.31 mm ( -4.30–0.16 ) in group F ( p = 0.6 ) . At 1-year follow-up , the mean migration was –0.17 mm ( -2.18–0.21 ) and -0.28 mm ( -4.31–0.11 ) , respectively ( p = 0.9 ) . There was no significant difference in stem rotations either ( p < 0.2 ) . The cup translations , rotations , and femoral head penetration were similar in the two groups ( p < 0.1 ) . There were no re-operations during the first year . Interpretation We did not find any adverse effect of full weight bearing immediately after operation , which justifies use of this regimen after uncemented total hip arthroplasty of the ABG type Mobile bearings were introduced to improve wear and knee kinematics . By uncoupling the forces generated at the articulation from the implant-bone interface this would , theoretically , also improve the fixation of the implant to bone . We did this study to evaluate whether mobile bearings  improve the fixation of the tibial component to bone .  Fifty-two consecutive knees in 47 patients ( average age , 72 years ; range , 62 - 84 years ) with primary osteoarthrosis were r and omized into two groups to receive a cemented total knee arthroplasty with either a fixed-bearing or mobile-bearing tibial component . The quality of fixation was analyzed with radiostereometric analysis for up to 2 years . Mobile bearings did not improve fixation . Both magnitudes and directions of component rotations were similar , and the number of implants with continuous migration was almost identical . Both implant types had a combination of subsidence and lift-off , but where the mobile bearing implants displayed more of subsidence , the fixed bearing knees showed more lift-off . It might be that the somewhat stiffer cobalt-chromium baseplate or the different joint conformity used in the mobile-bearing knees counteracts any potential effects of the mobile bearing . Level of Evidence : Therapeutic Level I. See the Guidelines for Authors for a complete description of levels of evidence PURPOSE OF THE STUDY Mobile-bearing total knee arthroplasty has become increasingly popular over the last few years since this option presents several theoretical advantages compared with the fixed-bearing models . The clinical advantage remains to be demonstrated . We therefore conducted a prospect i ve r and omized trial to ascertain the potential benefits . MATERIAL AND METHODS This study included patients treated by three senior orthopedic surgeons . Each group included 52 prostheses in 52 patients in the fixed-bearing group and 50 patients in the mobile-bearing group . The per- and postoperative protocol s were the same for both groups . Implants were cemented in all cases and patellae were resurfaced . The SF-12 , the Knee Society Score ( KSS ) , the Hospital of Special Surgery score ( HSS ) and pain and joint motion were noted before and after surgery . RESULTS Among the 104 prostheses implanted , 100 were review ed at mean follow-up of 36 months ( range 24 - 41 ) . One patient in the fixed-bearing group died six months after surgery from an unrelated cause . Three patients were lost to follow-up : one in the fixed-bearing group and two in the mobile-bearing group . There was no difference between groups for the SF-12 , KSS , HSS , pain and joint motion measured postoperatively . Postoperative femorotibial alignment was one degree varus on average in the fixed-bearing group and zero degree in the mobile-bearing group . At last follow-up , there were no radiological signs of prosthesis loosening . One patient in the fixed-bearing group developed a deep venous thrombosis , complicated by pulmonary embolism . Two of the mobile-bearing prostheses were revised , one for patellar fracture caused by a bicycle accident and one for prosthesis infection in a patient with endocarditis 1.5 years after implantation . DISCUSSION The clinical results were similar for the two groups in terms of function , pain , general status and complications . The outcome at 36 months was considered excellent or good in 90 % of the fixed-bearing group and 88 % in the mobile-bearing group . This study did not reveal any difference between the two groups regarding maximal flexion and anterior knee pain , two parameters which would theoretically show short-term improvement with the mobile bearing . Mid- and long-term follow will be required to confirm these findings and to determine the survival of these two types of implants Three hundred twenty-eight ceramic bearings were implanted by six surgeons in 316 patients as a part of a prospect i ve r and omized US Investigational Device Exemption study comparing alumina ceramic bearings with cobalt chrome-on-polyethylene bearings . There was no difference between the control metal-on-polyethylene and the alumina bearing couple patient cohorts regarding demographics or clinical scores through 7 years . Revision for any reason occurred in 2.7 % of the patients with alumina bearings and 7.5 % of the control patients with polyethylene bearings .  Osteolysis was found in 1.4 % of the patients with alumina bearings and in 14.0 % of the control patients . At an average followup of 5.0 years ( range , 1 - 86 months ) no ceramic fractures or ceramic bearing failures have occurred . Results of this study suggest that alumina ceramics  perform as well as the metal-on-polyethylene in clinical scores , but the patients with ceramic bearings had fewer revisions and less osteolysis . These results lead us to think that this new alumina ceramic bearing provides a safe option for younger and more active patients . Level of Evidence : Therapeutic study , Level I-1b ( r and omized controlled trial , no significant difference , but narrow confidence intervals ) . See the Guidelines for Authors for a complete description of levels of evidence
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 .
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 .