Large-diameter Delta ceramic-on-ceramic versus common-sized ceramic-on-polyethylene bearings in THA. Long-term comparison of fixed-bearing and mobile-bearing total knee replacements in patients younger than fifty-one years of age with osteoarthritis. A randomized trial of ceramic-on-ceramic bearing versus ceramic-on-crossfire-polyethylene bearing in total hip arthroplasty: five-year outcomes. [Fixed-bearing versus mobile-bearing total knee arthroplasty: a prospective randomized clinical and radiological study]. The squeaking hip: a phenomenon of ceramic-on-ceramic total hip arthroplasty. Comparison of Fixed-Bearing and Mobile-Bearing Total Knee Arthroplasties Comparison of Robotic-assisted and Conventional Acetabular Cup Placement in THA: A Matched-pair Controlled Study Does the Dual-Mobility Hip Prosthesis Produce Better Joint Kinematics During Extreme Hip Flexion Task? What Works Best, a Cemented or Cementless Primary Total Hip Arthroplasty?: Minimum 17-year Followup of a Randomized Controlled Trial What Can Be Learned From Minimum 20-year Followup Studies of Knee Arthroplasty? A prospective randomised study comparing rotating platform and fixed bearing total knee arthroplasty in a cruciate substituting design--outcomes at two year follow-up. The effects of different weight-bearing regimes on press-fit cup stability: a randomised study with five years of follow-up using radiostereometry 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 Delta Ceramic-on-Alumina Ceramic Articulation in Primary THA: Prospective, Randomized FDA-IDE Study and Retrieval Analysis High Incidence of Squeaking in THAs with Alumina Ceramic-on-ceramic Bearings Fixed-bearing versus mobile-bearing total knee arthroplasty: a prospective randomised, clinical and radiological study with mid-term results at 7 years. THA With Delta Ceramic on Ceramic: Results of a Multicenter Investigational Device Exemption Trial EBRA migration patterns of the Plasmacup with ceramic or polyethylene inserts: a randomised study. Zirconia versus Co-Cr Femoral Heads in Total Hip Arthroplasty: Early Assessment of Wear Antero-lateral minimal invasive (ALMI) approach for total hip arthroplasty technique and early results Mobile-bearing prosthesis did not improve mid-term clinical results of total knee arthroplasty Introduction of a new mobile-bearing total knee prosthesis: minimum three year follow-up of an RCT comparing it with a fixed-bearing device. A Comparison between Robotic-assisted and Manual Implantation of Cementless Total Hip 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 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 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 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 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 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 Improper acetabular component orientation in THA has been associated with increased dislocation rates , component impingement , bearing surface wear , and a greater likelihood of revision . Therefore , any reasonable steps to improve acetabular component orientation should be considered and explored . Questions / purpose sWe therefore sought to compare THA with a robotic-assisted posterior approach with manual alignment techniques through a posterior approach , using a matched-pair controlled study design , to assess whether the use of the robot made it more likely for the acetabular cup to be positioned in the safe zones described by Lewinnek et al. and Callanan et al. Methods Between September 2008 and September 2012 , 160 THAs were performed by the senior surgeon . Sixty-two patients ( 38.8 % ) underwent THA using a conventional posterior approach , 69 ( 43.1 % ) underwent robotic-assisted THA using the posterior approach , and 29 ( 18.1 % ) underwent radiographic-guided anterior-approach THAs .  From September 2008 to June 2011 , all patients were offered anterior or posterior approaches regardless of BMI and anatomy . Since introduction of the robot in June 2011 , all THAs were performed using the robotic technique through the posterior approach , unless a patient specifically requested otherwise . The radiographic cup positioning of the robotic-assisted THAs was compared with a matched-pair control group of conventional THAs performed by the same surgeon through the same posterior approach . The safe zone ( inclination , 30 ° –50 ° ; anteversion , 5 ° –25 ° ) described by Lewinnek et al. and the modified safe zone ( inclination , 30 ° –45 ° ; anteversion , 5 ° –25 ° ) of Callanan et al. were used for cup placement assessment . Matching criteria were gender , age ± 5 years , and ( BMI ) ± 7 units . After exclusions , a total of 50 THAs were included in each group . Strong interobserver and intraobserver correlations were found for all radiographic measurements ( r > 0.82 ; p < 0.001 ) . Results One hundred percent ( 50/50 ) of the robotic-assisted THAs were within the safe zone described by Lewinnek et al. compared with 80 % ( 40/50 ) of the conventional THAs ( p = 0.001 ) . Ninety-two percent ( 46/50 ) of robotic-assisted THAs were within the modified safe zone described by Callanan et al. compared with 62 % ( 31/50 ) of conventional THAs p ( p = 0.001 ) . The odds ratios for an implanted cup out of the safe zones of Lewinnek et al. and Callanan et al. were zero and 0.142 , respectively ( 95 % CI , 0.044 , 0.457 ) . Conclusions Use of the robot allowed for improvement in placement of the cup in both safe zones , an important parameter that plays a significant role in long-term success of THA . However , whether the radiographic improvements we observed will translate into clinical benefits for patients —such as reductions in component impingement , acetabular wear , and prosthetic dislocations , or in terms of improved longevity — remains unproven . Level of Evidence Level III , therapeutic study . See the Instructions for Authors for a complete description of levels of evidence 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  Total hip arthroplasty ( THA )  has been associated with high survival rates , but debate remains concerning the best fixation mode of THA . Questions / purpose sWe conducted a r and omized controlled trial ( RCT ) with 250 patients with a mean age of 64 years between October 1987 and January 1992 to compare the results of cementless and cemented fixation . Patients and Methods Patients were evaluated for revision of either of the components . One hundred twenty-seven patients had died ( 51 % ) and 12 ( 4.8 % ) were lost to followup . The minimum 17-year followup data ( mean , 20 years ; range , 17–21 years ) for 52 patients of the cementless group and 41 patients of the cemented group were available for evaluation . Results Kaplan-Meier survivorship analysis at 20 years revealed lower survival rates of cemented compared with cementless THA . The cementless tapered stem was associated with a survivorship of 99 % . Age younger than 65 years and male gender were predictors of revision surgery . Conclusions The efficacy of future RCTs can be enhanced by r and omizing patients in specific patient cohorts stratified to age and gender in multicenter RCTs . Including only younger patients might improve the efficacy of a future RCT with smaller sample sizes being required . A minimum 10-year followup should be anticipated , but this can be expected to be longer if the difference in level of quality between the compared implants is smaller . Level of Evidence Level I , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence Background Long-term evaluation of knee arthroplasty should provide relevant information concerning the durability and performance of the implant and the procedure . Because most arthroplasties are performed in older patients , most long-term followup studies have been performed in elderly cohorts and have had low patient survivorship to final followup ; the degree to which attrition from patient deaths over time in these studies might influence their results has been poorly characterized . Questions / purpose sThe purpose of this study was to examine the results at 20-year followup of two prospect ively followed knee arthroplasty cohorts to determine the following : ( 1 ) Are there relevant differences among the two implant cohorts in terms of revision for aseptic causes ( osteolysis , or loosening ) ? ( 2 ) How does patient death over the long followup interval influence the comparison , and do the comparisons remain valid despite the high attrition rates ? Methods Two knee arthroplasty cohorts from a single orthopaedic practice were evaluated : a modular tibial tray ( 101 knees ) and a rotating platform ( 119 knees ) design . All patients were followed for a minimum of 20 years or until death ( mean , 14.1 years ; SD 5.0 years ) . Average age at surgery for both cohorts was > 70 years . The indications for the two cohorts were identical ( functionally limiting knee pain ) and was surgeon-specific ( each surgeon performed all surgeries in that cohort ) . Revision rates through a competing risks analysis for implants and survivorship curves for patients were evaluated . Results Both of these elderly cohorts showed excellent implant survivorship at 20 years followup with only small differences in revision rates ( 6 % revision versus 0 % revision for the modular tibial tray and rotating platform , respectively ) . However , attrition from patient deaths was substantial and overall patient survivorship to 20-year followup was only 26 % . Patient survivorship was significantly higher in patients < 65 years of age in both cohorts ( 54 % versus 15 % , p < 0.001 modular tray cohort , and 52 % versus 26 % , p = 0.002 rotating platform cohort ) . Furthermore , in the modular tray cohort , patients < 65 years had significantly higher revision rates ( 15 % versus 3 % , p = 0.0019 ) . Conclusions These two cohorts demonstrate the durability of knee arthroplasty in older patients ( the vast majority older than 65 years ) . Unfortunately , few patients lived to 20-year followup , thus introducing bias into the analysis . These data may be useful as a reference for the design of future prospect i ve studies , and consideration should be given to enrolling younger patients to have robust numbers of living patients  at long-term followup . Level of Evidence Level III , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence BACKGROUND Fixed bearing ( FB ) total knee replacement is a well established technique against which new techniques must be compared . Mobile bearing ( MB ) prostheses , in theory , reduce polyethylene wear but the literature is yet to provide evidence that they are superior in terms of function or long-term survivorship . In addition there has been no comparison of patella resurfacing on the outcome of either design . The aims of this r and omised prospect i ve study were firstly to determine whether a mobile bearing prosthesis produced better clinical outcome and range of motion at two year follow-up and secondly to assess the effect of patella resurfacing on the outcomes of both types of bearing design . METHODS Three hundred fifty-two patients were r and omised into receiving either a PFC Sigma © cruciate sacrificing total knee arthroplasty either with a mobile bearing or a fixed bearing  , with a sub-r and omisation to either patella resurfacing or patella retention . All patients participated with st and ard clinical outcome measures and had their range of motion measured both pre-operatively and at follow-up . RESULTS The mobile bearing TKR design had no impact on range of motion ; Oxford Knee Score and American Knee Society knee and function scores when compared to its fixed bearing equivalent . CONCLUSIONS At two year follow-up there was no difference between the PFC Sigma © fixed and mobile bearing design s. With no clinical difference between the cohorts , we can not recommend one design over the other . Long term benefits , particularly with regards to polyethylene wear , may yet be demonstrated . Level of evidence --1B 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 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 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 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 Mobile-bearing ( MB ) total knee arthroplasty ( TKA ) was developed as an alternative to the established fixed-bearing ( FB ) design because of theoretical advantages . Short-term studies comparing these design s have not shown any differences in clinical and radiographic results . We compared the results at 7 years of a r and omised study of patients undergoing TKA using either a FB or a MB variant of the same prosthesis . Fifty-two patients ( 52 knees ) with an average age of 70 years received a FB posterior-stabilized prosthesis , and 50 patients ( 52 knees ) with an average age of 72 years , a MB prosthesis .  All implants were cemented and the patella was routinely resurfaced . Preoperatively , there were no differences between the two groups , and surgical procedure and postoperative protocol were the same for both . At an average follow-up of 7.1 years , no significant differences of FB over MB design could be demonstrated with respect to the American Knee Society score ( AKSS ) , pain score , a question naire of general health ( SF-12 score ) , range of motion ( ROM ) , or complication rates . Radiographs showed no significant difference in prosthetic alignment or evidence of loosening . Two knees with a MB design required reoperation , one for persistent joint stiffness and another to treat septic loosening . One patient with a MB prosthesis with signs of tibial component loosening was asymptomatic . We conclude that at mid-term follow-up there is no evidence to prove the superiority of MB over FB TKA with regard to the clinical and radiographic results 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 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 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 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 A prospect i ve study was performed to compare the clinical and radiological results of mobile- and fixed-bearing total knee arthroplasty  with specific attention to rotational alignment and range of motion . Sixty-one knees were assigned to total knee arthroplasty with either the NexGen LPS Flex fixed-bearing or with the NexGen LPS Flex mobile-bearing prosthesis . Postoperatively , knees were compared with regard to range of motion , clinical score , and radiographic findings . Rotational alignment of the femoral and tibial components was evaluated by computed tomography . The median follow-up period was 5.9 years ( range 2.1–8.8 years ) . Median postoperative Knee Society scores were 99 points ( 68–100 ) for the fixed-bearing group and 100 points ( 66–100 ) for the mobile-bearing group ( n.s . ) . The median postoperative flexion angles of 120 ° ( 90 ° –150 ° ) for the fixed-bearing group and 125 ° ( 90 ° –145 ° ) for the mobile-bearing group were not significantly different from each other ( n.s . ) . No knee required revision surgery due to wear of polyethylene or loosening of the component in either group . Computed tomography showed that 11 knees had rotational mismatches of more than 10 ° between the femoral and tibial components , but no significant difference was found in the postoperative extension and flexion angles or in the clinical score between the two treatment groups . Using the identical design for both fixed- and mobile-bearing prostheses , this prospect i ve , r and omized study did not show any clinical advantages of the mobile-bearing knee . Analysis of rotational alignment by CT scan did not reveal a particular advantage of the self-aligning mechanism of mobile-bearing implants As part of the step-wise validation of a new prosthesis ( TMK ) , we previously published the 1 year results of a r and omised controlled trial in patients undergoing bilateral knee replacement  [ Price A. , Rees J. , Beard D. , Juszczak E. et al. A mobile-bearing total knee prosthesis compared with a fixed-bearing prosthesis . JBJS B 2003;85-B-1:62 - 7 . ] . Forty patients had the new mobile-bearing prosthesis implanted in one knee and an established fixed-bearing device in the other ( AGC ) . We now report the 3 year status of these patients and , in addition , review a separate multi-centre cohort of 172 patients who had undergone unilateral arthroplasty with the TMK .  No significant differences were found in outcome ( American Knee Society Score and Oxford Knee Score ) between the two prostheses . The greater incidence of " clicking " in the mobile-bearing knee , reported in the previous review , persisted ( TMK=48 % , AGC=30 % ) . The presence of this mechanical noise was found to have no relationship with outcome in either of the prostheses . The unilateral cohort study showed an acceptable complication rate for the new prosthesis , although some patients reported subjective instability . The method of controlled introduction of the TMK , of which this constitutes a further step , has allowed us to assess the significance of a reported problem ( clicking ) and to provide scientific data from which other surgeons can decide about use of the implant Background The benefits of robotic techniques for implanting femoral components during THA are still controversial . Questions / Purpose sThe purpose of this study was to prospect ively compare the results and complications of robotic-assisted and h and -rasping stem implantation techniques . Method The minimum followup was 5 years ( mean , 67 months ; range , 60–85 months ) . One hundred forty-six primary THAs on 130 patients were included in this study .  Robot-assisted primary THA was performed on 75 hips and a h and -rasping technique was used on 71 hips . Results At 2 and 3 years postoperatively , the Japanese Orthopaedic Association ( JOA ) clinical score was slightly better in the robotic-assisted group . At 5 years followup , however , the differences were not significant . Postoperative limb lengths of the robotic-milling group had significantly less variance than the h and -rasping group . At 2 years postoperatively , there was significantly more stress shielding of the proximal femur in the h and -rasping group ; this difference was more significant 5 years postoperatively . Conclusions Substantially more precise implant positioning seems to have led to less variance in limb-length ine quality and less stress shielding of the proximal femur 5 years postoperatively . Level of Evidence Level II , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence
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  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 ?