human
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Summary Production of inflammatory mediators ( IM ) by cells and specifically macrophages around loosened implants may be responsible for their loosening . Our hypothesis was that different material s give rise to different amounts of these IM . It is thought that alumina/alumina for total hip replacement ( THR ) , which has been used for 15 years in our orthopedic department , may produce less IM than other systems . We initiated a clinical prospect i ve study to measure the level of prostagl and in E2 ( PGE2 ) in tissue surrounding loosened prostheses to quantify PGE2 production regarding the types of material involved in the friction couple , i.e. , alumina/alumina versus metal/polyethylene , and the type of fixation , i.e. , cemented versus cementless . A total of 29 THR revisions were performed in 28 patients . Four implant groups were identified : alumina/alumina cemented , alumina/alumina cementless , metal/polyethylene cemented , and metal/polyethylene cementless . For each revision , tissues surrounding the failed implants were harvested and processed , and the PGE2 was measured in a blind manner using an immunoassay technique . As the measuring technique was difficult , at least three determinations for each sample were necessary . Some sample s were excluded from the analysis for various reasons , for example , second or further revisions involving many different material s in the past , conjunction of metallic and alumina debris and sample s taken from nonloosened components . Finally , 15 sample s were considered adequate for inclusion in this study . Two groups were analyzed and compared : the alumina/alumina couple and the metal/polyethylene couple . Tissue surrounding the first group demonstrated a PGE2 level of 69 ± 56 fmol/mg wet weight compared to 202 ± 156 fmol/mg for the second . The Wilcoxon test was applied , and there was a statistical difference ( P < 0.05 ) . When the alumina/alumina cemented group was compared to the alumina/alumina cementless group , there was a tendency to less PGE2 with the cemented , but the difference was not statistically significant . Results thus demonstrate that alumina/alumina produces less IM than metal/polyethylene . However , these results do not indicate whether this is related to the type of debris , the amount , or both . This remains a preliminary study . Further studies with more sample s , other mediators and growth factors , and a precise comparison to histological findings are still necessary BACKGROUND In vitro analysis has shown that oxidized zirconium on ultra-high molecular weight polyethylene has better wear properties than cobalt-chromium on ultra-high molecular weight polyethylene . The purpose of this study was to determine if oxidized zirconium femoral components performed better than cobalt-chromium in vivo and if the use of oxidized zirconium components had clinical adverse effects . METHODS Forty consecutive patients ( eighty knees ) underwent simultaneous bilateral cruciate-retaining total knee arthroplasty for primary osteoarthritis from January 2002 to December 2003 . For each patient , the knees were r and omized to receive the oxidized zirconium femoral component , with the contralateral knee receiving the cobalt-chromium component . Outcome measures included the Western Ontario and McMaster Universities Osteoarthritis Index , Knee Injury and Osteoarthritis Outcome Score , Knee Society score , and British Orthopaedic Association patient satisfaction scale . Radiographic outcomes include the Knee Society total knee arthroplasty roentgenographic evaluation and scoring system and measurement of radiographic wear . Patients and assessors were blinded to the treatment groups and results . RESULTS There were no significant differences in clinical , subjective , and radiographic outcomes between the two implants at five days , six weeks , and one , two , or five years postoperatively . At five years following surgery , 38 % of the patients preferred the cobalt-chromium knee compared with 18 % who preferred the oxidized zirconium knee ( p = 0.02 ) and 44 % had no preference . CONCLUSIONS Five-year outcomes after total knee arthroplasty with oxidized zirconium and cobalt-chromium femoral components showed no significant differences in clinical , subjective , and radiographic outcomes . Patients had no preference or preferred the cobalt-chromium prosthesis to the oxidized zirconium prosthesis at the time of the five-year follow-up . There were no adverse effects associated with the use of oxidized zirconium femoral implants In a prospect i ve study , 194 knees undergoing total knee arthroplasty ( 110 knees with alumina ceramic prostheses ; 84 knees with Co – Cr alloy prostheses )  were clinical ly and radiologically evaluated . Average follow-up period was 66 months ( 36–124 months ) . Average age at the time of surgery was 66 years . In the ceramic prostheses , two revision surgeries were performed because of breakage of the tibial tray and late infection , whereas two revisions of the Co – Cr alloy prostheses were carried out due to loosening and late infection . In the other patients , there were no significant differences in clinical parameters ( HSS knee score and range of motion ) between the two prostheses . In radiological evaluation , we could not find any radiolucent lines around the femoral ceramic component while radiolucency was present in three knees ( 3.6 % ) around the Co – Cr femoral component . Beneath the tibial tray , three knees ( 2.7 % ) showed a radiolucent line around the former prosthesis while eight knees ( 9.5 % ) demonstrated a radiolucent line around the latter prosthesis . Chi-square tests showed a significant difference in the occurrence of radiolucent line around both of the femoral and tibial prosthesis . This study demonstrated that clinical results of the alumina ceramic PCL retaining total knee prosthesis are comparable to the st and ard Co – Cr alloy PCL retaining total knee prosthesis . Although we could not draw any conclusions regarding the superiority of the ceramic prosthesis with respect to UHMWPE wear and long-term survivorship , this report encouraged a long-term follow-up study on ceramic prostheses BACKGROUND New bearing surfaces for  total knee replacement  have been described in an attempt to reduce polyethylene wear and secondary osteolysis and improve longevity of implants .  Oxidized zirconium is a new material that combines the strength of a metal with the wear properties of a ceramic . However , there are no reports as to who documents the long term results . We report a 10 year follow-up note of a selected series of TKAs with an oxidized zirconium femoral component . METHODS We prospect ively follow 98 TKAs performed in 94 patients with an oxidized zirconium femoral component . Five patients ( 5 knees ) had died and 6 ( 6 knees ) were lost to follow-up at a minimum of 2 years ( mean , 6.3 years ; range , 2 - 9 years ) after the operation . For the remaining 83 patients ( 87 knees ) , the minimum follow-up was 10 years ( mean , 11.3 years ; range , 10.0 - 12.6 years ) . In 51 cases ( 58.6 % ) , a cruciate-retaining implant with a deep-dished , more conforming PE was used , and in 36 cases ( 41.4 % ) , a posterior-stabilized design was used . The patellae were resurfaced in 32 cases ( 36.7 % ) and in 55 cases ( 63.3 % ) were left unresurfaced . RESULTS Survivorship was 97.8 % at 10 years postoperatively . Two knees were revised for aseptic loosening of the femoral component . No major complication was observed clinical ly or radiologically . Mean Knee Society score improved from 36 to 84 and functional score from 37 to 83 . CONCLUSIONS Oxidized zirconium femoral component in TKA performs well over the first 10 years following implantation , with excellent survival rates and good clinical and radiological outcomes . LEVEL OF EVIDENCE Level IV , therapeutic study Background : The Bisurface knee prosthesis was design ed in 1989 to improve knee flexion without affecting the durability of the prosthesis . The prosthesis has a unique ball- and -socket joint in the midposterior portion of the femoral and tibial components , which functions as a posterior stabilizing cam mechanism and causes femoral rollback . The femoral component was made of alumina ceramic . The purpose of this study was to review the clinical results of the first 223 arthroplasties performed with this prosthesis in order to assess whether this new implant had achieved its design objectives . Methods : From December 1989 to May 1994 , all patients who were scheduled for primary total knee arthroplasty were enrolled in a prospect i ve study of the Bisurface knee . The patients were evaluated clinical ly according to The Hospital for Special Surgery knee-rating system and with a self-administered question naire , and they were evaluated radiographically according to the system of the Knee Society . Kaplan-Meier survivorship analysis was performed with revision of the knee or recommendation for revision as the end point . Results : One hundred and sixty-six patients treated with a total of 223 consecutive primary total knee arthroplasties were enrolled in the study , and 182 knees were followed for 3.9 to 9.0 years ( mean , 5.8 years ) . Preoperatively , the mean Hospital for Special Surgery knee score was 44.5 points . At the time of latest follow-up , the mean knee score was 86.3 points . The mean preoperative and postoperative ranges of flexion were 119 and 124 degrees , respectively . The patients , even those with a good preoperative range of motion , rarely lost deep flexion of the knee after the procedure . A revision operation was performed in eight knees ( because of infection in five , instability in two , and breakage of the peg of the patellar component in one ) . Two knees had recurrent medial-lateral subluxations of the femorotibial articulation , which were treated nonoperatively . No prosthesis had loosened aseptically and no alumina ceramic femoral component had broken by the time of latest follow-up . The rate of survival of the implant was 94 percent ( 95 percent confidence interval , 90 to 98 percent ) at six years . According to the patient question naires , 20 percent of the knees sometimes felt loose in daily living activities , which prompted us to improve the intrinsic stability of the prosthesis by improving the congruity of the ball- and -socket joint . Conclusions : Total knee arthroplasty with the Bisurface prosthesis result ed in an excellent range of motion and a high level of satisfaction with the operation ; the durability of the prosthesis is promising AIMS Oxidised zirconium was introduced as a material for femoral components in total knee arthroplasty ( TKA ) as an attempt to reduce polyethylene wear . However , the long-term survival of this component is not known . METHODS We performed a retrospective review of a prospect ively collected data base to assess the ten year survival and clinical and radiological outcomes of an oxidised zirconium total knee arthroplasty with the Genesis II prosthesis . The Western Ontario and McMaster Universities Osteoarthritis Index ( WOMAC ) , Knee Injury and Osteoarthritis Outcome Score ( KOOS ) and a patient satisfaction scale were used to assess outcome . RESULTS A total of 303 consecutive TKAs were performed in 278 patients with a mean age of 68 years ( 45 to 89 ) . The rate of survival ten years post-operatively as assessed using Kaplan-Meier analysis was 97 % ( 95 % confidence interval 94 to 99 ) with revision for any reason as the endpoint . There were no revisions for loosening , osteolysis or failure of the implant . There was a significant improvement in all components of the WOMAC score at final follow-up ( p < 0.001 ) . The mean individual components of the KOOS score for symptoms ( 82.4 points ; 36 to 100 ) , pain ( 87.5 points ; 6 to 100 ) , activities of daily life ( 84.9 points ; 15 to 100 ) and quality of life ( 71.4 points ; 6 to 100 ) were all at higher end of the scale . DISCUSSION This study provides further supportive evidence that the oxidised zirconium TKA gives comparable rates of survival with other implants and excellent functional outcomes ten years post-operatively . TAKE HOME MESSAGE Total knee arthroplasty with an oxidised zirconium femoral component gives comparable long-term rates of survival and functional outcomes with conventional implants A ceramic surfaced oxidized Zr femoral component  was used in total knee replacemdent . Prior mechanical testing had shown a decrease in adhesive and abrasive wear using this material as compared with CoCrMo suggesting its use in younger patients in whom long-term PE wear is a consideration . The alloy had no demonstrable Ni impurities and was applicable to patients with Ni or Co allergies . In a r and omized prospect i ve study comparing femoral components of the same design but fabricated either of cast CoCrMo or oxidized Zr , there was a more rapid return of flexion and regaining functional milestones in the oxidized Zr group . No adverse effects had been observed at the 2-year evaluation AIMS The Advance Medial-Pivot total knee arthropl 
    Output:
    
agent
Overall , there was a notable enhancement of joint function after the procedure , with a satisfactory mid- and long-term survival of the ceramic components , which is comparable to that of the conventional alloy components reported previously .
However , revision due to aseptic loosening , wear , and component fracture appeared to be rare , demonstrating the safety of in vivo use of ceramic bearings in the TKA procedure .
Conclusions Ceramic TKA implants show similar post-operative clinical results and survival rate compared to their conventional metallic counterparts .
Our results confirmed the safety of in vivo use of ceramic bearings in TKA , with rare implant breakage and aseptic loosening .
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Summary Production of inflammatory mediators ( IM ) by cells and specifically macrophages around loosened implants may be responsible for their loosening . Our hypothesis was that different material s give rise to different amounts of these IM . It is thought that alumina/alumina for total hip replacement ( THR ) , which has been used for 15 years in our orthopedic department , may produce less IM than other systems . We initiated a clinical prospect i ve study to measure the level of prostagl and in E2 ( PGE2 ) in tissue surrounding loosened prostheses to quantify PGE2 production regarding the types of material involved in the friction couple , i.e. , alumina/alumina versus metal/polyethylene , and the type of fixation , i.e. , cemented versus cementless . A total of 29 THR revisions were performed in 28 patients . Four implant groups were identified : alumina/alumina cemented , alumina/alumina cementless , metal/polyethylene cemented , and metal/polyethylene cementless . For each revision , tissues surrounding the failed implants were harvested and processed , and the PGE2 was measured in a blind manner using an immunoassay technique . As the measuring technique was difficult , at least three determinations for each sample were necessary . Some sample s were excluded from the analysis for various reasons , for example , second or further revisions involving many different material s in the past , conjunction of metallic and alumina debris and sample s taken from nonloosened components . Finally , 15 sample s were considered adequate for inclusion in this study . Two groups were analyzed and compared : the alumina/alumina couple and the metal/polyethylene couple . Tissue surrounding the first group demonstrated a PGE2 level of 69 ± 56 fmol/mg wet weight compared to 202 ± 156 fmol/mg for the second . The Wilcoxon test was applied , and there was a statistical difference ( P < 0.05 ) . When the alumina/alumina cemented group was compared to the alumina/alumina cementless group , there was a tendency to less PGE2 with the cemented , but the difference was not statistically significant . Results thus demonstrate that alumina/alumina produces less IM than metal/polyethylene . However , these results do not indicate whether this is related to the type of debris , the amount , or both . This remains a preliminary study . Further studies with more sample s , other mediators and growth factors , and a precise comparison to histological findings are still necessary BACKGROUND In vitro analysis has shown that oxidized zirconium on ultra-high molecular weight polyethylene has better wear properties than cobalt-chromium on ultra-high molecular weight polyethylene . The purpose of this study was to determine if oxidized zirconium femoral components performed better than cobalt-chromium in vivo and if the use of oxidized zirconium components had clinical adverse effects . METHODS Forty consecutive patients ( eighty knees ) underwent simultaneous bilateral cruciate-retaining total knee arthroplasty for primary osteoarthritis from January 2002 to December 2003 . For each patient , the knees were r and omized to receive the oxidized zirconium femoral component , with the contralateral knee receiving the cobalt-chromium component . Outcome measures included the Western Ontario and McMaster Universities Osteoarthritis Index , Knee Injury and Osteoarthritis Outcome Score , Knee Society score , and British Orthopaedic Association patient satisfaction scale . Radiographic outcomes include the Knee Society total knee arthroplasty roentgenographic evaluation and scoring system and measurement of radiographic wear . Patients and assessors were blinded to the treatment groups and results . RESULTS There were no significant differences in clinical , subjective , and radiographic outcomes between the two implants at five days , six weeks , and one , two , or five years postoperatively . At five years following surgery , 38 % of the patients preferred the cobalt-chromium knee compared with 18 % who preferred the oxidized zirconium knee ( p = 0.02 ) and 44 % had no preference . CONCLUSIONS Five-year outcomes after total knee arthroplasty with oxidized zirconium and cobalt-chromium femoral components showed no significant differences in clinical , subjective , and radiographic outcomes . Patients had no preference or preferred the cobalt-chromium prosthesis to the oxidized zirconium prosthesis at the time of the five-year follow-up . There were no adverse effects associated with the use of oxidized zirconium femoral implants In a prospect i ve study , 194 knees undergoing total knee arthroplasty ( 110 knees with alumina ceramic prostheses ; 84 knees with Co – Cr alloy prostheses )  were clinical ly and radiologically evaluated . Average follow-up period was 66 months ( 36–124 months ) . Average age at the time of surgery was 66 years . In the ceramic prostheses , two revision surgeries were performed because of breakage of the tibial tray and late infection , whereas two revisions of the Co – Cr alloy prostheses were carried out due to loosening and late infection . In the other patients , there were no significant differences in clinical parameters ( HSS knee score and range of motion ) between the two prostheses . In radiological evaluation , we could not find any radiolucent lines around the femoral ceramic component while radiolucency was present in three knees ( 3.6 % ) around the Co – Cr femoral component . Beneath the tibial tray , three knees ( 2.7 % ) showed a radiolucent line around the former prosthesis while eight knees ( 9.5 % ) demonstrated a radiolucent line around the latter prosthesis . Chi-square tests showed a significant difference in the occurrence of radiolucent line around both of the femoral and tibial prosthesis . This study demonstrated that clinical results of the alumina ceramic PCL retaining total knee prosthesis are comparable to the st and ard Co – Cr alloy PCL retaining total knee prosthesis . Although we could not draw any conclusions regarding the superiority of the ceramic prosthesis with respect to UHMWPE wear and long-term survivorship , this report encouraged a long-term follow-up study on ceramic prostheses BACKGROUND New bearing surfaces for  total knee replacement  have been described in an attempt to reduce polyethylene wear and secondary osteolysis and improve longevity of implants .  Oxidized zirconium is a new material that combines the strength of a metal with the wear properties of a ceramic . However , there are no reports as to who documents the long term results . We report a 10 year follow-up note of a selected series of TKAs with an oxidized zirconium femoral component . METHODS We prospect ively follow 98 TKAs performed in 94 patients with an oxidized zirconium femoral component . Five patients ( 5 knees ) had died and 6 ( 6 knees ) were lost to follow-up at a minimum of 2 years ( mean , 6.3 years ; range , 2 - 9 years ) after the operation . For the remaining 83 patients ( 87 knees ) , the minimum follow-up was 10 years ( mean , 11.3 years ; range , 10.0 - 12.6 years ) . In 51 cases ( 58.6 % ) , a cruciate-retaining implant with a deep-dished , more conforming PE was used , and in 36 cases ( 41.4 % ) , a posterior-stabilized design was used . The patellae were resurfaced in 32 cases ( 36.7 % ) and in 55 cases ( 63.3 % ) were left unresurfaced . RESULTS Survivorship was 97.8 % at 10 years postoperatively . Two knees were revised for aseptic loosening of the femoral component . No major complication was observed clinical ly or radiologically . Mean Knee Society score improved from 36 to 84 and functional score from 37 to 83 . CONCLUSIONS Oxidized zirconium femoral component in TKA performs well over the first 10 years following implantation , with excellent survival rates and good clinical and radiological outcomes . LEVEL OF EVIDENCE Level IV , therapeutic study Background : The Bisurface knee prosthesis was design ed in 1989 to improve knee flexion without affecting the durability of the prosthesis . The prosthesis has a unique ball- and -socket joint in the midposterior portion of the femoral and tibial components , which functions as a posterior stabilizing cam mechanism and causes femoral rollback . The femoral component was made of alumina ceramic . The purpose of this study was to review the clinical results of the first 223 arthroplasties performed with this prosthesis in order to assess whether this new implant had achieved its design objectives . Methods : From December 1989 to May 1994 , all patients who were scheduled for primary total knee arthroplasty were enrolled in a prospect i ve study of the Bisurface knee . The patients were evaluated clinical ly according to The Hospital for Special Surgery knee-rating system and with a self-administered question naire , and they were evaluated radiographically according to the system of the Knee Society . Kaplan-Meier survivorship analysis was performed with revision of the knee or recommendation for revision as the end point . Results : One hundred and sixty-six patients treated with a total of 223 consecutive primary total knee arthroplasties were enrolled in the study , and 182 knees were followed for 3.9 to 9.0 years ( mean , 5.8 years ) . Preoperatively , the mean Hospital for Special Surgery knee score was 44.5 points . At the time of latest follow-up , the mean knee score was 86.3 points . The mean preoperative and postoperative ranges of flexion were 119 and 124 degrees , respectively . The patients , even those with a good preoperative range of motion , rarely lost deep flexion of the knee after the procedure . A revision operation was performed in eight knees ( because of infection in five , instability in two , and breakage of the peg of the patellar component in one ) . Two knees had recurrent medial-lateral subluxations of the femorotibial articulation , which were treated nonoperatively . No prosthesis had loosened aseptically and no alumina ceramic femoral component had broken by the time of latest follow-up . The rate of survival of the implant was 94 percent ( 95 percent confidence interval , 90 to 98 percent ) at six years . According to the patient question naires , 20 percent of the knees sometimes felt loose in daily living activities , which prompted us to improve the intrinsic stability of the prosthesis by improving the congruity of the ball- and -socket joint . Conclusions : Total knee arthroplasty with the Bisurface prosthesis result ed in an excellent range of motion and a high level of satisfaction with the operation ; the durability of the prosthesis is promising AIMS Oxidised zirconium was introduced as a material for femoral components in total knee arthroplasty ( TKA ) as an attempt to reduce polyethylene wear . However , the long-term survival of this component is not known . METHODS We performed a retrospective review of a prospect ively collected data base to assess the ten year survival and clinical and radiological outcomes of an oxidised zirconium total knee arthroplasty with the Genesis II prosthesis . The Western Ontario and McMaster Universities Osteoarthritis Index ( WOMAC ) , Knee Injury and Osteoarthritis Outcome Score ( KOOS ) and a patient satisfaction scale were used to assess outcome . RESULTS A total of 303 consecutive TKAs were performed in 278 patients with a mean age of 68 years ( 45 to 89 ) . The rate of survival ten years post-operatively as assessed using Kaplan-Meier analysis was 97 % ( 95 % confidence interval 94 to 99 ) with revision for any reason as the endpoint . There were no revisions for loosening , osteolysis or failure of the implant . There was a significant improvement in all components of the WOMAC score at final follow-up ( p < 0.001 ) . The mean individual components of the KOOS score for symptoms ( 82.4 points ; 36 to 100 ) , pain ( 87.5 points ; 6 to 100 ) , activities of daily life ( 84.9 points ; 15 to 100 ) and quality of life ( 71.4 points ; 6 to 100 ) were all at higher end of the scale . DISCUSSION This study provides further supportive evidence that the oxidised zirconium TKA gives comparable rates of survival with other implants and excellent functional outcomes ten years post-operatively . TAKE HOME MESSAGE Total knee arthroplasty with an oxidised zirconium femoral component gives comparable long-term rates of survival and functional outcomes with conventional implants A ceramic surfaced oxidized Zr femoral component  was used in total knee replacemdent . Prior mechanical testing had shown a decrease in adhesive and abrasive wear using this material as compared with CoCrMo suggesting its use in younger patients in whom long-term PE wear is a consideration . The alloy had no demonstrable Ni impurities and was applicable to patients with Ni or Co allergies . In a r and omized prospect i ve study comparing femoral components of the same design but fabricated either of cast CoCrMo or oxidized Zr , there was a more rapid return of flexion and regaining functional milestones in the oxidized Zr group . No adverse effects had been observed at the 2-year evaluation AIMS The Advance Medial-Pivot total knee arthropl 
    Output:
    