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: The effect of bone cement viscosity and cement mantle thickness on the migration of the Exeter  total hip prosthesis  was studied in a prospect i ve , r and omized , double-blind clinical Roentgen Stereophotogrammetric Analysis study . Forty-one cemented total hip arthroplasty in 39 patients were included and r and omized into a low/medium Simplex P cement group and a high-viscosity Simplex AF cement group . At time of stem introduction , 5 minutes after mixing , the Simplex AF was more viscous than Simplex P. No statistical difference existed between the 2 cement groups , for neither translation nor rotation migration data . Subsidence of the stem at 2-year follow-up was 1.1 + /- 0.56 mm for Simplex AF cement and 1.5 + /- 1.00 mm for Simplex P cement . The mean rotation of the acetabular components about the sagittal axis was 1.7 degrees + /- 3.8 degrees in the Simplex AF group and 0.7 degrees + /- 2.1 degrees for the Simplex P group . No effect of cement mantle thickness on migration of neither the acetabular cups nor the femoral stems was found . Although there were no differences in migration data for the cups and the stems , 2 acetabular cups in the Simplex AF group ( almost 10 % ) were revised because of mechanical loosening . Because of these findings , we suggest caution before using this new high-viscosity bone cement for fixation of acetabular components 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 One hundred consecutive ABG ( Anatomique Benoist Giraud , Howmedica ) hydroxyapatite-coated hip arthroplasties in 97 patients were evaluated prospect ively with a follow-up time of 4 to 10 years ( mean , 6 years ) . Clinical results were excellent with an improvement in the Merle d'Aubigne score from 9 preoperatively to 17.4 at 5 years . Thigh pain was persistent in only 3 % ; it was mild in nature and controlled with simple analgesics . Kaplan-Meyer survivorship analysis was 100 % for the femoral stem and 95 % for the acetabular cup at 6 years . Of concern was the high polyethylene wear measured with an average of 0.24 mm/y ( range , 0.05 - 0.76 mm/y ) 155 patients ( 171 hips ) with a mean age of 50 years ( 24 - 64 ) were r and omized to uncemented PCA ( 84 hips ) or Harris-Galante type I ( 87 hips ) total hip arthroplasty .  Clinical and radiographic evaluations were done regularly . The improvements in the Harris hip and pain scores did not differ . Osteolysis developed in 5 PCA and 17 Harris-Galante hips . 13 hips in the PCA and 16 in the Harris-Galante ( HG ) group were revised because of mechanical failures and 1 hip ( HG ) because of infection after a mean follow-up of 9 years . Decreased 10-year survival rate , based on revision as end-point , was noted for the PCA ( 85 % ) , compared with the Harris-Galante cup ( 99 % ) . The corresponding survival rate of the PCA stem ( 96 % ) was higher than that observed for the Harris-Galante design ( 86 % ) . When radiographic failures were included , the survival rates of the 4 different components dropped to between 73 % and 94 % . These findings indicate that further revisions will be necessary and continuous radiographic follow-up is indicated to enable revision before severe bone destruction has occurred . Although the PCA and the Harris-Galante design s differed as regards the survival of the individual components , the overall clinical and radiographic survival rates of these cementless total hip arthroplasties were poor Surgery and other invasive therapies are complex interventions , the assessment of which is challenged by factors that depend on operator , team , and setting , such as learning curves , quality variations , and perception of equipoise . We propose recommendations for the assessment of surgery based on a five-stage description of the surgical development process . We also encourage the widespread use of prospect i ve data bases and registries . Reports of new techniques should be registered as a professional duty , anonymously if necessary when outcomes are adverse . Case series studies should be replaced by prospect i ve development studies for early technical modifications and by prospect i ve research data bases for later pre-trial evaluation . Protocol s for these studies should be registered publicly . Statistical process control techniques can be useful in both early and late assessment . R and omised trials should be used whenever possible to investigate efficacy , but adequate pre-trial data are essential to allow power calculations , clarify the definition and indications of the intervention , and develop quality measures . Difficulties in doing r and omised clinical trials should be addressed by measures to evaluate learning curves and alleviate equipoise problems . Alternative prospect i ve design s , such as interrupted time series studies , should be used when r and omised trials are not feasible . Established procedures should be monitored with prospect i ve data bases to analyse outcome variations and to identify late and rare events . Achievement of improved design , conduct , and reporting of surgical research will need concerted action by editors , funders of health care and research , regulatory bodies , and professional societies In a prospect i ve study of 100 consecutive Wagner resurfacing hip arthroplasties in ninety-three patients , the outcomes for all hips were determined for an eight to ten-year follow-up period . By survivorship analysis , the rate of survival of the arthroplasty was calculated to be 70 per cent at five years , but only 40 per cent at eight years . The major cause of failure was aseptic loosening of the acetabular or femoral component , or both . Fracture of the neck of the femur occurred in three hips . Although the medium-term results ( at fifty-six to eighty-three months ) were better than those in most comparable studies of resurfacing arthroplasty , the poor long-term results ( at ninety-one to 118 months ) show that meaningful studies of new prosthetic design s must continue for at least eight years , and , if at all possible , must include 100 per cent follow-up . The survival curve for the resurfacing arthroplasties in this study can serve as the basis for comparison of the early , medium , and long-term results of future design s of resurfacing hip prostheses We report an independent prospect i ve review of the first 230 Birmingham hip resurfacings in 212 patients at a mean follow-up of five years ( 4 to 6 ) . Two patients , one with a loose acetabular component and the other with suspected avascular necrosis of the femoral head , underwent revision . There were two deaths from unrelated causes and one patient was lost to follow-up . The survivorship with the worst-case scenario was 97.8 % ( 95 % confidence interval 95.8 to 99.5 ) . The mean Harris hip score improved significantly ( paired t-test , p < 0.05 ) from 62.54 ( 8 to 92 ) pre-operatively to 97.7 ( 61 to 100 ) at a mean of three years ( 2.1 to 4.3 ) , then deteriorated slightly to a mean of 95.2 ( 47 to 100 ) at a mean of five years . The mean flexion improved from 91.5 degrees ( 25 degrees to 140 degrees ) to 110.4 degrees ( 80 degrees to 145 degrees ) at a mean of three years with no further improvement at five years ( 111.2 degrees ; 70 degrees to 160 degrees ) . On radiological review at five years , one patient had a progressive lucent line around the acetabular component and six had progressive lucent lines around the femoral component . A total of 18 femoral components ( 8 % ) had migrated into varus and those with lucent lines present migrated a mean of 3.8 degrees ( 1.02 degrees to 6.54 degrees ) more than the rest . Superolateral notching of the femoral neck and reactive sclerosis at the tip of the peg of the femoral component were associated with the presence of lucent lines ( chi-squared test , p < 0.05 ) , but not with migration of the femoral component , and are of unknown significance . Our results with the Birmingham hip resurfacing continue to be satisfactory at a mean follow-up of five years We evaluated the clinical and radiographic outcomes of 100 consecutive primary total hip arthroplasties in which a proximally coated anatomically design ed femoral component was fixed without cement for the treatment of primary osteoarthritis . The minimum duration of follow-up was six years ( average , 7.1 years ) . The eighty-eight patients who had the arthroplasties were followed prospect ively with a st and ard clinical evaluation that involved use of the Harris hip score and a radiographic evaluation based on the criteria of the Hip Society . Bone ingrowth was evaluated with the method of Engh et al. The average age of the patients at the time of the operation was 62.6 years ( range , thirty-nine to eighty-four years ) . Fifty-one patients were men and thirty-seven were women . The average preoperative Harris hip score was 48 points , with an average pain score of 15 points and an average function score of 26 points . Nonmechanical complications that necessitated a revision operation included one deep hematogenous infection , one late periprosthetic fracture , and a 0.5-inch ( 1.27-centimeter ) limb-length discrepancy . At the time of the most recent follow-up , the average Harris hip score was 96 points , with an average pain score of 42 points and an average function score of 45 points . The prevalence of pain in the anterior part of the thigh was 5 percent ( five hips ) . One patient had a revision of the femoral component because of aseptic loosening , and one had a revision of the acetabular component because of recurrent dislocations . Radiographic assessment revealed consistent evidence of proximal bone ingrowth . No complete radiolucent line was identified , except around the stem that had loosened . Twenty-seven femoral components were associated with slight pedestal formation . No osteolytic lesion of the femur was identified . Nonprogressive pelvic osteolysis was identified in four hips , but none of the lesions were more than two millimeters in diameter . None of the acetabular components migrated , and no radiolucent line of more than two millimeters in thickness was seen around any acetabular cup . The data from this study , in which the minimum duration of follow-up was six years , indicate that the anatomically design ed prosthesis can provide good results , with low prevalences of pain in the thigh and loosening of the component , in younger , active patients Two series of 100 consecutive primary total hip arthroplasties , each using a single design of noncemented or cemented femoral component ( all 28 mm heads ) , were compared . One cemented and two noncemented stems underwent revision for aseptic loosening . Of unrevised hips , outcome data statistically favored cemented , rather than noncemented , stems . The data for cemented and noncemented stems , respectively , were : An excellent to good result in 97 % versus 88 % ; thigh pain in 3 % versus 40 % ; subsidence in 0 % versus 22 % ; and endosteal cavitation in 6 % versus 12 % . For patients with 25 unrevised matched pairs , selected by gender , age , diagnosis , and weight , outcome data also statistically favored cemented over noncemented stems , respectively : an excellent or good result in 25 versus 20 hips ; thigh pain in two versus eight hips ; and subsidence in none versus six hips . Midterm followup data for these concurrent total hip arthroplasty series of a mid1980s design revealed prevalence of mechanical failure of 1 % for cemented stems 
    Output:
    
agent
INTERPRETATION There was a clinical ly relevant association between early migration of acetabular cups  and late revision due to 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: The effect of bone cement viscosity and cement mantle thickness on the migration of the Exeter  total hip prosthesis  was studied in a prospect i ve , r and omized , double-blind clinical Roentgen Stereophotogrammetric Analysis study . Forty-one cemented total hip arthroplasty in 39 patients were included and r and omized into a low/medium Simplex P cement group and a high-viscosity Simplex AF cement group . At time of stem introduction , 5 minutes after mixing , the Simplex AF was more viscous than Simplex P. No statistical difference existed between the 2 cement groups , for neither translation nor rotation migration data . Subsidence of the stem at 2-year follow-up was 1.1 + /- 0.56 mm for Simplex AF cement and 1.5 + /- 1.00 mm for Simplex P cement . The mean rotation of the acetabular components about the sagittal axis was 1.7 degrees + /- 3.8 degrees in the Simplex AF group and 0.7 degrees + /- 2.1 degrees for the Simplex P group . No effect of cement mantle thickness on migration of neither the acetabular cups nor the femoral stems was found . Although there were no differences in migration data for the cups and the stems , 2 acetabular cups in the Simplex AF group ( almost 10 % ) were revised because of mechanical loosening . Because of these findings , we suggest caution before using this new high-viscosity bone cement for fixation of acetabular components 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 One hundred consecutive ABG ( Anatomique Benoist Giraud , Howmedica ) hydroxyapatite-coated hip arthroplasties in 97 patients were evaluated prospect ively with a follow-up time of 4 to 10 years ( mean , 6 years ) . Clinical results were excellent with an improvement in the Merle d'Aubigne score from 9 preoperatively to 17.4 at 5 years . Thigh pain was persistent in only 3 % ; it was mild in nature and controlled with simple analgesics . Kaplan-Meyer survivorship analysis was 100 % for the femoral stem and 95 % for the acetabular cup at 6 years . Of concern was the high polyethylene wear measured with an average of 0.24 mm/y ( range , 0.05 - 0.76 mm/y ) 155 patients ( 171 hips ) with a mean age of 50 years ( 24 - 64 ) were r and omized to uncemented PCA ( 84 hips ) or Harris-Galante type I ( 87 hips ) total hip arthroplasty .  Clinical and radiographic evaluations were done regularly . The improvements in the Harris hip and pain scores did not differ . Osteolysis developed in 5 PCA and 17 Harris-Galante hips . 13 hips in the PCA and 16 in the Harris-Galante ( HG ) group were revised because of mechanical failures and 1 hip ( HG ) because of infection after a mean follow-up of 9 years . Decreased 10-year survival rate , based on revision as end-point , was noted for the PCA ( 85 % ) , compared with the Harris-Galante cup ( 99 % ) . The corresponding survival rate of the PCA stem ( 96 % ) was higher than that observed for the Harris-Galante design ( 86 % ) . When radiographic failures were included , the survival rates of the 4 different components dropped to between 73 % and 94 % . These findings indicate that further revisions will be necessary and continuous radiographic follow-up is indicated to enable revision before severe bone destruction has occurred . Although the PCA and the Harris-Galante design s differed as regards the survival of the individual components , the overall clinical and radiographic survival rates of these cementless total hip arthroplasties were poor Surgery and other invasive therapies are complex interventions , the assessment of which is challenged by factors that depend on operator , team , and setting , such as learning curves , quality variations , and perception of equipoise . We propose recommendations for the assessment of surgery based on a five-stage description of the surgical development process . We also encourage the widespread use of prospect i ve data bases and registries . Reports of new techniques should be registered as a professional duty , anonymously if necessary when outcomes are adverse . Case series studies should be replaced by prospect i ve development studies for early technical modifications and by prospect i ve research data bases for later pre-trial evaluation . Protocol s for these studies should be registered publicly . Statistical process control techniques can be useful in both early and late assessment . R and omised trials should be used whenever possible to investigate efficacy , but adequate pre-trial data are essential to allow power calculations , clarify the definition and indications of the intervention , and develop quality measures . Difficulties in doing r and omised clinical trials should be addressed by measures to evaluate learning curves and alleviate equipoise problems . Alternative prospect i ve design s , such as interrupted time series studies , should be used when r and omised trials are not feasible . Established procedures should be monitored with prospect i ve data bases to analyse outcome variations and to identify late and rare events . Achievement of improved design , conduct , and reporting of surgical research will need concerted action by editors , funders of health care and research , regulatory bodies , and professional societies In a prospect i ve study of 100 consecutive Wagner resurfacing hip arthroplasties in ninety-three patients , the outcomes for all hips were determined for an eight to ten-year follow-up period . By survivorship analysis , the rate of survival of the arthroplasty was calculated to be 70 per cent at five years , but only 40 per cent at eight years . The major cause of failure was aseptic loosening of the acetabular or femoral component , or both . Fracture of the neck of the femur occurred in three hips . Although the medium-term results ( at fifty-six to eighty-three months ) were better than those in most comparable studies of resurfacing arthroplasty , the poor long-term results ( at ninety-one to 118 months ) show that meaningful studies of new prosthetic design s must continue for at least eight years , and , if at all possible , must include 100 per cent follow-up . The survival curve for the resurfacing arthroplasties in this study can serve as the basis for comparison of the early , medium , and long-term results of future design s of resurfacing hip prostheses We report an independent prospect i ve review of the first 230 Birmingham hip resurfacings in 212 patients at a mean follow-up of five years ( 4 to 6 ) . Two patients , one with a loose acetabular component and the other with suspected avascular necrosis of the femoral head , underwent revision . There were two deaths from unrelated causes and one patient was lost to follow-up . The survivorship with the worst-case scenario was 97.8 % ( 95 % confidence interval 95.8 to 99.5 ) . The mean Harris hip score improved significantly ( paired t-test , p < 0.05 ) from 62.54 ( 8 to 92 ) pre-operatively to 97.7 ( 61 to 100 ) at a mean of three years ( 2.1 to 4.3 ) , then deteriorated slightly to a mean of 95.2 ( 47 to 100 ) at a mean of five years . The mean flexion improved from 91.5 degrees ( 25 degrees to 140 degrees ) to 110.4 degrees ( 80 degrees to 145 degrees ) at a mean of three years with no further improvement at five years ( 111.2 degrees ; 70 degrees to 160 degrees ) . On radiological review at five years , one patient had a progressive lucent line around the acetabular component and six had progressive lucent lines around the femoral component . A total of 18 femoral components ( 8 % ) had migrated into varus and those with lucent lines present migrated a mean of 3.8 degrees ( 1.02 degrees to 6.54 degrees ) more than the rest . Superolateral notching of the femoral neck and reactive sclerosis at the tip of the peg of the femoral component were associated with the presence of lucent lines ( chi-squared test , p < 0.05 ) , but not with migration of the femoral component , and are of unknown significance . Our results with the Birmingham hip resurfacing continue to be satisfactory at a mean follow-up of five years We evaluated the clinical and radiographic outcomes of 100 consecutive primary total hip arthroplasties in which a proximally coated anatomically design ed femoral component was fixed without cement for the treatment of primary osteoarthritis . The minimum duration of follow-up was six years ( average , 7.1 years ) . The eighty-eight patients who had the arthroplasties were followed prospect ively with a st and ard clinical evaluation that involved use of the Harris hip score and a radiographic evaluation based on the criteria of the Hip Society . Bone ingrowth was evaluated with the method of Engh et al. The average age of the patients at the time of the operation was 62.6 years ( range , thirty-nine to eighty-four years ) . Fifty-one patients were men and thirty-seven were women . The average preoperative Harris hip score was 48 points , with an average pain score of 15 points and an average function score of 26 points . Nonmechanical complications that necessitated a revision operation included one deep hematogenous infection , one late periprosthetic fracture , and a 0.5-inch ( 1.27-centimeter ) limb-length discrepancy . At the time of the most recent follow-up , the average Harris hip score was 96 points , with an average pain score of 42 points and an average function score of 45 points . The prevalence of pain in the anterior part of the thigh was 5 percent ( five hips ) . One patient had a revision of the femoral component because of aseptic loosening , and one had a revision of the acetabular component because of recurrent dislocations . Radiographic assessment revealed consistent evidence of proximal bone ingrowth . No complete radiolucent line was identified , except around the stem that had loosened . Twenty-seven femoral components were associated with slight pedestal formation . No osteolytic lesion of the femur was identified . Nonprogressive pelvic osteolysis was identified in four hips , but none of the lesions were more than two millimeters in diameter . None of the acetabular components migrated , and no radiolucent line of more than two millimeters in thickness was seen around any acetabular cup . The data from this study , in which the minimum duration of follow-up was six years , indicate that the anatomically design ed prosthesis can provide good results , with low prevalences of pain in the thigh and loosening of the component , in younger , active patients Two series of 100 consecutive primary total hip arthroplasties , each using a single design of noncemented or cemented femoral component ( all 28 mm heads ) , were compared . One cemented and two noncemented stems underwent revision for aseptic loosening . Of unrevised hips , outcome data statistically favored cemented , rather than noncemented , stems . The data for cemented and noncemented stems , respectively , were : An excellent to good result in 97 % versus 88 % ; thigh pain in 3 % versus 40 % ; subsidence in 0 % versus 22 % ; and endosteal cavitation in 6 % versus 12 % . For patients with 25 unrevised matched pairs , selected by gender , age , diagnosis , and weight , outcome data also statistically favored cemented over noncemented stems , respectively : an excellent or good result in 25 versus 20 hips ; thigh pain in two versus eight hips ; and subsidence in none versus six hips . Midterm followup data for these concurrent total hip arthroplasty series of a mid1980s design revealed prevalence of mechanical failure of 1 % for cemented stems 
    Output:
    