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: PURPOSE Focal chondral or osteochondral defects can be painful and disabling , have a poor capacity for repair , and may predispose patients for osteoarthritis . New surgical procedures that aim to reestablish hyaline cartilage have been introduced and the results seem promising . The purpose of this study is to provide reliable data on chondral and osteochondral defects in patients with symptomatic knees requiring arthroscopy  and to calculate the prevalence of patients who might benefit from cartilage repair surgery . TYPE OF STUDY Prospect i ve study . METHODS One thous and consecutive knee arthroscopies were included in this study . Immediately after each arthroscopy , the surgeon completed a question naire providing detailed information about the findings . Chondral and osteochondral lesions were classified in accordance with the system recommended by the International Cartilage Repair Society ( ICRS ) . RESULTS Chondral or osteochondral lesions ( of any type ) were found in 61 % of the patients . Focal chondral or osteochondral defects were found in 19 % of the patients . In these patients , 61 % related their current knee problem to a previous trauma , and a concomitant meniscal or anterior cruciate ligament injury was found in 42 % ( n = 81 ) and 26 % ( n = 50 ) , respectively . The mean chondral or osteochondral total defect area was 2.1 cm(2 ) ( range , 0.5 to 12 ; st and ard deviation [ SD ] , 1.5 ) . The main focal chondral or osteochondral defect was found on the medial femoral condyle in 58 % , patella in 11 % , lateral tibia in 11 % , lateral femoral condyle in 9 % , trochlea in 6 % , and medial tibia in 5 % . It has been suggested that cartilage repair surgery may be most suitable in patients younger than 40 to 50 years old . A single , well-defined ICRS grade III or IV defect with an area of at least 1 cm(2 ) in a patient younger than 40 , 45 , or 50 years accounted for 5.3 % , 6.1 % , and 7.1 % of all arthroscopies , respectively . CONCLUSIONS Our study supports the contention that articular cartilage defects are common . It has the advantages of a prospect i ve design and use of a new classification system recommended by the ICRS . This modern system focuses on objective ly measurable parameters of the lesion 's extent and not its surface appearance Meta-analytic investigations sometimes use assessment s of research quality according to a formal protocol as a tool for improving research synthesis . We asked whether a particular  quality scoring system could have a direct use in adjusting the summary estimates of a treatment difference . In an empirical study of the relation of quality scores to treatment differences in published meta-analyses of 7 groups of controlled r and omized clinical trials comprising 107 primary studies , we found no relation between treatment difference and overall quality score . We also found no relation between quality score and variation in treatment difference . The level of quality scores has increased at a rate of 9 % per decade for three decades , averaging 0.51 on a scale of 0 to 1 for the 1980s , and leaving much room for improvement . Nevertheless , attention to quality of studies by editors , review ers , and authors may be raising both the level of research done and quality of the reports Background Marrow stimulation techniques such as drilling or microfracture are first-line treatment options for symptomatic cartilage defects . Common knowledge holds that these treatments do not compromise subsequent cartilage repair procedures with autologous chondrocyte implantation . Hypothesis Cartilage defects pretreated with marrow stimulation techniques will have an increased failure rate . Study Design Cohort study ; Level of evidence , 2 . Methods The first 321 consecutive patients treated at one institution with autologous chondrocyte implantation for full-thickness cartilage defects that reached more than 2 years of follow-up were evaluated by prospect ively collected data . Patients were grouped based on whether they had undergone prior treatment with a marrow stimulation technique . Outcomes were classified as complete failure if more than 25 % of a grafted defect area had to be removed in later procedures because of persistent symptoms . Results There were 522 defects in 321 patients ( 325 joints ) treated with autologous chondrocyte implantation .  On average , there were 1.7 lesions per patient . Of these joints , 111 had previously undergone surgery that penetrated the subchondral bone ; 214 joints had no prior treatment that affected the subchondral bone and served as controls . Within the marrow stimulation group , there were 29 ( 26 % ) failures , compared with 17 ( 8 % ) failures in the control group . Conclusion Defects that had prior treatment affecting the subchondral bone failed at a rate 3 times that of nontreated defects . The failure rates for drilling ( 28 % ) , abrasion arthroplasty ( 27 % ) , and microfracture ( 20 % ) were not significantly different , possibly because of the lower number of microfracture patients in this cohort ( 25 of 110 marrow-stimulation procedures ) . The data demonstrate that marrow stimulation techniques have a strong negative effect on subsequent cartilage repair with autologous chondrocyte implantation and therefore should be used judiciously in larger cartilage defects that could require future treatment with autologous chondrocyte implantation BACKGROUND Microfracture is a frequently used technique for the repair of articular cartilage lesions of the knee . Despite the popularity of the technique , prospect i ve information about the clinical results after microfracture is still limited . The purpose of our study was to identify the factors that affect the clinical outcome from this cartilage repair technique . METHODS Forty-eight symptomatic patients with isolated full-thickness articular cartilage defects of the femur in a stable knee were treated with the microfracture technique . Prospect i ve evaluation of patient outcome was performed for a minimum follow-up of twenty-four months with a combination of vali date d outcome scores , subjective clinical rating , and cartilage-sensitive magnetic resonance imaging . RESULTS At the time of the latest follow-up , knee function was rated good to excellent for thirty-two patients ( 67 % ) , fair for twelve patients ( 25 % ) , and poor for four ( 8 % ) . Significant increases in the activities of daily living scores , International Knee Documentation Committee scores , and the physical component score of the Short Form-36 were demonstrated after microfracture ( p < 0.05 ) . A lower body-mass index correlated with higher scores for the activities of daily living and SF-36 physical component , with the worst results for patients with a body-mass index of > 30 kg/m(2 ) . Significant improvement in the activities of daily living score was more frequent with a preoperative duration of symptoms of less than twelve months ( p < 0.05 ) . Magnetic resonance imaging in twenty-four knees demonstrated good repair-tissue fill in the defect in thirteen patients ( 54 % ) , moderate fill in seven ( 29 % ) , and poor fill in four patients ( 17 % ) . The fill grade correlated with the knee function scores . All knees with good fill demonstrated improved knee function , whereas poor fill grade was associated with limited improvement and decreasing functional scores after twenty-four months . CONCLUSIONS Microfracture repair of articular cartilage lesions in the knee results in significant functional improvement at a minimum follow-up of two years . The best short-term results are observed with good fill grade , low body-mass index , and a short duration of preoperative symptoms . A high body-mass index adversely affects short-term outcome , and a poor fill grade is associated with limited short-term durability Osteoarthritis is a major contributor to functional impairment and reduced independence in older adults ( 1 - 4 ) . It is the leading cause of arthritis in the United States , affecting an estimated 21 million persons ( 5 ) , and has substantial economic impact ( 6 , 7 ) . History of an injury to a joint , particularly at the knee and hip , is associated with an increased risk for osteoarthritis in cross-sectional and casecontrol studies ( 8 - 11 ) . Such studies , however , may overestimate this relation because persons with symptomatic osteoarthritis may be more likely to recall a past injury or to interpret early symptoms of osteoarthritis as indicative of joint injury . A prospect i ve cohort study can address this weakness by determining exposure status before the outcome develops . To date , prospect i ve studies have examined the relation between history of joint injury and osteoarthritis in middle-aged persons and senior citizens ( 12 , 13 ) , but not in young adults . However , many athletic injuries occur in high school and college . In addition , joint trauma may be a more common cause of osteoarthritis than has been previously recognized ( 14 ) . We performed a prospect i ve cohort study of 1321 young adults to examine the risk for knee and hip osteoarthritis associated with joint injury during young adult life . Methods Study Participants The Johns Hopkins Precursors Study was design ed by the late Caroline Bedell Thomas , MD , to identify precursors of the aging process ( 15 ) . A total of 1337 medical students , members of the graduating classes of 1948 through 1964 at the Johns Hopkins University School of Medicine in Baltimore , Maryl and , enrolled in the study . The cohort was 91 % male and 97 % white ; the mean age was 22 years . At entry , participants underwent a st and ard history and examination , including  assessment of musculoskeletal disorders , history of trauma , level of physical activity , and measurement of weight and height . Body mass index was calculated as weight in kilograms divided by height in meters squared . In addition , participants were asked to categorize their level of physical training during the past month as none , little , moderate , or much , as described elsewhere ( 16 ) . Since graduation , participants have been followed prospect ively with annual self-administered question naires to detect incident disease and to up date risk factor status over time . At the time that baseline data were collected , it was not customary to obtain informed consent . After establishment of the Joint Committee on Clinical Investigation at Johns Hopkins , the follow-up protocol was review ed and approved . Assessment of Injury Injury was defined as a report of trauma to the knee or hip joint , including internal derangement and fracture . During the baseline assessment , knee and hip injuries that occurred before graduation from medical school and the year of their occurrence were recorded . Postgraduation injuries were assessed by annual morbidity question naires . During every 5-year follow-up period , at least 86 % of the living participants responded at least once to the question naires . Injuries were assigned diagnosis codes according to the International Classification of Diseases , Ninth Revision , Clinical Modification ( ICD-9-CM ) ( 17 ) . Diagnoses included torn meniscus ( code 836.2 ) ; torn knee ligament ( code 844.9 ) ; tibial fracture ( code 823.8 ) ; femoral fracture ( code 821.01 ) ; fibular fracture ( code 823.81 ) ; patellar fracture ( code 822 ) ; broken leg , site not otherwise specified ( code 827.0 ) ; knee injury , not otherwise specified ( code 959.7 ) ; gunshot wound ( code 891 ) ; hemarthrosis ( code 844.9 ) ; shin splints ( code 844.9 ) ; and hip dislocation ( code 836.5 ) . Incidence of Osteoarthritis The methods used to determine osteoarthritis incidence in this cohort have been described elsewhere ( 18 ) . Briefly , all participants were mailed annual morbidity question naires . Before 1985 , respondents were queried about the development of physical and musculoskeletal disorders . Since 1985 , follow-up morbidity question naires have contained the specific question , Have you ever had arthritis ? and have asked those who respond affirmatively to provide the type of arthritis , year of onset , and treatment received . An event of osteoarthritis was defined as the self-report of osteoarthritis or degenerative arthritis in response to the question naire . The incidence date was determined by the reported year of osteoarthritis onset . Two rheumatologists review ed each report of osteoarthritis , assigned ICD-9-CM codes ( 17 ) to the most specific arthritis site reported by the respondent , and excluded inflammatory arthritides . For this analysis , only osteoarthritis at the knee ( code 715.96 ) and hip ( code 715.95 ) were included as outcomes . In 1995 , all surviving participants who had previously reported osteoarthritis were mailed a more detailed question naire . They were asked , Have you had pain in or around the knee , including back of the knee , on most days for at least 1 month ? and Have you had pain in or around either hip joint , including the buttock , groin , and side of upper thigh , on most days for at least 1 month ? These symptom-related questions were used to screen for knee and hip osteoarthritis , respectively , in the National Health and Nutrition Examination Survey ( NHANES ) ( 19 ) . Respondents were also asked whether they had undergone  radiographic evaluation of their knees and hips  and whether radiography revealed osteophytes , joint space narrowing , subchondral cysts , or bony sclerosis ( the radiographic hallmarks of osteoarthritis ) ( 20 ) . Statistical Analysis The association between baseline characteristics and injury status was assessed by using the Student t-test for continuous variables and the chi-square test for categorical variables . 
    Output:
    
agent
***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: PURPOSE Focal chondral or osteochondral defects can be painful and disabling , have a poor capacity for repair , and may predispose patients for osteoarthritis . New surgical procedures that aim to reestablish hyaline cartilage have been introduced and the results seem promising . The purpose of this study is to provide reliable data on chondral and osteochondral defects in patients with symptomatic knees requiring arthroscopy  and to calculate the prevalence of patients who might benefit from cartilage repair surgery . TYPE OF STUDY Prospect i ve study . METHODS One thous and consecutive knee arthroscopies were included in this study . Immediately after each arthroscopy , the surgeon completed a question naire providing detailed information about the findings . Chondral and osteochondral lesions were classified in accordance with the system recommended by the International Cartilage Repair Society ( ICRS ) . RESULTS Chondral or osteochondral lesions ( of any type ) were found in 61 % of the patients . Focal chondral or osteochondral defects were found in 19 % of the patients . In these patients , 61 % related their current knee problem to a previous trauma , and a concomitant meniscal or anterior cruciate ligament injury was found in 42 % ( n = 81 ) and 26 % ( n = 50 ) , respectively . The mean chondral or osteochondral total defect area was 2.1 cm(2 ) ( range , 0.5 to 12 ; st and ard deviation [ SD ] , 1.5 ) . The main focal chondral or osteochondral defect was found on the medial femoral condyle in 58 % , patella in 11 % , lateral tibia in 11 % , lateral femoral condyle in 9 % , trochlea in 6 % , and medial tibia in 5 % . It has been suggested that cartilage repair surgery may be most suitable in patients younger than 40 to 50 years old . A single , well-defined ICRS grade III or IV defect with an area of at least 1 cm(2 ) in a patient younger than 40 , 45 , or 50 years accounted for 5.3 % , 6.1 % , and 7.1 % of all arthroscopies , respectively . CONCLUSIONS Our study supports the contention that articular cartilage defects are common . It has the advantages of a prospect i ve design and use of a new classification system recommended by the ICRS . This modern system focuses on objective ly measurable parameters of the lesion 's extent and not its surface appearance Meta-analytic investigations sometimes use assessment s of research quality according to a formal protocol as a tool for improving research synthesis . We asked whether a particular  quality scoring system could have a direct use in adjusting the summary estimates of a treatment difference . In an empirical study of the relation of quality scores to treatment differences in published meta-analyses of 7 groups of controlled r and omized clinical trials comprising 107 primary studies , we found no relation between treatment difference and overall quality score . We also found no relation between quality score and variation in treatment difference . The level of quality scores has increased at a rate of 9 % per decade for three decades , averaging 0.51 on a scale of 0 to 1 for the 1980s , and leaving much room for improvement . Nevertheless , attention to quality of studies by editors , review ers , and authors may be raising both the level of research done and quality of the reports Background Marrow stimulation techniques such as drilling or microfracture are first-line treatment options for symptomatic cartilage defects . Common knowledge holds that these treatments do not compromise subsequent cartilage repair procedures with autologous chondrocyte implantation . Hypothesis Cartilage defects pretreated with marrow stimulation techniques will have an increased failure rate . Study Design Cohort study ; Level of evidence , 2 . Methods The first 321 consecutive patients treated at one institution with autologous chondrocyte implantation for full-thickness cartilage defects that reached more than 2 years of follow-up were evaluated by prospect ively collected data . Patients were grouped based on whether they had undergone prior treatment with a marrow stimulation technique . Outcomes were classified as complete failure if more than 25 % of a grafted defect area had to be removed in later procedures because of persistent symptoms . Results There were 522 defects in 321 patients ( 325 joints ) treated with autologous chondrocyte implantation .  On average , there were 1.7 lesions per patient . Of these joints , 111 had previously undergone surgery that penetrated the subchondral bone ; 214 joints had no prior treatment that affected the subchondral bone and served as controls . Within the marrow stimulation group , there were 29 ( 26 % ) failures , compared with 17 ( 8 % ) failures in the control group . Conclusion Defects that had prior treatment affecting the subchondral bone failed at a rate 3 times that of nontreated defects . The failure rates for drilling ( 28 % ) , abrasion arthroplasty ( 27 % ) , and microfracture ( 20 % ) were not significantly different , possibly because of the lower number of microfracture patients in this cohort ( 25 of 110 marrow-stimulation procedures ) . The data demonstrate that marrow stimulation techniques have a strong negative effect on subsequent cartilage repair with autologous chondrocyte implantation and therefore should be used judiciously in larger cartilage defects that could require future treatment with autologous chondrocyte implantation BACKGROUND Microfracture is a frequently used technique for the repair of articular cartilage lesions of the knee . Despite the popularity of the technique , prospect i ve information about the clinical results after microfracture is still limited . The purpose of our study was to identify the factors that affect the clinical outcome from this cartilage repair technique . METHODS Forty-eight symptomatic patients with isolated full-thickness articular cartilage defects of the femur in a stable knee were treated with the microfracture technique . Prospect i ve evaluation of patient outcome was performed for a minimum follow-up of twenty-four months with a combination of vali date d outcome scores , subjective clinical rating , and cartilage-sensitive magnetic resonance imaging . RESULTS At the time of the latest follow-up , knee function was rated good to excellent for thirty-two patients ( 67 % ) , fair for twelve patients ( 25 % ) , and poor for four ( 8 % ) . Significant increases in the activities of daily living scores , International Knee Documentation Committee scores , and the physical component score of the Short Form-36 were demonstrated after microfracture ( p < 0.05 ) . A lower body-mass index correlated with higher scores for the activities of daily living and SF-36 physical component , with the worst results for patients with a body-mass index of > 30 kg/m(2 ) . Significant improvement in the activities of daily living score was more frequent with a preoperative duration of symptoms of less than twelve months ( p < 0.05 ) . Magnetic resonance imaging in twenty-four knees demonstrated good repair-tissue fill in the defect in thirteen patients ( 54 % ) , moderate fill in seven ( 29 % ) , and poor fill in four patients ( 17 % ) . The fill grade correlated with the knee function scores . All knees with good fill demonstrated improved knee function , whereas poor fill grade was associated with limited improvement and decreasing functional scores after twenty-four months . CONCLUSIONS Microfracture repair of articular cartilage lesions in the knee results in significant functional improvement at a minimum follow-up of two years . The best short-term results are observed with good fill grade , low body-mass index , and a short duration of preoperative symptoms . A high body-mass index adversely affects short-term outcome , and a poor fill grade is associated with limited short-term durability Osteoarthritis is a major contributor to functional impairment and reduced independence in older adults ( 1 - 4 ) . It is the leading cause of arthritis in the United States , affecting an estimated 21 million persons ( 5 ) , and has substantial economic impact ( 6 , 7 ) . History of an injury to a joint , particularly at the knee and hip , is associated with an increased risk for osteoarthritis in cross-sectional and casecontrol studies ( 8 - 11 ) . Such studies , however , may overestimate this relation because persons with symptomatic osteoarthritis may be more likely to recall a past injury or to interpret early symptoms of osteoarthritis as indicative of joint injury . A prospect i ve cohort study can address this weakness by determining exposure status before the outcome develops . To date , prospect i ve studies have examined the relation between history of joint injury and osteoarthritis in middle-aged persons and senior citizens ( 12 , 13 ) , but not in young adults . However , many athletic injuries occur in high school and college . In addition , joint trauma may be a more common cause of osteoarthritis than has been previously recognized ( 14 ) . We performed a prospect i ve cohort study of 1321 young adults to examine the risk for knee and hip osteoarthritis associated with joint injury during young adult life . Methods Study Participants The Johns Hopkins Precursors Study was design ed by the late Caroline Bedell Thomas , MD , to identify precursors of the aging process ( 15 ) . A total of 1337 medical students , members of the graduating classes of 1948 through 1964 at the Johns Hopkins University School of Medicine in Baltimore , Maryl and , enrolled in the study . The cohort was 91 % male and 97 % white ; the mean age was 22 years . At entry , participants underwent a st and ard history and examination , including  assessment of musculoskeletal disorders , history of trauma , level of physical activity , and measurement of weight and height . Body mass index was calculated as weight in kilograms divided by height in meters squared . In addition , participants were asked to categorize their level of physical training during the past month as none , little , moderate , or much , as described elsewhere ( 16 ) . Since graduation , participants have been followed prospect ively with annual self-administered question naires to detect incident disease and to up date risk factor status over time . At the time that baseline data were collected , it was not customary to obtain informed consent . After establishment of the Joint Committee on Clinical Investigation at Johns Hopkins , the follow-up protocol was review ed and approved . Assessment of Injury Injury was defined as a report of trauma to the knee or hip joint , including internal derangement and fracture . During the baseline assessment , knee and hip injuries that occurred before graduation from medical school and the year of their occurrence were recorded . Postgraduation injuries were assessed by annual morbidity question naires . During every 5-year follow-up period , at least 86 % of the living participants responded at least once to the question naires . Injuries were assigned diagnosis codes according to the International Classification of Diseases , Ninth Revision , Clinical Modification ( ICD-9-CM ) ( 17 ) . Diagnoses included torn meniscus ( code 836.2 ) ; torn knee ligament ( code 844.9 ) ; tibial fracture ( code 823.8 ) ; femoral fracture ( code 821.01 ) ; fibular fracture ( code 823.81 ) ; patellar fracture ( code 822 ) ; broken leg , site not otherwise specified ( code 827.0 ) ; knee injury , not otherwise specified ( code 959.7 ) ; gunshot wound ( code 891 ) ; hemarthrosis ( code 844.9 ) ; shin splints ( code 844.9 ) ; and hip dislocation ( code 836.5 ) . Incidence of Osteoarthritis The methods used to determine osteoarthritis incidence in this cohort have been described elsewhere ( 18 ) . Briefly , all participants were mailed annual morbidity question naires . Before 1985 , respondents were queried about the development of physical and musculoskeletal disorders . Since 1985 , follow-up morbidity question naires have contained the specific question , Have you ever had arthritis ? and have asked those who respond affirmatively to provide the type of arthritis , year of onset , and treatment received . An event of osteoarthritis was defined as the self-report of osteoarthritis or degenerative arthritis in response to the question naire . The incidence date was determined by the reported year of osteoarthritis onset . Two rheumatologists review ed each report of osteoarthritis , assigned ICD-9-CM codes ( 17 ) to the most specific arthritis site reported by the respondent , and excluded inflammatory arthritides . For this analysis , only osteoarthritis at the knee ( code 715.96 ) and hip ( code 715.95 ) were included as outcomes . In 1995 , all surviving participants who had previously reported osteoarthritis were mailed a more detailed question naire . They were asked , Have you had pain in or around the knee , including back of the knee , on most days for at least 1 month ? and Have you had pain in or around either hip joint , including the buttock , groin , and side of upper thigh , on most days for at least 1 month ? These symptom-related questions were used to screen for knee and hip osteoarthritis , respectively , in the National Health and Nutrition Examination Survey ( NHANES ) ( 19 ) . Respondents were also asked whether they had undergone  radiographic evaluation of their knees and hips  and whether radiography revealed osteophytes , joint space narrowing , subchondral cysts , or bony sclerosis ( the radiographic hallmarks of osteoarthritis ) ( 20 ) . Statistical Analysis The association between baseline characteristics and injury status was assessed by using the Student t-test for continuous variables and the chi-square test for categorical variables . 
    Output:
    