***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: OBJECTIVE Risk of knee osteoarthritis ( OA ) associated with constitutional factors , history of joint injuries , and occupational factors was assessed in a case-control study among women in Japan . Results were contrasted with a comparable study in Britain . METHODS The study covered 3 health districts in Japan . Cases were women aged > /= 45 years old , diagnosed with knee OA by orthopedic physicians utilizing radiography .  No cases displayed established causes of secondary OA . Controls selected r and omly from the general population were individually matched to each case for age , sex , and residential district . Subjects were interviewed using structured question naires to determine medical history , including history of joint injury , physical activity , socioeconomic factors , and occupation . Height and weight were measured . RESULTS Interviews were obtained from 101 female cases and controls . The highest third of heaviest body weight in the past [ high ( > 62.0 kg ) vs low ( < 55 kg ) odds ratio = 4.42 , 95 % confidence interval 1.17 - 16.64 ] , previous injury to the knee ( OR 7.11 , 95 % CI 2.40 - 21.09 ) , sedentary work during initial employment ( OR 0.35 , 95 % CI 0.15 - 0.84 ) , and total working years ( OR 1.05 , 95 % CI 1.01 - 1.08 ) represented independent factors associated with knee OA , after controlling for other potential risk factors . CONCLUSION Heavy weight in the past appears to represent a risk factor for knee OA among women in Japan , as reported in Britain . Constitutional factors may represent important determinants for knee OA , regardless of race . Previous injury to the knee and occupational factors are also associated with knee OA in both Britain and Japan , although characteristic activities for work vary Although treatments for osteoarthritis of the knee are often directed at relieving pain , pain may cause patients to alter how they perform activities to decrease the loads on the joints . The knee-adduction moment is a major determinant of the load distribution between the medial and lateral plateaus . Therefore , the interrelationship between pain and the external knee-adduction moment during walking may be especially important for underst and ing mechanical factors related to the progression of medial tibiofemoral osteoarthritis . Fifty-three subjects with symptomatic radiographic evidence of osteoarthritis of the knee were studied . These subjects were a subset of those enrolled in a double-blind study in which  gait analysis and radiographic and clinical evaluations were performed after a 2-week washout of anti-inflammatory and analgesic treatment . The subjects then took a nonsteroidal anti-inflammatory drug , acetaminophen , or placebo for 2 weeks , and the gait and clinical evaluations were repeated . The change in the peak external adduction moment between the two evaluations was inversely correlated with the change in pain ( R = 0.48 , p < 0.001 ) and was significantly different between those whose pain increased ( n = 7 ) , decreased ( n = 18 ) , or remained unchanged ( n = 28 ) ( p = 0.009 ) . Those with increased pain had a significant decrease in the peak external adduction ( p = 0.005 ) and flexion moments ( p = 0.023 ) . In contrast , the subjects with decreased pain tended to have an increase in the peak external adduction moment ( p = 0.095 ) and had a significant increase in the peak external extension moment ( p = 0.017 ) . The subjects whose pain was unchanged had no significant change in the peak external adduction ( p = 0.757 ) , flexion ( p = 0.234 ) , or extension ( p = 0.465 ) moments . Thus , decreases in pain among patients with medial tibiofemoral osteoarthritis were related to increased loading of the degenerative portion of the joints . Additional long-term prospect i ve studies are needed to determine whether increased loading during walking actually results in accelerated progression of the disease This study tested whether the peak external knee adduction moments during walking in subjects with knee osteoarthritis ( OA ) were correlated with the mechanical axis of the leg , radiographic measures of OA severity , toe out angle or clinical assessment s of pain , stiffness or function .  Gait analysis was performed on 62 subjects with knee OA and 49 asymptomatic control subjects ( normal subjects ) . The subjects with OA walked with a greater than normal peak adduction moment during early stance ( p = 0.027 ) . In the OA group , the mechanical axis was the best single predictor of the peak adduction moment during both early and late stance ( R = 0.74 , p < 0.001 ) . The radiographic measures of OA severity in the medial compartment were also predictive of both peak adduction moments ( R = 0.43 to 0.48 , p < 0.001 ) along with the sum of the WOMAC subscales ( R = -0.33 to -0.31 , p < 0.017 ) . The toe out angle was predictive of the peak adduction moment only during late stance ( R = -0.45 , p < 0.001 ) . Once mechanical axis was accounted for , other factors only increased the ability to predict the peak knee adduction moments by 10 18 % . While the mechanical axis was indicative of the peak adduction moments , it only accounted for about 50 % of its variation , emphasizing the need for a dynamic evaluation of the knee joint loading environment . Underst and ing which clinical measures of OA are most closely associated with the dynamic knee joint loads may ultimately result in a better underst and ing of the disease process and the development of therapeutic interventions OBJECTIVE The adduction moment at the knee during gait is the primary determinant of medial-to-lateral load distribution . If the adduction moment contributes to progression of osteoarthritis ( OA ) , then patients with advanced medial tibiofemoral OA should have higher adduction moments . The present study was undertaken to investigate the hypothesis that the adduction moment normalized for weight and height is associated with medial tibiofemoral OA disease severity after controlling for age , sex , and pain level , and to examine the correlation of serum hyaluronan ( HA ) level with disease severity and with the adduction moment in a subset of patients . METHODS Fifty-four patients with medial tibiofemoral OA underwent gait analysis and radiographic evaluation .  Disease severity was assessed using the Kellgren-Lawrence ( K-L ) grade and medial joint space width . In a subset of 23 patients with available sera , HA was quantified by s and wich enzyme-linked immunosorbent assay . Pearson correlations , a r and om effects model , and multivariate regression models were used . RESULTS The  adduction moment  correlated with the K-L grade in the left and right knees ( r = 0.68 and r = 0.60 , respectively ) , and with joint space width in the left and right knees ( r = -0.45 and r = -0.47 , respectively ) . The relationship persisted after controlling for age , sex , and severity of pain . The partial correlation between K-L grade and adduction moment was 0.71 in the left knees and 0.61 in the right knees . For every 1.0-unit increase in adduction moment , there was a 0.63-mm decrease in joint space width . In the subset of patients in whom serum HA levels were measured , HA levels correlated with medial joint space width ( r = -0.55 ) , but not with the adduction moment . CONCLUSION There is a significant relationship between the  adduction moment and OA disease severity . Serum HA levels correlate with joint space width but not with the adduction moment . Longitudinal studies will be necessary to determine the contribution of the adduction moment , and its contribution in conjunction with metabolic markers , to progression of medial tibiofemoral OA OBJECTIVE To determine the relationship between change in body mass and knee-joint moments and forces during walking in overweight and obese older adults with knee osteoarthritis ( OA ) following an 18-month clinical trial of diet and exercise . METHODS Data were obtained from 142 sedentary , overweight , and obese older adults with self-reported disability and radiographic evidence of knee OA who underwent 3-dimensional gait analysis .  Gait kinetic outcome variables included peak knee-joint forces and peak internal knee-joint moments . Mixed regression models were created to predict followup kinetic values , using followup body mass as the primary explanatory variable . Baseline body mass was used as a covariate , and thus followup body mass was a surrogate measure for change in body mass ( i.e. , weight loss ) . RESULTS There was a significant direct association between followup body mass and peak followup values of compressive force ( P = 0.001 ) , result ant force ( P = 0.002 ) , abduction moment ( P = 0.03 ) , and medial rotation moment ( P = 0.02 ) . A weight reduction of 9.8 N ( 1 kg ) was associated with reductions of 40.6 N and 38.7 N in compressive and result ant forces , respectively . Thus , each weight-loss unit was associated with an approximately 4-unit reduction in knee-joint forces . In addition , a reduction in body weight of 9.8 N ( 1 kg ) was associated with a 1.4 % reduction ( 0.496 Nm ) in knee abduction moment . CONCLUSION Our results indicate that each pound of weight lost will result in a 4-fold reduction in the load exerted on the knee per step during daily activities . Accumulated over thous and s of steps per day , a reduction of this magnitude would appear to be clinical ly meaningful Elderly subjects with and without knee pain walked at a comfortable pace during gait analysis . Comparison of peak hip and knee internal extensor generalized muscle moments ( GMMs ) during loading response was made between groups . Walking velocity , peak hip internal extensor GMM , and knee range of motion ( ROM ) were significantly less for the group with knee pain than for the group without pain . Peak hip internal extensor GMM was strongly correlated with velocity , but peak knee internal extensor GMM was not . Knee ROM limitations may account for the increased peak knee internal extensor GMM in the knee pain group 
    Output:
    
RESULTS The magnitude and time course of KAM during gait appeared to be consistent across laboratories and computational methods .
Knee adduction moment increased with OA severity and was directly proportional to varus malalignment .
Classifying the patients on the basis of disease severity decreased the group variability , permitting the differences to be more detectable .
Biomechanical variables such as varus malalignment are associated with KAM and therefore may affect the disease process .