***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: OBJECTIVES To examine the objective physical function of the lower extremities , to measure the properties of quadriceps femoris muscle ( QFM ) , and to assess subjective disabilities in men with knee osteoarthritis ( OA ) and to compare the results with those obtained from age- and sex-matched control subjects . DESIGN Cross-sectional study . SETTING Rehabilitation clinic in a university hospital . PARTICIPANTS Male volunteers ( n=54 ) ( age range , 50 - 69y ) with knee OA and r and omly selected healthy , age- and sex-matched control subjects ( n=53 ) . INTERVENTIONS Not applicable . MAIN OUTCOME MEASURES Physical function evaluated with a test battery including the QFM composition measurement , the Western Ontario and McMaster Universities Osteoarthritis Index ( WOMAC ) , and the R AND 36-Item Short-Form Health Survey , version 1.0 .  RESULTS Knee OA patients had 13 % to 26 % poorer ( P range , .050-.001 ) physical function and muscle strength compared with the controls . There were also significant differences in QFM composition . WOMAC ( P range , .050-.001 ) and muscle strength ( P<.001 ) associated with physical function tests , but subjective pain correlated with neither physical function nor muscle strength in knee OA patients . The radiographic knee OA grade did not have any significant effect on physical function , but passive knee motion , knee extension strength , and WOMAC were related to the severity of the disease ( P<.05 ) . CONCLUSIONS The patients with knee OA exhibited impaired physical function and muscle strength and QFM composition compared with healthy controls . The severity of radiographic knee OA clearly had adverse effects on functional ability at the later stages of the disease . The results highlight the effect of QFM strength on physical function as well as the importance of patient 's subjective and objective physical function when deciding on knee OA treatment policy OBJECTIVE Although knee malalignment is assumed to correlate with knee osteoarthritis ( OA ) , it is still unknown whether malalignment precedes the development of OA or whether it is a result of OA . The aim of this study was to assess the relationship between malalignment and the development of knee OA as well as progression of knee OA . METHODS A total of 1,501 participants in the Rotterdam study were r and omly selected .  Knee OA at baseline and at followup ( mean followup 6.6 years ) was scored according to the Kellgren/Lawrence ( K/L ) grading system . Alignment was measured by the femorotibial angle on radiographs at baseline . Multivariable logistic regression for repeated measurements was used to analyze the association of malalignment with the development and progression of OA . RESULTS Of 2,664 knees , 1,012 ( 38 % ) were considered to have normal alignment , 693 ( 26 % ) had varus alignment , and 959 ( 36 % ) had valgus alignment . A comparison of valgus alignment and normal alignment showed that valgus alignment was associated with a borderline significant increase in development of knee OA ( odds ratio [ OR ] 1.54 , 95 % confidence interval [ 95 % CI ] 0.97 - 2.44 ) , and varus alignment was associated with a 2-fold increased risk ( OR 2.06 , 95 % CI 1.28 - 3.32 ) . Stratification for body mass index showed that this increased risk was especially seen in overweight and obese individuals but not in non-overweight persons . The risk of OA progression was also significantly increased in the group with varus alignment compared with the group with normal alignment ( OR 2.90 , 95 % CI 1.07 - 7.88 ) . CONCLUSION An increasing degree of varus alignment is associated not only with progression of knee OA but also with development of knee OA . However , this association seems particularly applicable to overweight and obese persons OBJECTIVES Foot orthoses are commonly used in the management of knee OA , although the relationship between foot function and knee OA is still unclear . The purpose of the study was to examine foot function during walking in people with and without medial compartment knee OA . METHODS Motion of the tibia , rearfoot and forefoot in 32 patients with medial compartment knee OA and 28 age-matched control subjects was investigated .  Multivariate analysis was used to compare the groups . RESULTS The knee OA group contacted the ground with a more everted rearfoot , demonstrated greater peak rearfoot eversion and exhibited reduced rearfoot frontal plane range of motion and reduced rearfoot peak inversion . The tibia was more internally rotated and laterally tilted throughout the gait cycle , with reduced peak external rotation . CONCLUSION People with medial compartment knee OA exhibit altered foot kinematics during gait that are indicative of a less mobile , more everted foot type . The presence and degree of tibial malalignment and the available rearfoot range of motion during walking may affect individual responses to load-altering interventions , such as foot orthoses and footwear modifications . TRIAL REGISTRATION Australian New Zeal and Clinical Trials Registry , www.anzctr.org.au/ , ACTRN12608000116325 OBJECTIVE To compare age-related patterns of gait with patterns associated with knee osteoarthritis ( OA ) , the following hypotheses were tested : ( H1 ) The sagittal-plane knee function during walking is different between younger and older asymptomatic subjects ; ( H2 ) The age-related differences in H1 are increased in patients with knee OA . DESIGN Walking trials were collected for 110 participants ( 1.70 ± 0.09 m , 80 ± 14 kg ) . There were 29 younger asymptomatic subjects ( 29 ± 4 years ) and 81 older participants ( 59 ± 9 years ) , that included 27 asymptomatic subjects and 28 and 26 patients with moderate and severe medial knee OA . Discrete variables characterizing sagittal-plane knee function were compared among the four groups using ANOVAs . RESULTS During the heel-strike portion of the gait cycle at preferred walking speed , the knee was less extended and the shank less inclined in the three older groups compared to the younger asymptomatic group . There were similar differences between the severe OA group and the older asymptomatic and moderate OA groups . Both OA groups also had the femur less posterior relative to the tibia and smaller extension moment than the younger group . During terminal stance , the severe OA group had the knee less extended and smaller knee extension moment than the younger asymptomatic and older moderate OA groups . CONCLUSIONS The differences in knee function , particularly those during heel-strike which were associated with both age and disease severity , could form a basis for looking at mechanical risk factors for initiation and progression of knee OA on a prospect i ve basis OBJECTIVE To describe the association between chondral defects , bone marrow lesions , knee and hip radiographic osteoarthritis ( OA ) , and knee pain . METHODS Knee pain was assessed by the Western Ontario and McMaster Universities Osteoarthritis Index . T1- and T2-weighted fat saturation magnetic resonance imaging was performed on the right knee to assess chondral defects and subchondral bone marrow lesions . Radiography was performed on the right knee and hip and scored for radiographic OA . Body mass index ( BMI ) and knee extension strength were measured . RESULTS A total of 500 r and omly selected men and women participated . The prevalence of knee pain was 48 % . In multivariable analysis , prevalent knee pain was significantly associated with medial tibial chondral defects ( odds ratio [ OR ] 2.32 , 95 % confidence interval [ 95 % CI ] 1.02 - 5.28 for grade 3 versus grade 2 or less ; OR 4.93 , 95 % CI 1.07 - 22.7 for grade 4 versus grade 2 or less ) , bone marrow lesions ( OR 1.44 , 95 % CI 1.04 - 2.00 per compartment ) , and hip joint space narrowing ( OR 1.36 , 95 % CI 1.07 - 1.73 per unit ) , as well as greater BMI and lower knee extension strength . It was not significantly associated with radiographic knee OA . These variables were also associated with more severe knee pain . In addition , there was a dose response association between knee pain and number of sites having grade 3 or 4 chondral defects ( OR 1.39 , 95 % CI 1.12 - 1.73 per site ) , with all subjects having knee pain if all compartments of the knee had these defects . CONCLUSION Knee pain in older adults is independently associated with both full and non-full-thickness medial tibial chondral defects , bone marrow lesions , greater BMI , and lower knee extension strength , but is not associated with radiographic knee OA . The association between radiographic hip OA and knee pain indicates that referred pain from the hip needs to be considered in unexplained knee pain BACKGROUND Given the complexity of the gait of patients with knee osteoarthritis , a multiple correspondence analysis may be helpful to optimise the extraction of relevant gait and clinical information . Therefore , the aims of this study are to identify the main associations with clinical and gait biomechanical parameters and to evaluate whether there are more specific knee osteoarthritis groups with different gait profiles . METHODS Ninety patients with severe knee osteoarthritis and twenty-six healthy individuals participated in this study .  Pain and function were assessed with the WOMAC Index  ;  knee joint deformity was assessed by the hip-knee-ankle angle on full-limb radiography ; and full body gait analysis was performed with a motion analysis system and force plates . FINDINGS Using multiple correspondence analysis , two categories of gait parameters that best explain the gait variance of patients with knee osteoarthritis were highlighted . The forward displacement category is composed of the parameters speed , stride length , hip flexion and knee flexion . The frontal category is composed of the parameters thorax obliquity and knee adductor moments . Moreover , based on these parameters , four distinct gait profiles were identified : two gait profiles were associated with knee varus deformities , increased thorax obliquity and different forward displacements , while two gait profiles were associated with valgus deformities and different forward displacements . INTERPRETATION These gait parameters can be used to simplify the characterisation of the gait of the knee osteoarthritis population . Patients in varus profiles increase thorax obliquity on the stance limb and may reduce forward displacement . Patients in valgus profiles , however , only reduce forward displacement OBJECTIVE To examine the relationship of knee malalignment to the occurrence of  knee osteoarthritis ( OA ) among subjects without radiographic OA at baseline to determine whether malalignment is a risk factor for incident disease or simply a marker of increasing disease severity . METHODS We selected 110 incident tibiofemoral ( TF ) OA case knees ( 76 subjects ) and 356 r and om control knees ( 178 subjects ) from among participants in the Framingham Osteoarthritis Study . Case knees did not have OA at baseline ( 1992 - 1994 examination ) but had developed OA ( Kellgren/Lawrence grade > or=2 ) at followup ( 2002 - 2005 examination ) ( mean of 8.75 years between examinations ) . Control knees did not have OA at baseline . St and ardized digital radiographs of the fully extended knee with weight-bearing were read using a st and ard protocol and eFilm viewing software . We measured the anatomic axis , the condylar angle , the tibial plateau angle , and the condylar tibial plateau angle . The interobserver intraclass correlation coefficient ( ICC ) ranged from 0.93 to 0.96 and the intraobserver ICC from 0.94 to 0.97 . In a knee-specific analysis , we examined the relationship of each alignment measurement to the risk of TF OA using generalized estimating equations , adjusting for age , sex , and body mass index ( BMI ) . We used the same approach to assess the association between each alignment measurement and the risk of medial TF OA . RESULTS Subjects in the case population were older and had a higher BMI than the controls . The alignment values were normally distributed and were not different between the cases and the controls . After adjustment for age , sex and BMI , there was no significant increase in incident OA in the highest quartile compared with the lowest quartile category for any of the alignment measures ( P for trend for anatomic axis and condylar tibial plateau angle was 0.83 and 0.80 , respectively ) . Similar results were also observed for medial compartment OA . CONCLUSION We found that baseline knee alignment is not associated with either incident radiographic TF OA or medial TF OA . These results suggest that malalignment is not a risk factor for OA , but rather is a marker of disease severity and /or its progression OBJECTIVE To compare the gait of adults with unilateral and bilateral symptomatic and radiographic knee osteoarthritis ( OA ) to determine whether these subgroups can be treated similarly in the clinic and when recruiting for r and omized clinical trials , and to use these data to generate future hypotheses regarding gait in these subsets of knee OA patients . METHODS Cross-sectional investigation of patients with unilateral and bilateral knee OA on gait mechanics using 136 older adults ( age ≥55 yrs ; 27 kg m(-2 ) ≥ BMI ≤ 41 kg m(-2 ) ; 82 % female ) with radiographic knee OA . Comparisons were made between the most affected side of the 
    Output:
    
Compared with healthy controls , patients with knee osteoarthritis have higher odds of having lower muscle strength , proprioception deficits , more medial varus-valgus laxity and less lateral varus-valgus laxity .
Conclusions Patients with knee osteoarthritis are more likely to display a number of biomechanical characteristics .