***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 Mechanical factors , in particular increased medial knee joint load , are believed to be important in the structural progression of knee osteoarthritis . This study evaluated the relationship of medial knee load during walking to indices of structural disease progression , measured on MRI , in people with medial knee osteoarthritis . Methods A longitudinal cohort design utilising a subset of participants ( n=144 , 72 % ) enrolled in a r and omised controlled trial of lateral wedge insoles was employed .  Medial knee load parameters including the peak knee adduction moment ( KAM ) and the KAM impulse  were measured at baseline using three-dimensional gait analysis during walking . MRI at baseline and at 12 months was used to assess structural indices . Multiple regression with adjustment for covariates assessed the relationship between medial knee load parameters and the annual change in medial tibial cartilage volume . Binary logistic regression was used for the dichotomous variables of progression of medial tibiofemoral cartilage defects and bone marrow lesions ( BML ) . Results A higher KAM impulse , but not peak KAM , at baseline was independently associated with greater loss of medial tibial cartilage volume over 12 months ( β=29.9 , 95 % CI 6.3 to 53.5 , p=0.01 ) . No significant relationships were seen between medial knee load parameters and the progression of medial tibiofemoral cartilage defects or BML . Conclusion This study suggests knee loading , in particular the KAM impulse , may be a risk factor for loss of medial tibial cartilage volume . As knee load is modifiable , load-modifying treatments may potentially slow disease progression Anterior cruciate ligament ( ACL ) injury can result in failure to return to pre-injury activity levels and future osteoarthritis predisposition . Single leg hop is used in late rehabilitation to evaluate recovery and inform treatment but biomechanical underst and ing of this activity is insufficient . This study investigated single leg hop for distance aim ing to evaluate if ACL patients had recovered : ( 1 ) l and ing strategies and ( 2 )  medio-lateral knee control . We hypothesized that patients with reconstructive surgery ( ACLR )  would have more similar l and ing strategies and knee control to healthy controls than patients treated conservatively ( ACLD ) . 16 ACLD and 23 ACLR subjects were compared to 20 healthy controls ( CONT ) .  Kinematic and ground reaction force data were collected while subjects hopped their maximum distance . The main output parameters were hop distance , peak knee flexor angles and extensor moments and Fluency ( a measure introduced to represent medio-lateral knee control ) . Statistical differences between ACL and control groups were analyzed using a general linear model univariate analysis , with COM velocity prior to l and ing as covariate . Hop distance was the smallest for ACLD and largest for CONT ( p<0.001 ; ACLD 57.1±14.1 ; ACLR 75.1±17.8 ; CONT 77.7±14.07 % height ) . ACLR used a similar kinematic strategy to CONT , but had a reduced peak knee extensor moment ( p<0.001 ; ACLD 0.32±0.14 ; ACLR 0.31±0.16 ; CONT 0.42±0.13 BW.height ) . Fluency was reduced in both ACLD and ACLR ( p=0.006 ; ACLD 0.13±0.34 ; ACLR 0.14±0.34 ; CONT 0.17±0.41 s ) . Clinical practice uses hopping distance to evaluate ACL patients ' recovery . This study demonstrated that aspects such as movement strategies and knee control need to be evaluated OBJECTIVE To determine how chronic anterior cruciate ligament deficient and surgically repaired subjects react to unexpected forward perturbations during gait as compared to healthy controls . DESIGN Gait testing of 10 chronic anterior cruciate ligament deficient subjects prior to and three months following reconstructive surgery , and 10 uninjured controls . BACKGROUND The ability of an anterior cruciate ligament injured individual to react and maintain equilibrium during gait perturbations is critical for the prevention of reinjury . No studies have investigated how these individuals respond to unexpected perturbations during normal gait . METHODS An unexpected forward perturbation was induced upon heel strike using a force plate capable of translational movement . RESULTS Prior to surgery , the anterior cruciate ligament subjects exhibited a greater knee extensor moment in response to the perturbation compared to healthy controls . Following surgery , the anterior cruciate ligament injured subjects exhibited a static knee position and a sustained knee extensor moment throughout stance in response to the perturbation as compared to controls . CONCLUSIONS These data suggest that chronic anterior cruciate ligament deficient subjects rely heavily on knee extensor musculature to prevent collapse in response to an unexpected perturbation . This same reactive response was more pronounced 3 months following surgery . RELEVANCE The results suggest that , prior to and following surgery , chronic anterior cruciate ligament injured subjects respond differently than healthy controls to an unexpected perturbation during gait . Anterior cruciate ligament injured or repaired subjects do not reduce or avoid vigorous contraction of the quadriceps muscles when responding to gait perturbations Reports that knee cartilage health is sensitive to kinematic changes , combined with reports of extension loss following ACL reconstruction , underscores the importance of restoring ambulatory knee extension in the context of preventing premature osteoarthritis . The purpose of this study was to test the relationship between individual variations in peak knee extension at heel-strike of walking and the anterior-posterior location of thickest cartilage in the medial and lateral femoral condyles of healthy contralateral and ACL reconstructed knees . In vivo gait analysis and knee MR images were collected from 29 subjects approximately 2 years after unilateral ACL reconstruction .  Knee extension was measured at heel-strike of walking and 3-D femoral cartilage thickness models were reconstructed from MR images . The ACL reconstructed knees had significantly reduced knee extension ( -1.5±4.2 ° ) relative to the contralateral knees ( -4.6±3.4 ° ) at heel-strike of walking but did not have side-to-side differences in the anterior-posterior location or magnitude of thickest medial and lateral femoral cartilage . The anterior-posterior location of the thickest medial femoral cartilage was correlated with knee extension at heel-strike in both the healthy contralateral ( R(2)=0.356 , p<0.001 ) and reconstructed ( R(2)=0.234 , p=0.008 ) knees . These results suggest that ACL reconstruction can impair terminal extension at periods of ambulatory loading known to be related to cartilage morphology in healthy joints . The fact that the femoral cartilage thickness distribution had not changed at 2 years post-op , even in the subset of subjects with extension loss , suggests that loads may be shifted to thinner cartilage regions , which could have important implication s on long-term joint health OBJECTIVE : To test the feasibility of creating a valid and reliable checklist with the following features : appropriate for assessing both r and omised and non-r and omised studies ; provision of both an overall score for study quality and a profile of scores not only for the quality of reporting , internal validity ( bias and confounding ) and power , but also for external validity . DESIGN : A pilot version was first developed , based on epidemiological principles , review s , and existing checklists for r and omised studies . Face and content validity were assessed by three experienced review ers and reliability was determined using two raters assessing 10 r and omised and 10 non-r and omised studies . Using different raters , the checklist was revised and tested for internal consistency ( Kuder-Richardson 20 ) , test-retest and inter-rater reliability ( Spearman correlation coefficient and sign rank test ; kappa statistics ) , criterion validity , and respondent burden . MAIN RESULTS : The performance of the checklist improved considerably after revision of a pilot version . The Quality Index had high internal consistency ( KR-20 : 0.89 ) as did the subscales apart from external validity ( KR-20 : 0.54 ) . Test-retest ( r 0.88 ) and inter-rater ( r 0.75 ) reliability of the Quality Index were good . Reliability of the subscales varied from good ( bias ) to poor ( external validity ) . The Quality Index correlated highly with an existing , established instrument for assessing r and omised studies ( r 0.90 ) . There was little difference between its performance with non-r and omised and with r and omised studies . Raters took about 20 minutes to assess each paper ( range 10 to 45 minutes ) . CONCLUSIONS : This study has shown that it is feasible to develop a checklist that can be used to assess the method ological quality not only of r and omised controlled trials but also non-r and omised studies . It has also shown that it is possible to produce a checklist that provides a profile of the paper , alerting review ers to its particular method ological strengths and weaknesses . Further work is required to improve the checklist and the training of raters in the assessment of external validity Abstract The aim of this study is to analyse the changes in select gait parameters following  anterior cruciate ligament ( ACL ) reconstruction .  The study was performed on 15 subjects who underwent ACL reconstruction by the bone-patellar tendon-bone technique .  Gait analysis was performed using the Elite three-dimensional ( 3D ) optoelectronic system ( BTS ) , a Kistler force platform and the Telemg telemetric electromyograph ( BTS ) .  Kinematic data were recorded for the principal lower limb joints ( hip , knee and ankle ) . The examined muscles include vastus lateralis , rectus femoris , biceps femoris and semitendinosus . The results obtained from the operated subjects were compared with those of 10 untreated subjects and 5 subjects without ACL damage .  In the operated subjects the knee joint angular values regained a normal flexion pattern for the injured limb during the stance phase . The analysis of joint moments shows : ( a ) sagittal plane : recovery of the knee flexion moment at loading response and during preswing ; ( b ) frontal plane : recovery of the normal patterns for both hip and knee adduction-abduction moments during the entire stance phase . The examination of ground reaction forces reveals the recovery of frontal component features . The EMG traces show the normal biphasic pattern for the operated subjects as compared to the untreated subjects . The results suggest that the gait parameters shift towards normal value patterns 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 OBJECTIVES To examine the effects of 2 gait retraining protocol s on the gait patterns of patients with bone-patellar tendon-bone anterior cruciate ligament ( ACL ) reconstruction . DESIGN R and omized control , repeated- measures design . SETTING Private orthopedic center and research facility . PARTICIPANTS Sixteen patients with bone-patellar tendon-bone ACL reconstruction , r and omly subdivided into 2 groups ( group 1 , n=8 ; group 2 , n=8 ) , and a healthy control group of 8 subjects . INTERVENTION The 16 subjects with ACL reconstruction were r and omly assigned to 2 different gait retraining protocol s over a 6-week training interval : ( 1 ) . a protocol using a predicted stride frequency calculated from the resonant frequency of a force-driven harmonic oscillator ( FDHO ) model or ( 2 ) . a protocol using the preferred stride frequency ( PSF ) . MAIN OUTCOME MEASURES Gait analyses examining the lower-extremity kinematic 
    Output:
    
Sagittal plane biomechanics , rather than the knee adduction moment , appear to be more relevant post-ACLR .
Better underst and ing of sagittal plane biomechanics is necessary for optimal post-operative recovery , and to potentially prevent early onset and progression of knee OA after ACLR .