***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: Background The effectiveness of anterior cruciate ligament reconstruction for restoring normal knee kinematics is largely unknown , particularly during sports movements generating large , rapidly applied forces . Hypothesis Under dynamic in vivo loading , significant differences in 3-dimensional kinematics exist between anterior cruciate ligament-reconstructed knees and the contralateral , uninjured knees . Study Design Prospect i ve , in vivo laboratory study . Methods Kinematics of anterior cruciate ligament-reconstructed and contralateral ( uninjured ) knees were evaluated for 6 subjects during downhill running 4 to 12 months after anterior cruciate ligament reconstruction , using a 250 frame/s stereoradiographic system .  Anatomical reference axes were determined from computed tomography scans .  Kinematic differences between the uninjured and reconstructed limbs were evaluated with a repeated- measures analysis of variance . Results Anterior tibial translation was similar for the reconstructed and uninjured limbs . However , reconstructed knees were more externally rotated on average by 3.8 ± 2.3 ° across all subjects and time points ( P = .0011 ) . Reconstructed knees were also more adducted , by an average of 2.8 ± 1.6 ° ( P = .0091 ) . Although differences were small , they were consistent in all subjects . Conclusions Anterior cruciate ligament reconstruction failed to restore normal rotational knee kinematics during dynamic loading . Clinical Relevance Although further study is required , these abnormal motions may contribute to long-term joint degeneration associated with anterior cruciate ligament injury/reconstruction STUDY DESIGN Prospect i ve descriptive study . OBJECTIVE To determine the extent of bone mineral density ( BMD ) interlimb differences at several hip locations in the involved versus noninvolved lower extremity following anterior cruciate ligament ( ACL ) surgery .  BACKGROUND Disuse following ACL reconstruction can be extensive . This disuse not only affects the soft tissue , but may also affect the skeletal structure . The extent of this disuse specific to the proximal femur has not been previously determined . METHODS AND MEASURES  BMD  was assessed in 15 subjects , 17 to 51 years old , who were between 6 and 32 months post-ACL reconstruction surgery .  Bone mineral content ( BMC ) and BMD of the femoral neck , trochanteric region , intertrochanteric region , and entire hip were measured as a primary emphasis of this study . BMD and BMC of the entire lower extremities were also measured bilaterally . RESULTS BMD was significantly less in the involved lower extremity compared to noninvolved lower extremity at several hip sites : 6.6 % less ( P<.001 ) for the trochanteric region , 4.0 % less ( P<.001 ) for the entire hip , and 3.4 % less ( P = .004 ) for the intertrochanteric region . No significant differences were noted comparing the entire lower extremities for either BMD ( 0.9 % , P = .48 ) or BMC ( 3.7 % , P= .09 ) . CONCLUSION BMD differences at the hip are significant in patient 's postoperative ACL reconstruction , especially in the trochanteric region 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 Thirty-seven patients who had undergone anterior cruciate ligament reconstruction were tested in a gait analysis laboratory at 2 and 6 weeks after surgery . Between test sessions , patients were r and omly assigned to a course of either closed or open kinetic chain resistance exercises ( 3 sessions per week for 4 weeks ) . Gait analysis consisted of bilateral calculations of knee joint angle , moment , and power during level walking , stair ascent , and stair descent . An analysis of variance on the effects of training group and test session indicated that the only variable to be significantly affected by the type of exercise program was the amount of knee flexion at the beginning of step-up ( P<0.05 ) . All other measures of knee angle , moment , and power ( 16 total variables ) showed no significant difference between the exercise groups . All variables measured on the injured side showed significant improvement from test 1 to test 2 ( P<0.05 ) , but the injured leg remained functionally deficient when compared with the uninjured leg . These data suggest that there are no clinical ly significant differences in the functional improvement result ing from the choice of open or closed kinetic chain exercises in the early period after this surgery 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 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 establish the gait adaptations of patients with anterior cruciate ligament deficiency during stair ascent .  DESIGN Joint kinematics and kinetics during stair climbing were measured in both knees of normal subjects and unilateral anterior cruciate ligament deficient patients . BACKGROUND As there is limited research pertaining to activities other than level walking , the purpose of the current study was to eluci date the gait of patients with anterior cruciate ligament deficiency during stair climbing  to determine the effects of the deficiency on knee joint motion and moments as compared with normal knee function . METHODS A motion analysis system was used to measure and  calculate kinematic and kinetic data  for six normal subjects and nine patients with unilateral anterior cruciate ligament deficiency during stair ascent on a specially constructed staircase .  Left and right leg data were analysed to reveal between-limb differences for each subject . RESULTS Patients with anterior cruciate ligament deficiency displayed a significant ( P < 0.05 ) reduction of up to 50 % in peak knee flexion moments in their involved knee . In the present study where a step height of 15.5 cm was used , peak flexion moments in all subjects ' limbs occurred at knee flexion angles of about 40 degrees during single limb support . CONCLUSION The current study showed that most patients with an anterior cruciate deficient knee adapted their gait during stair ascent . RELEVANCE As stair climbing is a common activity , its effect on gait is relevant to better underst and appropriate treatment and management strategies of patients with anterior cruciate ligament deficient knees Background Athletes who return to sport participation after anterior cruciate ligament reconstruction ( ACLR )  have a higher risk of a second anterior cruciate ligament injury ( either reinjury or contralateral injury ) compared with non — anterior cruciate ligament— injured athletes . Hypotheses Prospect i ve measures of neuromuscular control and postural stability after ACLR will predict relative increased risk for a second anterior cruciate ligament injury . Study Design Cohort study ( prognosis ) ; Level of evidence , 2 . Methods Fifty-six athletes underwent a prospect i ve biomechanical screening after ACLR using 3-dimensional motion analysis during a drop vertical jump maneuver and postural stability assessment before return to pivoting and cutting sports .  After the initial test session , each subject was followed for 12 months for occurrence of a second anterior cruciate ligament injury . Lower extremity joint kinematics , kinetics , and postural stability were assessed and analyzed . Analysis of variance and logistic regression were used to identify predictors of a second anterior cruciate ligament injury . Results Thirteen athletes suffered a subsequent second anterior cruciate ligament injury . Transverse plane hip kinetics and frontal plane knee kinematics during l and ing , sagittal plane knee moments at l and ing , and deficits in postural stability predicted a second injury in this population ( C statistic = 0.94 ) with excellent sensitivity ( 0.92 ) and specificity ( 0.88 ) . Specific predictive parameters included an increase in total frontal plane ( valgus ) movement , greater asymmetry in internal knee extensor moment 
    Output:
    
Knees with ACLD showed less peak knee flexion compared with that on contralateral sides during stair ascent , with minimal heterogeneity .
External knee flexion moments were lower for ACLR compared with those in controls and contralateral sides during ascent and descent , whereas these moments were decreased for the ACLD compared with controls only during ascent .
Differences for kinematics and kinetics for the ACL-injured knees indicate long-term compensatory and asymmetric movement patterns while ascending and descending stairs .