***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 Optimal alignment of the prosthesis in total knee arthroplasty results in improved patient outcomes . The goal of this study was to determine the most accurate technique for component alignment in total knee arthroplasty by comparing computer-assisted surgery with two conventional techniques involving use of an intramedullary guide for the femur and either an intramedullary or an extramedullary guide for the tibia . METHODS One hundred and seven patients were r and omized prior to surgery to one of three arms :  computer-assisted surgery for both the femur and the tibia ( the computer-assisted surgery group ) , intramedullary guides for both the femur and the tibia ( the intramedullary guide group ) , and an intramedullary guide for the femur and an extramedullary guide for the tibia ( the extramedullary guide group ) . Measurements of alignment on hip-to-ankle radiographs and computed tomography ( CT ) scans made three months after surgery were evaluated . The operative times and complications were compared among the three groups . RESULTS The coronal tibiofemoral angle demonstrated , on average , less malalignment in the computer-assisted surgery group ( 1.91 ° ) than in the extramedullary ( 3.22 ° ) and intramedullary ( 2.59 ° ) groups ( p = 0.007 ) . The coronal tibiofemoral angle was > 3 ° of varus or valgus deviation in 19 % ( seven ) of the thirty-six patients treated with computer-assisted surgery compared with 38 % ( thirteen ) of the thirty-four in the extramedullary guide group and 36 % ( thirteen ) of the thirty-six in the intramedullary guide group ( p = 0.022 ) . The increase in accuracy with computer-assisted surgery came at a cost of increased operative time . The operative time for the computer-assisted surgery group averaged 107 minutes compared with eighty-three and eighty minutes , respectively , for the surgery with the extramedullary and intramedullary guides ( p < 0.0001 ) . There was no significant difference in any of the outcomes between the intramedullary and extramedullary guide groups . CONCLUSIONS This study provides evidence that the implant alignment with computer-assisted total knee arthroplasty , as measured with radiography and computed tomography , is significantly improved compared with that associated with conventional surgery with intramedullary or extramedullary guides . This finding adds to the body of evidence showing an improved radiographic outcome with computer-assisted surgery compared with that following conventional total knee arthroplasty Background The Knee injury and Osteoarthritis Outcome Score ( KOOS ) is an extension of the Western Ontario and McMaster Universities Osteoarthrtis Index ( WOMAC ) , the most commonly used outcome instrument for assessment of patient-relevant treatment effects in osteoarthritis . KOOS was developed for younger and /or more active patients with knee injury and knee osteoarthritis and has in previous studies on these groups been the more responsive instrument compared to the WOMAC . Some patients eligible for total knee replacement have expectations of more dem and ing physical functions than required for daily living . This encouraged us to study the use of the Knee injury and Osteoarthritis Outcome Score ( KOOS ) to assess the outcome of total knee replacement . Methods We studied the test-retest reliability , validity and responsiveness of the Swedish version LK 1.0 of the KOOS when used to prospect ively evaluate the outcome of 105 patients ( mean age 71.3 , 66 women ) after total knee replacement .  The follow-up rates at 6 and 12 months were 92 % and 86 % , respectively . Results The intraclass correlation coefficients were over 0.75 for all subscales indicating sufficient test-retest reliability . Bl and -Altman plots confirmed this finding . Over 90 % of the patients regarded improvement in the subscales Pain , Symptoms , Activities of Daily Living , and knee-related Quality of Life to be extremely or very important when deciding to have their knee operated on indicating good content validity . The correlations found in comparison to the SF-36 indicated the KOOS measured expected constructs . The most responsive subscale was knee-related Quality of Life . The effect sizes of the five KOOS subscales at 12 months ranged from 1.08 to 3.54 and for the WOMAC from 1.65 to 2.56 . Conclusion The Knee injury and Osteoarthritis Outcome Score ( KOOS ) is a valid , reliable , and responsive outcome measure in total joint replacement . In comparison to the WOMAC , the KOOS improved validity and may be at least as responsive as the WOMAC To compare the alignment after computer-navigated total knee arthroplasty , 52 patients were r and omly allocated to 2 groups . Twenty-seven patients received a total knee arthroplasty with the aid of a kinematic computer-navigation system , and 25 patients received a total knee arthroplasty with the conventional method . Both groups were well balanced concerning demographic data and preoperative scores . At 3-month follow-up , the mechanical alignment of the leg reached the desired straight axis in more cases with the computer-navigated implantation . This difference was statistically significant . The femoral and tibial mechanical anteroposterior axis and the femoral and tibial sagittal tilt ( slope ) measured on sagittal x-rays were not significantly improved in this patient group Purpose This study aim ed to verify if the navigation system used in  high tibial osteotomy ( HTO ) adds precision to the procedure regarding mechanical axis correction and prevention of tibial slope increases . Methods In this historically controlled study , patients with medial osteoarthrosis and genuvarum underwent HTO between 2004 and 2012 ; the first 20 were operated with the conventional technique , using pre-planning correction by the Dugdale method and 18 further patients were operated with the navigation system introduced in our hospital . Results The two groups were similar for pre-operative mechanical axis ( mean 8.10 ± 3.14 for the control and 6.60 ± 2.50 for the navigated group ) , pre-operative tibial slope ( mean 8.95 ± 3.47 versus 8.17 ± 3.11 , respectively ) and Lyshom score ( 40.85 ± 15.46 and 44.83 ± 16.86 ) . After surgery , the control group presented mean mechanical axis of 3.35 ± 3.27 , tibial slope of 13.75 ± 3.75 and Lyshom score of 87.60 ± 11.12 . The navigated group showed a postoperative mechanical axis mean of 3.06 ± 1.70 , tibial slope of 10.11 ± 0.18 and Lyshom score of 91.94 ± 11.61 . Conclusions The navigation system allowed a significantly better control of tibial slope . Patients operated with the navigation system had significantly better Lysholm scores Background Computer-assisted surgery ( CAS ) can act as an intraoperative ruler in high tibial osteotomy ( HTO ) to visualize continuously the leg during surgery . Questions The aim of the study is to evaluate the accuracy of  CAS with respect to preoperative planning and postoperative deviation from the planned leg axis in HTO . In addition , the influence of surgeon experience as well as operation time and perioperative complications are analyzed . Methods A prospect i ve multicenter study case series with follow-up at 6 weeks was performed in six centers .  Medial open-wedge HTO with Tomofix ® was done using computer assisted navigation technique with the Brainlab VV Osteotomy 1.0 module . Results Fifty-one patients with medial gonarthritis were treated with navigated HTO . The follow-up rate was 98 % . The majority of HTO – CAS patients fell within the tolerated limit of ±3 ° for leg axis deviation , however , seven patients were reported with deviations outside of this range : three patients had deviations of > 3 ° –4.5 ° and four patients > 4.5 ° , respectively . Eight intraoperative complications were documented , partially result ing from technical problems associated with the navigation system . During the 6-week follow-up period , three postoperative complications were experienced , all not associated with navigation technology . Conclusions In about 85 % of cases , a perfect result in terms of deviation of the planned mechanical leg axis could be achieved . Computer assistance in HTO proved to be a helpful tool regarding intraoperative control of leg axis . Level of evidence Level I , High quality prospect i ve study ( all patients were enrolled at the same preoperative planning point with ≥80 % follow-up of enrolled patients ) Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more The authors used computer navigation to perform osteotomies around the knee . The purpose of this article is to present the authors ' surgical technique and to discuss  double-level osteotomy of the femur and tibia to avoid altered joint line obliquity in genu varum deformity . The authors conducted two studies . The first study was a cohort study comparing  navigated high tibial osteotomies and conventional high tibial osteotomies . The results showed a 96 % reproducibility in achieving a mechanical axis of 184 degrees + /- 2 degrees in the navigated group compared to a 71 % reproducibility in achieving a mechanical axis of 184 degrees + /- 2 degrees in the conventional osteotomy group ( P < .0015 ) . The second study was a prospect i ve study on double-level osteotomy and showed that the preoperative goal of 182 degrees + /- 2 degrees has been achieved in 91 % of patients High tibial osteotomy ( HTO ) is an established therapy for the treatment of symptomatic varus malaligned knees . A main reason for disappointing clinical results after HTO is the under- and overcorrection of the mechanical axis due to insufficient intraoperative visualisation . Twenty legs of fresh human cadaver were r and omly assigned to navigated open-wedge HTO ( n=10 ) or conventional HTO using the cable method ( n=10 ) . Regardless of the pre-existing alignment , the aim of all operations was to align the mechanical axis to pass through 80 % of the tibial plateau ( beginning with 0 % at the medial edge of the tibial plateau and ending with 100 % at the lateral edge ) . This overcorrection was chosen to ensure a sufficient amount of correction . Thus , the medial proximal tibia angle ( MPTA ) increased by 9.1±2.9 ° ( range 5.2 ° –12.3 ° ) on the average after navigated HTO and by 8.9±2.9 ° ( range 4.7 ° –12.6 ° ) after conventional HTO . After stabilization with a fixed angle implant , the alignment was measured by CT . After navigated HTO , the mechanical axis passed the tibial plateau through 79.7 % ( range 75.5–85.8 % ) . In contrast , after conventional HTO , the average intersection of the mechanical axis was at 72.1 % ( range 60.4–82.4 % ) ( P=0.020 ) . Additionally , the variability of the mean corrections was significantly lower in the navigated group ( 3.3 % vs. 7.2 % , P=0.012 ) . Total fluoroscopic radiation time was significantly lower in the navigated group ( P=0.038 ) whereas the mean dose area product was not significantly different ( P=0.231 ) . The time of the operative procedure was 23 min shorter after conventional HTO ( P<0.001 ) . Navigation systems provide intraoperative 3-dimensional real time control of the frontal , sagittal , and transverse axis and may increase the accuracy of open-wedge HTO . Future studies have to analyse the clinical effects of navigation on corrective osteotomies High tibial osteotomy ( HTO ) is an established treatment option for isolated medial osteoarthritis in young and active patients . One important factor for success of this procedure is the degree of correction of the weight-bearing line . Computer-assisted navigation systems are believed to improve the precision of axis correction through intraoperative real-time monitoring . This study investigates the precision of correction of the weight-bearing line in open-wedge HTO with and without a navigation system . Nineteen legs of well-preserved human cadaver were r and omly assigned to navigated ( n = 10 ) or conventional ( n = 9 ) HTO . In order to achieve a sufficient amount of correction in all legs the weight-bearing line was aim ed at 80 percent of the width of the tibial plateau . The mean deviation of the weight-bearing line from the desired 80 percent was 1 percent in the navigated and 8.6 percent in the conventional operated legs ( p = 0.002 ) . The weight-bearing line of all navigated but only 5 of the 9 conventional operated legs was within a ± 5 percent tolerance level ( p = 0.33).Navigated open-wedge HTO  achieved better correction of the weight-bearing line than the conventional method in human cadaver legs . Future studies have to prove this advantage in a clinical setting and it 's effect on patient outcome Although opening-wedge high tibial osteotomy ( HTO ) is used to correct deformities , it can simultaneously alter tibial slope in the sagittal plane because of the triangular configuration of the proximal tibia , and this undesired change in tibial slope can influence knee kinematics , stability , and joint contact pressure . Therefore , medial opening-wedge HTO is a technically dem and ing procedure despite the use of 2-dimensional ( 2-D ) navigation . The authors evaluated the posterior tibial slope pre- and postoperatively in patients who underwent navigation-assisted opening-wedge HTO  and compared posterior slope changes for 2-D and 3-dimensional ( 3 
    Output:
    
Postoperative clinical and functional scores were improved by navigated HTO although it is not demonstrated if there is significant improvement compared to conventional HTO .
Radiographic outcomes reported commonly were weight-bearing mechanical axis , coronal plane angle , and posterior tibial slope angle in the sagittal plane .
Studies have shown HTO gives significant correction of mechanical alignment and navigated HTO produces significantly less change in posterior tibial slope postoperatively compared to conventional .
Conclusion Navigation HTO results in improved mechanical axis alignment and demonstrates significantly better control over the tibial slope angle change postoperatively compared to conventional methods ; however , these improvements have not yet been reflected in clinical outcome scores .
Overall the studies report HTO does create significantly improved knee scores and functions compared to patients ’ preoperative ratings regardless of technique .