Comparative study between computer assisted-navigation and conventional technique in minimally invasive surgery total knee arthroplasty, prospective control study. Alignment in total knee arthroplasty. A comparison of computer-assisted surgery with the conventional technique. Comparison between patient-specific instruments and conventional instruments and computer navigation in total knee arthroplasty: a randomized controlled trial Functional outcome after computer-assisted versus conventional total knee arthroplasty: a randomized controlled study On the outcome of computer-assisted total knee replacement. Navigated total knee arthroplasty: a radiological analysis of 42 randomised cases. Comparison of radiographic alignment of imageless computer-assisted surgery vs conventional instrumentation in primary total knee arthroplasty. Computer-assisted gap balancing technique improves outcome in total knee arthroplasty, compared with conventional measured resection technique Computer navigation results in less severe flexion contracture following total knee arthroplasty. Limb alignment in computer-assisted minimally-invasive unicompartmental knee replacement. Minimally Invasive Computer-Assisted Total Knee Arthroplasty Compared With Conventional Total Knee Arthroplasty: A Prospective 9-Year Follow-Up. In-vivo alignment comparing patient specific instrumentation with both conventional and computer assisted surgery (CAS) instrumentation in total knee arthroplasty. Computer-assisted total knee arthroplasty using mini midvastus or medial parapatellar approach technique The radiological outcomes of patient-specific instrumentation versus conventional total knee arthroplasty Navigation Improves Accuracy of Rotational Alignment in Total Knee Arthroplasty Computer-navigated versus conventional total knee arthroplasty a prospective randomized trial. Slight undercorrection following total knee arthroplasty results in superior clinical outcomes in varus knees Clinical outcome using a ligament referencing technique in CAS versus conventional technique Accuracy of manual instrumentation of tibial cutting guide in total knee arthroplasty Five-year follow-up of minimally invasive computer assisted total knee arthroplasty (MICATKA) versus conventional computer assisted total knee arthroplasty (CATKA) - A population matched study. Computer navigation vs conventional total knee arthroplasty: five-year functional results of a prospective randomized trial. Comparison between computer-assisted-navigation and conventional total knee arthroplasties in patients undergoing simultaneous bilateral procedures: a randomized clinical trial. Conventional versus computer-navigated TKA: a prospective randomized study
BACKGROUND Both Minimally Invasive surgery ( MIS ) and Computer-Assisted Surgery ( CAS ) are useful in Total Knee Arthroplasty ( TKA ) . Minimally invasive total knee arthroplasty was associated with decreased blood loss , shorter hospital stays , and increased range of motion .  Computer-assisted surgery in total knee arthroplasty was developed to improve the positioning of implants during surgery . OBJECTIVE To evaluate radiographic results relative to component position and limb alignment when using a navigation system compared with conventional technique in MIS-TKA . MATERIAL AND METHOD A prospect i ve control study was performed in 180 patients who underwent total knee arthroplasty by one surgeon . All patients were r and omly divided into two groups , Conventional and Navigation TKA .  Intra- , post-operative data , and postoperative limb alignment were recorded for comparison in both groups . RESULTS The postoperative mechanical axis was within 3 degrees of neutral mechanical alignment in 94 % of the navigation group and 87 % in conventional group ( p = 0.13 ) . Registration time of navigation group is 13.58 minutes . No statistical significant difference was found in tourniquet time and postoperative blood loss in both groups . CONCLUSION The use of navigation in total knee arthroplasty increases accuracy in limb and implants alignment , and does not increase complications and surgical times Restoration of neutral alignment of the leg is an important factor affecting the long-term results of total knee arthroplasty ( TKA ) . Recent developments in computer-assisted surgery have focused on systems for improving TKA . In a prospect i ve study two groups of 80 patients undergoing TKA had operations using either a computer-assisted navigation system or a conventional technique .  Alignment of the leg and the orientation of components were determined on post-operative long-leg coronal and lateral films . The mechanical axis of the leg was significantly better in the computer-assisted group ( 96 % , within + /- 3 degrees varus/valgus ) compared with the conventional group ( 78 % , within + /- 3 degrees varus/valgus ) . The coronal alignment of the femoral component was also more accurate in the computer-assisted group . Computer-assisted TKA gives a better correction of alignment of the leg and orientation of the components compared with the conventional technique . Potential benefits in the long-term outcome and functional improvement require further investigation Abstract Purpose The current study investigated the accuracy in achieving proper lower limb alignment and individual component positions after total knee arthroplasty ( TKA ) with 3 different instrumentation techniques . It was hypothesized that patient-specific instruments ( PSI ) would achieve more accurate lower limb alignment and component positions compared to conventional instruments ( CON ) . Methods Ninety knees in 81 patients were r and omized in 1:1:1 ratio into  CON , computer navigation ( NAV )  and PSI  groups to receive TKA . The surgical routines were st and ardized . The lower limb mechanical axis and individual component positions were assessed on st and ard radiographs . Tourniquet time , operation time and patients ’ functional scores were documented . Results Conventional instruments and PSI were more likely to result in an excessively flexed femoral component ( p = 0.001 ) compared to NAV . Number of outliers in postoperative lower limb alignment , and other components positions in the coronal and sagittal plane showed no statistically significant difference . The mean tourniquet time and operation time was significantly shorter in CON and PSI groups than NAV group ( p < 0.001 ) . Four early complications occurred in the PSI group ( p = 0.015 ) . At 3-month follow-up , there was no difference in terms of the knee range of motion and patients ’ function among the 3 groups . Conclusion No significant radiological and clinical benefit could be demonstrated in using PSI over CON or NAV in TKA . Routine use of PSI is not recommended because of the extra cost and waiting time . Level of evidence Despite the frequent use of computer-assisted total knee arthroplasty ( TKA ) and better radiological results for coronal alignment reported in many studies , there is still no evidence of improved clinical outcomes when compared to conventional TKA . We compared alignment after navigated TKA and conventional TKA in 80 r and omized patients . Seventy three patients were available for physical and radiological examination at 20 month after surgery . Both groups showed similar Knee Society Score results , with medians of 89 points ( navigated 49–95 points , conventional 48–95 points , n.s . ) in the Knee Score and 70 points ( navigated 45–100 points , conventional 40–100 points , n.s . ) in the Function Score . The median improvement in the Knee Society Knee Score was 45 points ( −3 to 88 points ) in the navigated group and 35 points ( −13 to 62 points ) in the conventional group ( P = 0.03 ) , and the Knee Society Function Score improvement was 15 points ( −10 to 50 points ) in the navigated group versus 10 points ( −10 to 50 points ) in the conventional group ( n.s . ) . The current health state at follow-up using the EuroQuol question naire was similar in both groups , with medians of 67 points in the navigated group and 65 points in the conventional group . This investigation did show slightly greater functional improvement at short-term follow-up in the navigated TKA group . Longer follow-up will be required to assess the possible benefit of computer-assisted navigation A number of studies have reported a significant improvement of the postoperative alignment , when computer-navigated total knee arthroplasty ( TKA )  was compared with conventional techniques . However , no studies are available on the functional and patient-relevant outcomes after computer-assisted knee replacement . In a prospect i ve , r and omized trial comparing 27 computer-assisted TKAs with 25 conventional implantations  , the Knee Society Score was used to assess functional status , and the WOMAC question naire was used to record the disease-specific , patient-relevant outcome . At a twelve-month follow-up no significant difference was detected between the two patient groups in either the scores or the number of complications and range of postoperative knee flexion . The results are in agreement with those reported in other studies on the effect of conventional TKA . With the patient group of this size it can be concluded that computer-navigated TKA gives short-term resuits comparable with those achieved by conventional methods of implantation The purpose of this study was to evaluate the use of a  navigation device  in a cohort of 42 total knee arthroplasties ( TKA ) . The patients were r and omised into two groups . Total knee arthroplasties performed using the conventional technique formed the control group ( 21 knees ) ; the experimental group included 21 knees performed with the aid of a computed navigation system .  Postoperative mean values for the various measurements showed no significant difference in component alignment . However , the range of individual measurements for coronal and sagittal plane positioning was smaller in the navigated group , in which there were no outliers . Rotational alignment was not different between the two groups . This confirms the advantages and limitations of navigated TKA presented in larger studies A total of 208 patients were enrolled in a multicenter , prospect i ve r and omized , institutional review board-approved study that compared preoperative surgical plan to postoperative 2-dimensional radiographic alignment measured by a blinded review er for  primary total knee arthroplasty ( TKA ) implanted using computer-assisted surgery ( CAS ) compared with conventional TKA instrumentation . The results demonstrated a statistically significant improvement in the coronal tibial component alignment ( P < .03 ) and failed to demonstrate a statistically significant improvement in the mechanical axis , femoral coronal/sagittal , and tibial sagittal alignment . Knee Society Score knee and function scores and 6-minute walk test were equivalent between the 2 treatment groups at all postoperative intervals . There was a statistically significant increase in the skin-skin time ( P < .0001 ) and the time until first bone cut ( P < .0001 ) for the CAS knees compared with those implanted with conventional instrumentation . The use of CAS in this r and omized clinical trial conducted at high-volume centers did not offer a clinical ly meaningful improvement in postoperative alignment , clinical , functional , or safety outcomes compared with conventional TKA Purpose The objective of this prospect i ve study was to compare the functional outcome of conventional measured resection technique and computer-assisted gap balancing technique in TKA . Methods 140 patients were r and omized into two groups . The conventional measured resection technique without computer navigation was performed in Group 1 and the computer-assisted gap balancing technique in Group 2 . Range of motion , clinical laxity assessment with KT-1000 arthrometer , postoperative radiological films and various functional knee scores were documented at 6 months and 2 years . Results At 2 years , there were significantly more patients ( five patients , 7 % ) in the Group 1 with flexion contractures of more than 5 ° ( P = 0.05 ) . There were significantly more outliers in the Group 1 ( eight patients , 11 % ) , who demonstrated anterior tibial translation > 5 mm , than Group 2 ( two patients , 3 % ) ( P = 0.041 ) . The total excursion at 20 ° was significantly higher in Group 1 at 6 months ( P = 0.012 ) and after 2 years ( P = 0.031 ) . Group 2 was able to demonstrate significantly better limb alignment with fewer outliers ( more than 3 ° varus/valgus ) than Group 1 . At 6-month follow-up , Group 2 demonstrated better outcomes in Function Score ( P = 0.040 ) and Total Oxford Score ( P = 0.031 ) . At 2-year review , Group 2 had better outcome in the Total Oxford Score ( 0.030 ) . Conclusion Computer-assisted gap balancing technique was able to achieve more precise soft tissue balance and restoration of limb alignment with better knee scores as compared to the conventional measured resection technique in total knee arthroplasty . Level of evidence We compared  postoperative flexion contracture  in  navigated total knee arthroplasty ( TKA ) versus  conventional TKA .  Two groups ( Group 1 :  conventional  , Group 2 : navigated ) of 235 consecutive patients matched for age and gender were retrospectively compared . Range of motion , mechanical axes , Knee Society Scores , Oxford Knee Scores and Short Form-36 ® ( SF-36 ) scores were collected prospect ively and compared preoperatively and at 2years following TKA . At 2years , patients who underwent navigated TKA averaged significantly lesser flexion contracture of 1 degree compared to 6 degrees in patients who underwent conventional TKA . There were a significantly larger proportion of outliers in the conventional group . Computer navigation results in less severe flexion contracture and less frequent flexion contracture of more than 5 degrees as compared to conventional techniques Twenty patients underwent simultaneous bilateral medial unicompartmental knee arthroplasty . Pre-operative hip-knee-ankle alignment and valgus stress radiographs were used to plan the desired post-operative alignment of the limb in accordance with established principles for unicompartmental arthroplasty . In each patient the planned alignment was the same for both knees . Overall , the mean planned post-operative alignment was to 2.3 degrees of varus ( 0 degrees to 5 degrees ) . The side and starting order of surgery were r and omised , using conventional instrumentation for one knee and computer-assisted surgery for the opposite side . The mean variation between the pre-operative plan and the achieved correction in the navigated and the non-navigated limb was 0.9 degrees ( sd 1.1 ; 0 degrees to 4 degrees ) and 2.8 degrees ( sd 1.4 ; 1 degrees to 7 degrees ) , respectively . Using the Wilcoxon signed rank test , we found the difference in variation statistically significant ( p < 0.001 ) . Assessment of lower limb alignment in the non-navigated group revealed that 12 ( 60 % ) were within + /- 2 degrees of the pre-operative plan , compared to 17 ( 87 % ) of the navigated cases . Computer-assisted surgery significantly improves the post-operative alignment of medial unicompartmental knee arthroplasty compared to conventional techniques in patients undergoing bilateral simultaneous arthroplasty . Improved alignment after arthroplasty is associated with better function and increased longevity BACKGROUND Studies on minimally invasive computer-assisted total knee arthroplasty ( MICA-TKA ) have shown promising results , but are limited by short follow-up . The purpose of this study was to compare the midterm radiographic features and functional outcomes between patients who underwent MICA-TKA and conventional TKA .  METHODS A total of 108 patients who were r and omized to undergo MICA-TKA or conventional TKA during 2004 and 2005 were contacted for a prospect i ve follow-up review . Patients who were lost to contact , have passed away , or declined to participate in the study were excluded . Objective functional measurements and radiographs were obtained for assessment . RESULTS By the time of this study , 2 patients from the conventional group had undergone revision TKA , one due to infection and one due to aseptic loosening . A total of 67 patients ( 62.04 % ) were followed up for an average period of 9.07 years ( 8.51 - 9.61 years ) . At follow-up , functional scores were comparable between the 2 groups . No significant intergroup differences were found in mechanical knee alignment and component placement angle in the coronal views . No statistical or clinical significance were noticed in radiographic signs of component loosening . CONCLUSIONS MICA-TKA provided similar clinical , functional , and radiographic outcomes compared with conventional TKA after an average of 9-year follow-up . This technique can be used to exploit its short-term advantages without compromising midterm outcomes Patient specific instrumentation ( PSI ) was developed to increase total knee arthroplasty ( TKA ) accuracy and efficiency . The study purpose was to compare immediate post-operative mechanical alignment , achieved using PSI , with conventional and computer assisted surgery ( CAS ) instruments in high volume TKA practice s. This prospect i ve , multicenter , non-r and omized study accrued 66 TKA patients using PSI .  A computed tomography ( CT ) based algorithm was used to develop the surgical plan . Sixty-two percent were females , 99 % were diagnosed with osteoarthritis , average age at surgery was 66 years , and 33 was the average body mass index . A historical control group was utilized that underwent TKA using conventional instruments ( n=86 ) or CAS ( n=81 ) , by the same set of surgeons . Postoperative mechanical alignment was comparable across the groups . Operative time mean and variance were significant Background Despite the growing evidence in the literature there is still a lack of consensus regarding the use of minimally invasive surgical technique ( MIS ) in total knee arthroplasty ( TKA ) . Methods A prospect i ve , r and omized , international multicentre trial including 69 patients was performed to compare computer-assisted TKA ( CAS-TKA ) using either mini-midvastus ( MIS group ) or st and ard medial parapatellar approach ( conventional group ) .  Patients from 3 centers ( Maastricht , Zwickau , Adelaide ) with end-stage osteoarthritis of the knee were r and omized to either an MIS group with dedicated instrumentation or a conventional group to receive cruciate retaining CAS-TKA without patella resurfacing .  The primary outcome was to compare post operative pain and range of motion ( ROM ) . The secondary outcome was to measure the duration of surgery , blood loss , chair rise test , quadriceps strength , anterior knee pain , Knee Society Score (KSS),WOMAC scores , mechanical leg axis and component alignment . Results Patients in the MIS group ( 3.97 ± 2.16 ) had significant more pain at 2 weeks than patients in the conventional group ( 2.77 ± 1.43 ) p = 0.003 . There was no significant difference in any of the other primary outcome parameters . Surgery time was significantly longer ( p < 0.001 ) and there were significantly higher blood loss ( p = 0.002 ) in the MIS group as compared to the conventional group . The difference of the mean mechanical leg alignment between the groups was not statistically significant ( –0.43 ° ( 95 % CI –1.50 – 0.64 ) ; p = 0.43).There was no significant difference of component alignment between the two surgical groups with respect to flexion/extension ( p = 0.269 ) , varus/valgus ( p = 0.653 ) or rotational alignment ( p = 0.485 ) of the femur component and varus valgus alignment ( p = 0.778 ) or posterior slope ( p = 0.164 ) of the tibial component . Conclusion There was no advantage of the MIS approach compared to a conventional approach CAS-TKA in any of the primary outcome measurements assessed , however the MIS approach was associated with longer surgical time and greater blood loss . MIS-TKA in combination with computer navigation is safe in terms of implant positioning . Trial registration number Clinical Trials.gov NCT02625311 8 December Abstract Purpose The aim of this study was to investigate the post-operative radiological outcomes of patient-specific instrumentation ( PSI ) surgery versus conventional total knee arthroplasty ( TKA ) . Methods Sixty patients scheduled for a primary TKA were prospect ively divided into PSI or conventional technique . Coronal and sagittal radiographic long limb films were taken post-operatively . The accepted values for normal alignment were 180 ° ± 3 ° for hip-knee-ankle angle ; 90 ° ± 3 ° for coronal femoral component angle or coronal tibia component angle ; 0 ° to 3 ° flexion for sagittal femoral component angle and 0 ° to 7 ° posterior slope for sagittal tibia component angle . Results For hip-knee-ankle angle , there were 21 % more outliers in the PSI group compared to the conventional group ( p = 0.045 ) . Most of these outliers had valgus deformity in the PSI group and varus deformity in the conventional group ( p = 0.045 ) . For implant placement , there was no difference in the proportion of outliers between the two groups . There was also no difference in the duration of surgery . Conclusions This study showed that PSI surgery is associated with a larger proportion of outliers for lower limb alignment . PSI surgery as an alternative to conventional TKA is not advisable . Level of evidence II Successful total knee arthroplasty is dependent on the correct alignment of implanted prostheses . Major clinical problems can be related to poor femoral component positioning , including sagittal plane and rotational malalignment . A prospect i ve r and omized study was design ed to test whether an optical navigation system for total knee arthroplasty achieved greater implantation precision than a nonnavigated technique . The primary variable was rotation of the femoral component in the transverse plane , measured from postoperative radiographs and computed tomography images . Sixty-four patients were included in the study . All patients received the Duracon total knee prosthesis .  The patients were r and omly divided into two groups : Group C patients had conventional total knee arthroplasty without navigation ; Group N patients had total knee arthroplasty using a computer-assisted knee navigation system . Analysis showed that patients in Group N had significantly better rotational alignment and flexion angle of the femoral component than patients in Group C. In addition , superior postoperative alignment of the mechanical axis , posterior tibial slope , and rotational alignment was achieved for patients in Group N. The use of a navigation system provides improved alignment accuracy , and can help to avoid femoral malrotation and errors in axial alignment BACKGROUND The literature lacks studies that confirm whether the improved radiographic alignment that can be achieved with computer-navigated total knee arthroplasty improves patients ’ activities of daily living or the durability of total knee prostheses . The purpose of this study was to determine whether computer-navigated total knee arthroplasty improves the clinical function , alignment , and survivorship of the components . METHODS We prospect ively compared the results of 520 patients with osteoarthritis who underwent computer-navigated total knee arthroplasty for one knee and conventional total knee arthroplasty for the other . The assignment of the knee to navigation or not was done r and omly . There were 452 women ( 904 knees ) and sixty-eight men ( 136 knees ) with a mean age of sixty-eight years ( range , forty-nine to eighty-eight years ) at the time of the index arthroplasty . The mean follow-up period was 10.8 years ( range , ten to twelve years ) . The patients were assessed clinical ly and radiographically with the rating system of the Knee Society and with the Western Ontario and McMaster Universities Osteoarthritis Index ( WOMAC ) score at three months , one year , and annually thereafter . RESULTS Total knee scores , knee function scores , pain scores , WOMAC scores , knee motion , and activity scores did not show statistically significant differences between the two groups preoperatively or at the time of the final follow-up . Alignment and the survivorship of the components were not significantly different between the two groups . The Kaplan-Meier survivorship with revision as the end point at 10.8 years was 98.8 % ( 95 % confidence interval [ CI ] , 0.96 to 1.00 ) in the computernavigated total knee arthroplasty group and 99.2 % ( 95 % CI , 0.96 to 1.00 ) in the conventional total knee arthroplasty group . CONCLUSIONS Our data demonstrated no difference in clinical function or alignment and survivorship of the components between the knees that underwent computer-navigated total knee arthroplasty and those that underwent conventional total knee arthroplasty Purpose Restoration of correct alignment is one of the main objectives of total knee arthroplasty ( TKA ) . However , the influence of residual malalignment on clinical and functional outcomes is currently uncertain . This study was therefore undertaken to ascertain its influence in patients undergoing TKA for varus osteoarthritis of the knee . Methods A cohort of 132 consecutive patients ( 143 knees ) with pre-operative varus alignment was evaluated with a mean follow-up period of 7.2 years . Based upon the post-operative alignment , patients were stratified into three groups : neutral , mild varus , and severe varus . These groups were compared with respect to clinical and functional outcomes . Results All patients had post-operative improvements in Knee Society Score ( KSS ) . Knees that were left in mild varus scored significantly better for the KSS and the Western Ontario and McMaster Universities Arthritis Index , compared with knees that were corrected to neutral and knees that were left in severe varus exceeding 6 ° . No revisions occurred in any of the groups at midterm follow-up . Conclusion The results of this study contradict the conventional assumption that correction to neutral mechanical alignment leads to the best outcome following TKA . Patients with pre-operative varus had better clinical and functional outcome scores if the alignment was left in mild varus , as compared with patients with an alignment correction to neutral . Level of evidence Therapeutic study , Level III Purpose Computer-assisted surgery ( CAS ) for total knee arthroplasty ( TKA ) has become increasingly common over the last decade . There are several reports including meta-analyses that show improved alignment , but the clinical results do not differ . Most of these studies have used a bone referencing technique to size and position the prosthesis . The question arises whether CAS has a more pronounced effect on strict ligamentous referencing TKAs . Methods We performed a prospect i ve cohort study comparing clinical outcome of navigated TKA ( 43 patients ) with that of conventional TKA ( 122 patients ) . Patients were assessed preoperatively , and 2 and 12 months postoperatively by an independent study nurse using vali date d patient-reported outcome tools as well as clinical examination . Results At 2 months , there was no difference between the two groups . However , after 12 months , CAS was associated with significantly less pain and stiffness , both at rest and during activities of daily living , as well as greater overall patient satisfaction . Conclusion The present study demonstrated that computer-navigated TKA significantly improves patient outcome scores such as WOMAC score ( P = 0.002 ) and Knee Society score ( P = 0.040 ) 1 year after surgery in using a ligament referencing technique . Furthermore , 91 % were extremely or very satisfied in the CAS TKA group versus 70 % after conventional TKA ( P = 0.007 ) Purpose The aim of this study was to evaluate the accuracy of conventional instrumentation for tibial resection in total knee arthroplasty ( TKA ) as assessed by a computer-based navigation system during each phase of the surgical procedure . The hypothesis is that conventional instrumentation fails to achieve optimal accuracy in final implant positioning , thus leading to surgical errors . Methods Forty primary TKAs were performed .  The resection guide was placed using an extramedullary guide . Accurate guide positioning was assessed by the navigation system prior to the osteotomy . The alignment measurement was repeated after resection and after component implantation in order to quantify the deviation caused by the manual positioning of the prosthetic components . A deviation ≥2 ° was considered unsatisfactory . Results In the frontal plane , unsatisfactory results observed were as follows : 15 % with reference to manual positioning of the resection guide and 10 % with reference to definition of the resection plane with a tendency towards varus malalignment . In the sagittal plane , unsatisfactory results were as follows : 45 % with reference to manual positioning of the resection guide and 40 % with reference to definition of the resection plane with a trend of decreased tibial slope angle . The deviation between bone resection and subsequent implant placement was ≥2 ° in none of the cases . Conclusions The study confirms the hypothesis that conventional instrumentation fails to achieve optimal accuracy in the positioning of the tibial component . During each phase of the surgical procedure , a tendency towards varus malalignment and a decreased tibial slope angle were observed . Levels of evidence II BACKGROUND Minimally invasive surgery ( MIS ) has perceived advantages in the early post-operative stage such as reduced blood loss , decreased pain , earlier return to function and earlier discharge . The aim of our study was to confirm that longer term clinical outcome of TKA is not compromised when MIS is combined with computer assisted surgery . METHODS Eighty patients matched for age , gender , pre-operative Knee Society Score ( KSS ) and mechanical axis were prospect ively studied . Forty patients underwent minimally invasive computer assisted total knee arthroplasty ( MICATKA ) and 40 patients underwent conventional computer assisted TKA ( CATKA ) .  Functional scores were determined at 6 weeks , 6 , 12 , 18 , and 24 months and 5 years post-surgery . Long-leg alignment views were obtained 3 months post-operatively . RESULTS KSSs in the short term were significantly better in the MICATKA group than in the CATKA group ( p<000.1 ) . Tourniquet-time was 58 min in the MICTKA group and 60 min in the CATKA group ( p=0.3 ) . Straight leg raise was achieved by day one in 93 % of the MICATKA group compared to 30 % of the CATKA group ( p<0.001 ) . Length of stay for the MICATKA group has a mean of 3.25 days and a mean of 6 days for the CATKA group ( p<0.001 ) . KSSs up to 2-years were significantly better in the MICTKA group ( p<0.001 ) . At 5-years there was no significant difference in KSSs ( p=0.46 ) in the MICATKA and CATKA groups . CONCLUSION We confirm that the use of navigation in minimally invasive TKA permits a number of early post-operative advantages and that longer-term functional outcome is not compromised with its usage . LEVEL OF EVIDENCE Level II Seventy-one patients were r and omly allocated to undergo either computer-navigated or conventional arthroplasty . A statistically significant improvement in alignment was seen in the computer-navigated cohort . Five-year functional outcome was assessed using the Knee Society , Short Form-36 , Western Ontario and McMaster Universities Osteoarthritis Index , and a patient satisfaction score . At 5 years , 46 patients were available for assessment ( 24 navigated and 22 conventional knees ) . No patients had undergone revision . No statistically significant difference was seen in any component of any measure of outcome between navigated and conventional cohorts . Longitudinal data showed function to be well maintained with no difference in functional score between 2 and 5 years in either cohort . Despite achieving better alignment , 5 years postoperatively , the functional outcome with computer-navigated knee arthroplasty appears to be no different to that implanted using a conventional jig-based technique BACKGROUND Total knee arthroplasty has been increasingly used for young and active patients , and prosthesis durability is important in these patients . The accuracy of implant placement has been one of the major factors that determine the long-term survival of the prosthesis . The purpose of this study was to compare the accuracy of prosthetic alignment between computer-assisted-navigation and conventional total knee arthroplasties . METHODS From March 2007 to June 2008 , thirty-two patients with bilateral knee osteoarthritis underwent simultaneous bilateral total knee arthroplasty with the same type of implant in each knee .  The subjects included seven men and twenty-five women , with an average age of sixty-three years . For each patient , the bilateral total knee arthroplasty was performed with computer-assisted navigation in one knee and a conventional technique in the other . The operative technique and the order of the surgical procedures were r and omized . The patients and surgeons conducting the follow-up study and performing the imaging measurements were blinded to the type of surgical procedure . RESULTS There was a significant difference between the two groups with regard to the alignment of the knee prosthesis in the coronal and sagittal planes . Nine knee implants ( 28 % ) in the conventional group , compared with no knee implants in the computer-navigation group , deviated > 3 ° from the mechanical axis in the coronal plane . The coefficient variation of data in the conventional group was three times greater than that in the computer-navigation group . There was no significant difference in the rotational angle of the femoral component between the two groups . The Hospital for Special Surgery ( HSS ) scores at six months postoperatively were substantially increased compared with the preoperative scores in both groups . CONCLUSIONS Computer-assisted navigation consistently provided coronal plane alignment within 3 ° of the mechanical axis , which was significantly better than the alignment obtained with conventional total knee arthroplasty Purpose The purpose of this study was to assess the midterm results of total knee arthroplasty ( TKA ) implanted with  a specific computer navigation system in a group of patients ( NAV ) and to assess the same prosthesis implanted with the conventional technique in another group ( CON ) ; we hypothesized that computer navigation surgery would improve implant alignment , functional scores and survival of the implant compared to the conventional technique . Methods From 2008 to 2009 , 225 patients were enrolled in the study and r and omly assigned in CON and NAV groups ; 240 consecutive mobile-bearing ultra-congruent score ( Amplitude , Valence , France ) TKAs were performed by a single surgeon , 117 using the conventional method and 123 using the computer-navigated approach .  Clinical outcome assessment was based on the Knee Society Score ( KSS ) , the Hospital for Special Surgery Knee Score and the Western Ontario Mac Master University Index score . Component survival was calculated by Kaplan – Meier analysis . Results Median follow-up was 6.4 years ( range 6–7 years ) . Two patients were lost to follow-up . No differences were seen between the two groups in age , sex , BMI and side of implantation . Three patients of CON group referred feelings of instability during walking , but clinical tests were all negative . NAV group showed statistical significant better KSS Score and wider ROM and fewer outliers from neutral mechanical axis , lateral distal femoral angle , medial proximal tibial angle and tibial slope in post-operative radiographic assessment . There was one case of early post-operative superficial infection ( caused by Staph . Aureus ) successfully treated with antibiotics . No mechanical loosening , mobile-bearing dislocation or patellofemoral complication was seen . At 7 years of follow-up , component survival in relation to the risk of aseptic loosening or other complications was 100 % . There were no implant revisions . Conclusion This study demonstrates superior accuracy in implant positioning and statistical significant better functional outcomes of computer-navigated TKA . Computer navigation for TKAs should be used routinely in primary implants . Level of evidence II
The majority of adverse events associated with CNTKA were minor and comparable with those seen with conventional TKA .
Clinical outcomes were comparable between the two techniques , with longer-term follow-up suggesting that CNTKA provided no benefit over conventional TKA in terms of sustained functional improvements .
At present , it is unclear whether the significant improvements shown in radiological outcomes after CNTKA translate to measurable clinical benefits .
BACKGROUND Conventional total knee arthroplasty ( TKA ) and the more recently available computer-navigated total knee arthroplasty ( CNTKA ) use alternative methods to achieve correct limb alignment .
This systematic review was undertaken to assess the safety and effectiveness of CNTKA compared with conventional TKA .