title: Computer-assisted techniques versus conventional guides for component alignment in total knee arthroplasty: a randomized controlled trial. Comparison between computer-assisted-navigation and conventional total knee arthroplasties in patients undergoing simultaneous bilateral procedures: a randomized clinical trial. On the outcome of computer-assisted total knee replacement. Alignments and Clinical Results in Conventional and Navigated Total Knee Arthroplasty Leg axis after computer-navigated total knee arthroplasty: a prospective randomized trial comparing computer-navigated and manual implantation. Comparison of Early Postoperative Rehabilitation Outcome following Total Knee Arthroplasty Using Different Surgical Approaches and Instrumentation Are systemic emboli reduced in computer-assisted knee surgery?: A prospective, randomised, clinical trial. Embolic phenomena during computer-assisted and conventional total knee replacement. Computer-assisted and conventional total knee replacement: a comparative, prospective, randomised study with radiological and CT evaluation. Comparison of two minimally invasive implantation instrument-sets for total knee arthroplasty Computer-assisted knee arthroplasty versus a conventional jig-based technique. A randomised, prospective trial. Blood loss after total knee replacement: effects of computer-assisted surgery. Blood loss in computer-assisted mobile bearing total knee arthroplasty. A comparison of computer-assisted surgery with a conventional technique Functional outcome after computer-assisted versus conventional total knee arthroplasty: a randomized controlled study Computer-assisted surgery can reduce blood loss after total knee arthroplasty Navigated total knee arthroplasty: a radiological analysis of 42 randomised cases. Computer navigation versus conventional total knee replacement: no difference in functional results at two years. Coronal alignment correlates with outcome after total knee arthroplasty: five-year follow-up of a randomized controlled trial. Computer navigation vs conventional total knee arthroplasty: five-year functional results of a prospective randomized trial. Navigation Improves Accuracy of Rotational Alignment in Total Knee Arthroplasty Randomized control trial comparing radiographic total knee arthroplasty implant placement using computer navigation versus conventional technique. Fat emboli in total knee arthroplasty: a prospective randomized study of computer-assisted navigation vs standard surgical technique. Comparison of radiographic alignment of imageless computer-assisted surgery vs conventional instrumentation in primary total knee arthroplasty. Does accurate anatomical alignment result in better function and quality of life? Comparing conventional and computer-assisted total knee arthroplasty. Randomized trial of computer-assisted knee arthroplasty: impact on clinical and radiographic outcomes.
abstract: 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 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 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 In this prospect i ve , r and omized , controlled study , we compared the performance of conventional and navigated total knee arthroplasties .  Component alignment was measured in 60 patients operated on using navigation and in 60 patients operated on using the conventional technique .  The groups then were divided into a sub population to measure alignments of the distal femoral cuts in the three anatomic planes , the proximal tibial cut in the frontal and sagittal planes , and the result ing lower limb mechanical axis in the frontal plane . Postoperative weightbearing long-view radiographs  were evaluated as were clinical results using three st and ard question naires at 28 months followup . The intraoperative measurements ( mean ± st and ard deviation ) at the resection planes showed navigated surgeries result in more accurate alignments than conventional surgeries for the femur : in the frontal plane , 0.1 ° ± 0.9 ° and 0.7 ° ± 1.6 ° valgus , respectively ; in the sagittal plane , 1.1 ° ± 1.8 ° and 2.8 ° ± 2.0 ° flexion ; and in the transversal plane , 0.1 ° ± 1.2 ° and 0.9 ° ± 1.7 ° internal rotation . The navigated technique also reduced the number of cases with final mechanical axes greater than 3 ° from 20.0 % to 1.7 % . Postoperative radiographs showed better component alignment using navigation , particularly at the femur . However , clinical scoring systems showed this radiographic improvement did not necessarily result in a better clinical outcome at short-term followup . Level of Evidence : Level I , therapeutic study . See the Guidelines for Authors for a complete description of level of evidence 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 . To assess early postoperative rehabilitation outcome following  computer-assisted total knee arthroplasty ( TKA )  or st and ard instrumentation TKA using a medial parapatellar or subvastus approach . Methods . A prospect i ve controlled trial of 70 consecutive patients undergoing TKA with a low contact stress rotating platform prosthesis was conducted . Patients were r and omised to receive surgery with either computer navigation or st and ard instrumentation .  A medial parapatellar or subvastus approach was used according to the surgeons ' preference . Outcome measures included preoperative knee function , intra-operative factors , and postoperative rehabilitation . Results . Duration of surgery was significantly longer when using computer navigation ; however , operating time decreased with greater experience . A higher incidence and duration of early postoperative quadriceps dysfunction was associated with computer-assisted TKA through the medial parapatellar approach than through the subvastus approach or TKA performed with st and ard instrumentation . No patient who received surgery through the subvastus approach had a lag of more than 20 degrees , at 48 hours postoperatively , regardless of the instrumentation used . Conclusion . Computer-assisted TKA through a medial parapatellar approach was associated with delayed recovery of the quadriceps during early postoperative rehabilitation . This was due to the additional quadriceps dissection required to place the femoral tracking array . The subvastus approach is therefore recommended for computer-assisted TKA We undertook a prospect i ve , r and omised study using a non-invasive transcranial Doppler device to evaluate cranial embolisation in  computer-assisted navigated total knee arthroplasty ( n = 14 ) and compared this with a st and ard conventional surgical technique using intramedullary alignment guides ( n = 10 ) . All patients were selected r and omly without the knowledge of the patient , anaesthetists ( before the onset of the procedure ) and ward staff . The operations were performed by a single surgeon at one hospital using a uniform surgical approach , instrumentation , technique and release sequence . The only variable in the two groups of patients was the use of single tracker pins of the imageless navigation system in the tibia and femur of the navigated group and intramedullary femoral and tibial alignment jigs in the non-navigated group . Acetabular Doppler signals were obtained in 14 patients in the computer-assisted group and nine ( 90 % ) in the conventional group , in whom high-intensity signals were detected in seven computer-assisted patients ( 50 % ) and in all of the non-navigated patients . In the computer-assisted group no patient had more than two detectable emboli , with a mean of 0.64 ( SD 0.74 ) . In the non-navigated group the number of emboli ranged from one to 43 and six patients had more than two detectable emboli , with a mean of 10.7 ( sd 13.5 ) . The difference between the two groups was highly significant using the Wilcoxon non-parametric test ( p = 0.0003).Our findings show that computer-assisted total knee arthroplasty , when compared with conventional jig-based surgery , significantly reduces systemic emboli as detected by transcranial Doppler ultrasonography Systemic emboli released during  total knee replacement  have been implicated as a cause of peri-operative morbidity and neurological dysfunction . We undertook a prospect i ve , double-blind , r and omised study to compare the cardiac embolic load sustained during computer-assisted and conventional , intramedullary-aligned , total knee replacement , as measured by transoesophageal echocardiography . There were 26 consecutive procedures performed by a single surgeon at a single hospital . The embolic load was scored using the modified Mayo grading system for echogenic emboli .  Fourteen patients undergoing computer-assisted total knee replacement  had a mean embolic score of 4.89 ( 3 to 7 ) and 12 undergoing conventional total knee replacement  had a mean embolic score of 6.15 ( 4 to 8) on release of the tourniquet . Comparison of the groups using a two-tailed t-test confirmed a highly significant difference ( p = 0.004 ) . This study demonstrates that computer-assisted knee replacement results in the release of significantly fewer systemic emboli than the conventional procedure using intramedullary alignment After obtaining informed consent , 80 patients were r and omised to undergo a navigated or conventional total knee replacement .  All received a cemented , unconstrained , cruciate-retaining implant with a rotating platform . Full-length st and ing and lateral radiographs and CT scans of the hip , knee and ankle joint were carried out five to seven days after operation . No notable differences were found between computer-assisted navigation and conventional implantation techniques as regards the rotational alignment of the femoral or tibial components . Although the deviation from the transepicondylar axis was relatively low , there was a considerable range of deviation for the tibial rotational alignment . There was no statistically significant difference regarding the occurrence pattern of outliers in mechanical malalignment but the number of outliers was reduced in the navigated group Several choices of instrument systems are available for minimally invasive surgical approaches . There are reports that one alternative , the quadriceps sparing , side-cutting instrumentation , results in diminished implantation accuracy . A total of 108 patients were r and omized to undergo TKA either using side-cutting implant instrumentation ( Group A ) or anterior – posterior mini-incision instrumentation ( Group B ) . All TKAs were operated on with a minimal invasive , mini-midvastus surgical approach . 50 % of the TKAs were performed with computer-assistance in each cohort . The radiographic parameters , clinical outcomes and knee scores were evaluated preoperatively and 3 months postoperative . In Group B , we found significantly higher accuracy for the mechanical axis of the limb ( range ±3 ° : Group A 54 % versus Group B 89 % , p = < 0.001 ) , medial proximal tibial angle ( range ±3 ° : Group A 85 % versus Group B 98 % , p = < 0.027 ) and tibial slope ( range ±3 ° : Group A 59 % versus Group B 85 % , p = < 0.007 ) . The application of the navigation system could only significantly reduce outliers ( accuracy > 3 ° ) in Group B. Clinical outcomes and knee scores were similar in both groups and were not influenced by computer-assistance . Using the anterior – posterior , mini-incision instruments for minimally invasive TKA will lead to higher implantation accuracy when compared to the quadriceps sparing side-cutting instrumentation . The navigation technique could not compensate for shortcomings of the side-cutting instrumentation . The clinical relevance of this study is that the quadriceps sparing side-cutting instrumentation should not be used for TKA because of unacceptable reduced implantation accuracy We have compared a new technique of computer-assisted knee arthroplasty with the current conventional jig-based technique in 70 patients r and omly allocated to receive either of the methods .  Post-operative CT was performed according to the Perth CT Knee Arthroplasty protocol and pre- and post-operative Maquet views of the limb were taken . Intra-operative and peri-operative morbidity data were collected and blood loss measured . Post-operative CT showed a significant improvement in the alignment of the components using computer-assisted surgery in regard to femoral varus/valgus ( p = 0.032 ) , femoral rotation ( p = 0.001 ) , tibial varus/valgus ( p = 0.047 ) tibial posterior slope ( p = 0.0001 ) , tibial rotation ( p = 0.011 ) and femorotibial mismatch ( p = 0.037 ) . St and ing alignment was also improved ( p = 0.004 ) and blood loss was less ( p = 0.0001 ) . Computer-assisted surgery took longer with a mean increase of 13 minutes ( p = 0.0001 ) We carried out a prospect i ve r and omised study to evaluate the blood loss in 60 patients having a total knee arthroplasty and divided r and omly into two equal groups , one having a computer-assisted procedure and the other a st and ard operation . The surgery was carried out by a single surgeon at one institution using a uniform approach . The only variable in the groups was the use of intramedullary femoral and tibial alignment jigs in the st and ard group and single tracker pins of the imageless navigation system in the tibia and femur in the navigated group . The mean drainage of blood was 1351 ml ( 715 to 2890 ; 95 % confidence interval ( CI ) 1183 to 1518 ) in the computer-aided group and 1747 ml ( 1100 to 3030 ; CI 1581 to 1912 ) in the conventional group . This difference was statistically significant ( p = 0.001 ) . The mean calculated loss of haemoglobin was 36 g/dl in the navigated group versus 53 g/dl in the conventional group ; this was significant at p < 0.00001 . There was a highly significant reduction in blood drainage and the calculated Hb loss between the computer-assisted and the conventional techniques . This allows the ordering of less blood before the operation , reduces risks at transfusion and gives financial saving .  Computer-assisted surgery may also be useful for patients in whom blood products are not acceptable Computer-assisted surgery ( CAS ) in total knee arthroplasty ( TKA ) could be useful in reducing the overall blood loss . A prospect i ve r and omised study was performed with two groups of 50 patients each of whom were treated for knee arthritis . Patients of group A were treated by a conventional st and ard procedure , while for patients of group B a specific CAS procedure was used . We determined the intraoperative blood loss according to the Orthopaedic Surgery Transfusion Haemoglobin European Overview ( OSTHEO ) study . The average blood loss in patients of group A was 1,974 ml ( range : 450–3,930 ml ) compared to 1,677 ml of patients of group B ( range : 500–2,634 ml ) . A statistically significant difference was found between the two groups ( p = 0.0283 ) . Computer-assisted surgery is highly recommended in TKR to save blood . It creates more possibilities to operate on anaemic patients and subjects who can not accept blood products by reducing blood loss risk . RésuméLa chirurgie assistée par ordinateur dans les prothèses totales du genou peut être utile afin de réduire les pertes sanguines . Matériel et méthode : une étude prospect i ve , r and omisée , a été réalisée avec deux groupes de 50 patients , chacun , traités pour une arthrose du genou . Les patients du groupe A ont été opérés sur un mode conventionnel alors que l’autre groupe l’a été avec assistance informatique dans le cadre de la navigation . Nous avons déterminé les perte sanguines per-opératoires selon l’évaluation OSTEO . Résultats : le total des pertes sanguines du groupe A a été de 1974 ml en moyenne ( de 450 à 3930 ) en comparaison des 1677 ml des patients du groupe B ( de 500 à 2634 ml ) . La différence est statistiquement significative entre les deux groupes , p = 0,0283 ) . Conclusion : la navigation avec chirurgie assistée par ordinateur est recomm and ée pour les prothèses de remplacement articulaire afin de réduire les pertes sanguines . Cette technique donne plus de possibilité pour opérer les sujets anémiques qui ne peuvent supporter de grosses pertes sanguines 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 The aim of this study was to compare blood loss and transfusion requirements in patients undergoing computer-assisted total knee arthroplasty ( TKA ) and patients operated with conventional instrumentation with intra-medullar guides . A prospect i ve r and omized study of 87 patients undergoing a TKA assigned to conventional technique ( n = 44 ) or computer-assisted surgery ( n = 43 ) was conducted . All patients were operated by the same surgeon and in all cases a cemented arthroplasty and deep recovery drainage were used . Both groups were comparable in all variables except for duration of ischemia , which was 13.7 min higher in the computer-assisted group . Blood loss due to drainage was higher in the conventional technique group ( 613 vs. 447 ml ) , as was the number of patients in which blood from the blood recovery system was reinfused ( 53 vs. 23 % ) . Those patients undergoing computer-assisted surgery experienced less bleeding than those operated with the conventional technique . However , hemoglobin drop and allogenic transfusion rate were not statistically different in both groups 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 We previously compared the component alignment in  total knee replacement  using a computer-navigated technique with a conventional jig-based method . We r and omly allocated 71 patients to undergo either computer-navigated or conventional replacement .  An improved alignment was seen in the computer-navigated group . The patients were then followed up post-operatively for two years , using the Knee Society score , the Short Form-36 health survey , the Western Ontario and McMaster Universities osteoarthritis index , the Bartlett Patellar pain question naire and the Oxford knee score , to assess functional outcome . At two years post-operatively 60 patients were available for assessment , 30 in each group and 62 patients completed a postal survey . No patient in either group had undergone revision . All variables were analysed for differences between the groups either by Student 's t-test or the Mann-Whitney U test . Differences between the two groups did not reach significance for any of the outcome measures at any time point . At two years postoperatively , the frequency of mild to severe anterior pain was not significantly different ( p = 0.818 ) , varying between 44 % ( 14 ) for the computer-navigated group , and 47 % ( 14 ) for the conventionally-replaced group . The Bartlett Patellar score and the Oxford knee score were also not significantly different ( t-test p = 0.161 and p = 0.607 , respectively ) . The clinical outcome of the patients with a computer-navigated knee replacement appears to be no different to that of a more conventional jig-based technique at two years post-operatively , despite the better alignment achieved with computer-navigated surgery In a prospect i ve r and omized control trial comparing computer-assisted vs conventional total knee arthroplasty  , we previously reported that patients with coronal alignment within 3 ° of neutral had superior international knee society and Short-Form 12 ( SF-12 ) physical scores at 6 weeks , 3 months , 6 months , and 12 months after surgery . Computer-assisted total knee arthroplasty achieved greater accuracy in implant alignment , and this correlated with better knee function and quality of life . At 5 years , 90 of 111 patients assessed in our original study were review ed . Coronal alignment within 3 ° of neutral continued to be correlated with superior International Knee Society and SF-12 scores . Coronal alignment greater than 3 ° was associated with a significant decline in SF-12 mental health scores 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 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 The aim of this study is to assess the radiological outcome of conventional techniques versus computer-navigated surgery for total knee arthroplasty . Ninety patients with knee arthritis were prospect ively r and omized into 3 groups : conventional technique : extramedullary ( EM ) and intramedullary ( IM ) tibia guide versus computer navigation surgery ( CAS ) . Two surgeons performed all procedures . St and ardized long leg coronal and sagittal x-rays were evaluated by a blinded assessor . Our results showed that CAS had greater consistency and accuracy in implant placement . In the coronal view , 93.3 % in the CAS group had better outcomes compared with EM ( 73.4 % ) and IM ( 60.0 % ) . In the sagittal axis , 90.0 % CAS also had better outcomes compared with EM ( 63.3 % ) and IM ( 76.7 % ) . Computer-navigated total knee arthroplasty helps increase accuracy and reduce " outliers " for implant placement A prospect i ve exploratory study of fat emboli in patients undergoing total knee arthroplasty was performed in patients r and omly assigned to surgery with computer-assisted navigation or st and ard technique . Transesophageal echocardiography of the right atrium was recorded for 5 consecutive 1-minute intervals after tourniquet deflation . Emboli were grade d on a scale of 0 to 3 based on embolism size , amount of atrium filled , and duration of embolic shower , creating an overall score of 0 to 9 . The mean ( SD , range ) of the 5 overall scores for each total knee arthroplasty was 6.00 ( 0.76 , 4.6 - 7.4 ) for computer-assisted navigation ( 22 patients ) and 6.42 ( 0.97 , 4.6 - 7.9 ) for st and ard technique ( 22 patients ) ( P=.14 ) , with a 95 % confidence interval for the difference of -0.11 to 0.95 . We conclude that any difference in extent of emboli between the 2 surgical techniques is unlikely to be of clinical significance 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 This is a r and omized prospect i ve controlled trial comparing the alignment , function , and patient quality -of-life outcomes between patients undergoing conventional ( CONV ) and computer-assisted ( CAS ) knee arthroplasty . One hundred and fifteen patients ( 60 CAS , 55 CONV ) underwent cemented total knee arthroplasty .  Three patients were lost to follow-up . Eighty-eight percent ( CAS ) vs 61 % ( CONV ) of knees achieved a mechanical axis within 3 degrees of neutral ( P = .003 ) . Aligning femoral rotation with the epicondylar axis was accurately achieved in CAS and CONV with no significant difference . Patients with coronal alignment within 3 degrees of neutral had superior International Knee Society and Short-Form 12 physical scores at 6 weeks , 3 months , 6 months , and 12 months after surgery . Computer-assisted total knee arthroplasty achieves greater accuracy in implant alignment and this correlates with better knee function and improved quality of life Computer-assisted surgery in knee arthroplasty is gaining popularity ; however , the result ing outcome improvement is controversial . A double-blinded trial was performed with subjects r and omized to undergo surgery with either computer-assisted or nonassisted instruments .  Postoperatively , limb and implant alignment and rotation were assessed using both full-length radiographs and computed tomography in addition to clinical scores . One hundred twenty patients ( 141 knees ) were r and omized . No differences in Western Ontario MacMaster Osteoarthritis Score , Short Form-36 , or flexion were seen . More varus limb alignment was seen in the computer-assisted group ( 1.9 ° ) vs the nonassisted group ( 0.9 ° , P = .04 ) with no improvement in alignment precision . Rotational alignment of the components did not differ between groups . Computer-assisted surgery appeared to have minimal effect on knee implant arthroplasty with no improvement in limb alignment or early functional outcome
target: 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: 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 .