human
***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 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 
    Output:
    
agent
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 .
***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 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 
    Output:
    