Limitations of imageless computer-assisted navigation for total hip arthroplasty. Comparative Study on Anterior Cruciate Ligament Reconstruction: Determination of Isometric Points with and Without Navigation Comparison of gait in patients following a computer-navigated minimally invasive anterior approach and a conventional posterolateral approach for total hip arthroplasty: a randomized controlled trial. Impingement-free range of movement, acetabular component cover and early clinical results comparing 'femur-first' navigation and 'conventional' minimally invasive total hip arthroplasty: a randomised controlled trial. Outcomes after conventional versus computer-navigated anterior cruciate ligament reconstruction. Leg axis after computer-navigated total knee arthroplasty: a prospective randomized trial comparing computer-navigated and manual implantation. Comparative study between computer assisted-navigation and conventional technique in minimally invasive surgery total knee arthroplasty, prospective control study. Navigated and nonnavigated total hip arthroplasty: results of two consecutive series using a cementless straight hip stem. Limb alignment in computer-assisted minimally-invasive unicompartmental knee replacement. Accuracy of manual instrumentation of tibial cutting guide in total knee arthroplasty Reduction in variability of acetabular cup abduction using computer assisted surgery: a prospective and randomized study. Comparison between computer-assisted-navigation and conventional total knee arthroplasties in patients undergoing simultaneous bilateral procedures: a randomized clinical trial. Blood loss after minimally invasive total knee arthroplasty: effects of imageless navigation. Preliminary application of computer-assisted patient-specific acetabular navigational template for total hip arthroplasty in adult single development dysplasia of the hip. Comparison of robotic-assisted and conventional manual implantation of a primary total knee arthroplasty. Are systemic emboli reduced in computer-assisted knee surgery?: A prospective, randomised, clinical trial. Alignments and Clinical Results in Conventional and Navigated Total Knee Arthroplasty Accuracy and efficacy of osteotomy in total knee arthroplasty with patient-specific navigational template. Alignment in total knee arthroplasty. A comparison of computer-assisted surgery with the conventional technique. Randomized control trial comparing radiographic total knee arthroplasty implant placement using computer navigation versus conventional technique. Computer navigation vs conventional total knee arthroplasty: five-year functional results of a prospective randomized trial. [Clinical outcome following robotic assisted versus conventional total hip arthroplasty: a controlled and prospective study of seventy-one patients]. Navigated total knee arthroplasty: a radiological analysis of 42 randomised cases.
We prospect ively evaluated acetabular cup placement in total hip arthroplasty with an imageless computer navigation system  or using conventional manual technique . The achieved cup orientation in the manual group had substantially larger variances and greater placement error than the navigation cases . The use of navigation was ab and oned in 3 cases because of excessive pelvic tilt and unreliable registration of the pelvis . Computer navigation system helped improve the accuracy of the acetabular cup placement for total hip arthroplasty in this study . The variation between the intraoperative navigation readings and the computed tomographic values suggests that relying on palpation of bony l and marks through drapes and tissue is a limitation of this method . Further , the variation in pelvic tilt has an effect on cup placement that requires further studies OBJECTIVES : To compare the accuracy of  tunnel placement  and graft isometry for anterior cruciate ligament reconstruction performed using a computer-assisted navigation system ( Orthopilot ) and using traditional instruments . METHODS : The anterior cruciate ligament was removed intact from 36 pairs of human cadaver knees . From each pair , one knee was r and omized to Group 1 ( conventional ) and the other to Group 2 ( Orthopilot ) . An inelastic suture was then passed through the central points of the tibial and femoral tunnels . Neither of the tunnels was drilled . All knees were then dissected , and six parameters were obtained : distances from the tibial tunnel center to the 1 ) posterior cruciate ligament , 2 ) anterior horn of the lateral meniscus and 3 ) medial tibial spine ; 4 ) distance from the femoral tunnel center to the posterior femoral cortex ; 5 ) femoral tunnel coronal angle ; and 6 ) variation of the distance from the femoral to the tibial tunnel with the knee extended and at 90 degrees of flexion . RESULTS : The variation of the distance from the femoral to the tibial tunnel during flexion and extension was smaller in the Orthopilot group ( better isometry ) compared to the conventional group . There were no statistical differences in any other parameters between the groups , and all tunnels were considered to be in satisfactory positions . DISCUSSION : The results obtained for anterior cruciate ligament reconstruction depend on precise isometric point positioning , and a navigation system is a precision tool that can assist surgeons in tunnel positioning . CONCLUSION : No differences in tunnel position were observed between the groups . Nonetheless , better isometry was achieved in the Orthopilot group than with conventional instruments Minimally invasive total hip arthroplasty ( MIS THA ) aims at minimizing damage to muscles and tendons to accelerate postoperative recovery . Computer navigation allows a precise prosthesis alignment without complete visualization of the bony l and marks during MIS THA . A r and omized controlled trial ( RCT ) was conducted to determine the effectiveness of a computer-navigated MIS anterior approach for THA compared to a conventional posterolateral THA technique on the restoration of physical functioning during recovery following surgery . Thirty-five patients underwent computer-navigated MIS THA via the anterior approach , and 40 patients underwent conventional THA using the conventional posterolateral approach .  Gait analysis was performed preoperatively , 6 weeks , and 3 and 6 months postoperatively using a body-fixed-sensor based gait analysis system . Walking speed , step length , cadence , and frontal plane angular movements of the pelvis and thorax were assessed . The same data were obtained from 30 healthy subjects . No differences were found in the recovery of spatiotemporal parameters or in angular movements of the pelvis and thorax following the computer-navigated MIS anterior approach or the conventional posterolateral approach . Although gait improved after surgery , small differences in several spatiotemporal parameters and angular movements of the trunk remained at 6 months postoperatively between both patient groups and healthy subjects We report the kinematic and early clinical results of a patient- and observer-blinded r and omised controlled trial in which CT scans were used to compare potential impingement-free range of movement ( ROM ) and acetabular component cover between patients treated with either the navigated ' femur-first ' total hip arthroplasty ( THA ) method ( n = 66 ; male/female 29/37 , mean age 62.5 years ; 50 to 74 ) or conventional THA ( n = 69 ; male/female 35/34 , mean age 62.9 years ; 50 to 75 ) . The Hip Osteoarthritis Outcome Score , the Harris hip score , the Euro-Qol-5D and the Mancuso THA patient expectations score were assessed at six weeks , six months and one year after surgery . A total of 48 of the patients ( 84 % ) in the navigated ' femur-first ' group and 43 ( 65 % ) in the conventional group reached all the desirable potential ROM boundaries without prosthetic impingement for activities of daily living ( ADL ) in flexion , extension , abduction , adduction and rotation ( p = 0.016 ) . Acetabular component cover and surface contact with the host bone were > 87 % in both groups . There was a significant difference between the navigated and the conventional groups ' Harris hip scores six weeks after surgery ( p = 0.010 ) . There were no significant differences with respect to any clinical outcome at six months and one year of follow-up . The navigated ' femur-first ' technique improves the potential ROM for ADL without prosthetic impingement , although there was no observed clinical difference between the two treatment groups PURPOSE The purpose of this prospect i ve r and omized study was to assess biomechanical , radiographic , and functional results after single-bundle anterior cruciate ligament ( ACL ) reconstruction by use of a navigation system . METHODS ACL reconstruction was performed by use of the OrthoPilot navigation system ( B. Braun-Aesculap , Tuttlingen , Germany ) in 40 patients ( group 1 ) ; and in another 40 patients ,  surgery was done by the st and ard manual targeting technique  ( group 2 ) . The anterior laxity was measured with a KT-1000 arthrometer ( MEDmetric , San Diego , CA ) . Femoral and tibial tunnel position was evaluated radiologically according to the method described by Bernard and Hertel and by Harner et al. , respectively . The question naire-based Lysholm and International Knee Documentation Committee scales were included to compare the functional state in both groups . RESULTS The knees in group 1 were as stable as those in group 2 during the arthrometer testing , with a lower value of dispersion . The postoperative Lysholm and International Knee Documentation Committee scores had the same value in both groups . Statistical differences existed with regard to anterior-posterior femoral tunnel placement when the navigated and st and ard techniques were compared ; in the navigated group , more exact results were found . No significant complications were observed . CONCLUSIONS The only difference that we found between the navigated and st and ard groups was in radiographic tunnel position measurement . The computer-assisted navigation technique in our study result ed in more accurate tunnel placement in the femur ( but not the tibia ) than the traditional arthroscopic technique . However , the performed st and ard radiographic measurements are of limited precision in principle . Functional scales and stability tests gave similar results in both groups . LEVEL OF EVIDENCE Level I , therapeutic study 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 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 The purpose of this study was to compare conventional and navigated technique and a recently developed straight hip stem for uncemented primary total hip arthroplasty . The results of two consecutive implantation series of 42 patients ( nonnavigated ) and 42 patients ( navigated )  were analysed for implant positioning and complications . All surgeries were performed by the investigator . Radiographic analysis of cup position showed a significant improvement with reduced radiologic inclination ( 53 degrees nonnavigated /44 degrees navigated ; P < .001 ) and higher anteversion ( 7 degrees nonnavigated /12 degrees navigated ; P < .001 ) . The mean postoperative limb length difference was 6.2 mm ( SD , 9.0 for nonnavigated ) and 4.4 mm ( SD , 6.4 for navigated ) . Intraoperative and early postoperative complications were not different . No dislocation occurred in either group . There was one intraoperative trochanter fracture that was not revised ( nonnavigated ) and one revision because of a periprosthetic fracture caused by fall down during rehabilitation ( navigated ) . We conclude that acetabular implant positioning can be significantly improved by the use of navigated surgery technique . The data for postoperative limb length difference were still similar but within the expected range in both groups . The effect of improved cup positioning on mid and longterm results for both groups has to be investigated further 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 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 Optimal orientation of the acetabular component of a  total hip prosthesis  is an important factor in determining the early and long-term result of a  total hip arthroplasty ( THA ) . Conventional positioning of the cup component is usually done using a free-h and method , or with the help of a mechanical acetabular alignment guide . However , these methods have proven to be inaccurate , and a great variation in orientation of the cup is found postoperatively . In this study , we wished to determine if the variability of the abduction angle of acetabular cups could be reduced with the use of computer navigation . The abduction angles of the acetabular components of three groups of 50 THAs were assessed . In the first group , a free-h and method was used to position the cup component . This group was operated in the period before we started using computer navigation for hip surgery . In the second group , CT-based computer navigation was used to plan and help position the cup . The third group consisted of 50 THA cases in which a free-h and method was used to position the cup , although these procedures were performed in the period after we had begun using the Computer Assisted Surgery ( CAS ) system . The variability in cup abduction angle was assessed in all three groups and compared . There was a significant reduction in variability in the CAS group compared to the first group . There was also a reduction in variability in the CAS group compared to the third group , although this was not statistically significant . It is concluded that the use of computer navigation helped the surgeon to place the cup component with less variability of the abduction angle , and , more importantly , we found that no cups were placed in the more extreme positions ( outliers ) 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 prospect i ve cohort study of 100 patients undergoing primary minimally invasive total knee arthroplasty was carried out to determine blood loss after this procedure and to examine the efficacy of navigation on blood saving . The patients were divided into two groups according to the surgical technique , and underwent either computer-assisted navigation or manual procedures . All operations were performed by a single surgeon using an identical approach . To minimize blood loss , an intraoperative tourniquet was used , but no postoperative drainage was applied . Although the mean surgical time was longer in the navigated group than in the manual group ( 119.2 vs. 90.9 min ; p < 0.001 ) , the reductions in hemoglobin level ( 1.40 vs. 1.38 g/dL ; p = 0.642 ) and calculated blood loss ( 470.77 vs. 482.73 mL ; p = 0.796 ) were similar in both groups . Four patients in both groups required blood transfusion . With minimally invasive techniques and drainage avoidance , our study suggests that the blood loss after minimally invasive total knee arthroplasty was not significantly affected by the use of imageless navigation BACKGROUND The considerable variation in anatomical abnormalities of hip joints associated with different types of developmental dysplasia of hip ( DDH ) makes reconstruction in total hip arthroplasty ( THA ) difficult . It is desirable to create patient-specific design s for THA procedures . In the cases of adult single DDH , an accuracy-improved method has been developed for acetabular cup prosthesis implantation of hip arthroplasty . METHODS From October 2007 to November 2008 , 22 patients with single DDH ( according to the Crowe st and ard , all dysplasia hips were classified as type I ) were scanned with spiral CT pre-operatively . These patients scheduled for THA were r and omly assigned to undergo either conventional THA ( control group , n = 11 ) or navigation template implantation ( NT group , n = 11 ) . In the NT group , three-dimensional ( 3D ) CT pelvis image data were transferred to a computer workstation and 3D models of the hip were reconstructed using the Mimics software . The 3D models were then processed by the Imageware software . In brief , a template that best fitted the location and shape of the acetabular cup was ' reversely ' built from the 3D model , the rotation centre of the pathological hip determined by mirroring that of the healthy site , and a guiding hole in the template was then design ed . The navigational templates were manufactured using a rapid prototyping machine . These navigation templates guide acetabular component placement . RESULTS Based on the predetermined abduction angle 45 ° and anteversion angle 18 ° , after 1 year follow-up , the NT group showed significantly smaller differences ( 1.6 ° ± 0.4 ° , 1.9 ° ± 1.1 ° ) from the predetermined angles than those in the control group ( 5.8 ° ± 2.9 ° , 3.9 ° ± 2.5 ° ) ( P < 0.05 ) . CONCLUSIONS The template design s facilitated accurate placement of acetabular components in dysplasia of acetabulum . The hip 's center of rotation in DDH could be established using computer-aided design , which provides a useful method for the accurate location of prosthesis with a low cost-performance ratio without excessive technical workload on the surgical team This study was aim ed to compare robotic-assisted implantation of a total knee arthroplasty with conventional manual implantation . We controlled , r and omized , and review ed 72 patients for total knee arthroplasty assigned to undergo either conventional manual implantation ( excluding navigation-assisted implantation cases ) of a Zimmer LPS prosthesis ( Zimmer , Warsaw , Ind ) ( 30 patients : group 1 ) or robotic-assisted implantation of such a prosthesis ( 32 patients : group 2 ) . The femoral flexion angle ( gamma angle ) and tibial angle ( delta angle ) in the lateral x-ray of group 1 were 4.19 + /- 3.28 degrees and 89.7 + /- 1.7 degrees , and those of group 2 were 0.17 + /- 0.65 degrees and 85.5 + /- 0.92 degrees . The major complications were from improper small skin incision during a constraint attempt of minimally invasive surgery and during bulk fixation frame pins insertion . Robotic-assisted technology had definite advantages in terms of preoperative planning , accuracy of the intraoperative procedure , and postoperative follow-up , especially in the femoral flexion angle ( gamma angle ) and tibial flexion angle ( delta angle ) in the lateral x-ray , and in the femoral flexion angle ( alpha angle ) in the anteroposterior x-ray . But a disadvantage was the high complication rate in early stage 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 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 This study develops and vali date s a novel patient-specific navigational template for total knee arthroplasty ( TKA ) . A total of 70 patients who underwent TKA were r and omized and divided into conventional method group and navigational template group . In the navigational template group , the patient-specific navigational templates were design ed and used intraoperatively to assist 35 patients with knee arthroplasty . Information on operation time and blood loss was recorded . After surgery , the positions of the prosthesis were evaluated using CT scan and X-rays . Analysis showed significant differences in errors between the two techniques . In addition , mean operation time and mean blood loss were statistically and significantly lower in the navigational template group than in the conventional group . Overall , the navigational template method showed a high degree of accuracy and efficacy 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 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 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 AIM Robotic assisted total hip arthroplasty  remains controversial , since wider exposure of the proximal femur and placement of the leg in maximal hip adduction and external rotation using a rigid leg-holder apparatus may impair significantly the hip abductors . Consequently , it is the purpose of this study to analyse and report both clinical outcome and hip abductor function following robotic assisted versus conventional total hip arthroplasty . MATERIAL AND METHODS 36 robotic-assisted ( CASPAR , Orto-Maquet , Rastatt , Germany ) and 35 conventional cementless total hip arthroplasties  were followed on average for 18 months regarding incidence of complications , Harris hip score , the scoring system according to Merle d'Aubigné and Postel , hip abductor function ( using a spring-balance ) , and incidence of Trendelenburg 's sign ( according to the Kuhfuss-classification ) . Statistical analysis was performed in case of continuous data using the t test and the Mann-Whitney test , respectively , and in case of categorical data using Fisher 's exact test and the chi-squared test , respectively . The level of significance was set as p < 0.05 . RESULTS Average duration of surgery ( CASPAR : 100.6 min ; conventional : 51.5 min ; p < 0.0001 ) as well as average loss of haemoglobin ( CASPAR : 4.5 mg/dL ; conventional : 3.3 mg/dL ; p = 0.0002 ) differed significantly , whereas the incidence of complications ( CASPAR : two dislocations , one sciatic paresis , one deep infection ; conventional : one dislocation , two fissures ) , revision rate ( CASPAR : 5.6 % ; conventional : 2.9 % ) , and incidence of heterotopic ossifications ( CASPAR : 30.6 % ; conventional : 17.1 % ) was comparable following both procedures ( p > 0.05 ) . Improvement of the Harris hip score also was comparable in both groups ( CASPAR : 40.9 to 86.1 points ; conventional : 39.5 to 88.0 points ; p = 0.21 ) , whereas improvement of the score according to Merle d'Aubigné and Postel was significantly greater following the manual procedure ( CASPAR : 10.1 to 16.0 points ; conventional : 8.3 to 16.6 points ; p < 0.0001 ) . Differences between the two groups were also significant regarding hip abductor function ( CASPAR : 76.1 % ; conventional : 93.8 % of the contralateral hip ; p < 0.0001 ) and incidence of Trendelenburg 's sign ( CASPAR : 61.1 % ; conventional : 25.7 % ; p = 0.0014 ) . CONCLUSION The significant functional impairment following robotic assisted THA should be taken critically into consideration prior to initiating such procedure 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
Results Significant differences were found in the femoral offset and overall complication rate between the conventional and navigation groups .
Additionally , the conventional group had significantly less anteversion than the navigation group .
However , the navigation group had significantly better inclination .
The operation time was significantly shorter in the conventional than navigation group .
Conclusion Both the OrthoPilot navigation system and conventional total hip arthroplasty result in significant improvements in patient function with similar overall complication rates and have their own advantages in achieving good cup position .
The conventional procedure has a shorter operation time than does use of a navigation system
Objective This study was performed to compare the clinical efficacy between the OrthoPilot navigation system and conventional manual surgery in patients undergoing total hip arthroplasty .