Patient-specific Guides Do Not Improve Accuracy in Total Knee Arthroplasty: A Prospective Randomized Controlled Trial Patient-specific computed tomography based instrumentation in total knee arthroplasty: a prospective randomized controlled study Evaluation of the accuracy of a patient-specific instrumentation by navigation Contribution of patient-specific cutting guides to lower limb alignment for total knee arthroplasty. Component alignment during total knee arthroplasty with use of standard or custom instrumentation: a randomized clinical trial using computed tomography for postoperative alignment measurement. Comparison of radiographic alignment of imageless computer-assisted surgery vs conventional instrumentation in primary total knee arthroplasty. No radiological and clinical advantages with patient-specific positioning guides in total knee replacement Alignments and Clinical Results in Conventional and Navigated Total Knee Arthroplasty Intra-operative results and radiological outcome of conventional and patient-specific surgery in total knee arthroplasty: a multicentre, randomised controlled trial The radiological outcomes of patient-specific instrumentation versus conventional total knee arthroplasty Randomized control trial comparing radiographic total knee arthroplasty implant placement using computer navigation versus conventional technique. Patient-specific instrumentation in total knee arthroplasty: simpler, faster and more accurate than standard instrumentation—a randomized controlled trial Patient-matched instruments versus standard instrumentation in total knee arthroplasty: a prospective randomized study Accuracy of CT-based patient-specific guides for total knee arthroplasty in patients with post-traumatic osteoarthritis Good diagnostic performance of early migration as a predictor of late aseptic loosening of acetabular cups: results from ten years of follow-up with Roentgen stereophotogrammetric analysis (RSA). A comparison of patient-specific and conventional instrumentation for total knee arthroplasty: a multicentre randomised controlled trial. Rotational alignment of femoral component between custom cutting block and conventional technique in total knee arthroplasty.
Background Recently , patient-specific guides ( PSGs ) have been introduced , cl aim ing a significant improvement in accuracy and reproducibility of component positioning in TKA . Despite intensive marketing by the manufacturers , this cl aim has not yet been confirmed in a controlled prospect i ve trial . Questions / purpose sWe ( 1 ) compared three-planar component alignment and overall coronal mechanical alignment between PSG and conventional instrumentation and ( 2 ) logged the need for applying changes in the suggested position of the PSG . Methods In this r and omized controlled trial , we enrolled 128 patients . In the PSG cohort , surgical navigation was used as an intraoperative control . When the suggested cut deviated more than 3 ° from target , the use of PSG was ab and oned and marked as an outlier . When cranial-caudal position or size was adapted , the PSG was marked as modified . All patients underwent long-leg st and ing radiography and CT scan .  Deviation of more than 3 ° from the target in any plane was defined as an outlier . Results The PSG and conventional cohorts showed similar numbers of outliers in overall coronal alignment ( 25 % versus 28 % ; p = 0.69 ) , femoral coronal alignment ( 7 % versus 14 % ) ( p = 0.24 ) , and femoral axial alignment ( 23 % versus 17 % ; p = 0.50 ) . There were more outliers in tibial coronal ( 15 % versus 3 % ; p = 0.03 ) and sagittal 21 % versus 3 % ; p = 0.002 ) alignment in the PSG group than in the conventional group . PSGs were ab and oned in 14 patients ( 22 % ) and modified in 18 ( 28 % ) . Conclusions PSGs do not improve accuracy in TKA and , in our experience , were somewhat impractical in that the procedure needed to be either modified or ab and oned with some frequency . Level of Evidence Level I , therapeutic study . See instructions for authors for a complete description of levels of evidence Purpose The aim of this study was to compare radiological results of total knee arthroplasties ( TKAs ) performed with patient-specific computed tomography (CT)-based instrumentation and conventional technique . The main study hypothesis was that CT-based patient-specific instrumentation ( PSI ) increases the accuracy of TKA . Methods A prospect i ve , r and omized controlled trial was carried out between January and December 2011 . A group of 112 patients who met the inclusion and exclusion criteria were enrolled in this study and r and omly assigned to an experimental or control group . The experimental group comprised 52 patients operated on with the aid of the Signature ™ CT-based implant positioning system .  The control group consisted of 60 patients operated on using conventional instrumentation .  The radiographic evaluation of implant positioning and overall coronal alignment was performed 12 months after the surgery by using st and ing anteroposterior radiographs of the entire lower limb and st and ard lateral radiographs . Results Of the 112 patients initially enrolled for the study , 95 were included in the subsequent analyses . There were no statistically significant differences between groups in respect to coronal and sagittal component positioning and overall coronal alignment , except for frontal tibial component positioning . For this parameter , better results were obtained in the control group , with borderline statistical significance . Conclusions Our study did not reveal superiority of the CT-based PSI system over conventional instrumentation . Further high- quality investigations of patient-specific systems are absolutely indispensable to assess their utility for TKA . In our opinion , the surgeon applying PSI technology is required to have advanced knowledge and considerable experience with the conventional method Purpose The aim of this study is to evaluate the accuracy of a  patient-specific instrumentation ( PSI ) as assessed by the intraoperative use of knee navigation software during the surgical procedure . Methods Fifteen patients with primary gonarthrosis were selected for unilateral total knee arthroplasty . The first three patients were excluded from this study , as they were considered to be a warm up to set-up the procedure . All patients were operated on with a cemented posterior-stabilised prosthesis cruciate ligament-sacrificing by the same surgeon using the patient matched cutting jigs . The size of the implant , level of resection , and alignment in the coronal and sagittal planes were evaluated . An unsatisfactory result was considered an error ≥2 ° in both planes for each component as a possible error of 4 ° could result in aggravation . Results On the coronal plane the mean deviation of the tibial guide from the ideal alignment was 1.2 ± 1.5 ( range 0–5 ° ) and in the sagittal plane was 3.8 ± 2.4 ( range 0–7.5 ° ) . On the coronal plane the mean deviation of the femoral guide from the ideal alignment was 1.2 ± 0.6 and in the sagittal was 3.7 ± 2 . Conclusion On the basis of this preliminary experience the PSI system based only on data acquisition with A-P radiograms and RMN can not be defined as accurate . In cases of the use of the custom made cutting jigs it is recommended to perform an accurate control of the alignment before making the cuts , for any step of the procedure . Level of evidence II UNLABELLED Patient-specific cutting guides ( PSCG ) are an extension of preoperative planning for total knee arthroplasty ( TKA ) . We wanted to evaluate their contribution to postoperative lower limb alignment . This study involved primary TKA cases being performed with PSCG between 10/05/2010 and 05/03/2013 and then followed prospect ively . The analysis involved the PSCG usage and postoperative measurement of the patient 's HKA , medial distal femoral joint angle ( MDFA ) and medial proximal tibia joint angle ( MPTA ) .  Of the 104 eligible cases , 68 were included ; 11 of these cases were not performed completely with the PSCG as initially planned . Thus we compared these 11 cases with the 57 where PSCG were used . The preoperative HKA in the included cases was 175.8 ° ± 7.8 ; the postoperative angles on average were 179.2 ° ± 2.9 for the HKA , 89.9 ° ± 1.6 for the MDFA and 89.0 ° ± 2.3 for the MPTA . The average postoperative deviation from the target values was 2.22 ° ± 2.14 for the HKA angle , 1.07 ° ± 1.15 for the MDFA and 1.66 ° ± 1.90 for the MPTA . There were no significant differences between the two groups in any of the measurements . The lower limb alignment goal was achieved in 50 cases ( 73 % ) , with 41 of these achieved with PSCG ( 82 % ) . Of the 18 cases where the target was not achieved , PSCG were used 16 times ( 88 % ) . In this study cohort , lower limb alignment was not significantly closer to an HKA of 180 ° or achieved more often with the use of PSCG versus st and ard instrumentation . Since the results of the two groups can be superimposed , we found no evidence that use of PSCG  improves postoperative lower limb alignment . LEVEL OF EVIDENCE IV . STUDY TYPE Cohort BACKGROUND Patient-specific femoral and tibial cutting blocks produced with use of data from preoperative computed tomography ( CT ) or magnetic resonance imaging ( MRI ) scans have been employed recently to optimize component alignment in total knee arthroplasty . We report the results of a r and omized controlled trial in which CT scans were used to compare postoperative component alignment between patients treated with custom instruments  and those managed with traditional instruments . METHODS The in-hospital data and early clinical outcomes , including Knee Society scores , were determined in a r and omized clinical trial of forty-seven patients who had undergone a total of forty-eight primary total knee arthroplasties with patient-specific instruments ( twenty-two knees ) or st and ard instruments ( twenty-six knees ) . Orientation of the implants was compared by using three-dimensional CT data . RESULTS No significant differences were found between the study and control groups with respect to any clinical outcome after a minimum of six months of follow-up . The patient-specific tibial cutting block was ab and oned in favor of a st and ard external alignment jig in seven of the twenty-two study knees because of possible malalignment . A detailed analysis of intent-to-treat and per- protocol groups of study and control knees did not show any significant improvement in component alignment , including femoral component rotation in the axial plane , in the patients treated with the custom instruments . The percentage of outliers -- defined as less than -3 ° or more than 3 ° from the correct orientation of the tibial slope -- was significantly higher in the group treated with use of patient-specific blocks than it was in the control group , in both the intent-to-treat ( 32 % versus 8 % , p = 0.032 ) and the per- protocol ( 47 % versus 6 % , p = 0.0008 ) analysis . CONCLUSIONS There were no significant improvements in clinical outcomes or knee component alignment in patients treated with patient-specific cutting blocks as compared with those treated with st and ard instruments . The group treated with patient-specific cutting blocks had a significantly higher prevalence of malalignment in terms of tibial component slope than the knees treated with st and ard instruments 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 Background and purpose — Although the use of patient-specific positioning guides ( PSPGs ) in total knee replacement ( TKR ) in theory is promising , the technique has not yet proven its superior- ity compared with the conventional method . We compared radio- logical alignment and clinical outcome between TKR performed with the use of PSPGs and the conventional operation method . Patients and methods — 3 hospitals participated in a prospec- tive trial . 109 patients were r and omized to either the conventional method or to the use of PSPGs .  Postoperatively a full-length st and ing anteroposterior radiograph and a postoperative CT scan were taken . On the CT scan the alignments were measured for both the femoral and tibial components in the frontal , sagit- tal , and axial plane . The Knee injury and Osteoarthritis Outcome Score ( KOOS ) , the Eurocol-5D-3L ( Eq5D ) descriptive system and visual analogue scale ( VAS ) , a pain score ( NRS ) , and range of motion ( ROM ) were recorded preoperatively , and at 3 months , 1 , and 2 years . The operation time and length of hospital stay were recorded . Results — 90 patients were available for postoperative CT mea- surements . A statistically significant difference was found between the conventional TKR instrumentation and the use of PSPGs for the frontal femoral ( mean ( SD ) 0.6 ° ( 1.7 ) vs. –0.3 ° ( 2.2 ) , CI 0.08 to 1.69 ) and tibial ( –0.3 ° ( 1.5 ) vs. 0.9 ° ( 2.1 ) , CI –1.98 to –0.44 ) compo- nent angles and for the tibial alignment in the sagittal plane ( –3.8 ° ( 3.0 ) vs. –2.2 ° ( 2.5 ) , CI –2.72 ; –0.42 ) . The proportions of outliers were similar between the groups as well as the hip – knee – ankle angle , the KOOS sub scores , the Eq5D , pain ( NRS ) , ROM , opera- tion time , and length of hospital stay . Interpretation — The use of PSPGs requires a preoperative CT scan or MRI and the guides have an additional cost . As this study was not able to prove any extra benefit of the use of PSPGs we recommend the conventional operation method for TKR 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 Purpose This prospect i ve , double-blind , r and omised controlled trial was design ed to address the following research questions : firstly , is there a significant difference in outliers in alignment in the frontal and sagittal plane between PSG TKA and conventional TKA . Secondly , is there a significant difference in operation time , blood loss and length of hospital stay between the two techniques . We hypothesise that there will be fewer outliers with PSG TKA and that operation time , blood loss and length of hospital stay can be significantly reduced with PSG . Methods A total of 180 patients were r and omised for PSG TKA ( group 1 ) or conventional TKA ( group 2 ) in two centres . Patients were stratified per hospital . Alignment of the mechanical axis of the leg and flexion/extension and varus/valgus of the individual prosthesis components were measured on digital , st and ing , long-leg and st and ard lateral radiographs by two independent outcome assessors in both centres . Percentages of outliers ( > 3 ° ) were determined . We compared blood loss , operation time and length of hospital stay . Results There was no statistically significant difference in mean mechanical axis or outliers in mechanical axis between groups . No statistically significant difference was found for the alignment of the individual components in the frontal plane nor for the percentages of outliers . There was a statistically significant difference in outliers for the femoral component in the sagittal plane , with a higher percentage of outliers in the group 1 ( p = 0.017 ) . No such significant result was found for the tibial component in that plane . All interclass correlation coefficients were good . Blood loss was 100 mL less in group 1 ( p < 0.001 ) . Operation time was 5 min shorter in group 1 ( p < 0.001 ) . Length of hospital stay was identical with a mean of 3.6 days ( p = 0.657 ) . Conclusions The results in terms of obtaining a neutral mechanical axis and a correct position of the prosthesis components did not differ between groups . A small reduction in operation time and blood loss was found with the PSG system . Future research should especially focus on cost-effectiveness analysis and functional outcome of PSG TKA.Level of evidence Abstract Purpose The aim of this study was to investigate the post-operative radiological outcomes of patient-specific instrumentation ( PSI ) surgery versus conventional total knee arthroplasty ( TKA ) . Methods Sixty patients scheduled for a primary TKA were prospect ively divided into PSI or conventional technique . Coronal and sagittal radiographic long limb films were taken post-operatively . The accepted values for normal alignment were 180 ° ± 3 ° for hip-knee-ankle angle ; 90 ° ± 3 ° for coronal femoral component angle or coronal tibia component angle ; 0 ° to 3 ° flexion for sagittal femoral component angle and 0 ° to 7 ° posterior slope for sagittal tibia component angle . Results For hip-knee-ankle angle , there were 21 % more outliers in the PSI group compared to the conventional group ( p = 0.045 ) . Most of these outliers had valgus deformity in the PSI group and varus deformity in the conventional group ( p = 0.045 ) . For implant placement , there was no difference in the proportion of outliers between the two groups . There was also no difference in the duration of surgery . Conclusions This study showed that PSI surgery is associated with a larger proportion of outliers for lower limb alignment . PSI surgery as an alternative to conventional TKA is not advisable . Level of evidence II 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 Abstract Purpose This r and omized controlled trial was conducted to compare patient-specific instrumentation ( PSI ) to st and ard instrumentation regarding efficacy to achieve a good coronal alignment and differences in surgical time , blood loss and length of stay . Methods Ninety-five of 100 r and omized patients eligible for total knee arthroplasty were analysed .  PSI with magnetic resonance and long-leg radiograph was performed in 47 patients , while 48 patients received st and ard instrumentation .  Primary outcome measure was coronal alignment , evaluated with long-leg radiograph . Deviation > 3 ° varus/valgus was considered an outlier . Surgical time was compared from skin to skin . Length of stay was a post hoc analysis . Blood loss was evaluated comparing the number of blood units spent , fall in haemoglobin and haematocrit levels . Results St and ard instrumentation had a higher number of outliers in the coronal alignment with a relative risk of 3.015 , compared to PSI . Surgical time was reduced by 18 min ( 24.8 % ) with the  PSI  , as well as length of stay , with a half-day reduction . Number of blood units spent was significantly less in the PSI group . Relative risk of transfusion was 7.09 for patients in the st and ard instrumentation group . Difference in Hg and Htc levels were not significant . No patient had to ab and on PSI . Minor changes to preoperative plan occurred in 14.9 % of the patient : cut review in 4.3 % and insert change in 10.6 % . Conclusions Patient-specific instrumentation ( PSI ) is able to provide important advantages over st and ard instrumentation in total knee arthroplasty : it lowers the risk of outliers and transfusion , is a faster procedure and enables a shorter length of stay with a low rate of intraoperative adjustments . Level of evidence Summary Background Optimal positioning of implants and restoration of neutral mechanical axis are two primary surgical goals in total knee arthroplasty ( TKA ) . Despite modern instruments and improved surgical techniques , malalignment remains an important cause of early failure after TKA . The aim of this prospect i ve r and omized study was to compare the value of a new patient-matched instrument system ( PMI ) ( SignatureTM ; Biomet , Inc , Warsaw , Indiana ) to that of st and ard TKA surgical instrumentation ( STD ) in terms of coronal mechanical alignment , time of operation and blood loss . Patients and methods A total of 38 patients waiting for primary TKA were enrolled and r and omized into two groups ( 19 PMI and 19 STD ) . Magnetic resonance imaging was performed in all patients in the PMI group , and specific instruments for the femur and tibia were design ed preoperatively . All patients were operated on using the st and ard medial parapatellar approach with no use of tourniquet . Mechanical axis , time for the operation , and blood loss were evaluated . Results Patients in both groups had comparable age , body mass index , preoperative mechanical axis , Knee Society Score , and level of hemoglobin . Postoperative results showed that the PMI group fell significantly closer to neutral mechanical axis ( STD : 2.7 ± 1.7 , PMI : 1.7 ± 0.9 ; P = 0.013 ) with no outliers and a reduced time for the operation . There was no difference in the evaluation blood loss . Conclusions The use of PMI can contribute in achieving better mechanical axis with reduction in outliers and decreased operation time . Due to small differences between PMI and st and ard instruments , additional research are needed to confirm these preliminary results , and to discover potential benefits and functional improvements in the long-term outcome Abstract Published clinical trials who studied the accuracy of patient-specific guides ( PSG ) for total knee arthroplasty exclude patients with articular deformity of the knee joint . We prospect ively analysed a series of 30 patients with post-traumatic osteoarthritis of the knee joint with use of PSG . At 1 year post-operative , the achieved biomechanical ( HKA ) axis and varus/valgus of the femur and tibia components were measured on anterior – posterior ( AP ) long-st and ing weight-bearing radiographs . Flexion/extension of the femoral and AP slope of the tibia component was measured on st and ard lateral radiographs . Percentages > 3 ° deviation of the pre-operative planned HKA axis and individual implant components were considered as outliers . Approved and used implant size , median blood loss ( ml ) and operation time ( min ) were obtained from the operation records . Pre- and 1-year post-operative patient-reported outcome measures ( PROMs ) were performed . Eighty-three per cent of the patients had a HKA axis restored <3 ° of the pre-operative planned alignment . Varus/valgus outliers were 0.0 and 6.7 % for the femoral and tibial components , respectively . Percentages of outliers of flexion/extension were 36.7 % for the femoral component and 10.0 % for the AP slope of the tibial component . Median blood loss was 300 ml ( 50–700 ) , while operation time was 67 min ( 44–144 ) . In 20 % of all cases , the approved implant size was changed into one size smaller . One-year post-operative PROMs improved significantly . We conclude that the accuracy of CT-based PSG is not impaired in patients with post-traumatic osteoarthritis and this modality can restore biomechanical limb alignment BACKGROUND Excessive early migration of femoral stems following total hip arthroplasty and tibial components following total knee arthroplasty is associated with their long-term survival and allows reliable early evaluation of implant performance . However , a similar relationship involving acetabular components following hip arthroplasty has not been evaluated . This prospect i ve , long-term study with clinical and Roentgen stereophotogrammetric analysis ( RSA ) follow-up establishes the existence of this relationship and its associated diagnostic performance . METHODS Thirty-nine consecutive patients ( forty-one hips ) who underwent total hip arthroplasty with a cemented Exeter stem and a cemented Exeter all-polyethylene cup had prospect i ve clinical and RSA follow-up . Patients were evaluated postoperatively at six weeks , at three , six , and twelve months , and annually thereafter . Conventional anteroposterior and lateral radiographs were made at six weeks and at two , five , and ten years postoperatively as well as when indicated . The mean duration of follow-up ( and st and ard deviation ) was 9.4 ± 3.2 years . No patients were lost to follow-up ; fifteen patients died during the follow-up period . RESULTS Eleven acetabular components were observed to be loose on conventional radiographs after a mean of seventy-six months ( range , twelve to 140 months ) . During the first two postoperative years , the failed acetabular components showed markedly greater and more rapid cranial translation and sagittal rotation . Both cranial translation ( hazard ratio = 19.9 [ 95 % confidence interval , 4.94 to 80.0 ] , p < 0.001 ) and sagittal rotation ( hazard ratio = 11.1 [ 95 % confidence interval , 2.83 to 43.9 ] , p = 0.001 ) were strong risk factors for late aseptic loosening . Eight of the eleven failed components showed a distinctive pattern of excessive cranial translation combined with excessive sagittal rotation . The associated diagnostic performance of two-year cranial translation and /or sagittal rotation for predicting late aseptic loosening of the acetabular component was good ( area under the receiver operating characteristic curve , 0.88 [ 95 % confidence interval , 0.74 to 1.00 ; p < 0.001 ] and 0.84 [ 95 % confidence interval , 0.68 to 1.00 ; p = 0.001 ] , respectively ) . CONCLUSIONS Early migration , as measured by RSA at two years postoperatively , has good diagnostic capabilities for the detection of acetabular components at risk for future aseptic loosening , and this method appears to be an appropriate means of assessing the performance of new implants or implant-related changes In this study we r and omised 140 patients who were due to undergo primary total knee arthroplasty ( TKA ) to have the procedure performed using either patient-specific cutting guides ( PSCG ) or conventional instrumentation ( CI ) . The primary outcome measure was the mechanical axis , as measured at three months on a st and ing long-leg radiograph by the hip-knee-ankle ( HKA ) angle . This was undertaken by an independent observer who was blinded to the instrumentation . Secondary outcome measures were component positioning , operating time , Knee Society and Oxford knee scores , blood loss and length of hospital stay . A total of 126 patients ( 67 in the CI group and 59 in the PSCG group ) had complete clinical and radiological data . There were 88 females and 52 males with a mean age of 69.3 years ( 47 to 84 ) and a mean BMI of 28.6 kg/m(2 ) ( 20.2 to 40.8 ) .  The mean HKA angle was 178.9 ° ( 172.5 to 183.4 ) in the CI group and 178.2 ° ( 172.4 to 183.4 ) in the PSCG group ( p = 0.34 ) . Outliers were identified in 22 of 67 knees ( 32.8 % ) in the CI group and 19 of 59 knees ( 32.2 % ) in the PSCG group ( p = 0.99 ) . There was no significant difference in the clinical results ( p = 0.95 and 0.59 , respectively ) . Operating time , blood loss and length of hospital stay were not significantly reduced ( p = 0.09 , 0.58 and 0.50 , respectively ) when using PSCG . The use of PSCG in primary TKA did not reduce the proportion of outliers as measured by post-operative coronal alignment OBJECTIVE Rotation of femoral components could be optimized to improve function and durability of the knee joint . The purpose of the present study was to assess rotational alignment of femoral component comparing between CT-based , custom cutting blocks and the contemporary total knee arthroplasty , instrument technique . MATERIAL AND METHOD The prospect i ve control study of 80 patients underwent total knee arthroplasty by using PFC Sigma PS total knee design . Rotation offemoral component was analyzed in all patients using postoperative CT scan .  Forty patients were perfonned on by using CT-based , patient-specific cutting blocks with femoral rotational axis relative to transepicondylar axis while forty patients were performed on by using contemporaly instrumentation with alignment at 3 degrees external rotation from posterior condylar line . The rotation of the femoral component with external rotation ofmore than 3 degrees or internal rotation was considered outlier . RESULTS There was no statistically significant difference among ages , gender ; BMI , pre-operative mechanical axis between the two groups . There were eleven outliers in conventional group ( range , 5 degrees ofexternal rotation to 3 degrees of internal rotation ) , three femoral components were in excessive external rotation with the angle of more than 3 degrees and eight femnoral components were in internal rotation . In contrast with custom cutting block group was no outliers offemoral rotation . The average rotational alignment was 1.040 + /- 0.62 external rotation from epicondylar axis in custom cutting group and 1.58 + /- 1.750 in contemporary group . CONCLUSION Custom cutting , block technique significantly reduced the outlier of the femoral component rotation and aided in positioning of the femoral component in optimal alignment . The improvement of femoral rotation showed no difference in clinical outcome between the two groups
We found that there was no significant benefit from using PS instrumentation in primary knee arthroplasty to aid in the positioning of either the tibial or femoral components .
Furthermore sagittal plane tibial component positioning was worse in the PS than the traditional ST group .
Our results suggest that at present PS instrumentation is not superior to ST instrumentation in primary total knee arthroplasty .
OBJECTIVE The aim of this study was to review the radiological alignment outcomes of patient Specific ( PS ) cutting blocks and St and ard Instrumentation in Primary Total Knee Arthroplasty .
METHODS We hypothesized that the use of PS techniques would significantly improve sagittal , coronal and rotational alignment of the prosthesis on short term .