title: Rotation in total knee arthroplasty: no difference between patient-specific and conventional instrumentation Patient-specific Guides Do Not Improve Accuracy in Total Knee Arthroplasty: A Prospective Randomized Controlled Trial Component alignment during total knee arthroplasty with use of standard or custom instrumentation: a randomized clinical trial using computed tomography for postoperative alignment measurement. Intra-operative results and radiological outcome of conventional and patient-specific surgery in total knee arthroplasty: a multicentre, randomised controlled trial Patient-specific instrumentation does not shorten surgical time: a prospective, randomized trial. Patient-specific computed tomography based instrumentation in total knee arthroplasty: a prospective randomized controlled study Coronal alignment correlates with outcome after total knee arthroplasty: five-year follow-up of a randomized controlled trial. Small Improvements in Mechanical Axis Alignment Achieved With MRI versus CT-based Patient-specific Instruments in TKA: A Randomized Clinical Trial A comparison of patient-specific and conventional instrumentation for total knee arthroplasty: a multicentre randomised controlled trial. The accuracy of component alignment in custom cutting blocks compared with conventional total knee arthroplasty instrumentation: prospective control trial. A prospective randomised controlled study of patient-specific cutting guides compared with conventional instrumentation in total knee replacement. Is TKA Using Patient-specific Instruments Comparable to Conventional TKA? A Randomized Controlled Study of One System
abstract: Abstract Purpose It was our hypothesis that patient-specific instrumentation ( PSI ) can improve the accuracy of the rotational alignment in TKA based on the concept of the system and on the potential to clearly identify pre-operatively during planning the classical anatomical l and marks that serve as references to set-up the rotation both for the femur and tibia . Material s and methods In this prospect i ve comparative r and omized study , 40 patients ( 20 in each group ) operated in our institution between September 2012 and January 2013 by the 2 senior authors were included . R and omization of patients into one of the two groups was done by the Hospital Informatics Department with the use of a systematic sampling method . All patients received the same cemented high-flex mobile bearing TKA . In the PSI group , implant position was compared to the planed position using previously vali date d dedicated software . The position of the implants ( frontal and sagittal ) was compared in the 2 groups on st and ard X-rays , and the rotational position was analysed on post-operative CT-scan . Results 90 % of the patients add < 2 ° or mm of difference between the planned position of the implants and the obtained position , except for the tibial rotation where the variations were much higher . Mean HKA was 179 ° ( 171–185 ) in the PSI group with 4 outliers ( 2 varus : 171 ° and 172 ° :184 ° and 185 ° ) and 178.3 ° with 2 outliers ( 171 ° and 176 ° ) in the control group . No difference was observed between the two groups concerning the frontal and sagittal position of the implants on the ML and AP X-rays . No significant difference of femoral rotation was observed between the two groups with a mean of 0.4 ° in the PSI group and 0.2 ° in the control group ( p : n.s ) . Mean tibial rotation was 8 ° of internal rotation in the PSI group and 15 ° of internal rotation in the st and ard group ( p : n.s ) . Conclusion Based on our results , we were unable to confirm our hypothesis as PSI can not improve rotation in TKA . More work needs to be done to more clearly define the place of PSI in TKA , to keep on improving the accuracy of the system and to better define the individual targets in TKA in terms of frontal , sagittal and rotational positioning of the implant for each patient . Level of evidence Prospect i ve comparative r and omized study , Level II 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 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 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 The primary purpose of this prospect i ve , r and omized study was to determine if patient-specific instrumentation ( PSI ) for total knee arthroplasty ( TKA ) shortened surgical time . Secondarily the number of instrument trays and alignment were also compared to cases performed with traditional instrumentation ( TI ) .  Fifty-two cases ( 26 per group ) were r and omized and videotaped to measure the length of surgery , as well as each individual surgical step . Component alignment and mechanical axis was measured radiographically for each patient . Total surgical time was over 4 minutes shorter for patients in the TI group ( 57.4 minutes vs. 61.8 minutes ; P<0.01 ) . More instrument trays were used in the TI group ( 7.3 vs. 2.5 ; P<0.001 ) . There was no significant difference in mechanical alignment between groups on postoperative long alignment radiographs ( P=0.77 ) . In conclusion , PSI did not shorten surgical time or improve alignment compared with TI in this prospect i ve , r and omized trial , but did reduce the required number of trays 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 In a prospect i ve r and omized control trial comparing computer-assisted vs conventional total knee arthroplasty  , we previously reported that patients with coronal alignment within 3 ° of neutral had superior international knee society and Short-Form 12 ( SF-12 ) physical scores at 6 weeks , 3 months , 6 months , and 12 months after surgery . Computer-assisted total knee arthroplasty achieved greater accuracy in implant alignment , and this correlated with better knee function and quality of life . At 5 years , 90 of 111 patients assessed in our original study were review ed . Coronal alignment within 3 ° of neutral continued to be correlated with superior International Knee Society and SF-12 scores . Coronal alignment greater than 3 ° was associated with a significant decline in SF-12 mental health scores Background Patient-specific instrumentation in TKA has the proposed benefits of improving coronal and sagittal alignment and rotation of the components . In contrast , the literature is inconsistent if the use of patient-specific instrumentation improves alignment in comparison to conventional instrumentation . Depending on the manufacturer , patient-specific instrumentation is based on either MRI or CT scans . However , it is unknown whether one patient-specific instrumentation approach is more accurate than the other and if there is a potential benefit in terms of reduction of duration of surgery . Questions / purpose sWe compared the accuracy of MRI- and CT-based patient-specific instrumentation with conventional instrumentation and with each other in TKAs . The three approaches also were compared with respect to vali date d outcomes scores and duration of surgery . Methods A r and omized clinical trial was conducted in which 90 patients were enrolled and divided into three groups :  CT-based , MRI-based patient-specific instrumentation , and conventional instrumentation . The groups were not different regarding age , male/female sex distribution , and BMI . In all groups , coronal and sagittal alignments were measured on postoperative st and ing long-leg and lateral radiographs . Component rotation was measured on CT scans . Clinical outcomes ( Knee Society and WOMAC scores ) were evaluated preoperatively and at a mean of 3 months postoperatively and the duration of surgery was analyzed for each patient . MRI- and CT-based patient-specific instrumentation groups were first compared with conventional instrumentation , the patient-specific instrumentation groups were compared with each other , and all three approaches were compared for clinical outcome measures and duration of surgery . Results Compared with conventional instrumentation MRI- and CT-based patient-specific instrumentation showed higher accuracy regarding the coronal limb axis ( MRI versus conventional , 1.0 ° [ range , 0 ° –4 ° ] versus 4.5 ° [ range , 0 ° –8 ° ] , p < 0.001 ; CT versus conventional , 3.0 ° [ range , 0 ° –5 ° ] versus 4.5 ° [ range , 0 ° –8 ° ] , p = 0.02 ) , femoral rotation ( MRI versus conventional , 1.0 ° [ range , 0 ° –2 ° ] versus 4.0 ° [ range , 1 ° –7 ° ] , p < 0.001 ; CT versus conventional , 1.0 ° [ range , 0 ° –2 ° ] versus 4.0 ° [ range , 1 ° –7 ° ] , p < 0.001 ) , and tibial slope ( MRI versus conventional , 1.0 ° [ range , 0 ° –2 ° ] versus 3.5 ° [ range , 1 ° –7 ° ] , p < 0.001 ; CT versus conventional , 1.0 ° [ range , 0 ° –2 ° ] versus 3.5 ° [ range , 1 ° –7 ° ] , p < 0.001 ) , but the differences were small . Furthermore , MRI-based patient-specific instrumentation showed a smaller deviation in the postoperative coronal mechanical limb axis compared with CT-based patient-specific instrumentation ( MRI versus CT , 1.0 ° [ range , 0 ° –4 ° ] versus 3.0 ° [ range , 0 ° –5 ° ] , p = 0.03 ) , while there was no difference in femoral rotation or tibial slope . Although there was a significant reduction of the duration of surgery in both patient-specific instrumentation groups in comparison to conventional instrumentation ( MRI versus conventional , 58 minutes [ range , 53–67 minutes ] versus 76 minutes [ range , 57–83 minutes ] , p < 0.001 ; CT versus conventional , 63 minutes [ range , 59–69 minutes ] versus 76 minutes [ range , 57–83 minutes ] , p < .001 ) , there were no differences in the postoperative Knee Society pain and function and WOMAC scores among the groups . Conclusions Although this study supports that patient-specific instrumentation increased accuracy compared with conventional instrumentation and that MRI-based patient-specific instrumentation is more accurate compared with CT-based patient-specific instrumentation regarding coronal mechanical limb axis , differences are only subtle and of question able clinical relevance . Because there are no differences in the long-term clinical outcome or survivorship yet available , the widespread use of this technique can not be recommended . Level of Evidence Level I , therapeutic study . See the Instructions to Authors for a complete description of levels of evidence 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 BACKGROUND The purpose of this study was to assess whether custom cutting blocks improve accuracy of component alignment compared to conventional TKA instrumentation . METHODS Eighty primary TKA patients were enrolled in an open-label r and omized prospect i ve clinical trial and were divided into two groups , 40 custom cutting blocks and 40 conventional TKA instrumentations . The primary outcome was prosthetic alignment with respect to mechanical axis and epicondylar axis . Secondary outcomes included operative time , 24-hour postoperative blood loss and hemoglobin at discharged . RESULTS There were no statistical significant differences in the postoperative mechanical axis between the custom cutting blocks group and conventional TKA group , ( 95 % vs. 87.5 % within 3 ° of neutral mechanical alignment , p=0.192 ) . The average rotational alignment was statistically significantly different in the custom cutting blocks group ( 1.0 ° ±0.6 ° vs. 1.6 ° ±1.8 ° external rotation from epicondylar axis , p<0.001 ) . There were statistical significant differences in operation time  between custom cutting blocks group and conventional group , skin to skin [ 57.5±2.3 min vs. 62.1±1.5 , p<0.001 ] . We found an improvement in group 1 compared with group 2 regarding the proportion of patients with postoperative blood loss within 24 h. CONCLUSIONS Custom cutting blocks technique was a surgical procedure which provided better accuracy in rotational alignment but no statistical differences in mechanical axis , less operative time and reduced blood loss  than the conventional TKA instrumentation in the majority of patients Patient-specific cutting guides ( PSCGs ) are design ed to improve the accuracy of alignment of total knee replacement ( TKR ) . We compared the accuracy of limb alignment and component positioning after  TKR  performed using PSCGs or conventional instrumentation . A total of 80 patients were r and omised to undergo TKR with either of the different forms of instrumentation , and radiological outcomes and peri-operative factors such as operating time were assessed . No significant difference was observed between the groups in terms of tibiofemoral angle or femoral component alignment . Although the tibial component in the PSCGs group was measurably closer to neutral alignment than in the conventional group , the size of the difference was very small ( 89.8 ° ( sd 1.2 ) vs 90.5 ° ( sd 1.6 ) ; p = 0.030 ) . This new technology slightly shortened the bone-cutting time by a mean of 3.6 minutes ( p < 0.001 ) and the operating time by a mean 5.1 minutes ( p = 0.019 ) , without tangible differences in post-operative blood loss ( p = 0.528 ) or need for blood transfusion ( p = 0.789 ) . This study demonstrated that both PSCGs and conventional instrumentation  restore limb alignment and place the components with the similar accuracy . The minimal advantages of PSCGs in terms of consistency of alignment or operative time are unlikely to be clinical ly relevant Background Patient-specific CT-based instrumentation may reduce implant malpositioning and improve alignment in TKA . However , it is not known whether this innovation is an advance that benefits patients . Questions / purpose sWe evaluated ( 1 ) the precision of  patient-specific TKA by comparing the incidence of outliers in postoperative alignment between TKAs using  patient-specific instruments  and TKAs using conventional instruments , and ( 2 ) the reliability of patient-specific instruments by intraoperatively investigating whether the surgery could be completed with patient-specific instruments alone . Methods In this r and omized controlled trial , we compared  patient-specific TKA instruments from one manufacturer ( n = 50 ) with conventional TKA instruments ( n = 50 ) . Postoperative hip-knee-ankle angles , femoral component rotation , and coronal and sagittal alignments of each component were measured . The validity of the patient-specific instrument was examined using cross-checking procedures with conventional instruments during the surgeries . When the procedure could not be completed accurately with patient-specific instruments , the procedure was converted to TKA using conventional instruments , and the frequency of this occurrence was tallied . Results Outliers in the hip-knee-ankle angle were comparable between groups ( 12 % in the patient-specific instrument group and 10 % in the conventional instrument group ) . Other parameters such as sagittal alignment and femoral component rotation did not differ in terms of outliers . Patient-specific guides were ab and oned in eight knees ( 16 % ) during the surgery because of malrotation of the femoral components and decreased slope of the tibia . Conclusions Accuracy was comparable between TKAs done with patient-specific instruments and those done with conventional instruments . However , the patient-specific instrument procedures had to be aborted frequently , incurring expenses that did not benefit patients .Level of Evidence Level II , therapeutic study . See Instructions for Authors for a complete description of levels of evidence
target: 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 .
background: 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 .