title: Slight undercorrection following total knee arthroplasty results in superior clinical outcomes in varus knees Does A Kinematically Aligned Total Knee Arthroplasty Restore Function Without Failure Regardless of Alignment Category? Patient-specific instrumentation improves tibial component rotation in TKA 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 The Quality of Reporting of Randomized Trials in The Journal of Bone and Joint Surgery from 1988 through 2000 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. In-vivo alignment comparing patient specific instrumentation with both conventional and computer assisted surgery (CAS) instrumentation in total knee arthroplasty. The radiological outcomes of patient-specific instrumentation versus conventional total knee arthroplasty Patient-specific total knee arthroplasty: the importance of planning by the surgeon Patient specific cutting blocks are currently of no proven value. 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: Purpose Restoration of correct alignment is one of the main objectives of total knee arthroplasty ( TKA ) . However , the influence of residual malalignment on clinical and functional outcomes is currently uncertain . This study was therefore undertaken to ascertain its influence in patients undergoing TKA for varus osteoarthritis of the knee . Methods A cohort of 132 consecutive patients ( 143 knees ) with pre-operative varus alignment was evaluated with a mean follow-up period of 7.2 years . Based upon the post-operative alignment , patients were stratified into three groups : neutral , mild varus , and severe varus . These groups were compared with respect to clinical and functional outcomes . Results All patients had post-operative improvements in Knee Society Score ( KSS ) . Knees that were left in mild varus scored significantly better for the KSS and the Western Ontario and McMaster Universities Arthritis Index , compared with knees that were corrected to neutral and knees that were left in severe varus exceeding 6 ° . No revisions occurred in any of the groups at midterm follow-up . Conclusion The results of this study contradict the conventional assumption that correction to neutral mechanical alignment leads to the best outcome following TKA . Patients with pre-operative varus had better clinical and functional outcome scores if the alignment was left in mild varus , as compared with patients with an alignment correction to neutral . Level of evidence Therapeutic study , Level III Background Kinematically aligned TKA restores function by aligning the femoral and tibial components to the normal or prearthritic joint lines of the knee . However , aligning the components to the joint lines of the normal knee also aligns the tibial component in varus , creating concern that varus alignment might result in poor function and early catastrophic failure . Questions / Purpose sWe therefore determined whether function and the incidence of catastrophic failure were different when the tibial component , knee , and limb alignment were in a specified normal range , varus outlier , or valgus outlier . Methods We prospect ively followed all 198 patients ( 214 knees ) who underwent TKAs between February and October 2008 . We treated each knee in this cohort of patients with a kinematically aligned , cruciate-retaining prosthesis implanted using patient-specific guides . From a long-leg scanogram , we measured and categorized alignment of the tibial component as in range ( ≤ 0 ° ) or a varus outlier ( > 0 ° ) , alignment of the knee as in range ( between −2.5 ° to −7.4 ° valgus ) or a varus ( > −2.5 ° ) or valgus ( < −7.4 ° ) outlier , and alignment of the limb as in range ( 0 ° ± 3 ° ) or a varus ( > 3 ° ) or valgus ( < −3 ° ) outlier . We assessed function using the Oxford Knee Score and WOMAC ™ score , and reported catastrophic failure as the incidence of revision attributable to loosening , wear , and instability of the femoral or tibial components . The minimum followup was 31 months ( mean , 38 months ; range , 31–43 months ) . Results The mean Oxford Knee Score of 43 and WOMAC ™ score of 92 were similar between the three alignment categories . The incidence of catastrophic failure in each alignment category was zero . Conclusions Kinematically aligned TKA restores function without catastrophic failure regardless of the alignment category . Because 75 % of patients had their tibial component categorized as a varus outlier and also had high function and a zero incidence of catastrophic failure , the concern that kinematic alignment compromises function and places the components at a high risk for catastrophic failure is unfounded and should be of interest to surgeons committed to cutting the tibia perpendicular to the mechanical axis of the tibia . Level of Evidence Level IV , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence Purpose To compare the femoral and tibial components rotational alignment in total knee arthroplasty ( TKA ) performed either with conventional or with patient-specific instrumentation . Methods Forty-five patients underwent primary TKA and were prospect ively r and omized into two groups : 22 patients into the conventional instrumentation group ( group A ) and 23 patients into the Signature ™ patient-specific instrumentation group ( group B ) . All patients underwent computed tomography of the operated knee in the first week after surgery to measure  the components rotation . Results The femoral component rotation was 0.0 ° ( −0.25 , 1.0 ) in group A , and 0.0 ° ( 0.0 , 1.0 ) in group B. The tibial component rotation was −16.0 ° ( −18.5 , 11.8 ) in group A , and −16.0 ° ( −19.0 , −14.0 ) in group B. There were no significant differences between the two groups in tibial and femoral components rotation . The difference between the tibial component rotation and the neutral tibial rotation was similar in both groups [ 2.0 ° ( −0.5 , 6.3 ) in group A and 2.0 ° ( −1.0 , 4.0 ) in group B ] , but the dispersion around the median was different between the two groups . The amplitude of the difference between tibial rotation and neutral position was 27 ° ( −13 , 14 ) in group A and 9 ° ( −3 , 6 ) in group B. Conclusions There is a smaller chance of internal malrotation of the tibial component with the Signature ™ patient-specific instrumentation system , with less dispersion and amplitude of the tibial component rotation around the neutral position . Level of evidence II 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 : The purpose of this study was threefold : ( 1 ) to determine the scientific quality of published r and omized trials in the American Volume of The Journal of Bone and Joint Surgery from 1988 through 2000 , ( 2 ) to identify predictors of study quality , and ( 3 ) to evaluate inter-rater agreement in the scoring of study quality with use of a simple scale . Methods : H and search es of The Journal of Bone and Joint Surgery were conducted in duplicate to identify r and omized clinical trials . Of 2468 studies identified , seventy-two ( 2.9 % ) met all eligibility criteria . Two investigators each assessed the quality of the study under blinded conditions and abstract ed relevant data . Results : The mean score ( and st and ard error ) for the quality of the seventy-two r and omized trials was 68.1 % ± 1.6 % ; 60 % ( forty-three ) scored < 75 % . Drug trials had a significantly higher mean quality score than did surgical trials ( 72.8 % compared with 63.9 % , p < 0.05 ) . Regression analysis revealed that cited affiliation with an epidemiology department and cited funding were associated with higher quality scores . Failure to conceal r and omization , to blind outcome assessors , and to describe why patients were excluded result ed in significantly lower quality scores ( p < 0.05 ) , more than the 5 % decrease expected by removal of each item . A priori calculations of sample size were rarely performed in the review ed studies , and only 2 % of the studies with negative results included a post hoc power analysis . The Detsky quality scale met accepted st and ards of interobserver reliability ( kappa , 0.87 ; 95 % confidence interval , 0.70 to 0.95 ) . Conclusions : Few studies published in The Journal of Bone and Joint Surgery were r and omized trials . More than half of the trials were limited by a lack of concealed r and omization , lack of blinding of outcome assessors , or failure to report reasons for excluding patients . Application of st and ardized guidelines for the reporting of clinical trials in orthopaedics should improve quality 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 Patient specific instrumentation ( PSI ) was developed to increase total knee arthroplasty ( TKA ) accuracy and efficiency . The study purpose was to compare immediate post-operative mechanical alignment , achieved using PSI , with conventional and computer assisted surgery ( CAS ) instruments in high volume TKA practice s. This prospect i ve , multicenter , non-r and omized study accrued 66 TKA patients using PSI .  A computed tomography ( CT ) based algorithm was used to develop the surgical plan . Sixty-two percent were females , 99 % were diagnosed with osteoarthritis , average age at surgery was 66 years , and 33 was the average body mass index . A historical control group was utilized that underwent TKA using conventional instruments ( n=86 ) or CAS ( n=81 ) , by the same set of surgeons . Postoperative mechanical alignment was comparable across the groups . Operative time mean and variance were significant 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 Abstract Purpose The purpose of the study was to evaluate the accuracy of the planning of the patient-specific pin guides in total knee arthroplasty ( TKA ) . This planning was performed primarily by a technician of the company and offered to the surgeon . All parameters of the implantation can either be modified or accepted by the surgeon . The hypothesis was that the plan needs preoperative intervention by the surgeon . Methods A prospect i ve study in 50 patients was carried out . All patients received the same posterior-stabilised implant with patient-specific instrumentation . All surgical parameters ( coronal , sagittal , rotational alignment , femoral and tibial resection levels and implant sizes ) were checked by the orthopaedic surgeon and changed if necessary . Results Preoperatively , the femoral size was changed in 8 patients ( 16 % ) , the femoral flexion in 23 patients ( 46 % ) , the femoral shift in 34 patients ( 68 % ) , the tibial size in 24 patients ( 48 % ) and the tibial rotation in all patients . The epicondylar axis was accepted in 47 patients ( 94 % ) in the technician plan . Mean planning time was 8 ± 4 min . Intraoperatively , the femoral anterior – posterior size was in 50 patients ( 100 % ) the same as in the surgeon and in 42 patients ( 84 % ) the same as in the technician plan ( p = 0.003 ) . The tibial component implanted was in 42 patients ( 84 % ) the same as in the surgeon and in 19 patients ( 38 % ) the same as in the technician plan ( p < 0.0001 ) . A femoral distal recut was necessary in 31 patients ( 62 % ) and a change of the tibial proximal cut in 17 patients ( 34 % ) during surgery . Intraoperatively , no changes of the femoral and tibial alignment , the femoral anterior – posterior size , the femoral flexion , the femoral shift , the femoral and tibial rotation were necessary . Postoperatively , the coronal mechanical overall axis was within ±3 ° in 47 patients ( 94 % ) with a maximum deviation of 5.6 ° . Conclusions Significant changes of the technician plan were necessary to get an accurate preoperative plan . Intraoperative changes were significant less compared to the surgeon than to the technician plan . No major changes ( alignment , femoral anterior – posterior size and rotation ) of the surgeon plan were necessary . Surgeons using patient-specific pin guides in TKA may verify the default plan provided by the technician . A blind reply on the technician plan may be not recommended . Level of evidence Therapeutic study , Level III Patient specific cutting guides generated by preoperative Magnetic Resonance Imaging ( MRI ) of the patient 's extremity have been proposed as a method of improving the consistency of Total Knee Arthroplasty ( TKA ) alignment and adding efficiency to the operative procedure . The cost of this option was evaluated by quantifying the savings from decreased operative time and instrument processing costs compared to the additional cost of the MRI and the guide .  Coronal plane alignment was measured in an unselected consecutive series of 200 TKAs , 100 with st and ard instrumentation and 100 with custom cutting guides .  While the cutting guides had significantly lower total operative time and instrument processing time , the estimated $ 322 savings was overwhelmed by the $ 1,500 additional cost of the MRI and the cutting guide . All measures of coronal plane alignment were equivalent between the two groups . The data does not currently support the proposition that patient specific guides add value to TKA 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 conclude that PSI does not improve the accuracy of alignment of the components in TKR compared with conventional instrumentation
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