***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: A prospect i ve , r and omized , double-blind trial was carried out to compare  cruciate-retaining ( CR ) and posterior-stabilized ( PS ) total knee arthroplasties ( TKAs ) . A total of 40 knees were r and omized to receive either a NexGen CR ( Zimmer , Warsaw , IN ) or a Legacy PS ( Zimmer , Warsaw , IN ) TKA . All knees were implanted with identical surgical technique , making sure to balance precisely the flexion-extension gaps before implantation of the components . At 2-year follow-up , there was no difference between the CR and the PS TKAs with respect to their Knee Society clinical , functional , and radiographic scores . These findings suggest that with careful attention to surgical technique and balancing the knee , orthopaedic surgeons should expect similar results whether they use a CR or PS TKA We report the results of a prospect i ve r and omised trial which assessed the role of the posterior cruciate ligament ( PCL ) following  total knee replacement  ( Genesis I ; Smith and Nephew , Memphis , Tennessee ) . Over a four-year period , 211 patients underwent total knee replacement by the senior author ( TJW ) . They were r and omised at surgery to have the PCL either retained , excised or substituted with a posterior stabilised insert . If it was not possible to retain the ligament due to soft-tissue imbalance , it was released from its tibial insertion until suitable tension was obtained . This created a fourth group , those who were intended preoperatively to have the ligament retained , but in whom it was partially released as a result of findings at the time of surgery . All patients were evaluated using the Knee Society rating system ( adapted from Insall ) . A total of 188 patients ( 212 knees ) was available for follow-up at a mean of 3.5 years after surgery . Preoperatively , there was a varus deformity in 191 knees ( 90 % ) and a valgus deformity in 21 ( 10 % ) . There were no statistical differences in the knee or function scores or the range of movement between the excised , retained and substituted groups . There were , however , significantly worse knee and function scores in the group in whom the PCL was released ( p = 0.002 ) Abstract Purpose Posterior-cruciate-ligament-retaining ( PCR ) and posterior-cruciate-ligament-stabilized ( PS ) arthroplasties are two major common practice s in total knee arthroplasty ( TKA ) . The hypothesis of the present study was that compared with the PCR technique , the PS technique is associated with a higher amount of postoperative blood loss and greater need for blood transfusion in cemented TKA . Methods In this prospect i ve , r and omized study , 100 patients diagnosed with primary knee osteoarthritis were r and omly assigned to either the PCR group ( Group I ) or the PS group ( Group II ) . The exclusion criteria were rheumatological joint disease , previous knee surgery , anticoagulant therapy and hypertension . There were no significant differences in age , body mass index and gender , between the groups . The haemoglobin and haematocrit levels of each patient were recorded preoperatively and on postoperative days 1 , 3 and 5 . The postoperative suction drainage and blood transfusion volumes were also recorded . Results There were no statistically significant differences in haemoglobin or haematocrit levels between the groups on postoperative days 1 , 3 and 5 . There were also no statistically significant differences in the total measured blood loss volume , postoperative drainage amounts or transfusion rates between the groups . Conclusion Use of the PS technique during cemented TKA does not appear to influence the amount of perioperative blood loss or the need for postoperative blood transfusion in general . The clinical relevance of this study is that the difference in blood loss between the PCR and PS techniques does not need to be considered by surgeons when performing TKA.Level of evidence The superiority between the posterior cruciate-retaining and the posterior cruciate-substituting design s still remains controversial . We performed a prospect i ve , r and omized control study for evaluation of the superiority of these design s. This study investigated 58 knees in 29 patients with simultaneous bilateral total knee arthroplasty , in which the high-flex CR design was r and omly implanted in one knee and the high-flex PS design was implanted in the other knee . The follow-up duration averaged 5.0 years , with a minimum duration of 3 years . Postoperatively , Knee Score and pain points in Knee Score result ed in no significant differences between the 2 design s. However , postoperative arc of range of motion , patient satisfaction , and posterior knee pain at passive flexion in the PS design were significantly superior to that of the CR design A prospect i ve , r and omized comparison of posterior cruciate-retaining ( PCR ) and posterior stabilized ( PS ) total knee arthroplasties ( TKAs ) was conducted in 20 patients who underwent bilateral TKAs for osteoarthritis . All procedures were performed by a single surgeon . One knee was implanted with a PCR TKA , and a contralateral knee with a PS TKA . Both prosthetic design s were of the same TKA series , with comparable surface geometries . Patients had a clinical and radiographic evaluation at a mean of 31.7 months for PCR TKAs and 30.6 months for PS TKAs postoperatively . There were no significant differences between the PCR and PS TKAs in postoperative knee scores . However , postoperative improvement in range of motion was significantly superior in the PS group Introduction This study focused on the change in the range of motion ( ROM ) during the perioperative period , i.e. , the preoperative and intraoperative ROM , and that on discharge , and compared the difference between  posterior cruciate ligament-retaining ( PCLR ) and -sacrificing ( PCLS ) prostheses .  Material s and methods In this prospect ively r and omized study , we compared the changes in the ROM in  PCLR ( n = 50 ) and PCLS ( n = 50 ) total knee arthroplasties . Results The mean flexion in PCLR prostheses was 130.0 ° preoperatively , 120.0 ° intraoperatively , and 105.0 ° at discharge , and 125.0 ° , 120.0 ° , and 100.0 ° , respectively , in PCLS . The design s did not differ statistically in each period ( P > 0.05 ) . Both design s showed significant correlations between the preoperative and intraoperative ROM , and between the preoperative and discharge ROM . Only the PCLS showed a significant correlation between the intraoperative and discharge ROM , and a significant difference was observed in correlation of rank coefficient between the two prostheses ( P < 0.001 ) . Conclusions The PCLS design has an advantage in rehabilitation planning because of the predictable changes in the ROM during the perioperative period , although the acquired average ROM at discharge did not differ statistically Purpose Although the patella reduced or everted position has recently been recognised as an important factor influencing soft tissue balance during assessment in total knee arthroplasty ( TKA ) , the influence of patella height on soft tissue balance has not been well addressed . Therefore , the relationship between soft tissue balance and patella height was investigated and differences between cruciate-retaining ( CR ) and posterior-stabilised ( PS ) TKA were compared . Methods Forty consecutive patients blinded to the type of implant received , were r and omised prospect ively . Using lateral radiographs , pre-operative patella height was measured . Using an offset-type tensor design ed to measure the soft tissue balance with a reduced patellofemoral ( PF ) joint and femoral component in place , soft tissue balance was intra-operatively assessed in CR TKA ( n = 20 ) and PS TKA ( n = 20 ) in osteoarthritic patients . The joint component gap and varus ligament balance at zero , ten , 45 , 90 and 135 ° of knee flexion with the patella reduced were measured . Results In PS TKA , the joint component gap positively correlated with patella height at 90 and 135 ° of knee flexion . However , there was no correlation between joint component gap and patella height at other flexion angles in PS TKA and any flexion angle in CR TKA . Varus ligament balance showed no significant correlation with patella height in either CR or PS TKA . Conclusion Analysis of soft tissue balance and patella height only showed a positive correlation in joint component gap at a high flexion angle ( 90 and 135 ° ) in PS TKA but not in other parameters examined . Pre-operative measurement of patella height may be an important factor for predicting an intra-operative flexion gap in PS TKA We performed a prospect i ve , r and omised trial of 44 patients to compare the functional outcomes of a posterior-cruciate-ligament-retaining and posterior-cruciate-ligament-substituting total knee arthroplasty  , and to gain a better underst and ing of the in vivo kinematic behaviour of both devices . At follow-up at five years , no statistically significant differences were found in the clinical outcome measurements for either design . The prevalence of radiolucent lines and the survivorship were the same . In a subgroup of 15 knees , additional image-intensifier analysis in the horizontal and sagittal planes was performed during step-up and lunge activity . Our analysis revealed striking differences . Lunge activity showed a mean posterior displacement of both medial and lateral tibiofemoral contact areas ( roll-back ) which was greater and more consistent in the cruciate-substituting than in the cruciate-retaining group ( medial p < 0.0001 , lateral p = 0.011 ) . The amount of posterior displacement could predict the maximum flexion which could be achieved ( p = 0.018 ) . Forward displacement of the tibiofemoral contact area in flexion during stair activity was seen more in the cruciate-retaining than in the cruciate-substituting group . This was attributed mainly to insufficiency of the posterior cruciate ligament and partially to that of the anterior cruciate ligament . We concluded that , despite similar clinical outcomes , there are significant kinematic differences between cruciate-retaining and cruciate-substituting arthroplasties BACKGROUND The effect of total knee arthroplasty on proprioception , kinesthesia , and postural control remains controversial . It is argued that retaining the posterior cruciate ligament may help to preserve these sensorimotor functions and improve the longevity of the prosthesis and the functional outcome . We performed a prospect i ve , r and omized study to assess proprioception , kinesthesia , and balance following total knee arthroplasty with cruciate-retaining and posterior stabilized prostheses .  METHODS Twenty patients scheduled to undergo total knee arthroplasty were r and omly assigned to receive either a cruciate-retaining or a posterior stabilized prosthesis .  Joint-position sense , the threshold to detect joint motion , and the subject 's ability to balance on an unstable platform were assessed prior to and at least six months after the operation . Paired two-tailed t tests ( with a level of significance of p < 0.05 ) were used to assess the effect of the arthroplasty on the preoperative measures for all subjects . Analysis of covariance was performed to identify the effects of prosthetic design . RESULTS Following total knee arthroplasty , patients detected motion significantly faster and reproduced joint position with less error . The balance index also improved significantly from the preoperative to the postoperative evaluation . The group treated with the posterior stabilized prosthesis more accurately reproduced joint position when the knee was extended from a flexed position . CONCLUSIONS Total knee arthroplasty results in mild improvements in proprioception , kinesthesia , and balance . These changes may result from the retensioned capsuloligamentous structures and reduced pain and inflammation . Retention of the posterior cruciate ligament does not appear to significantly improve proprioception and balance compared with those functions in patients with a posterior stabilized total knee design Background Little information exists to support that patients care about flexion beyond what is needed to perform activities of daily living ( ADL ) after Total knee arthroplasty ( TKA ) . The purpose of this study was to investigate if the achievement of a higher degree of knee flexion after TKA would result in a better patient perceived outcome . Methods The study is a r and omized , double-blinded , controlled trial in which 36 patients ( mean age : 67.2 yrs ) undergoing one-stage bilateral TKA r and omly received a  st and ard cruciate-retaining ( CR ) TKA in one knee and a high-flex posterior-stabilized ( PS ) TKA in the contra lateral knee . At follow-up ROM , satisfaction , pain , “ feel ” of the knee and the abilities in daily activities were assessed . Results At 1-year follow-up we found an expected significantly higher degree of knee flexion of 7 ° in the high-flex knees ( p = 0.001 ) . The high-flex TKA ’s showed a mean active flexion of 121 ° . In both TKA ’s the median VAS pain score was 0 , the median VAS satisfaction score was 9 , and the median VAS score of the patient “ feel ” of the knee was 9 at 1-year follow-up . Further , there were no significant differences between the knees in the performance of daily activities . Conclusions As expected the high-flex TKA showed increased knee flexion , but no significant differences in the patient perceived outcomes were found . This suggests little relevance to the patients of the difference in knee flexion – when flexion is of this magnitude – as pain free ROM and high patient satisfaction were achieved with both TKA’s . Trial registration Clinical Trials.gov : Purpose The purpose of this study is to investigate whether the preservation of the posterior cruciate ligament ( PCL ) 
    Output:
    
Interpretation We found no clinical ly relevant differences between retention and sacrifice of the PCL in TKA , in terms of functional and clinical outcomes .
Based on the current evidence , no recommendation can be made as to whether to retain or to sacrifice the PCL