***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 A group of patients with a preoperative varus contracture of at least 15 ° underwent total knee replacement with retention of the posterior cruciate ligament .  Their outcomes at 10 years were compared with a group of patients with similar contractures in whom a posterior stabilized implant was used , and to a group of patients in whom there was no contracture . In the contracture group where the posterior cruciate ligament was retained , there was an increased incidence of pain , an increased incidence of bone cement radiolucencies , and a decrease in the eventual flexion arc . There was likewise an increased revision rate and a decreased survivorship . In patients with such contractures , the posterior cruciate ligament is a part of the deformity ; the deformity can not be corrected by medial release procedures alone . All these results suggest that for the patient with a fixed varus contracture a posterior cruciate release should be performed and a posterior stabilized type of implant used 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 ) 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 This study evaluated factors affecting range of motion at 24 months in 782 total knee arthroplasties ( TKAs ) performed between 1983 and 1987 in a nonr and omized , multicenter clinical trial by 17 independent surgeons . A mobile bearing prosthesis was used with either a posterior cruciate ligament (PCL)-retaining or PCL-sacrificing technique . Age and gender did not reveal any differences in outcome . For individual surgeons , the outcome was highly variable and did not reflect the number of cases performed . Postoperative range of motion was greater for the PCL-retaining implant ; however , there was also a significant difference in the preoperative motion compared with the PCL-sacrificing device .  Postoperative motion improved from preoperative for the whole group . Preoperative motion groups of < 90 degrees gained 28 degrees , 90 degrees to 105 degrees gained 15 degrees , and > 105 degrees lost 1 degree . The change in motion for patients without prior surgery was greater than for those with prior surgery The aim of this study was to compare 2 total knee arthroplasty ( TKA ) design s radiologically to determine if a posterior cruciate ligament (PCL)-substituting design led to a built-in error of elevation of the joint line postoperatively . The restoration of the true joint line is a goal in primary TKA , although its effect on outcome has not been established fully . A total of 47 patients had 56 TKAs performed by 2 surgeons using either the Howmedica Kinemax Plus ( Rutherford , NJ ) PCL-retaining or PCL-substituting TKAs .  The patients were r and omized to receive one of these design s , and the height of the joint line was assessed radiographically preoperatively and postoperatively . The joint line position preoperatively averaged 2.2 cm from the tibial tuberosity and postoperatively averaged 2.4 cm ( PCL substituting ) and 2.5 cm ( PCL sparing ) . No difference in the thickness of the polyethylene insert used was seen with either design . The theoretical elevation of the joint line that occurs with the sacrifice of the PCL was not found to occur radiologically 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 Range of motion is a crucial measure of outcome after total knee arthroplasty . In order for maximum flexion to occur , the femur must progressively shift posteriorly on the tibia , a movement that is known as femoral rollback . Mobile bearings with free anterior-posterior translation could improve knee flexion by allowing such motion . The purpose of the present study was to determine the influence of an anterior-posterior gliding mobile bearing on the postoperative range of knee motion in patients with an intact posterior cruciate ligament . METHODS We performed a prospect i ve , r and omized clinical trial of fifty consecutive total knee arthroplasties that were performed with use of the LCS-Universal prosthesis . Participants were r and omized to receive either a deep-dish rotating platform or a mobile bearing that allowed additional anterior-posterior translation , the latter of which requires an intact posterior cruciate ligament . The ranges of motion of the knees were assessed to detect a 15 degrees difference in the active non-weight-bearing range of motion with a power ( 1 - beta ) of 20 % and with the level of significance ( alpha ) set at 0.05 . The translation of the mobile bearing was measured with use of a st and ardized ultrasound technique and was correlated with maximum knee flexion . The participants and the assessor were blinded throughout the study . RESULTS At the time of the one-year follow-up evaluation , forty-eight knees were available for an intention-to-treat analysis . The mean active non-weight-bearing range of motion at one year was 113 degrees ( 95 % confidence interval , 108 degrees to 118 degrees ) in the twenty-six knees that had received a rotating platform and 111 degrees ( 95 % confidence interval , 115 degrees to 125 degrees ) in the twenty-two knees that had received an anterior-posterior gliding bearing ( p = 0.57 ) . In the latter group , a continuous rollback occurred in two knees . There was no significant correlation between knee flexion and anterior-posterior translation ( r(2 ) = 0.015 ) . CONCLUSIONS The use of a mobile bearing that allowed free anterior-posterior translation did not regularly restore femoral rollback and did not improve range of motion after total knee arthroplasty compared with the findings seen in association with the use of a rotating platform Abstract : The objective of this study was to measure three-dimensional knee motion during gait in patients with total knee replacements which either retained the posterior cruciate ligament ( n = 11 ) , or required sacrifice of the posterior cruciate ligament and replacement of its function with a posterior stabilizing articular surface ( n = 9 ) . Clinical ly meaningful translations ( anterior and posterior , medial and lateral , proximal and distal ) and rotations ( flexion and extension , internal and external rotation , abduction and adduction ) were measured using an instrumented spatial linkage . Although patients from both groups were able to achieve passive full extension and a minimum of 95 ° flexion , some of their translations and rotations during free speed walking were consistently less than those in a group of healthy controls . Motion during the swing phase of gait was similar for both knee replacement groups . However , abduction and adduction and proximal and distal translation were larger ( but neither difference was significant ) for the patients with implants with a posterior stabilizing surface , which suggests that the stabilizing surface may not reliably provide as much stability in these directions as does retention of the posterior cruciate ligament A systematic review of the literature will fail to provide information needed for evidence -based medicine ( EBM ) if the design , execution and reporting of individual trials do not adhere to strict guidelines . Experience gained while conducting systematic literature review s have revealed serious shortcomings in current literature . These limitations pertain to r and omisation , blinding , outcome assessment s and data reporting . The principles related to these issues are discussed with solutions and improvements provided We r and omised 129 knees which were to be replaced using a st and ard posterior-cruciate-ligament (PCL)-retaining cemented total knee replacement  into two groups . In one the PCL was retained in the normal way and in the other it was resected .  They were well matched , with a predominance of women , and a mean age of 67 years . There was no statistically significant difference in the Hospital for Special Surgery scores at a mean of 57 months ( 56 to 60 ) between the two groups although 21 patients ( 24 knees ) were lost to follow-up . Relief from pain , correction of deformity , range of movement , stability and strength were comparable in both . Radiological assessment showed femoral rollback in approximately 20 % of knees with a slightly higher incidence in the PCL-resected group . There was no significant loosening detected in either group at review at two years . At five years , one knee in the PCL-retained group had been revised because of infection and one patient in each group was awaiting revision for loosening . Our findings have shown no significant difference in the five-year results for a PCL-retaining total knee replacement if the PCL is excised or preserved . This suggests two important points . First , the PCL is not functional in most patients with a total knee replacement even when retained . Secondly , patients with an excised PCL show a good result with a PCL-retaining implant , thereby question ing the need for a posterior stabilised design in such a situation A r and omized controlled study was done to compare the clinical , radiographic , and quality of life outcomes between  posterior-stabilized and cruciate-retaining primary total knee implants . One hundred forty-three patients were enrolled in the study . Patients ranged in age from 57 to 89 years , had a primary diagnosis of osteoarthritis , and an intact functioning posterior cruciate ligament . Patients were excluded if they had a flexion contracture greater than 15 ° , a varus deformity greater than 20 ° , or a valgus deformity greater than 15 ° . Patients were r and omized to one of two study groups ,  posterior-stabilized AMK total knee implants (  76 patients )  or cruciate-retaining AMK total knee implants ( 67 patients ) . One hundred eight patients have had 
    Output:
    
We conclude that there is , so far , no solid base for the decision to either retain or sacrifice the PCL with or without use of a posterior stabilized design  during total knee arthroplasty .