***TASK*** the task is to summarize an input biomedical literature in six sentences 
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    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: Background The primary purpose of this r and omized controlled trial ( RCT ) was to compare knee-specific outcomes ( stiffness , pain , function ) between patellar retention and resurfacing up to 10 years after primary total knee arthroplasty ( TKA ) . Secondarily , we compared re-operation rates . Methods 38 subjects with non-inflammatory arthritis were r and omized at primary TKA surgery to receive patellar resurfacing ( n = 21 ; Resurfaced group ) or to retain their native patella ( n = 17 ; Non-resurfaced group ) . Evaluations were performed preoperatively , one , five and 10 years postoperatively by an evaluator who was blinded to group allocation . Self-reported knee-specific stiffness , pain and function , the primary outcomes , were measured by the Western Ontario McMaster Osteoarthritis Index ( WOMAC ) . Revision rate was determined at each evaluation and through hospital record review . Results 30 ( 88 % ) and 23 ( 72 % ) of available subjects completed the five and 10-year review respectively . Knee-specific scores continued to improve for both groups over the 10-years , despite diminishing overall health with no significant group differences seen . All revisions occurred within five years of surgery ( three Non-resurfaced subjects ; one Resurfaced subject ) ( p = 0.31 ) . Two revisions in the Non-resurfaced group were due to persistent anterior knee pain . Conclusions We found no differences in knee-specific results between groups at 5–10 years postoperatively . The Non-resurfaced group had two revisions due to anterior knee pain similar to rates reported in other studies . Knee-specific results provide useful postoperative information and should be used in future studies comparing patellar management strategies . Clinical Trials.gov During a two-year period , eighty-nine patients who were scheduled to have a total knee arthroplasty for the treatment of degenerative osteoarthrosis were r and omly assigned to one of two groups : resurfacing of the patella or retention of the patella . All patients received the same  posterior cruciate-sparing prosthesis  , and all operations were performed by , or under the direct supervision of , one of us . Three patients died in the early postoperative period . The remaining eighty-six patients ( 118 knees ; fifty-eight that had had resurfacing of the patella and sixty that had not ) formed the study group . They were followed for a mean of thirty months ( range , twenty-four to forty-four months ) . Evaluation was performed with use of the clinical scoring system of The Knee Society , a patient-satisfaction question naire , specific questions regarding patellofemoral symptoms and function , and radiographs . All clinical evaluations were performed by the same research nurse , without the involvement of a physician , in a blinded manner ( neither the nurse nor the patient had knowledge of whether the patella had been resurfaced ) . Preoperatively , the mean Knee Society score , on a scale ranging from 0 to 200 points , was 89.7 points ( range , 33 to 132 points ) ; postoperatively , this score improved to a mean of 172.7 points ( range , 98 to 200 points ) . With the numbers available for study , we could detect no significant difference between the knees that had had patellar resurfacing and those that had not with regard to the over-all score ( p = 0.63 ) , the subscore for pain ( p = 0.56 ) , or the subscore for function ( p = 0.77 ) . We also could detect no difference between the treatment groups , with the numbers available , with regard to patient satisfaction or the responses to questions involving the function of the patellofemoral joint , including the ability to exit from an automobile , to rise from a chair , and to climb stairs .  Thirty-two patients had bilateral total knee replacement with resurfacing of the patella in one knee and retention of the patella in the other . These patients expressed no clear preference for either knee . Eight ( 13 per cent ) of the sixty knees that had not had resurfacing were painful anteriorly compared with four ( 7 per cent ) of the fifty-eight that had ; this was not a significant difference ( p = 0.38 ) , with the numbers available . The anterior pain that was noted postoperatively was predominantly of new onset ; it had not been observed preoperatively in three of the four knees that had had resurfacing or in four of the eight that had not . No additional treatment options were offered to the patients who had anterior pain in the knee after resurfacing . However , six ( 10 per cent ) of the sixty knees that had not had resurfacing had it subsequently , because of anterior pain in the knee , after the twelfth postoperative month ( range , fifteen to thirty-nine months ) . The pain decreased in four of these knees . Thus , total knee arthroplasty with retention of the patella yielded clinical results that were comparable with those after total knee arthroplasty with patellar resurfacing , but it was associated with a 10 per cent prevalence of the need for subsequent resurfacing . The prevalence of anterior pain after total knee arthroplasty was not influenced by whether or not the patella had been resurfaced . The postoperative clinical scores , the postoperative development of anterior pain , and the need for subsequent resurfacing were not predicted by the presence of preoperative anterior pain , obesity , or the grade of chondromalacia observed intraoperatively . Because of the short duration of follow-up , these results should be considered preliminary . Additional follow-up is planned BACKGROUND The need for patella resurfacing remains an area of considerable controversy in total knee replacement surgery . There would appear to be no reported evidence on the effect of patella resurfacing on knee function , as measured by functional range of movement used in a series of tasks , in patients undergoing knee replacement . The object of this study was to measure knee joint motion during functional activities both prior to and following total knee replacement in a r and omised group of patients with and without patella resurfacing and to compare these patient groups with a group of normal age-matched subjects . METHODS The study design was a double blinded , r and omised , prospect i ve , controlled trial . The knee joint functional ranges of movement of a group of patients ( n=50 , mean age=70 years ) with knee osteoarthritis were investigated prior to and following total knee arthroplasty ( 4 months and 18 - 24 months ) along with a group of normal subjects ( n=20 , mean age=67 ) . Patients were r and omly allocated into two groups , those who received patella resurfacing ( n=25 ) and those who did not ( n=25 ) . Flexible electrogoniometry was used to measure the flexion-extension angle of the knees with respect to time in eleven functional activities . FINDINGS No statistically significant differences ( alpha level 0.05 ) in joint excursion of the affected knee were found between patients who received patella resurfacing and those who did not . INTERPRETATION Routine patella resurfacing in a typical knee arthroplasty population does not result in an increase in the functional range of movement used after knee replacement Mixed treatment comparison ( MTC ) meta- analysis is a generalization of st and ard pairwise meta- analysis for A vs B trials , to data structures that include , for example , A vs B , B vs C , and A vs C trials . There are two roles for MTC : one is to strengthen inference concerning the relative efficacy of two treatments , by including both ' direct ' and ' indirect ' comparisons . The other is to facilitate simultaneous inference regarding all treatments , in order for example to select the best treatment . In this paper , we present a range of Bayesian hierarchical models using the Markov chain Monte Carlo software WinBUGS . These are multivariate r and om effects models that allow for variation in true treatment effects across trials . We consider models where the between-trials variance is homogeneous across treatment comparisons as well as heterogeneous variance models . We also compare models with fixed ( unconstrained ) baseline study effects with models with r and om baselines drawn from a common distribution . These models are applied to an illustrative data set and posterior parameter distributions are compared . We discuss model critique and model selection , illustrating the role of Bayesian deviance analysis , and node-based model criticism . The assumptions underlying the MTC models and their parameterization are also discussed BACKGROUND Anterior knee pain is still a major problem in total knee arthroplasty ( TKA ) . Although the most widely accepted opinion is that anterior knee pain is often associated with a patellofemoral etiology , there is no clear consensus as to etiology or treatment . Disabling pain receptors by electrocautery could theoretically achieve denervation of the anterior knee region . The present prospect i ve r and omized controlled study aim ed to evaluate results after patellar denervation with electrocautery in TKA at a minimum follow-up of 2 years . HYPOTHESIS Patellar denervation provides some benefit in terms of pain and clinical outcomes after TKA without patellar resurfacing . PATIENTS AND METHODS Clinical and radiological results for 35 patients with single-stage bilateral TKA ( 70 knees ; 26 women , nine men ; mean age , 68 years [ range , 58 to 77 years ] ) were review ed . In addition to removal of all osteophytes , patellar denervation by electrocautery was performed on one patella ; and debridement alone , removing all osteophytes , was performed on the contralateral patella , as a control . KSS score and a visual analog scale ( VAS ) were used to assess pre- and postoperative anterior knee pain . RESULTS Mean follow-up was 36 months ( 24 to 60 months ) . No revisions or re-operations were performed . There were no patellar fractures . On all parameters ( KSS score , range of motion and VAS ) , there was a statistically significant pre- to postoperative difference in favor of the denervation group . DISCUSSION Patellar denervation with electrocautery can reduce anterior knee pain , with satisfactory clinical and radiological outcome , in TKA without patellar resurfacing . LEVEL OF EVIDENCE Level II : low-powered prospect i ve r and omized trial To find out the improvement of joint position sense after  total knee arthroplasty with patellar resurfacing  compared to total knee arthoplasty without patellar resurfacing , the study was carried out as a r and omised parallel trial in patients who had stage III and IV primary osteoarthrosis of only 1 side of the knee with a 2 year follow-up . Twenty-one patients underwent patellar resurfacing and 26 patients had no patellar resurfacing .  Joint position sense was evaluated by the average absolute different angle of the operated knees from the non operated knees which was the asymptomatic knee and acted as the reference knee . Position sense was improved significantly in both groups . However , the patients without patellar resurfacing had better improvement . The patients with patellar resurfacing had better results in terms of anterior knee pain and tenderness .  Patellar resurfacing should be used in severe articular cartilage damage , not as a routine operation Patellar resurfacing in total knee arthroplasty remains controversial . This study evaluates the results of resurfacing and nonresurfacing the patella in a r and omized controlled , clinical trial at a minimum of 10 years followup . One hundred knees ( 90 patients ) with osteoarthritis were enrolled in a prospect i ve r and omized clinical trial using a  posterior – cruciate-retaining total knee arthroplasty . Patients were r and omized to  receive resurfacing or retention of the patella .  Evaluations were done preoperatively and yearly , up to a minimum of 10 years ( range , 10.1–11.5 years ) postoperatively . Disease-specific ( Knee Society clinical rating score ) and functional ( stair climbing , flexion/extension torques , patellar examination ) outcomes were measured . Patient satisfaction , anterior knee pain , and patellofemoral question naires were completed . Intraoperative grading of the articular cartilage was done . No patients were lost to followup ; 45 patients remained alive . Nine revisions ( in nine of 90 knees ; 10 % ) were done in seven patients in the nonresurfaced group ( 15 % of knees ) and in two patients in the resurfaced group ( 5 % of knees ) . No significant difference was found between the groups regarding revision rates , Knee Society clinical rating scores , and functional , patient satisfaction , anterior knee pain , patellofemoral , and radiographic outcomes . Intraoperative cartilage quality was not a predictor of outcome . This study currently is the longest followup of a r and omized controlled , clinical trial that examines patellar resurfacing in total knee arthroplasty . The results showed no significant difference between the groups for all outcome measures at a minimum of 10 years of followup The efficacy of circumpatellar electrocautery in reducing the incidence of  post-operative anterior knee pain  is unknown . We conducted a single-centre , outcome -assessor and patient-blinded , parallel-group , r and omised , controlled trial to compare circumpatellar electrocautery with no electrocautery in total knee replacement in the absence of patellar resurfacing . Patients requiring knee replacement for primary osteoarthritis were r and omly assigned circumpatellar electrocautery ( intervention group ) or no electrocautery ( control group ) . The primary outcome measure was the incidence of anterior knee pain . A secondary measure was the st and ardised clinical and patient-reported outcomes determined by the American Knee Society scores and the Western Ontario and McMaster Universities ( WOMAC ) osteoarthritis index . A total of 131 knees received circumpatellar electrocautery and 131 had 
    Output:
    
Multiple active treatment comparisons indicated that patellar denervation result ed in greater improvement in KFS than patellar resurfacing .
Conclusion This review suggests that either patellar denervation or patellar resurfacing may be selected for the management of the patellofemoral component in total knee replacement .
Patellar denervation may help improve postoperative knee function , but does not improve pain when compared to patellar resurfacing