***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: OBJECTIVE To determine interobserver agreement between triage registered nurses ( RNs ) and emergency physicians ( EPs ) regarding indication for knee radiographs by applying the Ottawa knee rule ( OKR ) and individual components of the rule . METHODS This was a prospect i ve , observational study in a suburban , teaching emergency department . The study enrolled a convenience sample of patients aged > 17 years with traumatic knee injuries less than one week old . Patients with prior knee surgery or distracting conditions were excluded . Before study initiation , the RNs and EPs were in-serviced in the OKR . Nurses and EPs independently examined each patient for OKR criteria , blinded to the other 's assessment .  Knee radiographs were ordered at the discretion of the EP and were interpreted by board-certified radiologists . All patients received follow-up with a structured telephone interview to identify any undetected fractures . Kappa was calculated for each component and the overall application of the OKR to assess interobserver agreement . RESULTS Ninety-six patients were enrolled . The mean age was 39.6 + /- 18.7 years ; 50 % were male . Eight patients ( 8 % ) had knee fractures . Interobserver agreements between the RNs and EPs for individual components of the OKR were : age > or = 55 years ( kappa = 0.97 ) ; inability to weight bear ( kappa = 0.51 ) ; inability to bend knee to 90 degrees ( kappa = 0.52 ) ; fibular head tenderness ( kappa = 0.45 ) ; and isolated patellar tenderness ( kappa = 0.40 ) . The EPs and RNs agreed with OKR criteria for x-ray 71 % of the time ( kappa = 0.41 ) . CONCLUSIONS The only criterion that result ed in almost perfect agreement between the RNs and EPs was patient age ; agreement for the other four criteria and the overall decision to order x-rays was moderate OBJECTIVE To vali date a previously derived decision rule for the use of radiography in patients with acute knee injury . DESIGN Prospect ively administered survey . SETTING Emergency departments of two university hospitals serving adults . PATIENTS Convenience sample of 1096 of 1251 eligible adults with acute knee injuries ; 124 patients were examined by two physicians . MAIN OUTCOME MEASURES Attending emergency physicians assessed each patient for st and ardized clinical variables and determined the need for  radiography  according to the decision rule . Patients who did not have radiography  underwent a  structured telephone interview  at day 14 to determine the possibility of a fracture . The rule was assessed for ability to correctly identify the criterion st and ard , fracture of the knee . An attempt was made to refine the rule by means of univariate and recursive partitioning analyses . RESULTS The decision rule had a sensitivity of 1.0 ( 95 % confidence interval [ CI ] , 0.94 to 1.0 ) for identifying 63 clinical ly important fractures . Physicians correctly interpreted the rule in 96 % of cases , and the k value for interpretation was 0.77 ( 95 % CI , 0.65 to 0.89 ) . The potential relative reduction in use of radiography was estimated to be 28 % . The probability of fracture , if the decision rule were " negative , " is estimated to be 0 % ( 95 % CI , 0 % to 0.4 % ) . Attempts to refine the rule led to a model with improved specificity but with an unacceptable loss of sensitivity . CONCLUSION Prospect i ve validation has shown this decision rule to be 100 % sensitive for identifying fractures of the knee , to be reliable and acceptable , and to have the potential to allow physicians to reduce the use of radiography in patients with acute knee injury Abstract . Our objective was to determine the value of the Ottawa knee rules when applied by users with different levels of clinical training . We used a prospect i ve patient survey by the medical students and surgery residents of a European university trauma centre . The study group consisted of 261 eligible patients who presented with acute knee trauma during a 6-month period .  Radiography or  follow-up  was obtained for each patient . Data were separately analysed according to the degree of qualification of the initial examiner . The Ottawa knee rules had a sensitivity and a negative predictive value of 1.00 . Variable degree of medical competence of the users did not alter the accuracy of the rules . Application of the rules would have reduced knee radiography requests by 25 % . The Ottawa knee rules remain highly sensitive when applied by medical users with different levels of qualification , such as encountered in a teaching setting STUDY OBJECTIVE To derive a highly sensitive decision rule for the selective use of radiography in acute knee injuries . DESIGN Prospect ively administered survey . SETTING Emergency departments of two university hospitals . PARTICIPANTS Convenience sample of 1,047 adults with acute knee injuries . RESULTS Attending emergency physicians assessed each patient for 23 st and ardized clinical findings , which were recorded on data collection forms . A total of 127 patients was examined independently by two physicians to determine interobserver agreement . The outcome measure was fracture of the knee . Any patients who did not have ED radiography  underwent a  structured telephone interview  to determine the possibility of a missed fracture . Those variables found to be both reliable ( highest kappa values ) and strongly associated with a fracture ( highest chi 2 values ) were further analyzed by a recursive-partitioning multivariate technique . The derived decision rule included the following variables : ( 1 ) age 55 years or older , ( 2 ) tenderness at the head of the fibula , ( 3 ) isolated tenderness of the patella , ( 4 ) inability to flex to 90 degrees , and ( 5 ) inability to bear weight both immediately and in the ED ( four steps ) . The presence of one or more of these findings would have identified the 68 fractures in the study population with a sensitivity of 1.0 ( 95 % confidence interval [ Cl ] , .95 to 1.0 ) and a specificity of .54 ( 95 % Cl , .51 to .57 ) . Application of the rule would have led to a 28.0 % relative reduction in the use of radiography from 68.6 % to 49.4 % in the study population . CONCLUSION A practical , highly sensitive , and reliable decision rule for the use of radiography in acute knee injuries has been derived . Clinical application should await prospect i ve validation of the rule We design ed a prospect i ve observational study to attempt to vali date two recently described clinical decision rules for knee radiography .  Consecutive patients aged > or = 15 yr with acute knee injuries occurring less than 1 wk prior to presentation were included for study . Patients with distracting conditions , open knee injuries , or previous surgery were excluded . Each patient was assessed for 7 historical and 15 physical examination criteria that were recorded on a st and ardized data collection instrument . Radiographs were ordered at the discretion of the attending physician and were read by two board-certified radiologists . When radiographs were not ordered , structured telephone follow-up was performed after 3 wk . The main outcome parameter was the presence or absence of a clinical ly significant fracture . There were 351 patients in the study ; 26 ( 7 % ) had knee fractures . Fractures were significantly associated with an increased prevalence for two of the three criteria in the rule derived by Bauer : inability to weight bear immediately or in the emergency department ( ED ; 76.9 % of patients with a fracture vs. 29.8 % of patients without a fracture ) and effusion ( 53.8 % vs. 28.9 % , respectively ) . Ecchymosis was not significantly associated with fracture ( 19.2 % with fracture vs. 9 % with no fracture ) . Use of the Bauer rule would have led to a radiographic evaluation of 22 of the 26 patients with knee fractures ( sensitivity = 84.6 % , specificity = 48.9 % ) . Fractures were associated with a significantly increased prevalence for three of the five criteria in the decision rule proposed by Stiell : isolated patella tenderness ( 30.8 % with fracture vs. 14.5 % with no fracture ) , inability to flex the knee to 90 degrees ( 42.3 % vs. 19.7 % , respectively ) , and inability to weight bear immediately and in the ED ( 57.7 % vs. 18.8 % , respectively ) . Age > or = 55 yr ( 23.1 % vs. 12.0 % , respectively ) and fibula head tenderness ( 11.5 % vs. 5.5 % , respectively ) were not significantly associated with fracture . Use of the Stiell rule would have led to radiographic evaluation of 22 of the 26 patients with knee fractures ( sensitivity = 84.6 % , specificity = 49.8 % ) . We conclude that neither clinical decision rule is 100 % sensitive . Further refinement will be necessary to identify all patients with knee fractures STUDY OBJECTIVE Two separate clinical decision rules , one developed in Ottawa and the other in Pittsburgh , for the use of radiography in acute knee injuries have been previously vali date d and published . In this study , the rules were prospect ively vali date d and compared in a new set of patients . METHODS A prospect i ve , blinded , multicenter trial was conducted in the emergency departments of three urban teaching hospitals . A convenience sample of 934 patients with knee pain requiring radiographs was enrolled . A st and ardized data form was completed for each patient , comprising the 10 clinical variables included in the two rules . St and ard knee radiographs were then taken in each patient . The rules were interpreted by the primary investigator on the basis of the data sheet and the final radiologist radiograph reading . RESULTS In the 745 patients in whom the Pittsburgh rules could be applied there were 91 fractures ( 12.2 % ) . The use of the Pittsburgh rule missed one fracture , yielding a sensitivity of 99 % ( 95 % confidence interval [ CI ] , 94 % to 100 % ) ; the specificity was 60 % ( 95 % CI , 56 % to 64 % ) . The Ottawa inclusion criteria were met by 750 patients , with 87 fractures ( 11.6 % ) . The Ottawa rule missed three fractures , for a sensitivity of 97 % ( 95 % CI , 90 % to 99 % ) ; specificity was 27 % ( 95 % CI , 23 % to 30 % ) . CONCLUSION Prospect i ve validation and comparison found the Pittsburgh rule for knee radiographs to be more specific without loss of sensitivity compared with the Ottawa rule CONTEXT The Ottawa Knee Rule is a previously vali date d clinical decision rule that was developed to allow physicians to be more selective and efficient in their use of plain radiography for patients with acute knee injuries . OBJECTIVE To assess the impact on clinical practice of implementing the Ottawa Knee Rule . DESIGN Controlled clinical trial with before-after and concurrent controls . SETTING Emergency departments of 2 teaching and 2 community hospitals . PATIENTS All 3907 consecutive eligible adults seen with acute knee injuries during two 12-month periods before and after the intervention . INTERVENTION During the after period in the 2 intervention hospitals , the Ottawa Knee Rule was taught to all house staff and attending physicians who were encouraged to order knee radiography according to the rule . MAIN OUTCOME MEASURES Referral for knee radiography , accuracy and reliability of the rule , mean time in emergency department , and mean charges . RESULTS There was a relative reduction of 26.4 % in the proportion of patients referred for knee radiography in the intervention group ( 77.6 % vs 57.1 % ; P<.001 ) , but a relative reduction of only 1.3 % in the control group ( 76.9 % vs 75.9 % ; P=.60 ) . These changes over time were significant when the intervention and control groups were compared ( P<.001 ) . The rule was found to have a sensitivity of 1.0 ( 95 % confidence interval [ CI ] , 0.94 - 1.0 ) for detecting 58 knee fractures . The K coefficient for interpretation of the rule was 0.91 ( 95 % CI , 0.82 - 1.0 ) . Compared with nonfracture patients who underwent radiography during the after-intervention period , those discharged without radiography spent less time in the emergency department ( 85.7 minutes vs 118.8 minutes ) and incurred lower estimated total medical charges for physician visits and radiography ( US $ 80 vs US $ 183 ) . CONCLUSIONS Implementation of the Ottawa Knee Rule led to a decrease in use of knee radiography  without patient dissatisfaction or missed fractures and was associated with reduced waiting times and costs . Widespread use of the rule could lead to important health care savings without jeopardizing patient care STUDY OBJECTIVE To conduct an economic analysis of the implementation of the Ottawa Knee Rule . METHODS The decision analysis compared usual practice based on physician judgment with practice based on a clinical decision rule , which allows more selective use of radiography . The study participants were all adults with blunt knee trauma . The likelihood and cost of radiography , missed fracture , lost productivity , and medicolegal actions were defined by published data and an expert panel . Separate analyses considered US Medicare and Canadian hospital costs . Sensitivity analyses considered a range of values for each variable in the model , including costs in a US fee-for-service setting . The study outcome was the mean cost per patient 
    Output:
    
Discussion This systematic review shows that the Ottawa knee rule accurately excludes fractures in adult patients presenting with an acute knee injury .