***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 
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    Input: In this prospect i ve r and omised study two treatments after non-traumatic medial meniscal tear diagnosed with radiological examination and magnetic resonance imaging were compared ; arthroscopic partial meniscectomy followed by supervised exercise or supervised exercise alone . The aim was to evaluate knee function and physical activity . Ninety patients ( mean age 56 years ) were evaluated using the  Knee Injury and Osteoarthritis Outcome Score , the Lysholm Knee Scoring Scale , the Tegner Activity Scale and a Visual Analogue Scale for knee pain prior to the intervention , after 8 weeks of exercise and after 6 months . According to the outcome scores arthroscopic partial medial meniscectomy combined with exercise did not lead to greater improvement than exercise alone . After the intervention both groups reported decreased knee pain , improved knee function and a high satisfaction ( P < 0.0001 ) . Forty-one per cent of the patients returned to their pre-injury activity level after 6 months . In conclusion , when evaluated with outcome scores , arthroscopic partial medial meniscectomy followed by supervised exercise was not superior to supervised exercise alone in terms of reduced knee pain , improved knee function and improved quality of life Background — Arthroscopic meniscal surgery is the most common orthopedic procedure , and the incidence has increased in Denmark over the last 10 years . Concomitantly , several r and omized controlled trials have shown no benefit of arthroscopic procedures including arthroscopic partial meniscectomy in middle-aged and older individuals suffering from knee pain with or without knee osteoarthritis . We examined the annual incidence of meniscal procedures together with age , sex , and diagnosis for patients who underwent meniscal procedures in the period 2000–2011 in Denmark . Methods — Data on age , sex , diagnosis , and surgical procedures were extracted from the Danish National Patient Register for the years 2000–2011 , for all records containing meniscal surgery as a primary or secondary procedure . Results — The overall annual incidence of meniscal procedures per 100,000 persons in Denmark doubled from 164 in 2000 to 312 in 2011 ( i.e. 8,750 procedures to 17,368 procedures ) . A 2-fold increase was found for patients aged between 35 and 55 , and a 3-fold increase was found for those older than 55 . Middle-aged and older patients accounted for 75 % of all 151,228 meniscal procedures carried out between 2000 and 2011 . Interpretation — The incidence of meniscal procedures performed in Denmark doubled from 2000 to 2011 , with the largest increase in middle-aged and older patients . This increase contrasts with the mounting evidence showing no added benefit of arthroscopic partial meniscectomy over non-surgical treatments . Our observations illustrate the long delay in the dissemination , acceptance , and implementation of research evidence into the practice of arthroscopic surgery PURPOSE To determine whether preoperative magnetic resonance ( MR ) imaging could help identify factors associated with poor clinical outcome after arthroscopic partial meniscectomy ( APM ) in middle-aged and elderly patients with meniscal tears . MATERIAL S AND METHODS The prospect i ve , institutional review board-approved , HIPAA-compliant study was performed with informed consent in 53 men and 47 women ( average ages , 54.5 and 56.6 years , respectively ) . Patients underwent knee MR imaging before APM ; clinical symptoms were evaluated preoperatively and 1 year postoperatively with International Knee Documentation Committee ( IKDC ) question naire . Overall severity of knee joint degeneration and severity of each feature of joint degeneration were assessed with Boston Leads Osteoarthritis Knee ( BLOK ) scoring system . Tear length was measured , and type of meniscal tear was classified . Spearman correlation coefficients and relative risks showed the relationship between clinical outcome after APM ( difference between preoperative and postoperative IKDC scores ) and severity of joint degeneration . RESULTS Seventy-four patients with isolated medial APM had a significant ( P < .05 ) inverse correlation between clinical outcome and severity of cartilage loss and bone marrow edema in the medial femoral condyle and medial tibial plateau . Fifteen patients with isolated lateral APM had a significant ( P < .05 ) inverse correlation between clinical outcome and severity of cartilage loss in the lateral femoral condyle and lateral tibial plateau and bone marrow edema in the lateral femoral condyle . One hundred patients with APM had a significant ( P < .05 ) inverse correlation between clinical outcome and severity of meniscal extrusion , total BLOK score , and meniscal tear length . A significantly ( P < .05 ) increased relative risk that a patient would not definitely improve after APM was observed if a meniscal root tear was present . CONCLUSION Poorer clinical outcome after APM was associated with greater severity of cartilage loss and bone marrow edema in the same compartment as the meniscal tear , greater severity of meniscal extrusion , greater overall severity of joint degeneration , a meniscal root tear , and a longer meniscal tear at preoperative MR imaging Introduction Arthroscopic partial meniscectomy ( APM ) to treat degenerative meniscus injury is the most common orthopaedic procedure . However , valid evidence of the efficacy of APM is lacking . Controlling for the placebo effect of any medical intervention is important , but seems particularly pertinent for the assessment of APM , as the symptoms commonly attributed to a degenerative meniscal injury ( medial joint line symptoms and perceived disability ) are subjective and display considerable fluctuation , and accordingly difficult to gauge objective ly . Methods and analysis A multicentre , parallel r and omised , placebo surgery controlled trial is being carried out to assess the efficacy of APM for patients from 35 to 65 years of age with a degenerative meniscus injury . Patients with degenerative medial meniscus tear and medial joint line symptoms , without clinical or radiographic osteoarthritis of the index knee , were enrolled and then r and omly assigned ( 1 : 1 ) to either APM or diagnostic arthroscopy ( placebo surgery ) . Patients are followed up for 12 months . According to the prior power calculation , 140 patients were r and omised . The two r and omised patient groups will be compared at 12 months with intention-to-treat analysis . To safeguard against bias , patients , healthcare providers , data collectors , data analysts , outcome adjudicators and the research ers interpreting the findings will be blind to the patients ’ interventions ( APM/placebo ) . Primary outcomes are Lysholm knee score ( a generic knee instrument ) , knee pain ( using a numerical rating scale ) , and WOMET score ( a disease-specific , health-related quality of life index ) . The secondary outcome is 15D ( a generic quality of life instrument ) . Further , in one of the five centres recruiting patients for the r and omised controlled trial ( RCT ) , all patients scheduled for knee arthroscopy due to a degenerative meniscus injury are prospect ively followed up using the same protocol as in the RCT to provide an external validation cohort . In this article , we present and discuss our study design , focusing particularly on the internal and external validity of our trial and the ethics of carrying out a placebo surgery controlled trial . Ethics and dissemination The protocol has been approved by the institutional review board of the Pirkanmaa Hospital District and the trial has been duly registered at Clinical Trials.gov . The findings of this study will be disseminated widely through peer- review ed publications and conference presentations . Trial registration Clinical Trials.gov , number NCT00549172 OBJECTIVE To determine if visually-guided arthroscopic irrigation is an effective therapeutic intervention in patients with early knee osteoarthritis . DESIGN Ninety patients with knee osteoarthritis were r and omized in a double-blind fashion to receive either arthroscopic irrigation with 3000 ml of saline ( treatment group ) or the minimal amount of irrigation ( 250 ml ) required to perform arthroscopy ( placebo group ) . The primary outcome variable was aggregate WOMAC score . RESULTS The study did not demonstrate an effect of irrigation on arthritis severity as measured by aggregate WOMAC scores , the primary outcome variable ; the mean change in aggregate WOMAC score at 12 months was 15.5 ( 95 % CI 7.7 , 23.4 ) for the full irrigation group compared to 8.9 ( 95 % CI 4.9 , 13.0 ) for the minimal irrigation group ( P=0.10 ) . Full irrigation did have a statistically significant effect on patients ' self-reported pain as measured by the WOMAC pain subscale and by a visual analog scale ( VAS ) ( the secondary outcome variables ) . Mean change in WOMAC pain scores decreased by 4.2 ( 95 % CI -0.9 , 9.4 ) for the full irrigation group compared with a mean decrease of 2.3 ( 95 % CI -0.1 , 4.7 ) in the minimal irrigation group ( P=0.04 ) . Mean VAS pain scores decreased by 1.47 ( 95 % CI -1.2 , 4.1 ) in the full irrigation group compared to a mean decrease of 0.12 ( 95 % CI 0.0 , 0.3 ) in the minimal irrigation group ( P=0.02 ) . A hypothesis-generating post-hoc analysis of the effect of positively birefrigent intraarticular crystals showed that patients with and without intraarticular crystals had statistically significant improvements in pain assessment s and aggregate WOMAC scores at 12 months ; patients with crystals had statistically greater improvements in pain . CONCLUSIONS Visually-guided arthroscopic irrigation may be a useful therapeutic option for relief of pain in a subset of patients with knee OA , particularly in those who have occult intraarticular crystals Background : It is still debated whether a degenerative horizontal tear of the medial meniscus should be treated with surgery . Hypothesis : The clinical outcomes of arthroscopic meniscectomy will be better than those of nonoperative treatment for a degenerative horizontal tear of the medial meniscus . Study Design : R and omized controlled trial ; Level of evidence , 1 . Methods : A total of 102 patients with knee pain and a degenerative horizontal tear of the posterior horn of the medial meniscus on magnetic resonance imaging were included in this study between January 2007 and July 2009 . The study included 81 female and 21 male patients with an average age of 53.8 years ( range , 43 - 62 years ) . Fifty patients underwent arthroscopic meniscectomy ( meniscectomy group ) , and 52 patients underwent nonoperative treatment with strengthening exercises  ( nonoperative group ) . Functional outcomes were compared using a visual analog scale ( VAS ) for pain , Lysholm knee score , Tegner activity scale , and patient subjective knee pain and satisfaction . Radiological evaluations were performed using the Kellgren-Lawrence classification to evaluate osteoarthritic changes . Results : In terms of clinical outcomes , meniscectomy did not provide better functional improvement than nonoperative treatment . At the final follow-up , the average VAS scores were 1.8 ( range , 1 - 5 ) in the meniscectomy group and 1.7 ( range , 1 - 4 ) in the nonoperative group ( P = .675 ) . The average Lysholm knee scores at 2-year follow-up were 83.2 ( range , 52 - 100 ) and 84.3 ( range , 58 - 100 ) in the meniscectomy and nonoperative groups , respectively ( P = .237 ) . In addition , the average Tegner activity scale and subjective satisfaction scores were not significantly different between the 2 groups . Although most patients initially had intense knee pain with mechanical symptoms , both groups reported a relief in knee pain , improved knee function , and a high level of satisfaction with treatment ( P < .05 for all values ) . Two patients in the meniscectomy group and 3 in the nonoperative group with Kellgren-Lawrence grade 1 progressed to grade 2 at the 2-year follow-up . Conclusion : There were no significant differences between arthroscopic meniscectomy and nonoperative management with strengthening exercises in terms of relief in knee pain , improved knee function , or increased satisfaction in patients after 2 years of follow-up OBJECTIVES Patients with knee osteoarthritis ( OA ) often suffer pain that is not fully controlled by analgesics and often require intra-articular therapies . The aim of this study was to compare the benefits of intra-articular corticosteroid injections ( CSIs ) and tidal irrigation ( TI ) in patients with OA of the knee . METHODS We performed a dual-centre , single blind , r and omised , parallel group trial comparing TI and CSI .  Patients with knee OA were r and omised to either irrigation using a 3.2 mm arthroscope under local anaesthesia or an intra-articular injection of 40 mg triamcinolone acetonide and 1 % lidocaine . Patients were followed for 6 months . The primary outcome measure was the Western Ontario and McMaster Universities OA Index total pain score ( visual analogue scale , VAS ) . RESULTS One hundred and fifty patients were recruited of whom 71 received TI and 79 CSI . In both treatment groups , over 80 % of patients reported improvement at 2 and 4 weeks . After this time , the benefit of CSI decreased whereas that of TI was maintained : at 26 weeks the 
    Output:
    
There was no difference in the side effects between patients with AT and the control group .
AT in OA patients is not useless because there is evidence that a subgroup of patients with non-traumatic flap tears of the medial meniscus or patients with crystal arthropathy benefit from arthroscopy .