Objective To observe and analyze the follow-up of knee osteoarthritis patients under 50 years old after arthroscopy.Methods Retrospectively analyzed between January 2011 and December 2014 in our hospital of KOA patients undergoing arthroscopic surgery in 5 years of follow-up results, patients treated with conservative in comparison, with the use of analgesic drugs, the occurrence of the event total knee arthroplasty, K - L classification and the change of WOMAC score for evaluation basis, multi-angle study of patients with postoperative prognosis.Results A total of 263 cases were included in the study, including 76 cases in the arthroscopic lavage group (group A), 72 cases in the arthroscopic lavage + hyaluronic acid group (group B), and 115 cases in the conservative treatment group (group C).The overall analgesic drug utilization rate (P=0.000), NSAIDs drug utilization rate (P=0.035) and weak opioid drug utilization rate (P=0.048) of patients in group A and Group B were all lower than those in group C, and the differences were statistically significant.The proportion of new TKA in patients in group A and Group B in the first 1-3 years was lower than that in group C, and the difference was statistically significant (P=0.025; P=0.042; P=0.046).There were no statistically significant differences in the proportion of newly added TKA and overall TKA in the 4th and 5th year among the 3 groups (P > 0.05).5 years of follow-up, patients with group A, group B and group C K-L Ⅳ magnitude scale, WOMAC score were higher than group before the treatment, the patients of group C K-L Ⅲ level ratio is higher than before the treatment, the difference was statistically significant (P<0.05).There was no statistically significant difference in k-l grading and WOMAC score between the three groups before treatment and after 5 years of follow-up (P>0.05).Conclusion Arthroscopic surgery can delay the progression of knee osteoarthritis for a period of time and improve the symptoms of KOA patients under 50 years of age in the 5-year study.In the long run, arthroscopic surgery has no advantage over conservative treatment in delaying the progression of knee osteoarthritis.