DECREASING OF TOTAL AND UNILATERAL KNEE ARTHROPLASTIES DUE TO RHEUMATOID ARTHRITIS BUT INCREASING IN OSTEOARTHRITIS IN OUR INSTITUTES IN LAST DECADE OF SUPER-AGING SOCIETY

Background: The rate of elderly people over 65 year-old increased from 22.1 % in 2008 to 27.7% in 2017 in Japan, also from 27.1 % to 32.3 % in our super-aging area1, 2. The number of total and unilateral knee arthroplasty (TKA, UKA) have increased annually in all over the world according to the larger population of elderly people due to osteoarthritis (OA)3. In fact, the numbers of primary TKA predicted increasing from six hundred fifty-six thousand cases at 2010 to one million three hundred seventy-six thousand cases at 2020 in USA4. In the other hand, rheumatoid arthritis (RA) therapy have been remarkably improved from starting to use biologic agents since 2003 in Japan 5. The rate of orthopaedic surgery may reflect trends in disease severity and drug management of RA 5. Objectives: The aim of study is to reveal the rate of TKA, including UKA and revision TKA in elderly people in our super-aging area of Japan. Methods: We surveyed the number and cause of primary and revision TKA and UKA in our institutes using the data of diagnosis procedure combination and the record of surgeries in the last decade. Results: Figure 1. Conclusion: The number and rate of primary TKA/UKA due to RA decreased year by year because of progression of modern medication therapy. In the other hand, in case of OA increased because of increasing of elderly people affected by knee OA in the super-aging society. References: [1]National Institute of Population and Social Security Research. Japanese Mortality Database, 2018. http://www.ipss.go.jp/ [2]Yamagata prefecture, Health and longevity Promotion Section. Rate of elderly people in Yamagata prefecture, 2018. http://www.pref.yamagata.jp/ou/kikakushinko/020052/tokei/jinkel.html [3]Annual report 2017 of replacement arthroplasty in Japan. The Japanese Society For Replacement Arthroplasty The Japan Arthroplasty Register. https://jsra.info/jar-report.html [4]Kurtz SM, et al. J Bone Joint Surg Am. 96: 624-30, 2014. [5]Momohara S, et al. J Rheumatol. 41:862-5, 2014. Disclosure of Interests: None declared