Various factors could lead to a knee replacement surgery The primary factor is discomfort restrictive movement of the knee and compromised ADL Mostly seen in elderly patient in the age group of 50 to 60 years where the cause is age related degeneration of joint leading to primary osteoarthritis In young group of population where there is underlying disease such as rheumatoid arthritis or any other inflammatory arthritis joints get damaged secondary to other underlying disease Athletes and players who practise active sports are prone to knee injuries if they do not strengthen their knees If exertion on the field is excessive and knees are weak it could lead to ACL tear Many players who get an injury while being in action on the field get knee surgeries