Joint Movement to Increase Range of Motion in Knee Joint After Primary Total Knee Arthroplasty

The goal of this clinical trail is to investigate if specific active exercises, with a certain daily frequency improves the range of motion (ROM) in the knee joint after primary- or revision total knee arthroplasty (TKA) The main questions it aims to answer are: * Does it make a difference to the ROM of the knee joint to do specific active exercise 2 times a day compared to 8 times a day in an 18 days period of time * Analyze if range of motion in the knee joint after TKA has an impact on self-reported activity, pain and physical activity Participants will be instructed by a physiotherapist to do a specific exercise to improve the flexion of the knee-joint and and other to improve the extension of the knee-joint. One group will be instructed to do the exercises 2 times a day the other group to do the exercises 8 times a day in total of 18 days The two groups will be compared to see if there is an effect in ROM and if the effect is significant between the groups if the intervention is done 2 times versus 8 times a day.