The goal of this randomized controlled trial is to learn about the effect of a wearable activity tracker assisted physiotherapeutic intervention on the risk of poor patient reported outcome after a primary total knee replacement. The main question it aims to answer is whether a wearable activity tracker assisted physiotherapeutic intervention and remote monitoring may help to decrease the number of the poor patient reported post-operative outcome 12 months after a primary total knee replacement. Participants will receive standard postoperative care which includes physiotherapy appointments 4 weeks and 3 months after the surgery and they will use smart rings (Oura ring) 3 months postoperatively. Patients will be remotely monitored to follow their recovery from total knee replacement surgery: the study group physiotherapists will follow the patients' activity and sleep and if necessary, make a contact with patient if there seems to low activity indicating difficulties with recovering from the surgery. Researchers will compare the intervention group to a group of participants who will receive only standard postoperative care with physiotherapy appointments 4 weeks and 3 months, to see if the use of the Oura ring may decrease the number of participants with poor patient reported post-operative outcome after total knee replacement.