Knee arthroplasty is a surgical procedure that replaces severely arthritic or damaged knee joints. After undergoing this commonly performed procedure, there are still some patients who never fully recover. One of the reasons is the lack of patient compliance to the prescribed rehabilitation schedule. This paper describes the development of SEKO, a smart system which has the goal of improving the compliance of patients to the rehabilitation schedule after a knee arthroplasty. This is done by providing a system which connects a smart brace to a patient and his/her physiotherapist. The system exists out of three parts: the smart brace which uses multiple sensors that gather data of the movements and exercises performed by the patient, the mobile application which uses the gathered data to give feedback to the patient, and the web application which uses the data to keep the patient's physiotherapist up to date on the rehabilitation performance and progress of the patient. The result is a proof of concept in the form of a fully functioning prototype, which was preliminary evaluated on the technical aspects and the usage scenario.