Inclusion Criteria:  Primary, unilateral total knee and hip replacement patients Participant is min. 18 years of age Participant is able and willing to provide written informed consent Participant with ability to work with smart devices Participant having its own device (Apple iPhone or iPad with latest iOS version or Android tablet or smart phone min. Android version 6) and are able to handle the app and/or sensor  Exclusion Criteria:  Pregnancy Participant has mental in capabilities - unable to give informed consent Participants who are unwilling or mentally and/or physically unable to adhere to study procedures Participant is having orthopaedic co-morbidities such as: previous HTO at indexed joint or prior UKA Flexion contracture > 15° Varus/valgus deformity > 10° Participant is having dementia or other cognitive impairment