Inclusion Criteria:  Patients having had primary, unilateral THA or TKA due to osteoarthritis. Patients being referred to receive postoperative rehabilitation at our institution.  Patients being able to speak, read and understand Danish language. Patients aged ≥ 18 years.  Exclusion Criteria:  Patients not able to comply with exercise instructions. Patients who are discharged to a nursing-home facility or receiving in-home rehabilitation by home care.