Inclusion Criteria:  Patients after knee surgery (ACL reconstruction, total or partial knee arthroplasty, knee arthroscopy etc.) who are scheduled to a clinical follow up assessment by the surgeon between 4 months and 15 months after surgery. Informed consent  Exclusion Criteria:  Age below 18 years Patients who underwent surgery in the lower extremities within the last 4 months Patients with severe acute pain Patients with contraindications to perform the movements/exercises Patients who underwent surgery also at the contralateral leg since the surgery related to the current follow up visit Patients who cannot follow the instructions due to language or cognitive problems