Patellar Dislocation

This research study is designed to allow health care professionals and researchers to answer many questions about whether a new type of physical therapy called blood flow restriction training (called BFRT) will improve recovery for those with patellar instability.

The goal of this observational study is to learn about the outcomes of medial patellofemoral ligament (MPFL) reconstruction for the treatment of recurrent patellar instability. The main questions it aims to answer are: * What are the risk factors for recurrent patellar instability after MPFL reconstruction? * What functional outcomes do patients report after MPFL reconstruction? Participants undergoing MPFL reconstruction will answer survey questions about their knee and activity level 1 year and 2 years after surgery.

Study to evaluate the conservative treatment of patients after their first episode of primary lateral patellar dislocation. Randomized controlled trial with 2 groups: standard treatment (2-weeks with brace) followed by physical therapy, compared with knee taping and physical therapy. 1-year follow-up. Measurements include physical exam, radiographs and MRI. Outcomes: recurrence, lateral patellar tilt, functional scores, apprehension, pain. Hypothesis: less recurrence in the knee taping group, as well as better functional scores.

The investigators intend to establish a national cohort including all persons in the ages from 15-20 years old with patellar instability (PI) or a prior knee injury (ACL-ruptur or meniscus damage) . The cohort will be nicknamed "The Faroese Knee Cohort". The overall aim is to investigate two groups. 1. The patella instability group, in which we intend to investigate the following. * Prevalence of patellar dislocation and trochlear dysplasia in the Faroe Islands. * Risk factors for patellar dislocations- * Heredity of trochlear dysplasia. * If there is a specific gene responsible for the development of trochlear dysplasia. * The development of retropatellar artrhosis, its onset and its impact on quality of life and function, 2. Knee injury group (ACL-ruptur or meniscus injury) * The prevalence of ACL-rupture and/or meniscus injury in this specific group in the Faroe Islands. * The impact on quality of life and function.