Patients recruited from Linköping will have expanded follow-up data collection at baseline and 3, 6, 12 and 24 months after injury. At these follow-ups, a clinical examination will be completed by an orthopedic surgeon or physiotherapist, MRI, and blood and urine samples will be collected. A joint fluid sample will be acquired at baseline, and at the time of ACL reconstruction (if the patient has surgical treatment). Radiographs will be done at baseline and 5 years follow up. Patients who have ACL reconstruction will be followed up with new baseline at the time for reconstruction, but without MRI or blood and urine samples.