Development of Computational Models to Predict the Short-, Medium- and Long-term Cartilage Degeneration and Pain for Patients With Early-stage Osteoarthritis or Anterior Cruciate Ligament Injury

.3.1 ACL reconstruction group (n= 25) Inclusion criteria * Adults under 70 years * ACL injury within the last year and planned for ACL reconstruction at inclusion * Informed consent form signed Exclusion criteria (at inclusion) * Previous knee surgery before current knee trauma. * Severe ischemic or neurological sequelae. * BMI above 32. * Clinically significant joint disease (inflammatory or degenerative) to other joints than the ACL injured knee (according to the clinician). * Unsuitable for MRI (e.g. pacemaker or claustrophobia) * Participants not able to fit the MRI knee coil (Thigh circumference larger than 73.5 cm measured 10 cm above the kneecap and a maximum calf circumferences of 61.5 cm). * Drug addiction defined as the use of cannabis, opioids or other drugs as reported by the participant ACL no reconstruction group (n= 25) Inclusion criteria * Adults under 70 years * ACL injury within the last year and with no plans for ACL reconstruction at inclusion * Informed consent form signed Exclusion criteria (at inclusion) * Previous knee surgery before current knee trauma. * Severe ischemic or neurological sequelae. * BMI above 32. * Clinically significant joint disease (inflammatory or degenerative) to other joints than the ACL injured knee (according to the clinician). * Unsuitable for MRI (e.g. pacemaker or claustrophobia) * Participants not able to fit the MRI knee coil (Thigh circumference larger than 73.5 cm measured 10 cm above the kneecap and a maximum calf circumferences of 61.5 cm). * Drug addiction defined as the use of cannabis, opioids or other drugs as reported by the participant Early to moderate knee OA stage (n= 25) Inclusion criteria * Adults under 70 years * Diagnosis of knee OA (Kellgren Lawrence (KL) grade 1, 2 and 3 (Kohn et al., 2016). If there is no X-ray that is a maximum of 1 year old, a new one is taken. * Stress-related pain in the knee and knee stiffness * Informed consent form signed Exclusion criteria (at inclusion) * Previous knee surgery * Clinically significant joint disease (inflammatory or degenerative) of other joints than the knee at inclusion. * Severe ischemic or neurological sequelae in the lower extremities. * Clinically significant joint disease (inflammatory or degenerative) to other joints than the knees (according to the clinician). * BMI above 32. * Unsuitable for MRI (e.g., pacemaker or claustrophobia) * Participants not able to fit the MRI knee coil (Thigh circumference larger than 73.5 cm measured 10 cm above the kneecap and a maximum calf circumferences of 61.5 cm). * Drug addiction defined as the use of cannabis, opioids or other drugs as reported by the participant Control groups (3 groups of 10 control participants matched for each of the patient groups, n=30) Inclusion criteria * Adults under 70 years * Informed consent form signed * No radiological changes on a knee x-ray (Arendt-Nielsen et al., 2015). Exclusion criteria (at inclusion) * Previous knee surgery * Self-reported Knee problems (pain, stiffness) * Clinically significant joint disease (inflammatory or degenerative) at inclusion. * Severe ischemic or neurological sequelae in the lower extremities. * BMI above 32. * Unsuitable for MRI (e.g., pacemaker or claustrophobia) * Participants not able to fit the MRI knee coil (Thigh circumference larger than 34.3-73.5 cm measured 10 cm above the kneecap and a maximum calf circumferences of 61.5 cm). * Drug addiction defined as the use of cannabis, opioids, or other drugs as reported by the participant