Prepare II - Predictive Model Training and External Validation

This study is building and validating a predictive model to identify which patients are most likely to achieve good functional recovery after hip or knee replacement surgery. By training the model on historical patient data and then testing it on a new group, researchers hope to create a reliable tool that can help clinicians personalize rehabilitation plans after joint surgery. **You may be eligible if...** - You are 18 years or older - You had a total hip replacement (THR) or total knee replacement (TKR) at a specific Italian orthopedic hospital in 2018 - You were then transferred to inpatient rehabilitation at the same hospital - Your surgery was performed for osteoarthritis of the hip or knee (primary or secondary) **You may NOT be eligible if...** - You are under 18 years old Talk to your doctor to see if this trial is right for you.