Regarding how to determine whether the bone graft is viable or not, the following methods are generally adopted in clinical practice: 1. The imaging examination around the implanted bone should be reviewed regularly. If the fracture line between the implanted bone and the original bone can be seen on the plain film and there is a significant blurring, it suggests that the bone graft may be viable. If you can clearly see the continuous bone trabeculae through the gap or fracture line, you can be sure that the bone graft is fully viable. 2. You should judge by the clinical symptoms of the patient. Generally, after the bone graft has been revitalized, the pain at the site of the bone graft, if previously present, will be significantly reduced or even disappear, and the patient himself will feel a significant recovery. 3. In the period afterwards, the stability of the bone perimeter should also be assessed. This is often indicated in cases where there is joint fusion, for example, after a cervical spine related surgery, if there is a bone graft between the relevant vertebrae, the periarticular stability around the bone graft needs to be assessed at a later stage. The patient is asked to do hyperflexion and hyperextension of the neck. If there is no significant instability, or if there is no significant change in the inter-articular space seen on plain film at this time, the implant is fully viable.