X-rays were taken but nothing showed up. The pain occurs when he attempts to sit down or stand up. Not while he is sitting or lying down.
Ruth,
X-rays are not enough. Have him talk to his MM Specialist. They will order a CT scan or PET scan.
Pain may be referred to knees from spinal nerves CT or PET or MRI essential.
My left knee is very painful. Oncologist says...no chance of surgery.