Hi, Welcome to Health care magic forum. As you describe, some people will have the cramps after fixing the spinal fusions. I advise you to consult your orthopedic surgeon for relief. He may prescribe you injections of vitamin B1,6,and 12 for 10 consecutive days, and then periodically. multivitamins,calcium,diclofenac, and paracetamol. Wishing for a quick and complete recovery. Thank you.