If both me and my wife have sickle cell, what are the chances our child will as well?

Disease or Trait? Do you have sickle cell disease or trait (carrier)? Sickle cell disease is inherited in an autosomal recessive pattern. If both parents have sickle cell disease, then the child will have the disease. If both parents have sickle cell trait, then there is a 25% chance of having a child with sickle cell disease and 50% chance of having a child with sickle cell trait (carrier).
About 100% Assuming that you both have classical sickle cell with hemoglobin ss vs. Hemoglobin s beta thal, hemoglobin sc, etc. Then the chance of having a child with sickle cell is 100%.