Can Rib Bone Be Used As Cheek Implants?

Rib bone is used for a number of facial reconstructive procedures. However, it is a complex procedure to harvest and carve bone to make it look natural. It is much easier and likely more aesthetic to use a pre-formed implant made of an inert material, either silastic (silicone) or Medpor (polyethylene). These are very well tolerated by the body and come in a number of sizes and shapes that are specifically designed for this procedure.
With the new fillers, we can even enhance cheeks for 6 months to almost 2 years with no surgery at all.

Rib can be used as graft material, but for cheek implant almost never is. I personally never have performed that operation. Any rib graft demands a donor incision and it is painful.
Once in place, the bone can resorb (gradually dissolve) over time.
Regular cheek implants work quite well. They come out of a box and are easily positioned through an incision in the mouth. My preference is Medpore, but there are other materials available. If the patient doesn't like the result, they can be easily removed.
But the direct answer to your question is yes.