Your surgeon has probably already taken X-rays and given you some options to consider. If the rest of the implant is in good condition and isn't loose, then the surgeon may be able to cement the stem back together.
If there are other problems, the implant may have to be removed and replaced. Some of this decision will be made based on the condition of the remaining joint and strength of the surrounding bone.
If you aren't a good candidate for revision surgery, then it may be necessary to fuse the joint. The surgeon can fuse the elbow in a "functional" position. You won't be able to bend or straighten the arm but with the right position after fusion, you'll still be able to use that arm. Usually the fused elbow means you'll use the arm as an "assist" to the other arm and hand rather than as the primary mover.