You may be a good candidate for revision surgery. If the replaced side still looks healthy on X-ray, then a tricompartmental revision surgery might be recommended. In this case, the other half of the knee is replaced along with the kneecap.
You would end up with a total joint replacement, but it would come in three component parts. If there is too much wear and tear or loosening of the UKR it may be necessary to remove the UKR and replace the entire joint with a total knee replacement (TKR).
See your orthopedic surgeon for an evaluation and find out what are your options. You may be a good candidate for rehab or revision surgery. Knee replacement surgery has improved even in the last six years.