For relatively younger individuals who have disbling arthritis affecting a limited part of their knee, a partial knee replacement may be suitable.
Unicondylar Knee Replacement
For people with predominantly medial compartment osteoarthritis (affecting the inner half of the knee), a unicondylar knee replacement may be offered if I feel it is a reasonable option.
If the the back of the patella (knee cap) is badly worn out and but the remainder of the knee is relatively free of arthritis, this type or replacment may be an option. I will discuss reasonable options for treatment to help you make up your mind about your treatment.