There are a number of factors that determine this including the level of activity that the patient undergoes as well as the possibility of the arthritis extending into the compartments of the knee that were not replaced. The same is true for total knee arthroplasty and although unicompartmental knee arthroplasty patients can go onto require total knee arthroplasties, if selected appropriately then knee replacements can last a decade or even longer.

The procedure for replacing a single compartment in the knee takes slightly less time than the procedure for replacing the knee in its entirety. Although similar instruments and surgical steps are used and undertaken, because we are only replacing a single compartment within the knee, there are fewer surgical steps and so the surgery takes slightly less time than a standard knee replacement.
A total knee replacement would take anywhere from 45 minutes to an hour-and-a-half depending on the specific patient, their anatomy and the severity of their osteoarthritis whereas the unicompartmental knee arthroplasty generally will take between half an hour to an hour in total surgical time.

Given that unicompartmental knee replacements are less invasive than total knee replacement, it will take the patient slightly less time to recover from as compared to a total knee arthroplasty. We generally expect patient who undergoes a total knee arthroplasty to have recovered the majority of their recovery within 3 months of the surgery; however, usually by 6 weeks after the unicompartmental knee arthroplasty, patients are up walking and their pain levels are diminished significantly and they are close to their baseline level.

You will notice some swelling that will likely increase for the first few days after the surgery provided that you engage in exercise and ambulate on the knee normally as would be expected after the surgery. The swelling should begin to subside after the first few days and should be mostly gone by 2 weeks after the surgery.

Essentially, you will continue to be in pain. Arthritis is a progressive disease that, if left untreated will simply only get worse over time. There is a potential that, if you leave it too long, arthritis may set into your knee more extensively and you may go from being a possible candidate for unicompartmental knee arthroplasty to someone who would unfortunately be left only with the option of a total knee arthroplasty.

The goal of unicompartmental knee replacement is to remove the arthritis that is present in a single compartment of the knee and replace the arthritic bone that has worn away the knee cartilage with artificial replacement components. In this sense, yes it does get rid of arthritis in the knee.