John Waite

How would you explain to a patient what partial knee replacement is?
I spend quite a lot of my time trying to explain the difference between what is labelled a partial and a total knee replacement.  I think of a knee as three parts the inside or medial side of the knee, there’s the outside or lateral side of the knee, there’s underneath the kneecap or the patella femoral joint and I explain that effectively we are now capable of replacing all those three parts as an individual or we can replace them in one operation as a whole that there are patterns of osteoarthritis and not everybody fits into one pattern but there are very common patterns and we now know that the pattern of osteoarthritis where you wear out the inside of your knee first is by far the most common so there are a huge number of patients who come to see me where the only part of their knee that’s worn out is the inside, the medial part of the knee and assuming that they haven’t got a significant deformity, that the ligaments are ok and they haven’t got any inflammatory disease problems then just replacing that bit of the knee that’s worn out and leaving the remainder of the knee that’s in good condition seems to make sense and that’s borne out in the results for partial knee replacement surgery. 

Why do you perform partial knee replacement instead of total knee replacement?
I perform partial knee replacement surgery because I like to be as bone conserving as possible with the operation I am doing I believe that for me it depends on the pattern of the disease the patient has.  If they fulfil the criteria that I insist on for partial knee replacement then it does not make any sense to me to take away two-thirds of the knee if it’s normal, effectively. 

Anecdotally if you talk to patients a lot more of them feel that their knee feels more normal than it does if they have a total knee replacement and I discuss that with them post operatively.  I am not persuaded by anything other than their pattern of disease and for me if they fit that pattern of disease then that’s the best operation and that’s what I tell them

Who is the ideal patient for partial knee replacement?
The ideal patient for partial knee replacement is somebody that, well like for any op, they have to be motivated they have to have the right disease pattern which means that they have isolated disease and if we are talking about medial compartmental disease which is by far the most common, they need to have ligaments that are intact and functioning normally and preserved lateral and patella femoral compartment and if that’s the case then as far as I am concerned partial knee replacement on the medial side is the best operation for them.  I would never talk about total knee replacement in somebody that fulfils my criteria for having that condition and that’s irrespective of age, occupation, level of activity or anything really I would go by disease pattern rather than anything else as far as the patient is concerned.

Who would you not perform partial knee replacement on?
There are a few standard indications for partial knee replacement which include isolated disease in one compartment of the knee, intact ligaments, preserved remaining compartments of the knee and I think if you fulfil those criteria that then partial knee replacement is a good procedure.  There are occasionally people who have inflammatory joint disease that have osteoarthritis as well and I think partial knee replacement in that situation is the wrong thing to do so someone with rheumatoid arthritis for instance I think it is too risky so I would not perform it in that situation…but  If you go to meetings around the world you will hear particularly if you go to America patients will be judged on their age, their weight particularly and that sort of thing as far as I am concerned that has no bearing on my decision making about the operation, I perform it on patients ranging from 30’s up to 80’s and I’m not persuaded that age is a factor in fact I find that in particularly overweight people partial knee replacement surgery is technically a lot easier than total knee replacement surgery but again it is based on disease pattern not any other kind of existing factor so really obviously you need the joint to be free of infection and all the other obvious contra indications but I suppose inflammatory arthritis would be my main complication along with ligament deficiencies.

What are the main advantages of partial knee replacement?
Short term advantages I would say it’s a smaller operation in terms of the physiological insult to the patient, it’s done through a smaller incision it violates less of the soft tissues and obviously you’re taking away less bone so it tends to be less painful, patients tend to get over the operation quicker and get back to walking, driving and what they would describe as a normal level of activity quicker.

These interviews have been conducted and are being published upon obtaining patient and surgeon consent for this purpose