An osteotomy is a re-alignment operation to off-load a painful knee compartment. The most common type is an osteotomy performed on the tibia (shin bone) just underneath the knee to convert a bow-legged knee deformity (causing inside knee arthritis) into a knocked-knee position. This is called a high tibial opening wedge osteotomy. A plate is used to maintain the opened wedge until the bone heals in 3 months. The advantage of this operation is that it preserves the joint and allows any activity. The downside is that the operation needs to be protected with crutches for 6 weeks. This operation is typically performed in people who are too young to be considered for joint replacement or in people with high impact activities. There is a 90% chance no further surgery is needed in the 10 years following surgery.
knee replacement
When only one knee compartment is affected by arthritis a unicompartmental (partial) knee replacement can be performed. The inside compartment is the most commonly replaced part of the knee as it carries two thirds of the load when walking. Most people go home on the first or second day after surgery. People generally regard this as a more natural knee and are happier than patients with a full knee replacement. However, arthritis can develop in the other knee compartments which may require a revision operation to a total knee replacement. There is a 93% chance the prosthesis lasts for 10 years (national figures); in my practice the implant survivorship rate is 97% after 13 years (one of the best nationally).
I have been  using the Physica ZUK prosthesis since 2005 and I perform regular research which is presented at national and international meetings. I teach surgeons and trainees about the safe use of the prosthesis. and I am in a European expert panel with 15 colleagues.
The knee cap joint can be replaced in isolation as well but the results are not as good. A different prosthesis is used.
Total knee replacement
A total knee replacement is performed when 2 or 3 compartments of the knee are affected by arthritis. This operation is best done in people who have constant severe pain which causes significant restrictions in daily activities. Most people are happy with the results of surgery and experience good pain relief. However, reports show that 1 in 5 people are disappointed after the surgery for a variety of reasons. A total knee replacement does not allow full knee bending but bending up to at least right angles can be expected. Most people clearly feel this is an artificial joint and notice the restrictions in function, in particular when a more active life style is wanted. The 13-year survivorship of the best prostheses is around 97%. Unfortunately some people still experience pain despite a well performed operation and good x-ray appearances.
Revision knee
Implants can fail for a variety of reasons. Infection, mechanical loosening of the prosthesis and wear are the most common reasons. Several investigations are necessary to find out exactly why the implant is failing. When an implant fails it can cause pain and instability. Revision surgery involves taking the old implant out and replace it with a new one. In cases of infection the revision operation is often carried out in 2 stages. When an implant fails there is often loss of good bone support and the revision prosthesis has several options to add parts to it to compensate for bone loss and instability. Recovery is not dissimilar to that of a (first) total knee replacement depending on the amount of scar tissue and difficulty of surgery.
Major surgery