What is Knee Osteoarthritis?

Osteoarthritis of the knee is the most common joint disease in the world. It occurs when the layer of cartilage (a strong and flexible tissue that helps joints move smoothly and absorb shocks) on the end of the thigh bone or the top of the shin bone becomes damaged. This results in the bones rubbing against one another, causing pain and stiffness. Over time, this can cause even more damage as the abnormal movement wears away more cartilage and causes other abnormalities in the joint such as irregular bone growths. While the knee cartilage incurs some wear and tear from normal use, the ability of the body to repair it can be reduced by age, excessive stress or injury, and this is what leads to long-term degeneration of the joint.

What causes it?

When walking, much of the load is placed on the inside of the knee, due to the knees naturally ‘bowing’ slightly away from one another. This causes a greater amount of wear and tear on the cartilage on the inside of the knee. When combined with other factors such as age, this cartilage can become damaged, resulting in the bowing becoming progressively worse as the bones become closer together on the inside than the outside of the joint. This in turn leads to more stress and more damage, creating a cycle that ends in osteoarthritis. An attractive option in this case is to modify the joint to more equally distribute the weight across the knee, rather than replacing the entire knee with an artificial joint; this surgical procedure is called High Tibial Osteotomy (HTO). It involves a cut into the top of the shin bone (tibia) which is slightly opened to change the leg’s structure, resulting in a less bowed leg and more weight carried by the healthier tissue.

HTO a surgical alternative

As well as reducing pain and stiffness, this procedure has several other advantages. Perhaps the most attractive benefit of this procedure compared to a total or partial knee replacement is that preserving the natural joint allows for more normal use of the knee following surgery. This includes activities that would usually be unlikely after knee replacement, including sport!

HTO is, therefore, a joint preserving surgical treatment. Unlike knee replacement where the joint surface is permanently removed to host the artificial implant, in a well performed HTO the bone will regrow, and the reduced load often allows the damaged cartilage to regenerate.

Where knee replacement often leads to a sedentary lifestyle and associated other health conditions, HTO can allow greater activity levels with the associated benefits of activity. Depending on age and level of activity, a knee replacement may need to be replaced after 10 to 15 years of use, requiring a ‘revision’ or follow-up operation, resulting in a greater risk of infection or complications.

For younger and active patients, HTO is an attractive alternative to partial knee replacement (UKR) but also to total knee replacement (TKR).


TOKA applies novel technology to deliver pioneering HTO surgery precisely tailored to each patient.

The procedure requires a stabilising plate to support the tibial cut while it heals after the surgery. While traditional methods use a standard plate, TOKA offers a bespoke titanium 3D-printed implant which precisely fits the bone, potentially reducing the irritation to the surrounding skin and pain caused by larger ‘one size fits all’ solutions.

The plate is structurally optimised to be using for daily activities, and to encourage bone healing, resulting in a smaller profile and a faster recovery, following an initial period of reduced weight-bearing.

Helping yourself

Reducing excess stress on the knee joint is very important both before and after a surgery for osteoarthritis. The best way to do this is to lose weight and undertake light physical activity. Wearing soft soled shoes reduces the impact while walking – try to avoid high heels and hard soled shoes. Regular exercise will help as long as it is not too intense – swimming should be beneficial but weightlifting or running on hard surfaces will not.

Read more information and exercise advice for knee arthritis from Versus Arthritis here.