Total Knee Replacement Surgery

According to data from the National Joint Registry, the vast majority of people who have a knee replacement only need one. Modern knee replacements are very durable, with around 90% still functioning well after 18 years. With today’s improved materials, many can last 20 to 30 years, meaning the odds are strongly in favour of a single knee replacement lasting long term.

Rehabilitation plays a major role in recovery. By around six weeks, most people regain a good range of movement, although sleep disruption and ongoing stiffness or fatigue are still common. At approximately three months, many patients notice a return to higher levels of activity. Improvement can continue for up to 12 months following surgery.

Everyone’s recovery is individual, but in general, those who commit consistently to their rehabilitation tend to progress more quickly. You can learn more about how physiotherapy supports recovery on our Physiotherapy page.

A knee replacement is balanced according to the patient’s individual anatomy. Variations in ligament tension, whether increased laxity or tightness, are accommodated by adjusting the implant to the patient’s specific soft-tissue envelope.

Patients with hypermobility often report improved joint stability following knee replacement compared with their preoperative state.

As with any surgical procedure, knee replacement carries inherent risks. Most complications occur at a rate of approximately 1–2% and may include excessive bleeding, infection, injury to nerves, arteries, or veins, peri-operative fracture, or implant loosening.

A small proportion of patients experience limited or no symptomatic improvement following knee replacement. While this does occur, it is uncommon, with reported rates likely at the lower end of approximately 5%.

Overall risk varies depending on the underlying indication for surgery and the condition of the knee. Risk is therefore highly individual, with some patients having a higher-than-average risk profile and others a lower than average risk.

The main requirement for knee replacement surgery is pain, that is what you are trying to cure.

In theory, there is no upper BMI limit, as anyone can technically have a knee replacement. In reality, there is a commonly referenced BMI of 40 because evidence shows that risks increase significantly above this level, up to ten times the average risk.

Reducing weight, where possible, significantly increases the likelihood of a successful outcome.

At The Horder Centre, there is also an upper BMI limit related to the likelihood of needing high dependency care. If BMI is over 45, the risk is higher, and that level of care is not available there, so surgery is not undertaken in that setting for safety reasons.

For private patients, there is very little waiting time. It mainly depends on how quickly pre-assessment can be arranged, typically around six to eight weeks.

For NHS patients, waiting times are longer, usually in the region of three to six months, although this can vary depending on current NHS pressures.

Knee pain needs to be honed down to a specific cause. The knee is a complex joint, and different anatomical problems cause different types of pain. Once the cause is identified, it can be treated appropriately.

There is no large study proving this definitively, but anecdotal evidence and smaller studies suggest that inflammatory foods, such as those high in trans fats and sugar, can worsen pain.

Diets like the Mediterranean diet, rich in omega 3 fish oils, tend to be anti-inflammatory and may improve symptoms.

Many people notice their pain improves in warmer countries, which may also be related to dietary changes. Diet likely plays a role and certainly does no harm to try.

Steroid and Visco supplement injections are temporary symptomatic treatments. Relief may persist for up to one year in some cases but is often shorter. These injections reduce inflammation but do not address the underlying joint pathology, and therefore symptom relief may be limited.

Emerging injectable treatments, such as Arthrosamid, which are not absorbed by the body, can act as scaffolds for the body’s own cells, potentially providing longer-lasting relief over several years. Consequently, the role of steroid injections has diminished in comparison with these newer treatment options.

Some NHS centres in England do use robotic systems, but availability is limited and not standard across the NHS. While it is anticipated that such technology may become more widely available in the future, at present it is not a standard option.