Robotic-assisted partial knee replacement

What is a robotic-assisted partial knee replacement?

A robotic-assisted partial knee replacement is a procedure that is performed with the assistance of robotic technology. Partial knee replacements are a common treatment for knee osteoarthritis or injuries to the knee joint. As its name suggests, it involves replacing just one or two components of the knee with artificial elements, rather than the entire joint.

In a robotic-assisted partial knee replacement, the robot technology acts as a guide for the procedure, rather than performing the surgery itself.

What else is robotic-assisted partial knee replacement known as?

Robotic-assisted partial knee replacement is also sometimes referred to as “robotic half knee replacement” or “robotic unicompartmental knee replacement”. Both are essentially ways of saying that only part of the knee joint is being replaced.

What conditions may require robotic-assisted partial knee replacement surgery?

A partial knee replacement is often a last resort treatment for a number of different musculoskeletal conditions affecting the knee joint, including:

• Osteoarthritis: a condition characterised by accelerated wear and tear on the knee. This causes the cartilage that protects the bones to deteriorate, enabling them to rub together and generate friction, which causes pain, inflammation and other debilitating symptoms.
• Rheumatoid arthritis: this type of arthritis is an autoimmune condition that occurs when your body attacks its own healthy cells. In this case it attacks the lining of your joints, causing pain and mobility issues.
• Knee injury/knee fracture: these can include ligament tears, meniscus tears, tendonitis (inflammation of the tendons) or even a fracture, normally caused as a result of sporting or accidental injury.

What does a partial knee replacement look like?

There are three compartments inside your knee joint. These are:

• Medial component: this is the inner side of the joint closest to your knee, which mainly provides structural stability for your leg, and absorbs shock from movement.
• Lateral component: on the outer side of the knee, this component enables the hinge motion of your leg, stabilises your body when you bend side to side, twist or try to straighten your leg too excessively.
• Patellofemoral component: the component where the kneecap (patella) glides over the front of your thigh bone (femur) it helps you to straighten your leg, as well as increasing the strength of your thigh muscles.

A partial knee replacement uses an artificial (usually metal and plastic) component on one side of the knee joint, acting as a patch to cover the area where cartilage has worn down.

What are the different types of partial knee replacement?

The different types of partial knee replacement are simply differentiated by the compartment of the joint that they are to replace.

• A patellofemoral knee replacement replaces just the damaged cartilage behind the kneecap and femoral groove. It’s designed to treat cases of isolated patellofemoral arthritis.
• A lateral unicompartmental knee replacement is used to replace a damaged outer (lateral) knee compartment. It’s typically used in people who have lateral osteoarthritis.
• A medial unicompartmental knee replacement substitutes the damaged inner part of the knee and is also designed to treat isolated cases of osteoarthritis.
• Bicompartmental knee replacement is the name given to the replacement of any two of these elements at the same time.

Is robotic-assisted partial knee replacement surgery a new technology?

No, robotic-assisted knee replacement surgery isn’t a new technology. In fact, the first reported procedure took place in 2006 when it was used to complete knee revision surgery. However, the technology has evolved considerably since then, moving from fairly basic robotic guidance to providing advanced imaging that enables bespoke treatment planning using 3D models of the joint for optimal precision and accuracy.

What robotic systems are used in Nuffield Health’s partial knee replacement surgeries?

We use two of the most well-known robotic systems to carry out partial knee replacement surgeries at Nuffield Health hospitals across the UK.

Mako® robotic-arm assisted surgical system

MAKO® is one of the most widely recognised robotic platforms used for knee and hip replacement surgeries. The overall technique
combines CT scanning to create a 3D model of your joint (which is used to plan your treatment) with a robotic arm that will enhance your surgeon’s precision and accuracy.

The robotic arm does not operate alone but is instead controlled by your surgeon. However, it is steadier and more controlled than a human arm, which helps to reduce any risks associated with the knee replacement procedure.

CORI® robotic-assisted surgical system
The CORI® system doesn’t use CT imaging to create a plan for your surgery. Instead, a handheld probe is used to offer real-time optical navigation during the procedure. It also doesn’t have a robotic arm but uses a smart handheld device to control this navigation. This makes it smaller and easier to fit into some operating theatres.

Robotic vs conventional partial knee replacement - what’s the difference?

There is one core difference between robotic and conventional partial knee replacement, and that is whether the planning and guidance is carried out by technology or simply using your surgeon’s skill and experience.

Is robotic-assisted partial knee replacement surgery better than conventional surgery?

There are definitely some advantages of robotic-assisted partial knee replacement surgery over conventional techniques.

Advanced planning: The technology used in robotic-assisted partial knee replacement surgery enables an advanced level of planning for your surgery, using cutting-edge imaging to visualise the joint ahead of treatment. Meanwhile, conventional surgery is carried out by your surgeon using their own knowledge and experience of the joint, with no additional support.

Better implant positioning: Studies show that using robotics can improve the positioning of the implant used in partial knee replacement surgery.

Enhanced soft tissue preservation: Studies have also shown that using robotic techniques provides better soft tissue preservation, preventing unintentional damage to surrounding structures, when compared to manual knee surgery.

Improved patient experience: Robotic-assisted knee surgery has been associated with greater patient satisfaction and faster recovery.

What is the difference between a total and partial knee replacement?

The difference between a total knee replacement and partial knee replacement is the number of compartments being exchanged for artificial alternatives. In a total knee replacement, all three compartments are replaced, and the entire joint is resurfaced. This also means that more ligaments in the joint are affected.

As a larger procedure, a total knee replacement usually takes longer than surgery for a partial one; there is often more discomfort in the initial stages of healing, and recovery can take longer – up to 12 months compared to up to six months for a partial knee replacement.

Partial or total knee replacement: what's best for me?

Whether you need a partial or total knee replacement will depend on the extent of the damage to your joint. Your orthopaedic consultant will assess your individual circumstances and make a personalised recommendation.

Who is a good candidate for robotic-assisted partial knee replacement?

You may be a good candidate for a robotic-assisted partial knee replacement if:

• you have advanced osteoarthritis affecting only one compartment of your knee
• the ligaments supporting your knee, particularly your anterior cruciate ligament (ACL), are stable and healthy
• you are a healthy weight
• you’ve tried more conservative treatments like pain relief, physical therapy or steroid injections into the joint, with little to no success.

Who is not suitable for robotic-assisted partial knee replacement surgery?

You may not be suitable for robotic-assisted partial knee replacement surgery if you have:

• inflammatory arthritis
• osteoarthritis that is affecting all compartments of your knee
• severe ligament damage
• leg deformities such as bow-leggedness or knock knees
• a high BMI
• a history of infections in the knee joint.

Your consultant will take your medical history and lifestyle into account when deciding whether or not you are a good candidate for a partial knee replacement.

What are the alternatives to robotic-assisted partial knee replacement surgery?

There are a few alternative treatments to robotic-assisted partial knee replacement surgery. Firstly, you can always choose to have your surgery performed manually rather than using robotic technology. You could also try to delay the need for surgery using joint injections which can provide relief from symptoms for several months or more.

If you have fairly early-stage arthritis with limited damage to your knee cartilage, you may be a good candidate for a procedure called an osteotomy. This involves cutting, reshaping or realigning the joint to take pressure off the damaged cartilage. This could also help to delay knee replacement surgery.

How can I prepare for robotic-assisted partial knee replacement surgery?

Being prepared for your partial knee replacement surgery could help improve the outcome of your procedure, reduce your risk of complications and accelerate your recovery.

Proper preparation is sometimes known as prehabilitation and involves a number of elements.

• Eating a healthy, nutritious diet in the weeks before your surgery.
• Stopping smoking, as this increases your risk of complications during your surgery and could delay your recovery.
• Limit your alcohol intake.
• Stop taking any of your usual medications (if advised by your doctor).
• Complete gentle exercises to improve the strength in your quadriceps and hamstrings.

Your consultant will give you specific instructions to follow in the days and weeks before your surgery, and it’s important that you follow these to help minimise your risk of complications and ensure you are in the best possible health before your operation.

What to expect during robotic-assisted partial knee replacement surgery

On the day of your partial knee replacement surgery, you’ll be asked to come in a few hours before your procedure is scheduled. This is to give you time to check in, get comfortable and have pre-operative checks completed by your healthcare team.

Robotic-assisted partial knee replacement surgeries may be performed under a spinal block with sedation, or general anaesthetic. The first means you are awake but won’t feel any pain and will be very drowsy, while a general anaesthetic means you’ll be asleep the entire time.

Once you’re anaesthetised, your surgical team will finalise the robotic mapping of your knee, based on your pre-operative scans you’ll have had up to two weeks prior. Your surgeon will make a small incision into your knee, and the robotic technology will be used to remove the damaged cartilage and bone, before ensuring the implant is perfectly aligned.

Your surgeon will then close the wound using stitches or staples, and it will be dressed and you’ll be taken to recovery so that the anaesthesia can wear off. During this time, you’ll be closely monitored and given some initial pain relief.

Is robotic-assisted partial knee replacement surgery painful?

The surgery itself shouldn’t be painful, as it will be carried out either under a spinal block or general anaesthetic. However, many people do experience discomfort during the recovery process, and you’ll be given pain relief by your medical team.

How long does robotic-assisted partial knee replacement surgery take?

Typically, robotic-assisted partial knee replacement surgery takes between one and two hours. However, exact procedure times can vary between patients.

Does robotic-assisted partial knee replacement take longer than conventional surgery?

Sometimes, yes – but only by up to half an hour. This is because the mapping process and calibration of the robotic technology takes a little extra time.

How soon can I go home after robotic-assisted partial knee replacement surgery?

You may be able to go home the same day as your robotic-assisted partial knee replacement, but some patients are kept in overnight for additional monitoring. Your surgeon will advise you whether to expect to stay in hospital overnight after your robotic-assisted partial knee replacement surgery.

Do you spend less time in hospital with robotic-assisted partial knee replacement compared to conventional surgery?

Yes, studies show that patients tend to spend less time in hospital with robotic-assisted partial knee replacement compared to manual surgery.

How long does it take to recover after robotic-assisted partial knee replacement surgery?

Recovery after a robotic-assisted partial knee replacement is typically faster than in manual knee surgery. It can be broken down into three stages.

Early recovery
In the early stages of your recovery, you’ll need to balance resting your knee joint with physical therapy exercises. You’ll probably need a reasonable amount of pain relief, and to use crutches so you don’t bear full weight on your knee.

Weeks two to six
If you follow your physical therapy exercises, you should be able to start walking without crutches during this stage of your recovery. You will need to avoid any high-impact exercise, but activities like cycling and swimming may be possible with the permission of your doctor. You should also be able to return to work during this time, provided your role is mostly desk-based. You should also be able to start reducing your reliance on pain medication.

Long-term recovery
Beyond the first few months, you should notice increased improvement in the strength and mobility of your knee joint. Reliance on pain medication will continue to decrease and you may be able to start getting back to higher impact exercise.

It’s important to note that these recovery rates are estimates, and exactly how fast you get back to normal will depend on your own circumstances. Always follow the guidance of your consultant and Nuffield Health medical team.

When can I take a shower or bath after robotic-assisted partial knee replacement?

Staying clean is important for avoiding infection, but you’ll probably need to wait at least 24 hours before you can shower, to give your incision a chance to start healing. You’ll also be advised to avoid soaking in a bath, or going swimming, for at least six weeks or until the incision is completely healed.

What should I avoid after robotic-assisted partial knee replacement surgery?

Your consultant and medical team will give you strict instructions on things that you should avoid in the days and weeks after your surgery. There is an extensive list of recommendations, and these include but aren’t limited to:

• Sitting with your legs crossed
• Sitting for long periods
• Sitting in low or very soft chairs
• Soaking your incision
• Driving until you’ve been given permission to do so (usually three to six weeks after surgery)
• Heavy lifting
• High-impact exercise
• Twisting or turning the knee joint
• Kneeling
• Smoking, as this can increase your risk of post-operative complications and slow down your recovery.

What are the risks or complications unique to robotic-assisted partial knee replacement?

All surgeries come with a degree of risk, and robotic-assisted partial knee replacement surgery is no exception. Some of those associated with this particular surgery include:

• Pin-site complications. These can occur because robotic systems use small pins and trackers to guide the robot. Pain, infection and fracture are rare, but not impossible.
• Technical issues such as software glitches or mechanical problems.
• Soft tissue/bone injury caused by improper placement of drills or pins.

These complications are in addition to those usually associated with surgery such as:

• Infection
• Bleeding and blood clots
• Nerve injury.

Your consultant will be able to give you a complete list of potential risks and complications and answer any questions or concerns that you have.

How common is knee pain after partial knee replacement using robotic technology?

Knee pain is common after any partial knee replacement, whether robotic or otherwise. You’ll be given pain relief to help you to manage your discomfort during this time. Most people are able to move onto milder pain relief within a few weeks of their surgery.

It’s widely reported that people who have robotic-assisted partial knee replacement surgery have less post-operative pain than those who have had manual surgery.

What is the success rate of a robotic-assisted partial knee replacement?

The success rate of robotic-assisted partial knee replacement is reported to be very high at over 90%, although exact rates vary between individuals.

Can a robotic-assisted partial knee replacement come loose over time?

It’s fairly rare, but yes, a partial knee replacement can come loose over time. If this happens, it is usually a result of further degeneration of the knee joint, normally due to wear and tear or infection. Excessive stress on the joint from carrying too much weight or high levels of high-impact exercise can also accelerate the rate at which the joint breaks down, increasing the risk of implant loosening.

Nevertheless, studies show that the majority of knee replacement implants last for at least five to ten years after surgery.

How much does a robotic-assisted partial knee replacement cost at Nuffield Health?

For pricing information, please contact your local hospital. The hospital or your healthcare team will give you a fixed all-inclusive price for the treatment following your initial consultation.