A partial knee replacement is a type of surgery performed to replace part of a damaged knee rather than the whole knee (total knee replacement), preserving undamaged bone and surrounding tissue. It is a less invasive alternative to a total knee replacement that patients generally recover from faster, with fewer complications, and with a more natural-feeling knee.
If you have arthritis in your knee, persistent knee pain or another knee condition, a partial knee replacement might be right for you. Here, we explain what partial knee replacement surgery involves, what you can expect in terms of recovery from a knee replacement operation, and the advantages of having surgery with Ramsay Health Care.
Specialist orthopaedic surgeons are available at Ramsay Health Care hospitals across the UK, offering expert assessment and treatment for knee conditions.
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What is partial knee replacement?
A partial knee replacement, also called a unicompartmental knee replacement or a unicompartmental knee arthroplasty, is a surgical procedure to treat a damaged knee, usually due to knee arthritis or an injury.
Whereas a total knee replacement removes and replaces the entire knee joint with a prosthetic one, a partial knee replacement only removes the damaged part of the knee and replaces it with a prosthetic. It leaves the undamaged parts of the joint where they are.
A partial knee replacement operation is recommended when only one of three different parts of the knee (three different knee compartments) is damaged:
- Medial compartment (inside compartment): The inner side of the knee
- Lateral compartment (outside compartment): The outer side of the knee
- Patellofemoral compartment (kneecap compartment): Where the kneecap meets the thigh bone
Most often, the medial (inner) compartment is the one replaced, but the lateral (outside) and patellofemoral (kneecap) compartments can also be replaced. During the knee operation, the surgeon will remove the worn cartilage and damaged bone beneath it from the affected knee compartment. They will replace it with specially designed metal and plastic components.
The healthy cartilage, bone, and ligaments in the rest of the knee are preserved. Compared to a full knee replacement, this usually results in:
- A smaller incision
- Less disruption to surrounding tissues
- Faster recovery for many patients
- A lower risk of post-surgery complications
- A more natural-feeling knee after recovering from the surgery
Who is a candidate for a partial knee replacement?
Partial knee replacement is typically recommended for patients who have arthritis or knee damage that’s limited to one compartment of the knee joint only.
Conditions that may lead to partial knee replacement surgery
More patients are now being offered partial knee replacement surgery, with candidates spanning different ages and activity levels. You might be considered for a partial knee replacement operation if you have:
- Unicompartmental osteoarthritis: Arthritic wear and tear affecting only one compartment of the knee, or affecting one compartment more severely
- Ongoing pain or stiffness despite non-surgical treatment: Due to arthritis or a knee injury affecting one compartment
- Difficulty walking, climbing stairs or carrying out daily activities: Caused by arthritis or a knee injury affecting one compartment
Before any surgery recommendations, your doctor or orthopaedic consultant will usually discuss more conservative treatments with you first. These include:
- Physiotherapy for your knee
- Weight management and lifestyle improvements
- Pain relief medication
- Steroid injections into the knee
If these conservative treatments don’t prove effective enough, a partial knee replacement operation may be the best option.
Unicompartmental knee replacement eligibility criteria
Your orthopaedic consultant will assess whether you’re a suitable candidate for partial knee replacement. They’ll consider:
- Whether the damage is confined to one knee compartment
- If you have healthy cartilage and bone in the other two compartments
- If you have intact cruciate ligaments
- Whether you have an adequate range of knee movement
- Whether you have an overall stable knee joint
- Whether you have non-inflammatory arthritis (for example, osteoarthritis, rather than rheumatoid arthritis)
At Ramsay Health Care, your pathway will begin with a meeting with one of our specialist orthopaedic consultants. They’ll talk to you about your condition, symptoms, and lifestyle, as well as conduct a clinical examination. You’ll likely also be sent for one or more imaging scans, like an X-ray, MRI (magnetic resonance imaging) scan, or an ultrasound scan. Based on this, the most suitable form of treatment will be recommended, which may be a knee operation or more conservative treatments.
What happens during partial knee replacement surgery?
Partial knee replacement surgery is usually carried out under a general anaesthetic, although some patients may have a spinal anaesthetic. The procedure typically takes one to two hours, with additional time for pre-surgery preparation and post-surgery recovery.
The exact details of the surgery will vary between patients, depending on the condition of the knee and the surgeon’s preferences. Most partial knee replacement operations follow a similar pattern, including:
- Anaesthesia: Once in the operating theatre, you’ll be given either a general anaesthetic (put to sleep) or a spinal anaesthetic (numbed from the waist down)
- Incision: A small incision, typically 7 to 10 centimetres, is made over the knee to expose the damaged compartment
- Removal of damaged cartilage and bone: The surgeon removes only the diseased or damaged cartilage and underlying bone from the affected compartment. The healthy tissues and unaffected parts of the knee will be left intact
- Implant insertion: Metal and/or plastic prosthetic components will be secured in place where the bone was removed. A plastic spacer will then be inserted between the prosthetic components to create a smooth, functional gliding surface to allow the knee to move properly
- Closure: The incision is closed with staples or stitches, and a bandage and dressing will be applied
- Robot-assisted surgery: Ramsay offers robotic-assisted partial knee replacement surgery at selected hospitals, using advanced systems, including the CORI® Surgical System and Mako SmartRobotics™. Using 3D imaging and real-time data can improve surgical precision, result in smaller incisions, less post-operative pain, and faster rehabilitation. Your surgeon will advise whether robotic-assisted surgery is suitable for your case.
- Immediate recovery: After surgery, you will be taken to recovery and then to your private room. Most patients stay in the hospital for one to two days, depending on their progress.
If you have any questions or concerns about a partial knee replacement at Ramsay Health Care, your surgeon will be happy to address them with you.
Partial knee replacement recovery
It’s typically quicker to recover from a partial knee replacement than a total knee replacement. This is because less material is removed from the knee joint, and the surgical incision is smaller.
How quickly you recover from your knee operation will depend on the specifics of your surgery, your health and overall condition, and how well you follow your recovery plan. However, most patients experience the following recovery timeline:
Days 1 and 2: Early recovery in hospital
You’ll most likely stay in the hospital for one or two nights after your knee operation. You’ll be encouraged to stand and begin walking (with assistance) either on the same day as your surgery or the day after. Early movement can help improve circulation, reduce stiffness, and support healing.
During your hospital stay, you can expect:
- Support from nurses and physiotherapists to help you get out of bed safely
- To walk short distances using crutches, a frame, or sticks
- Pain relief medication to keep you comfortable
- Guidance on exercises to improve knee movement and strengthen muscles
- Advice on climbing stairs, getting dressed and managing daily tasks safely
Many patients are ready to go home within one to two days, once they are mobile, comfortable and medically well enough for discharge.
Weeks 1 and 2: Settling in at home
The first two weeks at home, you’ll focus on managing swelling, protecting the wound, and gradually increasing movement.
You’ll usually continue to:
- Walk with crutches or sticks for support
- Perform daily exercises recommended by your physiotherapist
- Keep the wound clean and dry
- Elevate your leg and use ice packs if advised
- Take pain relief as directed
It’s normal to experience swelling, bruising, pain and discomfort during this stage. Most patients notice steady improvement in their recovery each day.
Weeks 3 to 6: Building strength and confidence
As pain and swelling reduce, you should find it easier to move around and walk further distances. It’s important to follow your recommended exercises during this time. This is a key part of your recovery and will help to restore strength, flexibility, balance, and your confidence in being on your feet.
During this period, many patients can:
- Reduce or stop using walking aids
- Increase their walking distance
- Bend and straighten the knee more comfortably
- Return to light household tasks
- Return to office-based or light work, depending on their job
- Begin gentle low-impact exercise such as static cycling or swimming (if approved)
If your job involves heavy lifting, kneeling or prolonged standing, you may need more time away from work.
The 6-week mark: Returning to routine activities
By around six weeks, many patients can resume most normal day-to-day activities with much less pain and more mobility than before the knee operation.
You may be able to:
- Drive again once you can control the vehicle safely and perform an emergency stop comfortably
- Walk longer distances without aids
- Shop, socialise, and manage daily activities more easily
- Continue progressing your exercise programme
You should always check with your surgeon and your motor insurer before returning to driving to ensure you can do so safely and that you’ll be properly insured.
3 to 6 months: Returning to leisure activities
Sometime between three and six months, most patients feel significantly stronger and more mobile. Many can return to hobbies and recreational exercise. Sometimes this includes hobbies they couldn’t do before the surgery.
Suitable low-impact activities you could focus on include:
- Walking
- Swimming
- Cycling
- Golf
- Gentle gym-based exercise
You should only resume higher-impact sports or activities – that place heavy strain on the knee – once you’re advised to do so.
Up to 12 months: Continued healing
Although many people feel well much sooner, healing and subtle improvements can continue for up to a year after your partial knee replacement surgery. Strength, stamina, balance, and confidence often improve over time. You should find yourself in a better position than before you had the partial knee replacement operation.
The importance of physiotherapy for your recovery
Throughout your partial knee replacement recovery, physiotherapy and a well-structured rehabilitation programme are vital. Sticking to your rehabilitation plan diligently can make a significant difference to your recovery. It should help to restore range of movement, build muscle strength, reduce stiffness, and improve your balance. This is all aimed at getting you back to living with a good quality of life.
You should be able to enjoy the activities and pastimes you did before your surgery, especially the ones your knee may have even prevented you from doing.
What are the risks and complications of a partial knee replacement?
Partial knee replacement operations are typically successful procedures, and the risk of complications is generally lower than that associated with total knee replacement.
As with any surgery, complications can happen, such as:
- Lasting stiffness and limited mobility: Reduced range of motion or significant scar tissue formation that impedes mobility after recovery
- Persistent pain or swelling: Chronic pain or excessive swelling around the joint
- Leg length differences: The operated leg can shorten. This is usually by a small amount and is typically relatively easy to manage
- Implant Issues: The prosthesis may become loose, wear out, or fracture the surrounding bone
- Progression of your arthritis: The development of arthritis in the non-replaced compartments of the knee, which may necessitate a total knee replacement later
- Nerve and/or blood vessel damage: In rare instances, damage can occur to the surrounding nerves or vessels during surgery
- Blood clots: Blood clots can form in a vein, called deep vein thrombosis (DVT). This can lead to dangerous conditions, like pulmonary embolism (PE). The risk can be managed with blood thinners and focusing on early movement during recovery
- Infection: Infections can occur at the incision site or deep around the prosthesis
At Ramsay Health Care, we carry out surgery in modern orthopaedic theatres. Our experienced consultants and clinical teams focus purely on patient safety. Your consultant surgeon will discuss the risk of your procedure with you and will address any questions or worries you have.
Partial knee replacement vs. total knee replacement
Partial knee replacement and total knee replacement operations can both be effective treatments for knee conditions and damage. They suit different patients in different situations.
The key differences between each type of knee operation are:
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Partial Knee Replacement
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Total Knee Replacement
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A smaller incision is made
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A larger incision is made
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More cartilage and bone are preserved
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More cartilage and bone are removed
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Faster recovery for most patients
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Longer recovery for most patients
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The new knee often feels more natural
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The new knee often feels slightly less natural
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Suitable when one knee compartment is damaged
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Suitable when multiple knee compartments are damaged
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Can be revised to total knee replacement later if needed
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The full joint is replaced, but it can be replaced again if required
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The right option for you will depend on the condition of your knee, your symptoms, and your goals.
At Ramsay Health Care, one of our consultant orthopaedic surgeons will assess your knee joint and your overall case. They will advise whether a partial or total knee replacement is the most appropriate treatment for you.
Why choose a private partial knee replacement?
Opting to go private for partial knee replacement surgery can offer a range of advantages, such as:
- Enhanced privacy and dignity – Your own private room during consultations and procedures for maximum comfort and discretion.
- Faster access to healthcare - Without the delays of a waiting list, you can get the expert treatment you need quickly.
- Continuity of care - You’ll typically see the same Ramsay consultant throughout your treatment journey, helping to ensure a more personalised and consistent approach to your care.
- Flexible appointments – Consultations are arranged at times that work around your schedule, including evenings and weekends at some locations.
Partial knee replacement cost at Ramsay Health Care
The cost of a partial knee replacement with Ramsay Health Care will depend on the details of your operation and which Ramsay hospital you attend.
After a consultation with one of our orthopaedic surgeons, we’ll provide you with a personalised quote for your knee operation. This will be valid for up to 60 days.
We offer a range of payment options for your partial knee replacement, including:
- 0% Payment Plans: Allowing you to spread the cost of your knee operation with fixed, monthly payments made over a time period that suits you.
- Self-fund treatment: With our all-inclusive Total Care package, you’ll make a one-time payment at a pre-agreed price that covers all the treatment you’ll need.
- Your own medical insurance: Your private healthcare insurance may cover your partial knee replacement surgery. You should get written confirmation from your insurance provider before booking your procedure with us.
For a personalised quote or to discuss payment options in more detail, please contact us.
Partial knee replacement surgery at Ramsay Health Care
Choose Ramsay for your partial knee replacement surgery to get timely access to the expert treatment you need.
Ramsay’s orthopaedic consultants are experts in knee replacement operations, and our whole health care team will support you at every step of the treatment process, including recovery and rehabilitation.
Your Ramsay experience includes:
- Convenient locations across the UK, many with on-site parking.
- State-of-the-art facilities with access to the latest surgical technology.
- Comprehensive care and follow-up to monitor your recovery and long-term outcomes.
- Dedicated patient support with easy access to your specialist team throughout your journey.
Contact us today to speak with one of our friendly advisors, find out more about partial knee replacement surgery at Ramsay Health Care, and book your consultation.
Partial Knee Replacement FAQs
