Partial Knee Joint Replacement

If only one part of the knee joint is affected with arthritis then you may be suitable for a partial knee replacement. The criteria for doing a partial knee replacement is a lot more strict than for a total knee replacement and Nigel will give you the option of partial knee replacement if you meet those criteria.

Partial Knee Replacement VS Total Knee Replacement

The benefits of partial knee replacement compared with total knee replacement are:

  • Smaller incision
  • Shorter hospital stay
  • Faster recovery
  • Better knee function
  • A more normal feeling knee
  • Less complications (they are similar to total knee joint replacement)

Partial Knee Joint Replacement

Otherwise known as uni-compartmental knee replacement (UKA).It is an operation performed to alleviate pain, stiffness, swelling, instability, and disability in those patients who suffer from osteoarthritis (wear and tear).

Having a partial knee joint replacement is a big deal. It requires an open and at times quite frank discussion between Nigel and the patient about:

  • Why a partial knee replacement is being done
  • What a partial knee replacement is
  • What the benefits of partial knee replacement are
  • How the partial knee replacement works
  • What the patient can expect immediately after the operation, the weeks after, and then in the coming years
  • What Nigel’s expectations are for you
  • How patients react to having a partial knee replacement
  • How long a partial knee replacement will last
  • What the risks are for partial knee replacement not only in the short term, but in the longer term. (These will be explained in the consent)

Why do a partial knee replacement?

Knee osteoarthritis is progressive and it will get worse with time. All other forms of treatment decrease the symptoms and may make them more manageable such that you may not need a partial knee replacement, but in the majority of cases this only helps for a short period of time. Only a partial knee replacement will get rid of the arthritis ultimately in that part of the joint. It will not stop arthritis from developing in the other parts of the knee.

Partial knee replacement is done to eliminate pain first and foremost. You may well still be left with residual pain as a result of the surgery but it should be far less than what you had prior to surgery.

Other reasons to do a partial knee replacement are:

  • Allow movement (in knee replacement the best guide to how much movement you will have post-surgery is how much you had before the surgery).
  • Enable you to perform activities of daily living with ease.
  • Let you return to certain sports or leisure activities.
  • Return you to work.
  • Give you freedom.

What is a partial knee replacement?

  • A partial knee replacement is an artificial joint composed of man-made materials.
  • The femur is made of chrome-cobalt-molybdneum alloy.
  • The tibia is made of titanium.
  • The insert in between the two pieces of metal is made of polyethylene (plastic).

The Benefits of Partial Knee Replacement

  • Pain relief
  • Pain free movement
  • Less sleep interruption
  • Allows daily activities to be done more easily
  • Allows return to leisure activities
  • Allows return to certain sports
  • Allows return to work
  • Allows you to travel or drive

It must be remembered that although these are the ideal goals of partial knee replacement, not everyone will be able to achieve these goals and problems do arise.

How a partial knee replacement works

The partial knee replacement aims to reproduce what you had prior to the development of arthritis, as normal a (native) knee as possible.

Your new knee works by allowing it to act as it did before, like a modified hinge joint. The polyethylene (plastic) insert allows the femoral (thigh) component to move in all three planes.

However a partial knee replacement although being extremely effective and allowing you to be able to do a lot of normal activities will never be the same as a native knee.

There are so many factors as to why an artificial knee will not be quite the same as a native knee - the design, the geometry, the loss of feedback between the knee and the brain, and it is an artificial joint.

It is a major surgical procedure to remove only the damaged area of the joint and replace them with an artificial joint. Only the worn-out surfaces of the joint are replaced. Nigel replaces the end of the femur (thigh bone) and the top of the tibia (shin bone).

Surgical Procedure

During partial knee replacement, a straight incision is made toward the inside of the knee, exposing the joint. Nerves, blood vessels, muscles and the patella are carefully moved aside.

Femur: Surgical tools are used to remove the worn-out surface and shape the end of the femur. The metal component, similar in size and shape to the end of the femur, is cemented to the bone.

Tibia: The tibia is cut flat across the bone. A metal plate is attached to the top of the tibia and cemented in place. A plastic component is then inserted to act as a cushion; it is attached to the metal plate.

Ligaments: The ligaments are preserved so the new joint can move as normally as possible.

Once the components are inserted, Nigel checks that they fit properly and that the new joint moves correctly. The skin will be closed with absorbable sutures. The operation takes about one hour to complete.

Pre-surgery and Post-surgery information – Partial Knee Joint Replacement

What to Expect Before the Operation

Prior to the surgery itself, Nigel will ask you to see the following Health Professionals:

  • This is to give you exercises to do before the operation.
  • To optimise the muscles around your knee, the knee itself, your core strength.
  • To get an idea of what help you may need when you leave hospital.
  • To give you an idea of what is expected of you when you leave hospital.
  • For follow-up after you leave hospital.


  • To make sure that the kind of anaesthetic planned is safe for you.
  • That we make sure your medical conditions if you have any are being well managed and looked after.
  • To discuss with you the risks of anaesthesia and minimise your risk of any complication following surgery.


Not everyone will need to see a physician.

Those that do, will do so to make sure you are on the correct 
medication and that your medical condition/s are optimised for surgery. The surgery will be carried out at an appropriate hospital that has an appropriate level of cover for you.

To minimise any risk to you Nigel may require you to have:

  • An up to date x-ray may be required of your knee, generally speaking if more than 6 months since your last x-ray, or if your condition has deteriorated significantly.

Other radiology: You may require other imaging of your knee, which may include MRI scan, CT scan, or a Bone Scan.

Blood tests: This will depend on what kind of operation you are having, medical conditions you have, your gender, and what age you are.


Before the operation it is important to tell Nigel, the Anaesthetist, and if you have seen a physician what medications you are taking. If you are taking a medication particularly one that affects blood clotting such as:

  • Aspirin
  • Warfarin
  • Clopidogrel 

Aspirin does not need to be stopped but Warfarin and Clopidogrel do need to be. If you have a history of blood clots the medical team needs to know as we will have to take important steps to make sure that your blood is thinned enough to stop clots from occurring. 
All other medications need to be mentioned even natural remedies / medications as they can interfere with medication being given to you in hospital, such as antibiotics, painkillers and anti-inflammatories.

Length of Stay

You will be in hospital for 2-5 days generally. This is only a guide. There is no race. You have to be safe before you are sent home. To be safe you need to be independent with:

  • Mobilisation and moving (this will be with crutches or on a frame)
  • Dressing
  • Toileting / Showering / Bathing
  • Getting into and out of
  • Bed
  • Chair
  • Car
  • Able to stand for periods of time 

The Physiotherapists and nursing staff are the most important people in the immediate post-surgery phase to get your knee moving and your leg working.

What to Expect on the Day of Surgery

  • Do not have anything to eat or drink within 6 hours of your operation. If you do there is a good chance your operation will not be performed on that day and will have to be rescheduled.
  • The nursing staff will make sure that all x-rays, blood tests, and medications are present. That all pre-surgery protocols are followed. The area being operated on will be clipped, washed and prepped.
  • You will be asked many times what operation you are having done. This is so that no mistake is made.
  • Nigel will meet with you, will mark the operation site, make sure the consent form is signed, ask you if you have any questions, will check to see that next of kin details are correct so he can call them after the operation is performed.
  • Nigel’s assistant will also meet with you, along with the Anaesthetist, and members of the surgical team.
  • It is completely normal to be nervous, and anxious, but if you feel that things are getting on top of you, please inform a staff member, because we will be able to give you a medication to help calm you. 

What to Expect Immediately After the Surgery

  • Your knee should not be painful due to the anaesthetic given and also the injection of local anaesthetic around your knee.
  • Your knee will be wrapped up in a big bandage.
  • There may be a drain coming out of your knee.
  • You will have a line going into one of your veins.
  • You will have compression stockings on both legs with mechanical pumps helping blood flow in your calf muscles.
  • You will spend a period of time in recovery before being transferred back to the ward or the High Dependency Unit (HDU).
  • Nigel will call your next-of-kin and tell them how the surgery went.

What to Expect on the Ward - Day 0

A nurse will be looking after you and your observations will be monitored:

  • Heart / Pulse rate
  • Blood pressure
  • Breathing rate
  • Pain score
  • Warmth / colour / sensation of the operated limb
  • Fluid input and output

You will be offered pain relief.
You will be given:

  • Antibiotics
  • Blood thinning medication
  • Pain relief if you request it
  • ICE for your knee 

A Physiotherapist will come and see you and if your observations have been good, will get you to stand and maybe take a couple of steps. 

Nigel will come to see you at the end of his operating list and tell you how the operation went. 

What to Expect on the Ward - Day 1

  • In the morning Nigel will see you.
  • The nursing staff will continue to monitor you.
  • Blood tests will be done.
  • X-rays will be done.
  • The drain will be removed (if one is in place).
  • Antibiotics will stop.
  • Blood thinning medication will continue.
  • ICE treatment will continue on your knee.
  • The physiotherapist will start moving you, and your knee.
  • If one of the blood tests comes back low (haemoglobin) you will need to have a blood transfusion.

What to Expect on the Ward - Day 2 to Discharge

  • The expectation is that each day you will do a bit more.
  • There are going to be times where you feel fantastic and may do too much.
  • There are going to be times when you feel sore, sick, or lethargic and do not do enough.
  • Your pain will develop by day 2 but hopefully will be controlled with oral pain-killers (it is still going to be sore though).
  • Your movement will increase both from a knee perspective and from you moving around your room and the ward.
  • You will progress from a frame to crutches (not everybody though).
  • You will become more independent with your activities of daily living.

What to Expect on the Day of Discharge

  • You will need to be able to get yourself toileted, showered, dressed and in-out of bed.
  • You will be given an appointment card to see Nigel at the 6-week mark.
  • You can get in contact with Nigel’s rooms at any stage if you have any concerns or issues. Please do not hesitate to do so.
  • You will be asked to see the practice nurse at your local GP 10-14 days post surgery to have your wound checked and in some cases clips removed.
  • You may be transferred to a rehabilitation hospital. This is considered an intermediate step towards going home and is extremely useful for patients. The usual duration of stay is 10-14 days. Nigel recommends that those patients who live alone consider rehabilitation. In certain cases rehabilitation can be done in your home but this is dependent on your insurance fund and suitability. Outpatient rehabilitation or physiotherapy will be arranged prior to discharge for those patients who are going straight home.
  • Recovery takes time. You will need help when you go home. Arrange for an adult to stay with you for 1-2 weeks after surgery.

What to Expect in the First 6 Weeks

  • Pain will improve.
  • Movement will increase.
  • The wound is inspected in Nigel’s clinic, by your GP, or in a rehabilitation hospital around the 2-week post-surgery mark.
  • An exercise program is an important part of recovery. These exercises help prevent stiffness and regain knee movement.
  • Independence will return.
  • Continue with ICING of the knee.
  • You will start to feel better about having had the knee replacement done.
  • You may find that you can walk without a crutch or both of them.
  • To help you walk, crutches may be needed for a month or so. Muscle strength in the leg, often lost due to inactivity prior to the surgery, will return with exercise and as pain resolves.
  • YOU CANNOT DRIVE FOR THE FIRST 6 WEEKS no negotiation if the RIGHT knee has been replaced. There may be some negotiation at the 4-week mark if the LEFT knee has been replaced.
  • If you have any concerns, do not drive until seen by Nigel in clinic. If you are unsure, you can contact your motor vehicle insurer to see if you are covered or not.

Nigel will see you at the 6-week mark and at that stage will hopefully be able to give you indications regarding:

  • Driving
  • Work
  • Return to activities
  • Medication
  • Use of walking aids

What to Expect - 6 Weeks to 1 Year

  • It will take a good 6 months for you to forget you have had a partial knee replacement.
  • At three months you should be able to return to almost all activities.
  • Minimal or no pain relief will be required.
  • You should have returned to all your previous work, leisure, and daily activities. 

  • Strength and flexibility of your knee should improve over 12 months; the time does vary however. 

Nigel's Expectations 

I expect you to have a nearly completely pain free knee that moves at the same degree if not slightly better than what you had prior to the operation. To have a knee replacement that allows you to do all your daily activities, most leisure activities, and certain sports without feeling pain, giving you the freedom in your life, to recapture and enjoy your life, those around and close to you, without worrying about your knee.

Patient's Reactions

It is difficult to know who will do well and who will not do well. It never fails to amaze me how when I think someone will do well and they do not and then when you are dreading the result of someone else how well they do. I believe in providing a well informed approach is the key to how well a patient does, giving them no illusions, being realistic, and providing plenty of encouragement to the patient from all members of the team. As many patients tell me, it is their knee, if they want to do well, they will. I also believe that it is important for you to discuss with your family and friends that you are having a knee replacement and to ensure that you have the appropriate level of help on discharge. Seek out people who have had a knee replacement, as they will be able to tell you what their experiences are.

How Long Will it Last?

This is the one question I always get asked, especially by younger patients. Generally speaking if you are over 65 your new knee will last you out. If you are under 65 you may well need to have part or all of your knee revised at some stage.The kind of partial knee replacement I use is still in 92% of people at 10 years and is the best performing partial knee replacement in the Australian Orthopaedic Association Joint Registry.

Complications - General

As with any operation the benefits of the operation do outweigh any risks, but there is always a potential for complications to arise, orthopaedic or otherwise. Nigel will discuss the orthopaedic complications when he consents you outlining in detail what these are and when they are likely to occur. He will give you a general complication rate but will also mention his complication rate.

Complications –Partial Knee Joint Replacement Surgery


  • Perhaps the most devastating of all complications.
  • Around 1% (including skin infection likely to be 3-4%).
  • Infection may include the skin or incision which can be treated with oral antibiotics.
  • Deep infection (that is infection in your new knee joint) although less than 1% is the most devastating outcome for both the patient and the surgeon. It has been estimated that each knee joint replacement infection in the USA costs between $400,000 - $800,000 to treat.

Deep Vein Thrombosis (DVT)

  • Is a Blood clot in a vein of the leg or thigh.
  • 30% of all patients having a knee replacement.
  • Seen on an ultrasound scans of the thigh / leg veins.
  • Well over 90% of patients and doctors are not aware that a DVT may have occurred.
  • Not all DVTs need to be treated with medication.
  • If a DVT occurs that requires treatment you will be put on a medication that helps to thin the blood and break down the clot.

To prevent a DVT from occurring Nigel will assess your risk profile for DVT and grade you high, medium, or low risk according to the American Academy of Orthopaedic Surgeons guidelines on DVT prevention. Once this assessment is completed you will either be given aspirin, or an injection of an anti-coagulant (blood thinning) medication whilst in hospital and on discharge from hospital.

  • All patients who take aspirin are to keep taking their aspirin.
  • If you are on warfarin then you will need to stop 5 days prior to surgery.
  • If you are on Clopidogrel you will need to stop at least 5 days prior to surgery.
  • Nigel may need to discuss your medication use with your GP, cardiologist, or physician before deciding on the best approach at aiming to reduce the risk of a DVT developing.

Pulmonary Embolus (PE)

  • This is a blood clotin the lung.
  • This occurs in 1/500 patients having knee replacement (0.2%).
  • Unfortunately 1/1700 patients the PE will result in death (0.06%).
  • All PE’s are treated with an injection in the short term and with warfarin long term.

Aseptic Loosening

  • This refers to the lifetime or potential survival of your prosthesis.
  • There are lots of reasons why your knee replacement may not last or fail.
  • We do know that if you are under 65, if you are male, obese or are not happy with your
knee replacement, then you are more likely to require revision.
  • The particular prosthesis that Nigel uses, so far is the best performing prosthesis 
available in Australia and 92% are still in patients at 10 years.


  • All patients will have a different degree of pain immediately following knee replacement.
  • Of the 20% of patients who are not happy following knee replacement the vast majority are because of pain.
  • Nigel will detail in no uncertain terms that although the operation is done to relieve your arthritic pain, there may be an element of pain with your knee joint replacement that could last for 12-18 months.
  • Because only one part of your knee is being replaced you may well develop pain in other areas of your knee as the years go by.

Stiffness / Lack of Movement

  • Generally speaking if you have over 110° you will retain that movement. If you have 90-110° then you may gain movement. If you have less than 90° it is difficult to predict how much movement you will gain.
  • The best predictor of movement post-surgery is what movement you had pre-surgery.
  • Nigel will outline though to you what his expectations for movement are following your joint replacement. 

  • Your new knee may click. This is completely normal and does not reflect any underlying abnormality.


  • Following your joint replacement your thigh, leg, and foot will swell.
  • The swelling will persist for up to 6-9 months.
  • Your knee will always look slightly more swollen than the other non-replaced 
  • For some people there will be a persistent swelling in the knee joint. This should be assessed either by Nigel or your GP to rule out infection or a problem with the knee replacement.

Damage to nerves and blood vessels

  • 70% of people at one year will have numbness on the outside part of their knee. This occurs because the small nerves that are involved with touch are cut during the knee replacement.
  • 1/3000 - 1/4000 (0.03 – 0.04%) patients having a knee replacement will have an injury to the nerves and blood vessels at the back of the knee. This is a serious complication, but thankfully occurs incredibly rarely.

Blood transfusion

  • <1% of patients will require a blood transfusion following knee replacement surgery.
  • Blood products are only given if it is felt in the best interest of the patient, to aid in their recovery or if the patient has symptoms resulting from a low blood count. 

Other Risks 

There are general risks of having a knee replacement that are non-orthopaedic related. The Anaesthetist will be the best person to answer these questions but generally include:

  • Stroke
  • Heart-attack
  • Death
  • Post-surgery confusion
  • Not being able to empty the bladder 

Report to your Nigel or GP

If you develop any of the following:

  • Temperature higher than 38.5 °C (fever) or chills.
  • Severe pain or tenderness.
  • Redness around the incision that spreads.
  • Heavy bleeding from the incision.
  • Nausea or vomiting.
  • Worsening flexibility or an inability to bend the knee.
  • Loss of mobility after a fall.
  • Any concerns you may have regarding your knee replacement.

View Case Study – Partial Knee Replacement