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Unicompartmental Knee Replacement

Unicompartmental or partial knee replacement replaces the worn part of the knee whilst retaining the healthy part of the knee.

This is not a new concept but there has been resurgence in popularity recently. Better instruments allow for better tissue balancing and also allow for minimally invasive surgery.

Most commonly the medial compartment of the knee is replaced though occasionally in patients with disabling lateral compartment or patellofemoral (knee cap) arthritis this procedure would be suitable.

Unicompartmental or partial knee replacement replaces the worn part of the knee whilst retaining the healthy part of the knee.

This is not a new concept but there has been resurgence in popularity recently. Better instruments allow for better tissue balancing and also allow for minimally invasive surgery.

Most commonly the medial compartment of the knee is replaced though occasionally in patients with disabling lateral compartment or patellofemoral (knee cap) arthritis this procedure would be suitable.


  • Infection: (1-2%) Fortunately, with good surgical technique and the use of antibiotics this is a rare complication but if it does occur it is serious and may result in the need to remove the artificial joint components.
  • Blood Clots: after joint replacement surgery are common. The risk is reduced by giving blood-thinning medication that starts the night after surgery. Rarely, these clots can break off and go into the lungs leading to severe breathing problems or even death.
  • Nerve Damage: Occasionally nerves that run close to the knee can be bruised, leading to weakness of the toe or foot movements. You can also expect some numbness adjacent to the scar.
  • Stiffness: Occasionally the knee may stiffen after surgery and require manipulation or even further open surgery. This is less of a problem than with T.K.R.
  • Kneeling: Even though the scar is small, kneeling can still be difficult, if not impossible.
  • Loosening: The component may loosen or the other parts of the knee joint may develop painful arthritis with time. This may necessitate surgery, where the knee component is removed and replaced with a full knee replacement (overall chance of 5-10% by 10 years).

Realistic Expectations

The aim of the surgery is to relieve the majority of your pain and enable you to walk comfortably. You may still have some aching and may still struggle with stairs and kneeling. You may not regain a greater range of movement with surgery and will not be able to run. In summary, don’t expect a completely normal knee.

This is a good time to make sure your home will be a safe environment for you upon your discharge from hospital.

Position furniture to give you clear walkways and roll up any rugs which might cause you to slip.

Put commonly used items within reach in your bathroom and kitchen to prevent you needing to kneel.

It is also a good time to commence some gentle exercises to tone up your muscles, especially the quadriceps. Not all exercises will be possible because of pain or stiffness. Examples of suitable exercises are included in this information. Your physiotherapist will advise which of these exercises will be appropriate after your operation.

Most hospitals encourage a pre-admission visit to show you the hospital, streamline the admission process and explain the hospital stay.

You are also encouraged to see the Anaesthetist prior to surgery.

You will usually be admitted to hospital on the morning of surgery and will be seen by the Nursing Staff and your Anaesthetist.

Please bring with you any medication that you take regularly and your X-rays, along with your pyjamas, toiletries, etc.


If you are a smoker it is advisable to stop smoking or at least reduce the number of cigarettes that you smoke, in order to reduce the risk of chest and circulation problems after surgery. The hospital is a SMOKE FREE ZONE.

Anti-Inflammatory Medication

Anti-Inflammatory medication including VOLTAREN, FELDENE, NAPROSYN, CELEBREX and ASPIRIN should NOT be taken for seven days, prior to your surgery, as they affect the way your blood clots.

Anti-Platelet Medication

Anti-platelet medication including ASTRIX, CARTIA, CLOPIDOGREL (eg. PLAVIX, ISCOVER) and TICLOPIDINE (eg. TICLID, TILODENE) can also affect the way in which your blood clots. These medications should NOT be taken for seven days prior to your surgery.

If you are unsure about your current medications and the possible complications, please speak with your Doctor prior to surgery.

Hospital Admission

The Orthopaedic Liaison Nurse will phone you prior to your admission to hospital to arrange a suitable time for you to visit the Pre-Admission Clinic. During this visit the nurse will discuss details of your hospital stay and the recovery process and answer any questions that you or your family may have. To streamline the admission process a nursing history and health assessment will be carried out. The aim of this visit is to provide information that will better prepare you for surgery and to commence planning for your recovery.

During your hospital stay, the Orthopaedic Liaison Nurse may visit you on the ward to check on your progress.

This service offers ongoing support and assistance as required after discharge from hospital.

The Orthopaedic Liaison Nurse can be contacted at any time if you or your family have any concerns, queries or problems – phone (08) 8267 8267.

On the day of surgery

You will usually be admitted on the morning of surgery. You will be required to fast for about six hours before surgery. The operation itself takes approximately two hours. Some time is then spent in the recovery room prior to you returning to the Ward or High Dependency Unit.

The Nursing Staff will:

  • Explain hospital routine and orientate you to your new surroundings.
  • Record your temperature, pulse rate, blood pressure.
  • May shave your knee and wash it with Betadine.
  • Answer any questions you may have.
  • Discuss your medical and surgical history and current medications.
  • Check your heart and lungs.
  • May order other tests, eg. chest X-ray, ECG etc.

Length of stay

The length of hospital stay is usually between 3-5 days. We aim to plan your length of stay and have discharge arrangements in place prior to your admission.


Your surgeon and Anaesthetist will discuss with you whether you would be best suited to a general anaesthetic or spinal anaesthetic.

After surgery

You may need to spend some time in the High Dependency area where there is a higher ratio of nurses to patients. You will have an intravenous drip in one arm. This is to ensure that you receive adequate fluids and also to give you regular antibiotics, which prevent infection. The drip may also be used to administer pain relieving medication or blood transfusion should this be required.

You will have a small tube coming from your wound, which is attached to a bottle. This prevents blood collecting in the wound.

You may have an oxygen mask on your face.

Sometimes a catheter to drain urine from your bladder will be required.

Your pain will be controlled by intravenous, epidural medication or regular medication. Whilst some pain is inevitable, with modern drugs pain relief is much improved compared with years past.

The following routine is a guideline only. It depends on your speed of recovery and individuals do differ in the time needed for muscle strength to return. Each stage has to be completed before progressing to the next.


The Physiotherapist will:
Assist you to become mobile again following your operation and teach you specific exercises.

You will stand and begin walking the day after surgery. All the “tubes” are removed by two days after surgery. A physiotherapist will assist you with exercises and walking. The aim is to walk early and often. This minimises complications.

The joint is stable immediately after the procedure, but the weakened muscles and soft tissue surrounding the joint require a longer-term program of physiotherapy and exercise to be restored to normal functioning.

Your mobility will gradually increase and with it, your independence. Physio continues and once your wound has healed you may go to the hydrotherapy pool with the physiotherapist to perform exercises in water.

Pain Control

During the first few days you will experience some pain. This will be controlled by intravenous and then oral medication. It is important, initially, to take the pain relieving medication on a regular basis. This will allow you to exercise and move more freely. It may also be necessary to continue taking pain relief tablets when you return home. The nursing staff or pharmacist will instruct you on appropriate doses.

Anti-Coagulant (Blood Thinning Medication)

A small injection into the skin of your abdomen of anti-coagulant is usually administered once a day during your stay in hospital. This helps to thin the blood and helps prevent the formation of clots in your legs.

Suture Line

You will have a suture line on your knee that requires a dressing while you are in hospital. The nursing staff will attend to this.

Sometimes you may have sutures that lie underneath the skin surface. These do not need to be removed and will dissolve in about 2 weeks. Skin staples are normally removed around ten days.

Prior to discharge your nurse will speak to you regarding care of your suture line once you are home. Wash your suture line daily and pat it dry with a clean towel. Avoid using any powders until the healing is complete as they “clog” the suture line and cause bacteria to grow.

Observe your suture line for any signs of tenderness, redness, swelling or discharge. If you have any problems, contact your Surgeon, Local Doctor or the Orthopaedic Liaison Nurse.

Sleep Disturbances

As you might expect, wound discomfort and restriction of position will mean adopting a sleep position, which is unnatural for you. This may result in a disturbance to your sleep pattern, and/or restlessness.

Oral analgesia and warm drinks before going to bed may assist in relaxation.


Your decreased activity level and appetite, reduced fluid intake and some medication may lead to bowel irregularity. You will be encouraged to drink fluids, increase the fibre content of your diet and, if necessary, take mild laxatives.

Sexual Activity

Resumption of sexual activity depends on when you feel comfortable. There are no restrictions if you keep to the guidelines given to you by your surgeon and physiotherapist for your daily activities.


Ice helps to reduce pain, swelling and stiffness. The nurse may apply ice to your knee. You may also apply ice at home by using crushed ice inside a damp towel. Leave the ice on for 15 minutes, then remove it for 15 minutes, and then reapply for another 15 minutes. This can be repeated up to three times per day if necessary.

Never apply ice directly to the skin.

Doctor’s Appointment

Your surgeon will want to see you about 6 weeks after your surgery. The appointment will be made before you leave hospital by the nursing staff. It is important that you keep this appointment, as your surgeon will want to check your progress. You will be able to ask the surgeon questions regarding increasing your level of activity.


It is to your advantage to put some time into exercises to tone up your muscles especially your quadriceps before surgery. Below are some suggested exercises. Not all may be possible because of pain or stiffness. Your physiotherapist will advise which of the exercises will be suitable for you following your operation.

Do the following exercises 10 times each and at least 3 times per day.

  1. Gently bend your feet up and down to help circulation in your legs.
  2. Gently bend your knee so that your foot moves along the bed towards your buttocks. A mild stretching over the front of your knee is normal.
    Hold for 5 seconds then relax.
  3. Tighten the muscles on the top of your thigh by pushing your knee down onto the bed. Keep your knee as flat on the bed as possible.
    Hold for 5 seconds, then relax.
  4. With your knee over a bolster, straighten you knee by tightening the muscles on the top of your thigh. Be sure to keep the back of your knee pressed onto the bolster.
    Hold for 5 seconds, then relax.
  5. Tighten the thigh muscle so your knee straightens. Now lift your leg to 45 degrees, keeping it as straight as possible.
    Hold for 5 seconds, then relax.

Discharge Advice

This information and instruction, is meant to be used as a guide as you return home.

  • Continue with your exercises as described by your physiotherapist.
  • Continue to take short and frequent walks, gradually increasing the distance in a slow progressive manner. This will be based upon your strength and pain level.
  • Allow time for resting – frequently.
  • Avoid placing a pillow under your knee.
  • Do not drive a motor vehicle until advised by your doctor. (You may be a passenger however).
  • Use arms to help rise from chair or bed.
  • When using stairs lead up with the non-operative leg, down with the operative leg.

Call your Orthopaedic Surgeon if you notice any of these symptoms:

  • Increased pain not controlled by medication.
  • Increased redness, swelling or drainage around the incision.
  • Elevated or persistent temperature.
  • Tenderness, redness or swelling of your calf.
  • Chest pains or shortness of breath.

Visits to the dentist
If you ever suffer a gum infection or abscess your dentist will need to prescribe antibiotics.
This is not necessary for routine dental care – eg. fillings or cleaning.

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