Partial Knee Replacement:

Partial Knee Replacement, also known as Unicompartmental Knee Arthroplasty (UKA) or Knee Hemiarthroplasty is an orthopaedic surgical procedure in the surgeon resurfaces only the arthritic aspect of the knee joint rather thanall of the knee.  This may entail replacing either the inside half of the knee (i.e the medial compartment); the outside part of the knee (lateral compartment); or the patellofemoral joint (knee cap).

Partial knee replacement offers several potential advantages versus full knee replacement:

  • The incision for partial knee replacement is smaller
  • Less bone is removed
  • The soft tissues of the knee are preserved
  • Recovery is usually quicker

However, patient selection is important. Partial knee replacement is only suited to patients where the area of arthritis is limited to one aspect of the knee. Performing only a partial knee replacement in a knee with widespread arthritis would be unlikely to fully relieve a patient’s pain.

Successful partial knee replacement is also sensitive to accurate implant positioning.

partial knee replacementA number of advanced technologies are now available to assist orthopaedic surgeons to reliably achieve accurate implantation of partial knee replacement prostheses.

These technologies include:
(i)  Patient-Specific Instruments
(ii) Robotic-assisted surgery

In Patient-Specific (PSI) Partial knee replacement, a three dimensional imaging scan of the patient’s knee is obtained. The 3D scan is then uploaded to Europe where the images are computer modelled and a 3D mould of the knee is then printed on a high grade  3D medical printer.
Patient-specific instruments are designed,  3D printed and are then be sent to Australia in time for the surgery.

Mr Freedman utilises 3D-printed patient specific instruments for most of his partial and total knee replacement surgeries and finds that this technology facilitates efficient, accurate and reliable implant positioning.

Another technology used to assist partial knee replacement surgery is to use a robotic-assisted platform.  Here, a robot maps out the position of the knee joint and helps the surgeon to plan the implant alignment and prepare the bone surfaces.  The most commonly used robotic platform is called “Mako” robot and so some people will refer to a robotic-assisted partial knee replacement as a “Makoplasty”procedure. Other robotic platforms include the Navio Bluebelt robot and the ThinkSurgical robot.

In Mr Freedman’s experience, the robotic platforms can be thought of much like a GPS navigation system in your car. GPS is very useful if one is driving somewhere they don’t travel to frequently but is unnecessary if you are driving a route you travel frequently. Similarly, robotic-assisted platforms may improve accuracy for low volume surgeons who don’t do  many partial knee replacement procedures but are cumbersome, slow and unnecessary for high volume surgeons who perform this surgery regularly.

Mr Freedman will be happy to discuss the merits of the respective technologies and options with you at your consultation.

Selection Criteria:

When selection criteria are followed, the results for partial knee replacement are generally very good. To be a candidate for partial knee replacement a patient requires:

(1) Minimal deformity of the knee joint
(2) A good range of motion
(3) An intact anterior cruciate ligament
(4) Absence of inflammatory arthritis (e.g. no rheumatoid arthritis)
(5) Isolated wear of only one compartment of the knee,


To  evaluate whether partial knee replacement is an option for you and/or to discuss the various new technologies available for parital knee replacement with Mr Freedman please contact our office for an appointment. At your consultation Mr Freedman will assess your knee symptoms and scans will and advise you as to whether you are a suitable candidate for partial knee (unicompartmental) replacement surgery.

Partial Knee Replacement FAQs:

  • Should I expect to have much pain after partial knee replacement surgery?

    No. Modern anaesthesia methods have completely transformed orthopaedic surgery. Patients can now expect to wake up from surgery with little to no pain. You may have some discomfort as the pain meds wear off but this is usually minimal and well tolerated.

  • How much does partial knee replacement surgery cost?

    If you have private health insurance, the majority of the cost of surgery will be covered by your health insurance. The full cost of the prosthesis and of the hospital stay will usually be covered by your insurance. There may be some medical out of pocket or gap fees, depending on your level of insurance cover.  If you do not have insurance you will personally invoiced for the various components of the surgery. Our office will be able to calculate a quote for you after your consultation.

  • What prosthesis does Mr Freedman use for partial knee replacement?

    Mr Freedman prefers the Zimmer ZUK prosthesis for most partial knee replacement cases. This prosthesis consistently has the best results on the Australian Joint Replacement registry. Prosthesis selection may differ depending on individual patient anatomy.

  • Does Mr Freedman perform Patient Specific Partial Knee Replacement?

    Yes, Mr Freedman uses PSI Technology for most of his partial knee replacement cases. The patient-specific instruments are 3D printed by Materialise in Belgium.

  • I am quite a heavy patient. Is there a weight limit for partial knee replacement candidates?

    Generally, no.  While we advise all patients to maximise their health prior to elective surgery (e.g. weight reduction and smoking cessation), recent research indicates that larger patients are still appropriate candidates for partial knee replacement surgery. 

  • How long will I be in hospital after surgery?

    Most patients will be in hospital for only 1 night after surgery and will be discharged home the next day.