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Knee Arthroplasty, also known as Knee Replacement, is a surgical procedure that replaces an arthritic knee joint or its part with an artificial joint. The primary goals of this surgery are to alleviate pain, restore function, and preserve knee anatomy.
Depending on the extent of the joint destruction it can involve replacing the whole knee joint, total knee replacement, or only its part, unicompartmental knee replacement.
With a Unicompartmental Knee Replacement, only the affected portion of the knee joint is replaced, hence it is a less invasive procedure than would normally be used for a total knee replacement. As a result, most patients resume their daily activities more quickly than those who undergo a total knee replacement.
Please find below more detailed information on the unicompartmental knee arthroplasty procedure, which includes what to expect before, during, and after the surgery, as well as information on the recovery period.
You can find about general benefits of knee replacement here. There are also some specific benefits related particularly to Unicompartmental Knee Replacement:
The approach to unicompartmental knee replacement involves surgically replacing only the damaged or arthritic part of the knee joint, preserving the healthy areas. With such an approach knee function can be restored with less surgical damage to the knee tissues and preserving more of the natural patient’s tissues. In a UKR, only the damaged compartment is replaced with metal and plastic components. The remaining healthy cartilage and bone in the rest of the knee are left untouched.
Unicompartmental Knee Replacement surgery is performed under spinal or general anaesthesia. The entire procedure typically takes one to two hours.
Step 1: Bone Preparation
An incision of about 7cm is made to expose the bones of the knee joint. The damaged cartilage surfaces at the ends of the femur (thigh bone) and tibia (shin bone) are carefully removed.
Step 2: Implant Positioning
Specialised jigs are used to precisely cut the femur and tibia at the appropriate angles. Test components are then inserted to check the accuracy of the cuts and determine the thickness of plastic required to be placed between the two components.
Each knee is unique to the patient, and the knee replacement implants come in various sizes to cater to individual needs. If there is more than the standard amount of bone loss, additional pieces of metal or bone may be added.
Step 3: Implant Insertion and Spacer Placement
The surgeon replaces the damaged cartilage and bone with permanent implants that closely resemble the former structure of the joint. Implants can be fixed in place with medical-grade cement or a press-fit technique that encourages bone growth onto the implant.
To create a smooth, gliding surface within the knee joint, a medical-grade plastic spacer is inserted between the metal components. This spacer enhances the knee’s mobility and helps prevent friction, providing a more comfortable experience.
After these steps are completed, the knee is thoroughly checked to ensure that all components are correctly positioned and working as intended. The knee is then meticulously closed, then a dressing and drains are applied.
Following the surgery, patients will be taken to the recovery room for monitoring. Once their condition stabilises, they will be transferred to the ward.
The patient will be set up with a button for self-administered pain relief through a machine called a PCA machine (Patient-Controlled Analgesia). It is crucial for patients to use the PCA machine as prescribed by their healthcare provider to avoid overmedication.
Patients will be encouraged to start moving their knee and walking within a day or two of the surgery. The surgical wound dressing will usually be reduced on the second day post-op to make movement easier. A physiotherapist will be available to guide them through exercises and assist with rehabilitation and mobility.
Discharge: The expected hospital stay after the surgery is approximately three to five days. Depending on individual needs and situations, patients may be discharged home or transferred to a rehabilitation hospital. It is essential to continue with the prescribed physiotherapy exercises for a successful recovery.
Following discharge, patients may require a walker or crutches for about six weeks. As their leg gains strength and control, they can transition to using a walking stick under the guidance of a healthcare provider. Patients may resume driving around the six-week mark, but only when they feel confident that they’ve regained leg control.
The degree of knee flexion will vary from patient to patient, but ideally, the goal is to achieve at least 120 degrees of movement.
Upon returning home, an occupational therapist will assess the patient’s living space and provide necessary precautions. This may include installing rails in the bathroom or adjusting sleeping arrangements if there are stairs in their home.
Patients typically experience a reasonable level of comfort while walking within six weeks after the procedure. Engaging in more physically demanding activities, such as sports, may require up to three months to achieve a comfortable level of performance.
If patients are worried about their level of pain, experience significant bleeding, or notice fever or redness around the surgical site, they should contact the office immediately. If assistance is needed after hours, patients can contact the hospital where the surgery was performed, and they will contact Professor Al Muderis on their behalf.
Norwest Private Hospital: (02) 8882 8882
Macquarie University Hospital: (02) 9812 3000
For further information, click here or to check your eligibility, please contact our team.
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Professor Munjed Al Muderis is an orthopaedic surgeon and a clinical professor at Macquarie University and The Australian School Of Advanced Medicine. He specialises in hip, knee, trauma and osseointegration surgery. He is a fellow of the Royal Australasian College of Surgeons and Chairman of the Osseointegration Group of Australia.