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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.
The surgery is usually recommended for older patients who suffer from pain and a loss of function due to arthritis, especially when other conservative treatments have proven unsuccessful.
Total knee replacements are considered one of the most successful medical procedures. The surgery typically takes between one and two hours and involves replacing the ends of the femur (thigh bone) and tibia (shin bone) with a metal surface and a plastic spacer between them. In many cases, the patella (kneecap) surface is also replaced. The prosthesis replicates the knee’s natural ability to roll and glide smoothly as it bends.
In cases of less extensive knee damage, a partial knee replacement or unicompartmental knee replacement can be performed to replace only one segment of the joint.
While successful knee replacement surgery offers excellent benefits, it is essential for patients to take care of their new artificial knee by avoiding movements that may stress or damage its components. With proper care, patients’ efforts should be rewarded for many years to come.
Please find below more detailed information on the knee arthroplasty procedure, including what to expect prior to, during, and after the surgery, as well as information on the recovery period.
The most common indication for knee replacement (knee arthroplasty) is degenerative arthritis (osteoarthritis) of the knee joint. This type of arthritis is generally associated with ageing, congenital abnormalities of the knee joint, or prior trauma to the knee.
Other conditions that may necessitate a joint replacement include avascular necrosis, osteochondritis, past infection, and inflammatory arthritis.
While knee arthroplasty does not have any absolute contraindications, it is important to be mindful of certain relative contraindications, including cases involving skeletally immature patients and individuals with active sepsis joint infections, poor bone stock or patients with general conditions precluding any surgery.
Patients should discuss the potential benefits and risks of knee replacement with their healthcare provider. The decision to undergo the procedure should be based on individual medical history, condition, and the expertise of the surgical team.
Knee arthroplasty can be performed through various approaches. Total Knee Replacement typically involves a front incision, while Unicompartmental Knee Replacement is used for limited knee damage, requiring smaller incisions. The choice of approach depends on the patient’s condition and the surgeon’s expertise, with Total Knee Replacement being the most common method for comprehensive knee joint replacement.
Knee arthroplasty, whether total or partial knee replacement, is performed under spinal or general anaesthesia. The entire procedure typically takes up to two hours.
Step 1: Bone Preparation
An incision 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 along with a small amount of the underlying bone.
Step 2: Implant Positioning
Specialised jigs are used to precisely cut the femur and tibia at the appropriate angles. In our practice, many knee surgeries are performed with the use of a specialized robot for superior precision. 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. Depending on the condition of the knee, the patella (kneecap) may also be replaced.
Step 3: Resurfacing the Kneecap
In some cases, the undersurface of the kneecap is cut and resurfaced with a plastic button. However, not all knee replacement surgeries involve this step; it depends on the specific case and the patient’s needs.
Step 4: Spacer Insertion
A medical-grade plastic spacer is carefully inserted between the metal components. This spacer serves as a smooth, gliding surface, allowing the knee joint to move freely and function properly.
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, dressed and bandaged, and the patient is carefully monitored during recovery.
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 knees 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.
The expected hospital stay after the surgery is approximately three to five days.
Discharge: 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.
Regular follow-up appointments with the team will help monitor your progress and address any concerns:
Patients may resume driving around the six-week mark, but only when they feel confident that they’ve regained leg control. More demanding physical activities, such as sports, may resume comfortably after three months.
The degree of knee flexion will vary from patient to patient, but ideally, by six weeks, the knee should be able to bend to about 90 degrees. The goal is to achieve a range of movement between 110 and 115 degrees after surgery. This goal should be discussed with and determined by your healthcare provider.
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.
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.