What is a knee replacement?
Knee replacement’s are one of the most commonly performed orthopaedic procedures around the world. A knee ‘replacement’ involves removing the diseased or arthritic portion of the knee, and ‘replacing’ it with a combination of highly engineered ‘metal’ and ‘plastic’. The ‘metal’ components are positioned on the ends of the femur (‘thigh bone’) and tibia (‘shin bone’). The plastic component (polyethylene) is positioned in between the metal components, to allow a smooth articulation.
Who should consider a total knee replacement?
A total knee replacement is designed to alleviate pain and restore function in patients suffering from knee arthritis. While knee arthritis typically affects older patients, it can be seen in people of all ages. A knee replacement is typically reserved for patients of middle to older age, who are experiencing daily knee pain that is limiting their quality of life.
Knee Replacement – How long do they last?
This is a question that is commonly asked. While it is difficult to give a specific time frame to an individual, the best data that we have available is the Australian Joint Registry. This data collects all of the knee replacements done around Australia over the past 15 years. It is a very useful resource and allows us to look at the average ‘life span’ of knee replacements in Australia. Looking at all age groups, 93% of knee replacements have ‘survived’ 15 years after they have been done. There are a number of factors that will influence these figures, and Dr. Mike Smith will have a detailed discussion with you regarding the best management plan.
Knee replacement -Specialised techniques
Knee replacements can be performed via a number of different techniques. While they all have a similar design with a combination of metal implants and a ‘plastic’ insert, the method used to determine the positioning of these implants may vary.
Dr. Mike Smith utilises two specialised approaches to perform total knee replacements depending upon the individual.
Computer navigation refers to ‘Computer assisted Surgery’.
This technique utilises a specialised marking instrument to ‘map’ the patient’s individual anatomy during the case. An advanced camera and computer system, then communicate with each other during the case, and provide immediate feedback to the surgeon for accurate positioning of the knee replacement components.
Patient Specific Instrumentation
This technique refers to using 3D printed cutting guides that have been individually created specifically for the patient, based off preoperative imaging with either a CT scan or an MRI.
Above all, Dr. Smith will incorporate the latest techniques for pain relief and rapid rehabilitation, to ensure that patients are as comfortable as possible following the procedure. This includes the use of local anaesthetic infiltrated throughout the tissues of the knee, and specialised medications in the days following the procedure. This pain relief regimen is carried out in conjunction with the anaesthetist and tailored to the individual.
What does a knee replacement involve?
After arriving at the hospital 1-2 hours prior to the procedure, you will be admitted into the hospital and changed into a theatre gown. Your knee will be scrubbed with an antiseptic agent and any excessive hair will be removed. You will be seen by the anaesthetist at this stage. Typically a spinal anaesthetic is used, which allows early mobilisation following the procedure.
The procedure itself involves a skin incision down the front of the knee. Once access to the knee joint has been gained, the computer navigation or patient specific cutting guides are positioned on the knee. Using these techniques, the diseased cartilage and underlying bone is removed with the use of saws. The components are positioned and checks and balances are conducted to ensure good alignment and balancing has been achieved. The final components are then inserted, often with cement fixation, and the wound is closed.
You will be encouraged to mobilise early following your procedure, with the aid of Physiotherapists and Nursing staff. You will receive antibiotics through a drip for 24 hours, and will commence on a blood thinning agent (such as aspirin) for 6 weeks to reduce the risk of getting a blood clot. Dr. Mike Smith has a strong interest and focus on pain relief following surgery, and staff will frequently ensure that you are comfortable.
Typically you will spend 2-4 days in hospital, and be able to transition home once you are comfortable and safe with mobilising. You will have a followup appointment made with Dr. Smith 2 weeks following the procedure.