Total Knee Replacement
A total knee replacement is considered the gold-standard treatment for end-stage arthritis. End-stage arthritis will present with the following symptoms:
- Pain that is worse with activity, and eases with periods of rest
- Pain that wakes you at night
- Joint stiffness, often worse of a morning or with prolonged sitting
- Decreased range of movement of the joint
- Reduced physical activity/work capability due to pain
- Locking, catching, clicking and grinding within the joint with activity
A total knee replacement involves removal of the diseased bone and cartilage from the top of the tibia (shin) and bottom of the femur (thigh), and replacing the surfaces with ones made of metal and plastic. Dr Host performs this procedure using the Zimmer Nexgen knee system, which utilises a highly polished cobalt-chrome alloy femoral component articulating on a highly cross-linked polyethylene insert. This plastic insert is firmly attached to a metal tray, itself firmly attached to the top of the shin bone. Each component is specifically sized to the individual, and Dr Host performs the operation using computer navigation to ensure optimal mechanical alignment is obtained.
What are the benefits?
The aim of the procedure is not to give you back the knee you had when you were 18, though some people do have excellent results. The main goal we are trying to achieve is to reduce the pain associated with the arthritis, and to restore a functional range of movement. The functional range is at least 0-90 degrees – the ability to be able to stand up with straight legs, and sit on the average chair. After the surgery we will push the physiotherapy with the aim of obtaining 0-110+, as this will allow the individual to perform nearly all tasks of everyday life. It is unusual for someone to be able to achieve full knee flexion (heel to buttock) after knee replacement surgery, and so activities involving deep squatting or kneeling can be problematic. A total knee replacement is a great option to consider when pain and loss of motion are restricting your quality of life.
What are the risks?
For anyone who has seen the operation on the internet or TV, it is clear quite quickly that a knee replacement is far from a delicate procedure. The procedure involves cutting and reshaping bones, impacting or cementing components in place, and a moderate incision to allow access. There is going to be pain after the procedure, and this needs to be well understood. There will be pain from the operation, and there will be the pain of moving the knee during rehab over the following months. If the rehab is not performed, a poor outcome is likely, and so the pain must be managed. A large part of that is up to the individual and being mentally prepared for the challenge, but rest assured you will be helped in managing it with a comprehensive analgesic regime.
Knee stiffness will lead to a knee lacking a functional ROM. Every knee replacement will try to become stiff, and it is only with ongoing physiotherapy and activity that this can be avoided. The surgical part of the knee replacement is by far and away the easier part of the whole process – the results long term rely on you consistently performing your knee exercises and maintaining mobility.
Infection is a big concern, with the overall infection rate at ~1%, but deep infections (infection down onto the implants themselves) rarer at ~0.2%. A deep infection can be a disaster however, requiring at the very least further surgeries to washout the area in conjunction with long term antibiotics, and at times removal of the infected implants, spacing with antibiotic cement, and repeat knee replacement once the infection is cleared. Factors that increase your risk of risk for infection include cigarette smoking, excessive alcohol intake, poorly controlled diabetes, malnourishment, and any open wounds on the limb at the time of surgery. You will be assessed prior to surgery to ensure that you are in the best possible shape to undergo the operation, and surgery will be delayed if it is felt that you can be made better.
Deep venous thromboses (DVTs or clots in the legs) and pulmonary emboli (PE or clots in the lungs) are a risk, and you will be treated with calf compressors, stockings and medications to thin your blood.
Dr Host will discuss with you all the pros and cons prior to any consideration for surgery.
How long will the knee last?
This is a difficult question to answer as no two people have the same disease, and the load we all place on our joints is different. For the implant system that Dr Host utilises, the literature supports >95% of the implants remaining in place and functional at 15 years. Obviously that translates as ~5% who will require revision or other intervention to restore a functional knee. That is not a small number, but the odds are certainly in your favour for a positive result. Technology is always improving, and our ability to assess outcomes, be they good or bad, is also improving. Our expectation is that implants survival will improve as technology and surgical techniques continue to improve.
How long will the procedure take?
The average time in theatre is around 2 hours, with around 90 minutes of that being the surgery itself.
How long am I in hospital?
You will be discharged home when you have achieved the target ROM (0-90 degrees), are mobilising safely with an aide that can be used at home, and have pain that is adequately controlled. For most, this translates to 3-5 days in hospital, but some are home day 2, and others require a longer admission in the rehabilitation unit to be fit enough to survive in their home.
How can I prepare for the surgery?
There are some simple steps that you can take to ensure you have the best chance of a good result:
- ensure you attend your pre-admission check-up and follow all instructions from staff.
- cease smoking, even if only for the month around the time of surgery.
- if diabetic, ensure your glucose levels are well controlled for the month prior to surgery.
- if you are on blood thinning medications, cease these are per your discussion with Dr Host
- if you are worried about any cuts or scratches on the operative limb, contact Dr Host for review prior to the day of surgery.
- I you have come down with any coughs or colds, or any other health complaint that you are worried will cause problems with surgery, seek review with Dr Host urgently.
Your outcome after surgery is closely related to how fit and active you are before the surgery. Though pain and stiffness are an issue, the more physical activity you can do, the easier you will find your rehabilitation after the surgery. Dr Host will discuss with you how best to achieve this, and it is well worthwhile visiting a physiotherapist to establish an appropriate exercise regime prior to surgery,
Do I need to attend a pre-admission clinic review?
Yes, all patients are to attend a pre-admission clinic review to ensure you are as well as you can be prior to surgery, as well as to ensure you have all the information you need.
What should I do after my surgery?
You will be given detailed instructions on all that is required of you prior to being discharged from hospital. To obtain a good or excellent result, you need to be diligent with your physical therapy and maintain your ROM and mobility.
What should I look out for following surgery?
If you develop any increasing redness or heat in your wound, or have ongoing wound discharge, you should seek review with Dr Host or your local doctor.
If you develop any symptoms such as chest pain or tightness, shortness of breath, or lower limb/calf swelling and pain, you should seek emergency review at your nearest hospital.
What rehabilitation must I do after the procedure?
A detailed rehabilitation plan will be tailored for you to ensure that you achieve and maintain a functional ROM and mobility.
When can I drive after my procedure?
You are not allowed to drive for at least 2 weeks after the surgery, regardless of the limb involved. Following this, it depends on your function. If you are safely able to control the vehicle, you are able to drive. If your ROM and mobility are slower to recover, delay driving longer. You do not want to cause harm to yourself or others that could have been avoided – a sensible approach is best.
When can I return to work or sports?
Dr Host recommends at least a 2 week period off work – this allows for adequate wound healing and resolution of much of the swelling. If possible, it is recommended to take 4-6 weeks off work, and return once your daily activities can be performed pain free. For those in sedentary work environments, it is possible to return earlier however. Swelling can be an issue, and is best treated with limb elevation – discuss this with your employer prior to returning. If your work is particularly strenuous, longer periods of absence may be required. Any work certificates required will be issued by Dr Host to cover your rehab period. It is worth, when possible, planning such surgery for a time of life that will not be too busy.