Total Knee Replacement on the horizon
There is a lot of fear when a surgery is advised for knee arthritis.
What is arthritis?
When the knee joint wears out we call it arthritis. This may be age related wear and tear (osteoarthritis) or inflammatory (rheumatoid).
The joint gradually wears out leading to loss of cartilage cover and an end stage arthritis which then needs some definitive and long lasting solution. Basically the worn out surface of the knee now needs to be replaced by a artificial surface called “KNEE REPLACEMENT”
Latest advances have made knee replacement an excellent long term solution for a pain free active life and a satisfying achievement for arthroplasty surgeons like myself.
In majority of patients we need to replace the entire knee surface with a total knee replacement (TKR)
In some patients where the joint has only one sided damage we can fine tune the joint by replacing only the worn out area. This is known as a Uni-compartmental knee replacement or a UKR. Its a very special technique with great results.
Such patients return to a normal life and its difficult for anyone to figure out that this individual was a arthritis patient.
Certain advances have made which I will expand on shortly. These advances have made the TKR more like your own natural knee joint, longer lasting and able to stand forces of some sports and recreational activity.
These are basic types of knee replacements
- Standard total knee replacement (age old, tested with time and proven)
- Stabilised (some ligaments can be sacrificed)
- Cruciate retaining (tissue preserving)
- HI-flex (allows more bending)
- Rotating platform (design variation to reduce stresses)
- medial pivot (mechanics like a normal knee joint)
- Gender specific (specific designs for men and ladies. accommodates for tiny bones)
- Oxynium/ceramic (long lasting coating on alloy)
- Revision knee replacement (designed to be used when original knee replacement wears out)
- Unicompartmental knee and microplasty (replaces just the worn out part leaving normal part untouched
- highly cross linked polyethylene or vitamin E impregnated bearings.
Choice of replacement hardware for the surgeon is plenty. What is right for you is best advised by your surgeon according to your needs, age, activity levels and condition of your knee.
Anatomy
The knee comprises the joint between the femur and the tibia but also the joint between the patella and the front of the femur. Either or all of these parts of the knee may be affected by arthritis to various degrees.
Who Needs TKR and who doesnt?
Whoever has arthritis which has progressed to an end stage will have significant pain, need to take painkillers, reduced mobility, limp. These are the symptoms which decide on need of TKR. we don't necessarily wait for all these symptoms to appear. ability to sustain pain varies from person to person.
because of excellent technology and expertise available patients may choose to avail the benefit of surgery before symptoms get bad.
when symptoms are significant the effects on the knee are showing up. deformities arise and accordingly I have to plan the hardware.
What are the risks?
we do tests before surgery. They are bloodwork, X-ray chest, ECG and Echocardiogram. this tells me about fitness. majority of patients are able to achieve fitness for a safe anaesthetic and surgery.
Often I do TKR on both knees in a single sitting.
Some patients with multiple medical problems like poor heart function or bad lungs are likely to have major complications and surgery may not be possible. However age is not a criterion. I have seen many old people with excellent and well preserved health. Such elderly candidates benefit immensely from TKR.
Can I choose the knee I want?
Certainly but only to an extent. You must rely on surgeon’s guidance to understand what type of TKR design is good for your future years of mobility and freedom from pain.
What if I don’t want TKR?
If you have end stage arthritis and unable to have TKR because of fitness problems then there may be a solution but it”s a difficult one. Fusion or arthrodesis of the knee can be done but along with pain all movement will be lost.
Not choosing to have the surgery because of fear will not allow me to help you much.
Surgical technique
My anaesthetist will either use a spinal - epidural anaesthetic or a general anaesthesia. depending upon what is safe for you.
once I prepare the knee with antiseptic solution an incision of 15 cm is made in front of the knee
If a uni or partial knee replacement is being performed, a smaller incision sometimes of only 5 cm in length may be used.
Knee replacement is performed in following steps. Whole procedure takes hour and half or so.
- Tibia (leg bone) is shaped precisely horizontal to receive the base plate.
- Femur (thigh bone) is shaped to receive the femoral cap. basic cut is parallel to Tibia cut
- Ligaments are balanced during above steps so that the cuts remain perfectly parallel and knee can function as a hinge
- patella (knee cap) is shaped to receive the patellar button
- Trial components are fitted to ensure in tibia, femur and patella to ensure smooth and balanced motion
- Final components are fitted with an acrylic polymer (bone-cement) which sets in 10 minutes to ready the knee for many years to come
- wound is closed in layers after infiltrating pain killers.
The recovery from the operation requires about two to four days in hospital. In this time physiotherapy is commenced.
Physiotherapy
The day following surgery the physiotherapist will get you out of bed to commence walking with the help of crutches or a walking frame.
Initially the leg will be placed on a continuous passive motion machine to gently move the knee through a pre-set range of motion. In addition, exercises to improve the strength of the quadriceps muscles are performed.
The machine will be removed soon for you to perform your own exercises.
The physiotherapist will also begin to encourage you to bend the knee. Sitting over the side of the bed may assist.
Early exercises and mobilising of the knee will cause some discomfort and swelling. However, this is normal and we have a pain team to look after your comfort.
After 5-10 days usually you are able to walk with minimal pain, with the assistance of sticks, crutches or a frame. You should be able to manage stairs with the assistance of a banister, and to care for yourself around the home.
Whilst at home the exercise program of quadriceps exercises should be vigorously continued. Approximately 20 minutes couple of times a day will be ample. Out patient physiotherapy sessions should be arranged during this period.
Various modern techniques to enhance the results.
1. Minimally Invasive Surgery: MIS
Minimally invasive surgery involves the use of not only smaller wound incisions but the tissues are anatomically preserved.
These techniques usually result in significant advantages in respect to improve the speed of recovery, speed of mobilisation, shorten hospital stay reduce the period off work and reduce the time until functional and sporting activities can be resumed. The techniques also usually reduce the amount of post-operative pain experienced and the need for post-operative pain relief and analgesia.
special instrumentation to enable surgery to be undertaken.
2. computerised navigation
the geometric cuts in the bone are calibrated using classic mechanical instruments which are precise.
However use of computerised navigation during the surgery can improve on the precision even further.
here the readings from the patients knee are relayed to a computer which then guides us precisely.
when we perform surgery on youngsters or if the case is very difficult this navigation is immensely useful.
3. virtual surgery or patient specific (customised) knee replacement
its like doing your homework the before school.
a CT scan of your knee is used to get a 3D print. This 3D life sized model is used to predetermine the cuts on the bone.
Once this homework is complete the surgery is completely planned even before patient is in hospital.
It ensures a precisely performed TKR and any difficulties in surgery anticipated well before the actual operation.
4. Robotics-
one step ahead of customisation. ultimate precision attained by using a surgeon controlled robot to perform certain mechanical steps of surgery
Results and Complications
Modern techniques and technology ensure that the complication rate is minimal. Beside the anaesthetic risks, which are very low, infection that involves the joint is less than 1:100. This would present as the knee becoming hot, swollen, throbbing and painful after 2-4 days, or alternatively at any period thereafter. Venous thrombosis is in the order of 1:50. To avoid thrombosis anti-coagulant therapy will be given for a short period after the operation. Generally, the results of knee replacement are excellent and as good as or better than hip replacement.
I expect that a knee replacement should, if cared for, last 15 years in over 90% of patients. After joint replacement, in order to avoid infection of the new joint, all infections or dirty wounds must be adequately treated with antibiotics. A yearly review should be undertaken. This is to ensure that the prosthesis is not becoming loose.
No comments:
Post a Comment