You can only walk without pain when the bones in your knee joint are smooth and cushioned by healthy smooth cartilage. You also need strong muscles and ligaments for stability because your knee is more than a simple hinge joint: each time you bend your leg to walk or climb stairs, the bone rotate, roll and glide on each other.
Knee pain and stiffness often result from osteoarthritis from injury or wear and tear. Other knee problems include rheumatoid arthritis (an inflammatory joint disease), previous infection, or poor alignment of your bones. With Osteoarthritis, your cartilage “cushion” wears away. Bones become rough and rub together, causing pain. With rheumatoid arthritis, your joint may also be inflamed and swollen.
A painful, stiff knee can keep you from doing the simple things in life, even walking without pain. Now your orthopaedic surgeon can replace your problem knee. After your knee replacement, you’ll have some restrictions on using your new knee, but you can look forward to returning to many of your activities of daily living.
Preparations for Surgery
You are asked to provide your surgeon with information regarding:
- Your general health
- Medications that you are taking – especially oral contraceptives, steroids, aspirin
- Previous operations
- Bleeding disorders
- Other bone and joint problems
A number of investigations will be carried out before the operation. Some blood tests and
X-rays are generally required. You may be referred to a Specialist Physician or Anaesthetist to optimise your fitness for the operation.
- The operation takes one to one and a half hours
- The incision overlies the front of the knee joint
- Antibiotics will be given to you in the operating theatre
- You will have an intravenous drip inserted into your arm and a urinary catheter to help you pass urine during and after operation
- The operation will normally be performed under epidural anaesthesia or general anaesthesia or a combination of both
Once you have recovered and can bend your knee enough to go home, your surgeon discharges you. Most patients are able to go home five to seven days after the operation. You will be given instructions regarding exercises and medications before you discharge. You should feel free to ask your discharge nurse any questions you may have. You should have appointments made for outpatient physiotherapy and a post-operative visit to your surgeon before discharge.
- The exercises you carried out during your hospital stay should be continued at home. These exercises are aimed at improving mobility and strength of your knee. You require crutches as long as your surgeon advises you
- You should visit your physiotherapist as arranged after your discharge from hospital. He will check your progress and advise you on any additional exercises you may require
- Your surgeon will see you within a fortnight of the operation and your stitches will usually be removed at the stage. He will also assess your ability to walk, the mobility, strength and stability of your knee. He will then advise you on how you can get to the next level of function
- You are capable of driving a car 6 weeks after the surgery. You may walk any distance within your comfort. Swimming is permitted and indeed encouraged. Activities such as dancing, golf and bowling can usually start after 2 months
- Your knee will serve you well and painlessly if you are able to put in the time for the exercises. The new knee should last for many years if you exercise reasonable caution. Heavy impact sports, jumping and violent twisting of the joint can cause early failure
Total knee surgery is now safe and effective as total hip surgery. However, there are definite risks and complications associated with the operation of Total Knee Replacement. Although they are rare, and your orthopaedic surgeon and the hospital staff will do their best to try and prevent these complications from occurring, unfortunately, they can occur. Some of these complications are:
- Anaesthetic Complications
- Deep Venous Thrombosis and Pulmonary Embolism
- Wound Complications
- Fat Embolism
- Pressure Sores
- Vessel and Nerve Injury
- General Medical Problems
Prevention of Infection
If you get an infection anywhere in your body, (e.g. skin, urine, chest, throat, teeth), the infection can get into the blood stream and spread to your knee. Therefore call your doctor:
- Before you have any dental work
- Before any other operation or invasive procedure, e.g. Endoscopy, Sigmoidoscopy, Urinary Catheter, Gynaecological Procedures
- If you suspect you have an infection anywhere
- If your wound becomes red, hot, swollen, more painful or discharges any fluid
Do’s and Don’t’s
- Do always use your crutches when you walk until told otherwise
- Do walk frequently on level ground when you go home
- Do follow the directions given to you at the hospital
- Do ring your doctor if you are worried
- Don’t drive a car until your doctor gives you permission
- Don’t bend your trunk forward more than 90 degrees when sitting or standing
- Don’t cross your leg whilst sitting or lying down
- Don’t twist at the hip – turn your whole body
- Don’t sit on low chair, use a firm high chair with arms
MINIMAL INVASIVE UNI COMPARTMENTAL KNEE REPLACEMENT
The natural knee consists of three inter-connected compartments – the medial, lateral and patello-femoral (knee cap) compartments. Arthritis may affect one, two or all three compartments of the knee. The total knee replacement is today a highly reliable and effective operation for arthritis of the knee which involves two or three compartments of the knee joint. In this operation two or three compartments are resurfaced. Some knees are only affected in one compartment.
These patients do not require the full scale replacement operation. They can obtain very effective pain relief and return of good knee function by an operation that resurfaces only the diseased compartment.
The partial replacement of the knee join is known as Uni Compartmental Knee Replacement (UCR). This form of surgery has been available for almost as long as Total Knee Surgery had been performed. The early varieties of UCR were associated with variable outcome. Many patients obtained excellent results, but up to one in four patients who received a UCR in the seventies and eighties required a revision operation. Today, we have a better idea about patient selection for the operation. And there are better designs and better materials for the UCR. The modern UCR is capable of 98% survivorship after 10 years of implantation. Such a result comes close to matching the best outcome of the TKR.
The standard method of performing a UCR requires a full exposure of the knee joint. As such the operation is only slightly less major than a TKR. A newer method of performing a UCR is now possible.
The Minimal Invasive technique for UCR represents a major technical advancement in the art of joint replacement surgery. For the first time, surgeons are able to offer their patients a method of replacing the knee joint without the need for prolonged hospital stay, blood transfusion or a prolonged rehabilitation. The operation is performed through a relatively small incision and blood loss is usually under 60mls. Because of the operation is of a much smaller scale than a TKR, surgeons and patients are more comfortable with simultaneous surgery to both knees if the need arises. It takes 3 – 4 weeks for most patients to achieve full recovery. The surgery however demands more technical expertise to perform and the choice of prosthesis is an important factor for the success of the operation. A dedicated rehabilitation programme is necessary to achieve the best outcome.
There is quite considerable variation with the pace which patients “recover fully”. This is related to differences in age, physical fitness and a number of other factors. Most patients are quite comfortable and independently mobile after 4 weeks. Your new knee will serve you well for general, non-impact activities. You should avoid high impact activities such as jumping and running. You may participate in sports such as swimming, cycling, golf and bowls.
The prosthesis may loosen after many years of use. Most UCR are expected to last beyond 10 years. If the replacement fails conversion to a Total Knee Replacement is usually effective.
All operations are associated with complications and the MIUCR is no exception. Some of the risks associated with the operation are listed below (others that maybe specific to your case will be discussed with you by your surgeon).
- Anaesthetic related complications
- Mal-alignment of limb and components
- Loosened and unstable components, dislocations and subluxation
- Joint stiffness
- Residual or incomplete pain relief
- Clots (thromboembolic disease)
- General medical complications
COMPUTER AIDED TOTAL JOINT REPLACEMENT
Ever since the first Charnley hip was implanted at the Wrightington Hospital for Joint Diseases in Wigan in 1961, millions of patients worldwide have benefited from total joint replacement. Although the basic principle has remained, there have been great strides in development in this field since Charnley’s time.
The main challenge today is to improve implant longevity and function and to this end there is a push for better material, improved design and improved surgical technique. One of the most recent innovations is computer aided total joint replacement.
Traditionally, preparation of the joint surfaces to accept the prosthesis is done by mechanical jigs and visual aids. Although this is acceptable in the majority cases, problems are encountered in obese patients, severe deformities and soft tissue abnormalities. One of the common causes for early prosthesis failure is misalignment of the new joint which is basically a technical error. It is envisaged that with computer assistance, this can be overcome.
Most suppliers in the joint replacement market will provide a computer assisted module for implantation of their products for the lower limb. Although the specifications may vary, the principle is the same i.e. to position the implant so as to re-establish the mechanical axis (hip-knee-ankle) of the lower limb.
They use GPS type technology for the surgeon-computer interface. Wireless trackers inserted in the patient relays information through infrared optics to the computer. The computer with its’ unique tracker software will in turn inform the surgeon continuously as to the position of the patient’s limb in space at any given time.
The procedure starts with registration of the patient’s anatomy. Unlike image guided surgery which requires pre-operative imaging (either MRI, CT or Fluoroscopy), computer aided surgery uses the information gathered by the surgeon during the operation to allow for the creation of a “morph” of the patient’s anatomy. The cutting jigs use trackers to communicate with the computer to ascertain that the saw cuts to be done will align the implant in the appropriate alignment to the accuracy of 0.5º.
Since the computer allows for real time display of the patient’s joint in space, one can ascertain the alignment and kinematics of the joint with the trials in place, allowing the surgeon to modify the implant position or balance the ligaments at the trial stage if necessary. This instantaneous feedback remains one of the major advantages of computed aided surgery over the traditional jig-based procedure where in the latter the surgeon can only ascertain the implant position from the post-operative X-ray.
There are other advantages. As the medullary canals are not breached (as in the traditional jigs), blood loss is less and therefore negating or minimising blood transfusion. This also leads to a lower incidence of fat embolism. As the alignment of the implant is optimal and with ability of the kinematics to be modified intra-operatively, post operative function is improved. Being an extra tool to “help us see”, there is also a great potential in doing joint replacement procedures through minimal incisions, again improving post-operative rehabilitation.
In prospective randomised studies 1,2 comparing computer assisted knee arthroplasty to conventional technique, the former has been shown to give significantly better results in terms of post-operative alignment and blood loss. We have performed computed aided total knee and hip replacement at the Sunway Medical Centre since October 2005. Comparing to a matched group of traditional jig-based total knee replacement done in the same centre, the computer aided group showed consistent result in terms of femoral, tibial and tibio-femoral alignment. Out-liers seen in the jig-based group were not detected in the computer aided group. Measurement using CT scannogram showed that the femoral, tibial and tibio-femoral mechanical axis together with the joint line coronal alignment all fall in the acceptable range of ± 3º. Out of these, 85%, 94%, 82% and 94% respectively fall in the ± 1º range.
We are encouraged by our initial results. It is envisaged that the computer will replace traditional methods in all total joint replacement in our centre and elsewhere in the future.