Knee Procedures

TOTAL KNEE REPLACEMENT SURGERY

What is Arthritis?

Arthritis is a condition whereby joint cartilage is destroyed. The most frequent type is osteoarthritis, which may result from previous joint injury or mal-alignment of the leg. Idiopathic osteoarthritis is a term we apply to osteoarthritis of indeterminate origin. Another significant subset of arthritis is caused by conditions associated with inflammation within the body. Rheumatoid arthritis is the most frequent of these conditions. Other causes of inflammatory arthritis include gout and systemic lupus erythematosus. Occasionally arthritis happens as a consequence of the death of the bone around the joint due to lack of blood supply; a condition referred to by the medical term Osteonecrosis.

You may be a candidate for total knee replacement surgery if you have advanced arthritis of the knee with debilitating pain, and you are not coping with activities that ordinarily form part of your daily routine. Your family doctor or other health care professional may have already suggested that you need knee replacement surgery. A brief interview followed by examination and review of your radiographs will help confirm whether you are indeed a candidate for knee replacement surgery. You will learn about the risks and benefits of knee replacement surgery, and only once you are mentally and physically ready to undergo the procedure, will we schedule surgery.

What is a Total knee Replacement?

Total knee replacement is a surgery that aims to resurface the entire arthritic knee using plastic and metal parts to cap the bone's ends that form the knee cap and joint. The knee joint consists of three compartments and these may be affected by arthritis to a varying extent. The three compartments of the knee joint include:

  • The patellofemoral compartment is the compartment between the knee cap (patella) and the lower end of the thigh bone (femoral trochlea).
  • The lateral compartment is the compartment between the thigh bone and the lower leg (tibia) on the outside.
  • The medial compartment is the compartment between the thigh bone and the lower leg on the inside.

Total knee replacement is a surgical procedure whereby the diseased knee joint is replaced with artificial parts. The articular surface of the femur is resected and replaced with a metal alloy part that is attached to the bone. Similarly, the upper part of the tibia, which forms part of the knee joint is also resected and replaced with a metal alloy part. A moulded insert made of special plastic (Polyethylene) is then placed between the two metal parts to restore smooth movement in the new knee. The articulating surface of the knee cap can also be replaced with a Polyethylene part.

The actual surgery takes just over an hour. Still, the entire process of administering the anaesthetic, doing the surgery and waking you up after that takes approximately two and a half hours.

Total knee replacement surgery is considered a major surgical procedure. When anti-inflammatories, cortisone and viscosupplementation injections or physical therapy don’t work, knee replacement surgery remains a last resort to relieve pain.

Patient-Specific Jigs in Knee Replacement Surgery

Total knee replacement

One of the main factors that influence the longevity of a knee replacement is the alignment of the implanted parts. Knee replacement parts have to be well aligned once implanted in the body to ensure that they perform optimally and last for a minimum of ten years. Conventional methods of aligning the knee during surgery involve the use of specialised instruments, which make use of rods that are inserted into the thigh bone (femur) and at times the lower leg (tibia).

Patient-specific instrumentation (PSI) is a recent development. PSI involves pre-operative Cat scans (CT) or Magnetic Resonance Imaging (MRI) of the leg to determine overall alignment and morphology of the knee. The scans are emailed to an Orthopaedic engineering facility where computer models are made of the knee based on the scan information. Appropriate bone cuts of the knee are simulated, and instruments are designed to achieve these cuts. Your Orthopaedic surgeon is an integral part of the process as he has to approve the design of PSI instruments. The instruments are specific to you and the knee to be operated, i.e. they cannot be used on other patients, and they cannot be used for the right knee is designed for the left knee. Once Dr Mokete is satisfied with the design, he then gives the engineers the go-ahead to manufacture the PSI instruments. The finished product, specified to your knee, is packaged and sterilised. Dr Mokete uses the finished product in preparation for your surgery. PSI is not a new type of knee replacement but merely a tool that helps achieve alignment of the knee replacement parts – implanted parts are the same as those used in conventional knee replacements.

If you desire PSI for your knee operation, you have to be aware of the following facts:

  • Your medical aid may not cover the cost of PSI in full, in which case you may have to contribute to the price of the pre-operative scans.
  • Once you have committed to PSI, you have to have knee surgery within three months of the scan.
  • Rarely you may be requested to have the CT scan or MRI scan repeated if the captured images lack the requisite clarity.
  • This type of knee surgery may be unsuitable if you have had previous surgery to the knee and have metal plates or screws close to the knee joint.
What to bring to the hospital

Expect to be in the hospital for five to ten days. Please bring along a change of underwear, nightclothes and comfortable, loose-fitting day clothes like tracksuit pants, slip-on shoes and trainers (takkies). Other essential items include a small bag of toiletries and reading material.

Free WIFI is available for inpatients in the hospital, and there are personal television sets where you can access a select number of channels. Do not forget to bring along your regular walking aid and medication that you usually take.

If you use spectacles, a hearing aid or dentures, you should also bring these items with you. Please do not bring expensive jewellery and mountains of cash. The hospital provides security boxes for personal belongings with only limited liability.

What to expect in the hospital

Before Surgery

The first port of call is the hospital reception. The hospital staff will be expecting you, and once formal registration has taken place, you will be escorted to the ward. Nursing staff will welcome you to the Orthopaedic department and make every effort to ensure you are comfortable. Please prepare yourself for a hospital stay for a minimum of four days. You will have blood tests, x-rays and urine test following admission to the ward. You will then be seen by a physician who will assess medical conditions that you have and she may change/add medication to ensure that your state of health is optimum for the surgery. You will be requested to sign a form that indicates that informed consent has been obtained from you for total knee replacement surgery– this is a legal requirement. The Anesthetist will visit you in the ward the following day for a check-up and final preparation for surgery. He often prescribes an anxiolytic, which may leave you feeling drowsy. Some medical aid plans require that medical assessments be done on an outpatient basis before surgery. We will facilitate these consultations, and hospital admission would then be on the day of the knee surgery.

Day of Surgery

You are not permitted to eat or drink for six hours before total knee replacement surgery. Family and friends (maximum of two persons) may accompany you to theatre reception – they are not allowed in the theatre room itself. Following knee surgery, you may be sent to the high care ward to monitor vital signs closely. Observation is generally for less than 24 hours. A physiotherapist will visit you during the post-operative period to start breathing exercises. The physician will continue to be involved in your recuperation reviewing your condition and adjusting medication as is necessary.

Day One After Surgery

The physiotherapist will do bed exercises with you, get you to stand and sit you out in a chair. If you have had an epidural catheter inserted at the time of knee surgery, your legs may still be too weak to allow you to stand. The physiotherapist is trained to be able to make the call regarding whether it is safe to get you out of bed.

Day Two

Most of our efforts are focused on your rehabilitation from day two of your post-operative hospital stay. Physiotherapy takes centre stage and treatments will consist of a minimum of two sessions per day.

The aim is to get you standing, sitting and walking independently and reasonably comfortably. Particular emphasis will be on exercises designed to get the knee bending as far back as is possible from the outset of the active physiotherapy sessions.

The physiotherapist will supply and adjust crutches or a walker as appropriate. You need not be concerned that you will be 'rushed' as the physiotherapist will supervise all treatment sessions and progress you to the next stage as you safely reach set milestones.

Day Three and Beyond

You will experience more of the same with a significant part of the day being devoted to rehabilitation treatments and achievement of at least 90 degrees of active knee bending. The physiotherapist will get you to negotiate stairs carefully as one of the last milestones in the in-hospital rehabilitation process.

Once she is satisfied that you are safe and fit to get around, she will recommend that you be discharged from the hospital. However, the final decision on discharge rests with the doctors. Nurses will inspect the surgical wound before you are discharged, and Dr Mokete also has to be satisfied that your condition is stable enough to allow discharge from the hospital. Partial Knee Replacement involves the limited replacement of certain parts of the knee.

The most commonly done partial replacement is where the medial compartment is replaced. This procedure is referred to as ‘Unicondylar knee replacement'. This type of surgery is only suitable for a minority of patients. The lateral compartment can also be replaced, but the results of such operation are less predictable, and in such instances, Dr Mokete prefers to replace the entire joint.

Arthritis may be isolated to the patellofemoral joint. This isolated arthritis is sometimes the case in those patients who have had childhood knee cap disorders and may have undergone surgery in their adolescence. Patellofemoral joint replacement involves resection of the diseased part of the joint and replacement with a metal alloy part and Polyethylene on the knee cap. Hospital stays, rehabilitation and return to normal function is often shorter following partial knee replacement surgery.

Post-op Information/Expectations

What do I take home?

You will be discharged from the hospital with prescription medication, which includes pain medication and oral blood thinners. The pain medication will help ease any discomfort you experience. Pain often occurs towards the end of the day, and the pain medication will also help you sleep better at night during the first few days at home. The blood thinners are to prevent blood clots in the legs, and these are typically taken for 14 days. You will go home with a walking aid that is appropriate for you and a toilet seat-raise if your toilet seat at home is low.

What can I expect to be able to do at home?

You will be able to walk around the house, get to the toilet without help and make yourself a sandwich and a hot beverage. Preparing a full meal will be a challenge. You should arrange for a responsible person to spend the first two weeks with you to allow you to settle in at home following the total knee replacement surgery.

When do I come back for a post-operative visit?

The first post-operative visit is at two to three weeks. Please contact the office to arrange an appointment soon after you have been discharged from the hospital. During this visit, we will check with you and determine whether you are making good progress in rehabilitating the operated knee. We will also inspect the wound and advise you on appropriate wound care.

When can I expect to drive?

You can drive when you can perform an emergency stop comfortably. Driving occurs during the seventh week following the knee surgery. Start by driving short distances in the neighbourhood during quiet periods with little or no traffic.

When can I expect to get back to work?

In general, you can resume light duties at seven weeks if your job is mostly office-based and three months if your ordinary tasks are more complicated. You should be in a position to put in a full day at work from four months.

Can I go to the gym?

You can go to the gym once you can confidently move about outside of the house. You should only do exercises that have been recommended by the physiotherapist and remember to take it easy in the beginning. You should build up slowly under the direction of the physiotherapist. Occasionally the gym may request a letter indicating that you are fit to resume gym activities – the physiotherapist will help in this regard.

What do I do with the wound?

Please do not disturb the wound dressings. We will endeavour to apply a water-resistant wound dressing which will allow you to be able to take a shower. Please do not immerse the operated limb in the bathwater. There is no need to expose the wound and to change dressings. You are likely to introduce infection from the outside by doing so. If you are concerned about the wound, please contact the office or the hospital emergency department outside office hours.

What can go wrong?

Knee replacement surgery is a significant procedure. The medical team looking after you will assess whether your body systems have the necessary reserve to withstand the operation of this magnitude. 

Blood Transfusion

There is a risk of blood loss, but with modern techniques, we can get the vast majority of patients through knee surgery without the need for blood transfusion.

Infection

As with any surgery, there is a risk of infection. The risk is minimal (less than one patient in a hundred) as we are meticulous with knee surgery and you get given antibiotics at the time of surgery.

Blood Clots

You can develop clots in the legs (Deep Venous Thrombosis) with knee surgery, but the risk is minimal. We administer preventative medication daily throughout your stay in hospital and extend the pain medication to a couple of weeks after your discharge. You can help reduce the risk of developing clots by enthusiastically partaking in the physiotherapy supervised exercise program before and after knee surgery. Rarely the clots may migrate from the legs to the lungs compromising the function of the heart and your ability to breathe (Pulmonary Embolism).

Repeat Knee Replacement Surgery

Once the knee replacement parts are implanted into the body, they do have a lifespan. There are wear and tear because of the movement of the parts, and they can ultimately become loose. Many factors determine the length of time the implants will continue to function well, but in general, the pieces should last 10 to 15 years before there is a need for another knee replacement operation.

Confusion

Transient confusion can happen in the elderly patient in the immediate post-operative period.

Do's and Dont's following Total Knee Replacement Surgery include:
  • Do continue your prescribed exercise routine daily.
  • Do eat a balanced diet.
  • Avoid low chairs. You should sit in chairs with arms.