Treatment of Osteoarthritis of the Knee and Knee Replacement Surgery

What is osteoarthritis of the knee?

The knee joint is the largest joint in the body but also a very vulnerable joint. It is placed under a lot of strain from activities of daily living like lifting, kneeling, running as well as high impact activities like contact sports.

The knee joint is formed by the femur (thighbone), the tibia (shin bone) and the patella (kneecap).

Like other joints, the bone ends are covered with articular cartilage that acts as shock absorbers. The cartilage is smooth, allowing easy and pain-free range of motion. When the joint is diseased or damaged, the bone under the cartilage becomes exposed. This leads to arthritis causing pain, swelling, stiffness, and limping.

Common causes of knee arthritis are:

  • Osteoarthritis – the most common form because of age-related wear and tear.
  • Inflammatory arthritis like rheumatoid arthritis, causing inflammation in the lining of the joint and eventual joint damage.
  • Post-traumatic / injury related arthritis after fractures, sport injuries etc.
  • Growth disorders / congenital defects.

How is arthritis in the knee diagnosed?

Symptoms of knee arthritis include:

Pain: Pain in the knee. Pain may radiate to the hip / ankle. Pain after activities like walking / prolonged standing and other exercises. Pain gets worse with time and eventually you can have pain at rest.

Night pain: Pain at night pain is very common – it can wake you up at night.

Stiffness: It is common to lose range of motion with knee arthritis. You might have difficulty bending and straightening the knee or squatting.

Catching / grinding or locking: This is called crepitus.

Weakness: You might have trouble standing up from a sitting position and with stairs as a result of muscle weakness especially the quadriceps muscle.

A complete history and physical examination will be done – this includes assessing range of motion, checking for fluid (effusion) in the knee, stability of the knee by testing ligaments, strength, and neurovascular examination of the leg. You might need to have further tests done to confirm the arthritis.

These tests include:

  • X-ray of the knee.
  • CT (Computed tomography) scan.
  • Magnetic resonance imaging (MRI).


Treatment of Arthritis:

Treatment of arthritis depends on the type of arthritis, the stage of the arthritis, the severity of the pain as well as your age. Treatment for early osteoarthritis consists of the following:

  • Range of motion exercises to keep the knee as mobile and as flexible as possible. This is low impact exercises like hydrotherapy, swimming and cycling. A physiotherapist might help you with this in the early stages.
  • Modification of activities-this is to try and avoid activities that causes pain and discomfort in your knee. This might mean reducing the number of times you play any sport like tennis or golf.
  • Cold and heat packs. Heat packs are great to use before exercises and cold packs is are really good to use after activities
  • Weight loss
  • Medication to treat arthritis may help but it does have potential complications. Oftentimes initial treatment will be with Paracetamol. You may also benefit from anti-inflammatory medication. This should be used with caution and only when needed.
  • Injection of cortisone. This is normally done under ultrasound control and in combination with a local anaesthetic. This can help to reduce inflammation and pain in the knee for a reasonable amount of time. Cortisone injections can increase the risk of infection with knee replacements and should be avoided for at least 6 months before
  • Injection of hyaluronic acid: Is also called viscosupplementation. It is the injection of synthetic joint fluid that can give pain relief for a while. It has been used in knee arthritis for a long time.
  • Walking aids like a wheelie walker, cane or walking frame.

Surgery to treat arthritis of the knee is normally indicated when the treatments above fail, and your quality of life starts to suffer because of the arthritis.

This includes:

  • Difficulty to do simple daily tasks like getting dressed or climbing stairs and walking.
  • Inability to get a good night’s rest because of night pain and interruption of sleep.
  • Inability to participate in activities that you enjoy for instance playing sports, dancing, going for walks, etc.


The decision to proceed with knee replacement surgery should be taken after discussion of the procedure with your surgeon. Once you have all the relevant information, you can make an informed decision about proceeding with your knee replacement.

Types of Surgery:

The type of surgery depends on the severity of the arthritis as well as the age of the patient.

Knee Arthroscopy:

With this type of surgery, a small camera is placed inside the knee joint, and instruments placed through small incisions to "clean out" or debride the joint. This type of surgery is normally done in patients with very early arthritis. Although this gives pain relief for a certain amount of time, the surgery is not a permanent solution. There is increasing evidence coming out that arthroscopies are not any better than non-operative / conservative treatment.

Partial Knee Replacement:

In a partial knee replacement, only the damaged part of the knee is replaced. This can be the inside (medial compartment), the outside (lateral compartment) or the patellofemoral joint (kneecap). Only few patients are eligible for a partial knee replacement because most of the arthritis involves the whole knee.

Total knee replacement:

During a total knee replacement an incision is made over the front of the knee. Dr. Pretorius uses a robotic arm to do knee replacements. The robot makes very accurate cuts, and causes less soft tissue injury, which in turn leads to less pain and discomfort. This allows for accurate placement of the prosthesis after assessing the ligaments. Robotic surgery allows the surgeon to closely reconstruct your knee to your own anatomy.

Once the appropriate size of the femur and tibia is selected, it is fixed by the either bone cement, or an uncemented prosthesis, depending on the quality of the bone. A high-density plastic is inserted between the femur and the tibia to act as a cushion. Sometimes the back of the patella (kneecap) will be resurfaced with a contoured plastic button.

General risks of surgery:

  • Knee replacement surgery is usually done under spinal anaesthesia (a needle is placed in your back after a local anaesthetic injection) and sedation (It will numb the area below your waist. You will be sedated (asleep) during surgery. Unexpected death from an anaesthetic is very rare.
  • Antibiotics are routinely used during surgery to prevent infection - some patients may have an allergic reaction or anaphylaxis.
  • Sometimes a catheter is inserted to drain your bladder.
  • Wound infection.
  • Bleeding in the wound with haematoma (big collection of blood) formation.
  • Pain / numbness around the incision.
  • Allergies to antiseptic solutions used to clean the surgical site.
  • Allergies to sutures and / or dressings.
  • Deep vein thrombosis – there is always a risk of DVT with surgery of the lower limb.
  • Nausea and vomiting after surgery.

Specific Risks with Knee Replacement Surgery:

  • Infection in the knee joint – can happen early after operation or later if an infection causes bacteria in your blood. Please check before having dental or other surgery.
  • Injury to nerves which is very rare. The sensory nerves that supply the feeling to the front of the knee is cut during the midline incision in front of the knee. This is inevitable. It ALWAYS result in some numbness on the outside of the knee. This will improve over time but can be permanent.
  • Injury to blood vessels.
  • Blood clots in legs and rarely in lungs.
  • Constipation from pain medication.
  • Fractures of femur or tibia is extremely rare.
  • Ongoing swelling in the leg.
  • Ongoing pain and stiffness.
  • Loosening of the prosthesis (bone / cement) or failure of bone to grow onto prosthesis. Loosening happens gradually over time and is more likely towards the end of the knee replacement’s ‘life’ (20 – 25 years).

Recovery after Knee Replacement Surgery:

Following your total knee replacement, you will wake up in the recovery room. The nurses in the recovery room will monitor your recovery by regularly checking your vital signs (pulse, blood pressure, etc), pain level and level of consciousness.

Once you get to the ward, an ice pack may be applied to your knee to help for pain and swelling.

Once the spinal anaesthetic has worn off, a physiotherapist will get you to stand up next to the bed. This might happen on the same day of your surgery, depending on what time the surgery takes place. You will be encouraged to start mobilising as soon and as much as possible.

I cannula will be placed in the knee for continuous infusion of a local anaesthetic drug for the 1 st 3 days. If an indwelling catheter has been inserted into the bladder, this will be removed the next day.

As soon as you can demonstrate that you are able to walk with crutches and able to climb stairs, you will be able to go home. This is normally between 3 – 5 days.

Some elderly patients may have trouble going straight home, especially if they live alone. Arrangements can be made for a transfer to a rehabilitation unit after surgery, if this is covered by their health fund. When you get home, you will need to continue with elevation of the leg, application of ice packs for 30 minutes 4 – 6 times a day. You will need to continue to use 2 crutches for about 4 weeks and then one crutch for 2 weeks (use one crutch in opposite hand). You will be discharged home with strong pain medication. Try to use the stronger pain medication only when normal pain medication like Paracetamol is not effective.

It is important to keep the surgical area clean and dry and to keep the wound dressings intact.

After surgery, hospital staff will let you know when you need to make an appointment with Dr. Pretorius for your follow-up. These follow-ups are generally between 10 – 14 days post-surgery for a general check-up, removal of stitches, checking on your wound(s) and for further instructions on the continuation of care. 

A physiotherapist will see you in hospital and will supply you with some initial exercises. It is important for you to book an appointment with your physiotherapist of choice to continue with your rehabilitation.

During recovery, it is important to follow the advice below, especially in the first 6 weeks:

  • Avoid sitting on low chairs.
  • Use an elevated toilet seat.
  • Please use nonslip socks, slippers or slip-on shoes.
  • It is important to avoid falls: Stairs and the bathroom are especially hazardous places.
  • Driving an automatic light vehicle is allowed after 2 weeks with a left knee replacement and 6 weeks with a right knee replacement.

Every patient’s recovery will be different from the next. The rehabilitation is as important as the surgery. Your effort and motivation are really important to ensure successful recovery and an optimal outcome. Your knee will keep improving for up to 2 years after the surgery.

Please contact the surgery immediately if you have any of the following:

  • Any redness, swelling, bleeding or drainage from your incision site.
  • Any fever or chills.
  • Any increase in pain around the incision site.
  • Any pain in your calf or thigh with increased swelling in the leg.
  • Loss of movement.
  • Any other concerns you may have.

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