Total knee replacement - A new knee joint.

Diseases like osteoarthritis and rheumatoid arthritis damage the smooth articular cartilage covering the ends of bone. As the cartilage starts to wear away, the bone ends are exposed and then rub against each other and in severe cases themselves become worn. This causes the knee to become painful, stiff, and deformed.

 

When do you need a new knee joint?

The decision is straightforward if you have one or all of the following:

• Severe pain, both day and night that is not relieved by painkillers or other treatment.
• If you can't walk far.
• If you develop increasing deformity of the knee.
• X- ray shows arthritis.

In the majority of cases, patients are aged 60 or over. It is not wise to delay the operation because with time the muscles become weaker, stiffer and more deformed. This reduces the chances of a successful outcome after surgery.

 

Your new knee joint and how it works.

A new knee joint procedure simply means replacing the worn surface of the bones with prosthesis. The thighbone (femur) is resurfaced by a single piece of metal. The shinbone (tibia) is replaced by a metal plate and a plastic is placed over the metal to act like a cartilage. This allows a smooth movement and marked improvement in pain, function and mobility.

Recent advances in knee replacement allow better range of movement and longer working life of the implant. In certain cases only part of the knee joint is replaced (unicondylar knee). The choice of implant depends on the condition of the knee joint, the physical demand placed on the knee and the age of the patient.

 

What's new in knee joint replacement surgery?

New design in implants allows higher degree of flexion and better longevity of the implant.

 

What can you expect from a knee replacement?

The success following total knee replacement depends upon the surgeon’s experience, the type of implant and the condition of the knee before surgery. The patient’s expectation, motivation and cooperation during rehabilitation are also factors.

Contrary to common belief, total knee replacements are as successful as total hip replacements. About 95% of the knee replacement will last more than 10 years.

Pain - a majority of patients report 95% improvement in pain following surgery.

Flexion (bend) - 90% of patients will achieve knee flexion of 100-110 degrees. The most recent knee implant designs allow an even better range of movements and tend towards normal, provided the patient has the normal range of movement before surgery.

Walking distance - most people can walk 45 minutes or more with little or no discomfort. As the walking distance increases, it also helps the heart and lungs and patients generally feel fitter with time.

Function – a majority of patients find it much easier to perform a wide range of daily activities (climbing stairs, shopping, dressing and personal hygiene etc).

Leisure & Sports - activities like swimming, general fitness exercise and golf are possible after knee replacement.

Limitations - kneeling, heavy impact exercises & heavy manual work should be avoided.

Please remember a replaced knee joint will never act or behave like a normal knee.

 

What can you do to get a better result?

• try to lose weight if you are overweight.
• exercise your thigh muscles regularly before and after surgery. Miss a meal do not miss your exercise.
• keep moving your new knee joint.
• keep motivated and well informed.
• try to stop smoking at least 6 weeks before surgery.

 

What happens before the operation?

Your surgeon will explain to you in detail about the total knee replacement procedure: the advantages, disadvantages, and possible complications. You can also ask him questions about the surgery to remove any doubts from your mind.

He will ask you about your general health, medication and any allergies. If you are on warfarin then please make sure your surgeon knows about it.

Investigations like an x-ray of the knee joint, a chest x-ray, heart tracing (ECG), a routine blood test and cross match are all required before surgery. These investigations help us decide whether you are fit enough for the operation and most hospitals now perform them in a pre-operative assessment clinic. If you have any source of infection in your body then it is critical that you tell the nurse or your surgeon about it.

 

Potential source of infection are:  

• open wound or ulcers on the skin
• mouth, teeth or gum
• cough, cold or chest infection
• bladder and groin area
• skin space in between your toes

 

What happens on the day of admission?

You will be admitted to hospital a day before surgery.

The nurse, surgeon and the anaesthetist will see you. They will once again ask you questions about your general health and fitness for surgery.

Your surgeon will explain once again about surgery and ask you to sign a consent form for surgery. Your leg will be marked.

You will have the opportunity to ask your team about all aspects of the surgery – from the anaesthesia to the aftercare.

You will be asked to shower using an antiseptic soap on the day of admission and on the day of surgery before going to operating theatre.

 

Type of anaesthesia

Your anaesthetist will decide the most appropriate anaesthesia for you. Commonly a combination of general anaesthetic and nerve block is used. You will be asleep during the procedure. The nerve block will take away the pain in your leg after surgery. The effect of the block usually lasts 12-24 hours. In certain medical conditions a spinal or epidural anaesthesia may be used. This involves inserting a needle in your back to freeze the body from the waist down.

 

After your operation

You will return to the ward after a short stay in the recovery room. Your leg will have a bandage and a drain tube which helps reduce bleeding and collection of blood. This will be removed after 24-48 hours.

Due to the nerve block, you may not have much feeling in your leg. This also helps reduce the pain after surgery.

You will have a drip in your arm, which may be used to give medications, fluid and blood if required. It is usually removed after 48 hours. You will receive oxygen.

The nursing staff will check your pulse, blood pressure, temperature and your leg at regular intervals.

They will place ice packs (cryocuffs) over the knee joint to reduce bleeding.

 

Pain

Total knee replacement is a major surgery and some degree of discomfort after surgery is expected. The following steps help to reduce pain.

1.  Nerve block - The effect usually lasts 12-48 hours.
2.  Patient controlled analgesia, pain killing injections are given through a pump controlled by a button.
3. Tablets to be taken while in hospital and to be taken home on discharge.
4. The majority of the pain will subside in 2-3 weeks. Minor discomfort may last up to 3 months.
5. A decreasing dose of painkillers and anti-inflammatory agents may be required for 3 months.

 

Bleeding and transfusion

Some bleeding is expected after major surgery. We will monitor it and take steps to minimise it. In a small number of cases a blood transfusion may be required. It is wise to take it easy for the first 6 weeks.

 

Swelling

Swelling following knee replacement is common. Usually major swelling will settle down in 6 weeks and minor swelling may be present up to 12 months. Swelling of the ankle may occur for 3 months. You can minimise it by moving your ankle and toes.

 

Movement

Most knee implants allow you to achieve a functional range of movement from 0 - 110 degrees. New implant design allows an even better range of movement.

There are several factors that affect this movement range:
1.  Range of movement of the knee before surgery
2.  Muscle strength
3.  Experience of the surgeon
4.  Type of implant
5.  Motivated and well informed patients

 

Warmth

The knee may feel slightly warm up to 12 months after surgery

 

Rehabilitation & Physiotherapy

Exercise is vital to your recovery. It will start on the day of the operation and continue till you are back on your feet and achieving good knee function. A physiotherapist will visit you daily and help with therapeutic exercises:

1.  They will help you sit out of bed the day after your operation and stand with support. Early mobilisation reduces the risk of blood clots and pressure sores.
2.   You will be shown the correct exercises for your knee. These help to strengthen your muscles and regain movement, balance and function. You must continue these exercises at home. It is important to do them for at least 10 minutes everyday throughout your life. Exercise that strengthens your quadriceps muscle is the key to success.
3.  Most patients are able to walk with one or two stick within 4-5 days.
4.  Walk regularly.
5.  Most patients are allowed to return back to light work at around 6-8 weeks.
6.  Driving is usually allowed at 6 weeks.
7.  Try to avoid heavy lifting and twisting on your knee.
8.  If you’re a golfer, you can play again after 3 months.
9.  It is not advisable to go back to heavy manual work after knee replacement.

 

Discharge from hospital (going home)

This varies with age and medical conditions. Most patients go home safely between 5-10 days.

1.  You should be able to walk along the corridor without help.
2.  Able to manage steps and stairs independently.
3.  Able to easily bend your knee to about 90 degrees.
4.  You will go home when you, your surgeon, physiotherapist, and nurses are happy with your progress.
5.  Part of your stitches will be removed just before discharge. The rest are dissolvable.

 

Review in clinic

You will be seen in the outpatient department at 2 weeks, 6 weeks, 3 months and 6 months after surgery. Further appointments may be required in some cases.

 

Main risk of Knee replacement

Replacement surgery is a major operation. The risk and complications are very low. Precautions are taken at each and every step to avoid them.

Infection – it is accepted that despite best efforts, infection can occur in some cases. Deep infection is a rare but serious complication. This may require hospital admission, further surgery, antibiotics and in the worse case, removal of the knee implant. To reassure you, Mr Singh’s infection rate is 0% in private practice and 1% in the NHS.

 

Avoiding infection

Surgery is performed in an operating theatre with a laminar airflow and use of body exhaust system.
      Shower with antiseptic soap
      Use of antibiotics
      Small wound and shorter surgery time
      Minimal wound handling after surgery

 

Thrombosis – a blood clot can occur either in hospital or at home after surgery. The patient will experience pain, swelling and a slight discolouration of the calf or leg. It normally gets better with treatment.

Avoiding thrombosis

      Anti-embolism (TED) stockings and a foot pump to improve blood flow.
      Injection given at the time of surgery.
      Getting out of bed next day with early mobilisation.
      Aspirin for 6 weeks after surgery.

General complications - Complications like heart attack, stroke, clot in lung and even death are extremely rare and can occur in less than 1% of cases .