ORTHOPAEDIC SURGEON
Do I Need a Knee Replacement?
Damage to the articular cartilage (the tissue that covers the bone in the joint) of the knee joint surfaces lead to wear and tear changes in the knee joint, also known as arthritis. The vast majority of patients have osteoarthritis, a small number have inflammatory arthritis and occassionally it can be caused following a fracture in a part of the knee. or more commonly by damage to the shock absorbers in the knee called the meniscus. Patients typically complain of pain in the knee and sometimes of stiffness.
Early treatments for arthritis in the knee joint include pain relief medication, physiotherapy and injection therapy. When this has failed and arthritis is causing you significant pain or impacting on your quality of life it is time to consider a knee replacement.
What is a Knee Replacement made from?
There are many different types of knee replacements available on the market and it is your surgeon who will decide on what type suits you best.
The procedure is preformed by a verticle incision approximately 10cm long on the front of the knee. The joint surfaces from the thigh bone (femur) and shin bone (tibia) are removed and occasionally the undersurface of the knee cap (patella) is also removed. The new knee consists of a metal shell on the thigh bone and the tibia with a plastic liner in the middle. They can be secured with bone cement or by a special coating on the implants that encourages bony ingrowth to the implants.
The implants are made from metal, normally a titanium alloy or other metal. The liner (the plastic piece that fits between the two metal pieces) is made from a highly cross linked polyethylene (plastic).
Complications of Total Knee Replacement Surgery
1. Urinary Tract Infections
Can occur frequently following surgery. It is important to drink loads of water following surgery to try to prevent this. If you notice any buring or stinging tell your healthcare team.
2. Pain
Your knee will be sore following surgery and particularly once the spinal anesthetic wears off. It is very important to keep pain under control by taking the prescribed pain medication, using ice and elevating the leg. By controlling pain this enables you to progress with physiotherapy and your rehabiliitation.
1. Blood Clots - Deep Vein Thrombosis
Mobilising following surgery by taking frequent walks, staying well hydrated and anti clotting medications will help prevent blood clots.
2. Bleeding
During surgery you can bleed. Medication is sometimes used to reduce this. If bleeding is significant you may require a blood transfusion. If you have religious beliefs with regard to blood transfusion you must inform your surgeon.
3. Nerve Injury
The common peroneal nerve which runs down the outside of your leg can get streched during the procedure. If this happens it can cause a foot drop which can be permanent or temporary and involves wearing a foot splint to help control your foot. Damage to this nerve also results in changes to the sensation to the skin in the leg.
4. Difficulty passing urine
5% of patients require a urinary catheter for the 24 hours following surgery. It is most common in patients who have a history of difficulty passing urine eg prostate conditions
5. Loosening of the knee
Over time eg 10-20 years the knee can loosen. If this occurs it may be necessary to have further surgery to replace your knee replacement.
6. Stiffness in the knee
Scar tissue can form within the knee joint following surgery (arthrofibrosis). Engaging with physiotherapy is important to reduce the chances of this occuring. If this problem persists it may be necessary to manipulate the knee under anesthetic to help with gaining full movement.
Infection
There are different types of infection that can occur following a knee replacement which occur at different times up to years later.
There is a higher risk associated with smoking, obesity, diabetes and immunocompramised patients. Many strategies are used to try to prevent this occuring such as antisceptic washes, sterilistaion techniques, antibiotic use etc
1.Superficial Infection (cellulitis) is an infection of the overlying skin. This occurs in the weeks following surgery and can be treated with antibiotics. If you notice any redness around your wound contact your orthopaedic team immediately.
2. Deep Joint Infection - Early & Late
This is one of the most worring complications as the impact on the patient is so significant.
It may be necessary to washout the joint, remove the knee replacement and put in a spacer (a temorary knee with antibiotics) and when the infection has cleared up, put in a new knee replacement.
Patients require prolonged courses of antibiotics for several months.
1. Death
2 in every 1000 patients die within one month of surgery. Risk is increased for patients with medical comorbidities such as heart or lung problems.
2. Fracture
Rarely the femur or tibia can fracture when the implants are inserted. This can result in the need for further surgeries ( a revision knee replacement)
4. Pulmonary Embolus
A clot forming in the lungs is a rare complication and can result in a wide severity of symptoms from mild cough to death.
Post Operative Care