Anatomy of the healthy knee
The knee joint is the largest and most complex joint in the human body. In addition to bending and stretching, other movements are possible in the joint, such as rotation and sliding.
The natural knee consists of three bones: the thighbone (femur), the shinbone (tibia), and the kneecap (patella). In the knee joint, the ends of the femur, tibia, and the back of the kneecap are covered with smooth cartilage. This cartilage allows for smooth movement between the two bone ends. When a healthy knee makes a movement, the two articular surfaces move easily and without pain in relation to each other. Between the two ends of the femur and tibia is another cartilaginous structure called the “meniscus,” which acts as a cushion. The knee joint is enclosed by a joint capsule, which contains a membrane. Strong ligaments connect the femur to the tibia, covering the joint and stabilizing it. The movements of the knee are directed and controlled by the strong thigh muscles (quadriceps) and the muscles of the lower leg. A healthy knee allows the leg to move freely within its range of motion and absorbs the shock created by activities such as walking and running.
The degenerative knee
Knee wear is characterized by the deterioration of cartilage and meniscus. Small cracks, pits, and tears can develop in these tissues. As a result, you may experience pain, swelling, and reduced functionality (such as walking, climbing stairs, and cycling). Wear and tear typically occur due to age but can also occur at a younger age due to rheumatism or as a result of an accident. This condition is more frequently observed in individuals with strenuous occupations, a long time after a sports-related injury, and in overweight individuals.
Knee Arthroplasty
The purpose of implanting a knee replacement is:
- Reduce pain and improve quality of life.
- Correct any deformities, such as bowlegs or knock-knees.
- Restore any lost function in your knee.
Implanting a knee prosthesis means replacing the ends of the femur, tibia, and, if necessary, the back of the kneecap with a prosthesis. Knee prostheses are specially designed to closely replicate the anatomy of the knee. There are various types of knee prostheses available. The most suitable prosthesis is chosen in consultation with you. However, the final decision is made during the operation.
Total Knee Arthroplasty
The ends of the femur and tibia are provided with a new surface. The kneecap does not always receive a new layer.
Each knee prosthesis consists of several parts:
1. The femoral (thigh bone) portion forms the new surface of the femur and is made of a metal alloy.
2. The kneecap portion, although not always replaced, covers the bottom of the kneecap and interacts with the thigh bone. The kneecap part is entirely made of plastic.
3. The lower leg section comes in two pieces. The two-part variant consists of a metal surface that is attached to the bone and a plastic insert (polyethylene or PE) for a smooth surface over which the thigh bone slides.
3D Personalized protheses
Custom-made ‘personalized’ prostheses offers the advantage of fully respecting the patient’s anatomy, theoretically resulting in fewer compromises in terms of size, contour, and joint line of the prosthesis. Slight to moderate axial deviations can be addressed smoothly. However, severe abnormalities cannot yet be treated.
Unicompartmental Knee Arthroplasty (UKA)
Only one part of the knee is damaged and only this part receives a new surface. The parts of the knee that are not damaged do not receive a new layer.
Patello-Femoral Arthroplasty
Only the kneecap and the trochlea (another term for the groove in which the kneecap moves) are replaced. The parts of the knee that are not damaged are not replaced.
Revision Total Knee Arthroplasty
Re-surgery of a previously placed knee prosthesis that has worn out, is not functioning properly, or has become loose. The previously placed parts are removed in whole or in part and replaced with new ones. Usually, the revision prosthesis is larger and extended with a stem for better fixation.
Allowed Activities
Frequently Asked Questions
Most prostheses are implanted between the ages of 57 and 77, with an average age of 67.5 years. Two-thirds of these patients are female.
Typically, patients report being able to walk for less than 1 hour and experiencing daily pain, often requiring the frequent use of analgesics before a prosthesis is implanted. The X-ray should show a clear narrowing of the joint space. In exceptional cases, a prosthesis may be deemed necessary at a younger age (under 55 years), but more complications are also observed in these younger patients. Alternative treatments such as pain relief, injections, physiotherapy, staying active, and weight reduction should be attempted before opting for prosthesis placement. Discuss this with your doctor!
This depends on the strength and coordination of your knee. Your physiotherapist can assess when it is responsible to resume participation in traffic. Usually, this is possible between weeks 4-6.
This obviously depends on the type of work and can range from 6 weeks to 6 months.
Our goal is 3 nights. Once the wound is dry and physiotherapy is progressing smoothly, you can go home!
As soon as the wound is dry, a waterproof bandage can be applied, allowing for showering.
This is indeed normal and is explained by the fact that the cutaneous nerves run from the inside of the knee to the outside. When the skin is incised, a few skin nerves will therefore be cut, causing numbness in this area just beyond the scar, on the outside of the knee. This area may be quite large initially and often shrinks during the first year, but it never completely disappears.
Complications after total knee replacement surgery are rare. Serious complications, such as infections, occur in less than 2% of cases. Major complications like a heart attack or stroke are even rarer. More complications can be observed in chronic conditions. Although rare, complications can impede or limit rehabilitation. Discuss this thoroughly with your doctor before surgery. Blood clotting and phlebitis may occur. If these clots break free, they can travel to the lungs and cause a life-threatening pulmonary embolism. To minimize this risk, injections with a blood thinner are administered for 40 days. Infections can occur around the wound or deeper around the prosthesis. This can happen immediately after prosthesis placement, during your hospital stay, or even much later. Superficial wound infections can, in most cases, be treated with antibiotics. Deep infections typically require additional surgery, which may even necessitate removal of the prosthesis. Any infection, e.g., a tooth abscess or urinary tract infection, can spread to the prosthesis. Antibiotics are administered during the procedure to minimize the risk of infection. The design and materials from which prostheses are made are constantly improving. Nonetheless, prosthetic components can wear out and become loose. Although an average bend of 120 degrees is achieved, excessive scar tissue can form and stiffen the joint. This is more frequently observed in younger patients and patients with limited mobility before surgery. A limited number of patients may still experience pain after surgery. Damage to blood vessels and nerves is extremely rare but can occur during surgery.