Knee

The Knee is the largest joint in the body. Normal knee function is very important to perform day today activities. Knee is made up of the lower end of thigh bones (femur) which rotates on the upper end of the shin bone (tibia) and the knee cap which slides in a groove on the end of the femur.

The Joint surface is covered with a smooth substance that cushions the bones and enables them to move easily. All remaining surfaces of the knee are covered by a thin, smooth tissue liner .This is membrane releases a special fluid that lubricates the knee, reducing friction to nearly zero in a healthy knee. Normally, all of this mechanism works in harmony. But disease or injury can create disorder in this harmony, resulting in pain, muscle weakness, and reduced function.
Functioning Of Knee Joint:
The knee joint performs similar to a hinge joint. It consists of three bones:

• Thigh bone (Femur)
• Leg bone (Tibia)
• Knee cap (Patella)

The junction where the femur and tibia couple together is called the femorotibial joint. The region of the knee where the patella and femur form a junction is called the patella femoral joint. These two joints are what allow the bending and straightening of the knee. It is these joints that are replaced in a total knee joint replacement.
Total knee replacement

Total knee replacement (TKR), also referred to as Total Knee Arthroplasty (TKA), is a surgical procedure where worn, diseased, or damaged surfaces of a knee joint are removed and replaced with artificial surfaces.

Knee replacement surgery is performed to treat advanced or end-stage arthritis or to the patient who has severe pain in the knee joint.
Causes Of Knee Replacement:

• Osteoarthritis resulting from “wear and tear” is the most common reason for individuals to undergo knee replacement surgery.
• Rheumatoid arthritis, an inflammation of the tissue surrounding the joints, can cause deterioration of cartilage and other parts of the joint and also result in the need for knee replacement.
• Post-traumatic arthritis, a type of arthritis that can arise following an injury to the joint cartilage or through damage to the ligaments leading to an unstable knee.
• Avascular necrosis results from an inadequate supply of blood to the bone end inside the joint

When Does One Need Knee Replacement?

Generally a person would be considered for a Total Knee Replacement if the individual experiences daily pain, restricting not only work and recreation, but also the ordinary activities of daily living. There must also be evidence of significant destruction of the knee as seen on an x-ray.
Knee Replacement Procedure

Once the anesthesia has been given and the patient is prepared, the damaged joint surfaces are removed. An incision approximately eight inches in length is made on the front of the knee. The damaged joint surfaces are removed from all 3 bones making up the knee joint. Sometimes, depending on the surgeon, the back of the knee cap is left intact if it is not badly affected by the arthritis. The surrounding muscles and most of the ligaments are preserved. The lower end of the thigh bone (femur) is resurfaced with a metal cap. The upper end of the leg bone (tibia) is replaced with a plastic and metal implant with cement and or screws. The actual procedure takes about 1 ½ to 2 hours.
Types of Implants:

• Cemented Implants: – The components of the implant are fixed to the bone with a grout-like cement known as polymethyl-methacrylate. This cement allows the implants to perfectly fit to the irregularities of the bone.
• Non-cemented Implants: – In a non-cemented procedure, components of the implant have a roughened porous surface designed to allow bone to grow into it, eliminating the need for cement. The implants are “press fit” against the bony surfaces that are precisely cut through the use of multiple cutting jigs.
• Hybrid Fixation Implants: – Consists of a combination of the cemented and non-cemented technique. In this method the femoral component is not cemented and the tibia component is cemented.

Post – Operative Care

Once the anesthesia has been given and the patient is prepared, the damaged joint surfaces are removed. An incision approximately eight inches in length is made on the front of the knee. The damaged joint surfaces are removed from all 3 bones making up the knee joint. Sometimes, depending on the surgeon, the back of the knee cap is left intact if it is not badly affected by the arthritis. The surrounding muscles and most of the ligaments are preserved. The lower end of the thigh bone (femur) is resurfaced with a metal cap. The upper end of the leg bone (tibia) is replaced with a plastic and metal implant with cement and or screws. The actual procedure takes about 1 ½ to 2 hours.
Benefits Of Knee Replacement Surgery:

• The general goal of total knee replacement is designed to provide painless and unlimited standing, sitting, walking, and other normal activities of daily living. It Improves quality of life and restores mobility.
• It has very high success rates, relieves the pain and disability from degenerative arthritis, meniscus tears, osteoarthritis, cartilage defects, and ligament tears
• Technology has led to the development of materials used in the artificial knee joint allowing it to last over fifteen years.
• Artificial joint replacement for arthritis of the knee and hip is one of the most successful surgeries of the last century.

Individuals are able to begin walking the day following surgery and pain relief is achieved in greater than 95% of people.

With proper care individuals who have had a Total Knee Replacement can expect many years of faithful function. Studies show that patients can expect a greater than 95 percent chance of success for at least 20 years.