Total knee prosthesis

Introduction

A total knee prosthesis (TKP also called total knee arthroplasty TKA or total knee replacement TKR) is a surgical procedure whereby the diseased knee joint is replaced with artificial material. The knee is a hinge joint which provides motion at the point where the thigh meets the lower leg. The thighbone (or femur) abuts the large bone of the lower leg (tibia) at the knee joint. During a TKP, the end of the femur bone is removed and replaced with a metal shell. The end of the lower leg bone (tibia) is also removed and replaced with a channeled plastic piece with a metal stem.
Depending on the condition of the kneecap portion of the knee joint, a plastic “button” may also be added under the kneecap surface.
The posterior cruciate ligament is a tissue that normally stabilizes each side of the knee joint so that the lower leg cannot slide backward in relation to the thighbone. In total knee replacement surgery, this ligament is either retained, sacrificed, or substituted by a polyethylene post. Each of these various designs of total knee replacement has its own particular benefits and risks.

total-knee-prot

OUTCOMES

For an optimal outcome after total knee replacement surgery, it is important for patients to continue in an outpatient physical-therapy program along with home exercises during the healing process. Patients will be asked to continue exercising the muscles around the replaced joint to prevent scarring (and contracture) and maintain muscle strength for the purposes of joint stability. These exercises after surgery can reduce recovery time and lead to optimal strength and stability.
The wound will be monitored by the surgeon and his/her staff for healing. Patients also should watch for warning signs of infection, including abnormal redness, increasing warmth, swelling, or unusual pain. It is important to report any injury to the joint to the doctor immediately.
Future activities are generally limited to those that do not risk injuring the replaced joint. Sports that involve running or contact are avoided, in favor of leisure sports, such as golf, and swimming. Swimming is the ideal form of exercise, since the sport improves muscle strength and endurance without exerting any pressure or stress on the replaced joint.
Ten years after surgery 92-95% of all primary total knee prostheses is still functioning well.

Total knee surgery is considered for patients whose knee joints have been damaged by either progressive arthritis, trauma or other rare destructive diseases of the joint. The most common reason for knee prosthesis is severe osteoarthritis of the knees

ACS-total-knee-prosthesis-X-ray

Regardless of the cause of the damage to the joint, the resulting progressively increasing pain and stiffness and decreasing daily function lead the patient to consider total knee replacement. Decisions regarding whether or when to undergo knee replacement surgery are not easy. Patients should understand the risks as well as the benefits before making these decisions.

Risks of total knee replacement include blood clots in the legs that can travel to the lungs (pulmonary embolism). Pulmonary embolism can cause shortness of breath, chest pain and even shock. Other risks include urinary tract infection, nausea and vomiting (usually related to pain medication), chronic knee pain and stiffness, bleeding into the knee joint, nerve damage, blood vessel injury, and infection of the knee which can require reoperation.

All these complications are very uncommon (less than 0,5 percent of the patients)

Before surgery, the joints adjacent to the diseased knee (hip and ankle) are carefully evaluated. This is important to ensure optimal outcome and recovery from the surgery. Replacing a knee joint that is adjacent to a severely damaged joint may not yield significant improvement in function as the nearby joint may become more painful if it is abnormal.
Finally, a knee replacement surgery is less likely to have good long-term outcome if the patient’s BMI is greater 35. Excess body weight simply puts the replaced knee at an increased risk of loosening and/or dislocation and makes recovery more difficult.

All patients are assessed by the anaesthesiologist before the operation to evaluate your operative risks.

You will get an anesthetic before your knee prostheis. This may be:

  • regional (numbs you from the waist down)
  • general (puts you completely to sleep)

A total knee replacement generally requires between 50 and 80 minutes of operative time . After surgery, patients are taken to a recovery room, where vital organs are frequently monitored. When stabilized, patients are returned to their hospital room.

total kneee

We use the cemented ACS Knee System® from the firm Implantcast GmbH, Buxtehude, Germany. Implantcast has a worldwide sales network with more than 65 international sales partners.

Passage of urine can be difficult in the immediate postoperative period, and this condition can be aggravated by pain medications. A catheter inserted into the urethra (a Foley catheter) allows free passage of urine until the patient becomes more mobile.
Physical therapy is an extremely important part of rehabilitation and requires full participation by the patient for optimal outcome. Patients can begin physical therapy a few hours after surgery. Some degree of pain, discomfort, and stiffness can be expected during the early days of physical therapy. Knee immobilizers can be used in order to stabilize the knee while undergoing physical therapy, walking and sleeping. They may be removed under the guidance of the therapist for various portions of physical therapy.

Patients will start walking using a walker and crutches. Eventually, patients will learn to walk up and down stairs and grades. A number of home exercises are given to strengthen thigh and calf muscles.