Knee Replacement

Knee arthroplasty, also known as knee replacement surgery, is the substitution of the joint with metal and polyethylene components. It is indicated for the most severe cases of osteoarthritis that do not respond well to less invasive treatments (learn more about osteoarthritis here). The prosthesis can replace just one compartment of the knee, which is a unicompartmental prosthesis, or replace two or three compartments, which is a total prosthesis.

Components of total knee replacement

Ideal candidate for surgery

The ideal candidate for total knee replacement surgery is a patient with severe osteoarthritis, which is characterized by significant wear and tear of the knee, associated with limiting pain and poor quality; and for those who have not had a good response to less invasive treatments, such as:

Change of habits;
Weight loss;
Analgesic and anti-inflammatory medications;
Rehabilitation with physiotherapy.
Acupuncture;
Joint injections.

Preoperative evaluation

Before considering surgery, several tests must be performed to ensure that surgical planning is as accurate as possible.

In orthopedic surgery, the most frequently requested tests are simple X-rays of the knee, in anteroposterior and lateral views with weight-bearing, and axial views of the patella. Another radiographic incidence that can be useful for visualizing knee osteoarthritis is the Rosenberg view.

A panoramic X-ray of the lower limbs with weight-bearing is also often requested so that the axis of the limb can be assessed and bone cuts can be planned.

Since patients with osteoarthritis are often elderly, it is important that a careful general clinical evaluation be performed. Therefore, it is common for the orthopedic doctor to request a preoperative evaluation by the patient's general practitioner and also other general tests, such as blood tests, electrocardiogram, chest X-ray, urine test, among others.

What is the surgery like?

The surgery is performed in a hospital setting and admission is usually 3 to 4 hours before the scheduled time for the procedure.

The patient must bring everything the doctor has requested to the hospital, which usually includes:

Personal identification documents;
Health insurance document;
Related tests;
7/8 medical compression stockings;
4-leg walker.

The type of anesthesia used is chosen by the orthopedic doctor and the anesthesiologist. Usually, spinal anesthesia is used.

To perform total arthroplasty, an incision is made in the center of the knee. From there, the doctor reaches the joint and bone cuts are made in both the femur and the tibia, through which the worn part of the joint is removed.

After the bone resection, metal components are placed in the femur and tibia. To facilitate the sliding of the joint, a polyethylene component is fixed to the tibial metal base.

The patellar component may or may not be used, depending on the surgeon's choice and the intraoperative conditions.

What happens after the surgery?

Once the procedure is complete, the patient is taken to the anesthesia recovery area, which is located inside the surgical center. After a few hours, if everything is fine, the patient is sent to the room. It is worth noting that the patient may often spend the first day after surgery in the ICU, so a closer monitoring can be carried out.

Rehabilitation with physiotherapy begins in the first hours after the procedure, when the operated limb begins to be manipulated.

On the first day after surgery, if the patient is comfortable, the team can help him or her to stand up and even take a few steps with the help of a walker.

In some situations, the doctor may choose to leave a drain in the joint, which is usually removed 24 to 48 hours after surgery.

When the patient is clinically well, with the pain under control and has already started walking training with physiotherapy, hospital discharge can be considered.

Once at home, the patient must change the dressings as per medical advice, continue rehabilitation with physiotherapy and take medications as prescribed by the doctor.

The stitches are usually removed approximately 3 weeks after surgery, in the doctor's office.

Results and risks

The outcomes after total knee arthroplasty surgery are generally very satisfactory, with an improvement in joint function, pain and, most importantly, the quality of life of patients.

However, although rare, some risks are related to the procedure, such as:

Joint stiffness;
Residual pain;
Venous thromboembolism;
Infection;
Prosthesis loosening;
Blood loss.

The durability of the prosthesis varies, since there are several factors involved, such as patient demand, age, activity level, etc. However, prostheses generally last around 15 to 20 years.