Definition and Overview

Total knee arthroplasty is a surgical procedure wherein the knee joint is replaced with an artificial one consisting of plastic and metal parts. It is the most advanced type of knee surgery. While a partial knee arthroplasty is one in which the surgeon only replaces the damaged portion of the knee, in a total replacement surgery, the entire knee is replaced.

The procedure is commonly performed on patients whose knees are severely damaged and can no longer be treated using other means. Such damage to the knee is typically caused by arthritis but is sometimes also due to injury. The procedure is expected to help patients regain the use of their knees and recover their lost mobility as well as provide long-lasting pain relief.

Although it may seem like an invasive procedure, improvements in surgical technology have made the procedure safer and more effective than in the past.

Who Should Undergo and Expected Results

Total knee arthroplasty is highly recommended for patients who suffer from extreme pain and disability due to their damaged knee, and those whose conditions do not improve with the use of non-surgical treatments such as medications and supportive devices.

Knee damage that may result to a need for total knee replacement surgery can be caused by:

  • Osteoarthritis - This is known as the most common reason for knee replacement surgeries in most countries. Osteoarthritis is the most common type of arthritis; it is caused primarily by aging and the normal wear and tear of the joints in the body. In its severe stages, osteoarthritis can cause significant and disabling pain that only total knee arthroplasty can relieve.

  • Rheumatoid arthritis – This is another type of arthritis that occurs when the synovial membrane surrounding the knee joint becomes inflamed, thus causing long-term damage to the cartilage.

  • Injury – A serious knee injury can also cause a special form of arthritis called post-traumatic arthritis. This is a very common complication of knee fractures or torn knee ligaments.

With these conditions, patients may experience the following symptoms:

  • Progressive pain while moving and even at rest

  • Night pain or pain that wakes them up at night

  • Reduced knee function

  • Knee deformity or bowing

  • Reduced mobility

Most patients who are prescribed to undergo arthroscopic knee surgery often have difficulty walking, climbing up and down the stairs, or even sitting down. These symptoms can significantly affect the overall quality of the patient’s life. Once they undergo the procedure, however, patients are expected to be relieved of their pain and regain complete knee motion. As such, they can live normally again but with some limitations in terms of activity level. Patients may be able to walk normally without pain, but may not be able to do certain activities like high-impact sports. For this reason, the procedure is more commonly indicated in older patients whose activities are less physically strenuous.

Nevertheless, patients are advised to exhaust all other conservative treatment options first, such as anti-inflammatory medications and cortisone injections, before they decide to undergo total knee replacement surgery.

How is the Procedure Performed?

Total arthroscopic knee surgery is a major procedure that is performed under regional or general anaesthesia in a hospital operating room. The appropriate type of anaesthesia used depends mainly on the patient’s overall medical condition. This is why all patients undergo a comprehensive physical examination before the surgery. The exam may involve x-rays and other tests such as an MRI scan, which can help determine the actual condition of the bone and soft tissues in the knees. During the exam, the patient’s medical history is also evaluated.

Once the patient is prepped, the surgeon begins the procedure by first making an incision over the knee. He will then cut away the damaged bone and cartilage from the kneecap and from where it is attached to the thigh and shin bones. A small amount of underlying bone is also removed.

Once the whole knee joint is removed, an artificial knee joint is put in its place. It may be press-fit into the bone but is also sometimes cemented into place. Once properly positioned, the surgeon will insert a medical-grade plastic spacer between the metal parts of the knee joint to allow them to glide smoothly.

Surgeons use different types of knee prostheses for the procedure depending on the patient’s age, weight, overall health, and activity level. These prosthetics are made of metal alloys, high-grade plastics, and special polymers. They come in different kinds and designs such as:

  • Fixed bearing

  • Rotating platform and mobile bearing

  • PCL-substituting

  • Medial pivot

So far, the most advanced knee prosthetics are able to roll and glide like a natural knee joint.

A full knee arthroscopy procedure may take around 1 to 2 hours, after which the patient is moved to a recovery room until the effects of the anaesthesia wear off. After the operation, patients are required to undergo extended hospitalization during the initial stages of their recovery. It is normal to experience some post-surgical pain during this period, but patients will be given pain medications and local anaesthetics to help them cope. Special precautions are also taken to prevent blood clots; these include the use of blood thinners and compression stockings.

The surgery is followed by physical therapy to help patients restore their lost knee function and mobility.

Possible Risks and Complications

Total knee replacement surgery, like any other knee operation, comes with certain risks and potential complications. These include:

  • Infection

  • Blood clots

  • Stroke

  • Nerve damage

  • Heart attack

After the procedure, patients are given antibiotics. However, if they suffer from common symptoms of infection, they are advised to consult their doctor. Symptoms of an infection include:

  • High-grade fever higher than 100 degrees

  • Chills

  • Drainage from the surgical wound

  • Increasing pain and swelling

  • Redness and tenderness

For severe infections, the patient will require another surgery to remove the artificial knee and treat the infection first. Once the infection passes, the patient may then undergo another knee replacement procedure.

Aside from the common risks of undergoing surgery, patients who undergo a knee arthroscopy are also at risk of artificial joint failure. This is a complication wherein the artificial joint placed wears out and becomes damaged. Although this may not happen immediately after the operation, patients who have excessive weight or those who subject their artificial knees to high-impact physical activities are considered to be at high risk of joint failure.

References:

  • “Total knee replacement.” OrthoInfo, American Academy of Orthopaedic Surgeons. http://orthoinfo.aaos.org/topic.cfm?topic=a00389

  • Martin GM MD. “Patient education: Total knee replacement (arthroplasty) (Beyond the Basics).” http://www.uptodate.com/contents/total-knee-replacement-arthroplasty-beyond-the-basics

  • Palmer SH. “Total knee arthroplasty.” Medscape. http://emedicine.medscape.com/article/1250275-overview#a2

  • Shiel WC Jr. “Total knee replacement.” MedicineNet. http://www.medicinenet.com/totalkneereplacement/article.htm

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