Knee Replacement Surgery - Understanding the Procedure

Knee replacement surgery, also known as arthroplasty, is a surgical procedure where portions of the bones that form the knee joint are removed and replaced with artificial implants. This procedure is primarily performed to relieve knee pain and stiffness caused by osteoarthritis.

Types of Knee Replacement Surgery

There are two main types of knee arthroplasty surgery:

  • Total Knee Replacement: In this procedure, the entire knee joint is replaced with artificial surfaces. This is the more common of the two procedures.
  • Partial Knee Replacement: In this procedure, only one damaged compartment of the knee is replaced. This is also known as a unicompartmental replacement and is usually recommended for younger adults with symptoms in only one section of the knee.

Understanding Knee Replacement

The knee joint has three compartments or sections: inside (medial), outside (lateral), and under the kneecap (patellofemoral/anterior). Partial knee arthroplasty fixes a single section, whereas total knee replacement addresses all three sections. Partial knee replacement is generally recommended for patients who have symptoms in only one section of the knee and are not suitable candidates for total knee arthroplasty.

Knee Replacement

Materials Used in Knee Arthroplasty Implants

The selection of knee arthroplasty prosthesis design and materials depends on each individual patient. The main implant components are typically made of metal, such as titanium or chrome-cobalt alloys. These implants are fixated in place either with a cement bonding agent or by osseointegration, in which a porous metal stem extends into the tibia and the patient's natural bone grows into it. A plastic platform or spacer made of polyethene is inserted between the tibial and femoral implant surfaces. The femoral components can be made of metal alloys (cobalt chromium) or metal-ceramic alloys (oxidized zirconium), while the patellar component is typically plastic (polyethene) and the tibial insert component is also plastic (polyethene) or made of materials such as cobalt chromium, titanium, or polyethene.

Can Knee Replacement be Avoided or Postponed?

The decision to undergo knee replacement surgery depends on various factors, including the condition of the knee joint and the patient's age and activity level. In cases where the damage from arthritis is minimal or the patient does not have a very active lifestyle, nonsurgical treatments may be tried first, including physical therapy, nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, weight loss to reduce pressure on the knees, and Visco supplements.

Indications for Knee Replacement Surgery

You may need knee arthroplasty surgery if you experience the following:

  1. Stiff and swollen knees
  2. Pain throughout the day, even at rest
  3. Difficulty and pain while walking, getting up, or climbing stairs
  4. Inadequate relief from medication and therapy
  5. Severe damage to knee cartilage results in "bone on bone" contact, where the bones of the joint scrape together.

Longevity of Knee Replacement Implants

Knee arthroplasty implants are designed to function for at least 15 to 20 years in 85% to 90% of patients. However, it's important to note that the implants do not last forever and may require revision surgery in the future.

Knee replacement surgery requires an inpatient stay, typically one to two nights after the surgery. As with any surgery, knee arthroplasty surgery carries risks, including infection, blood clots in the leg vein or lungs, heart attack, stroke, and nerve damage.