Knee Arthroplasty

Has the onset of knee left you or a loved one with questions?

The section below will help you better understand conditions that can cause knee pain and discomfort, and learn about available treatments that can bring relief.


What are some common causes of knee pain?

Painful knee problems can develop slowly over time from degenerative osteoarthritis or Rheumatoid arthritis. Symptoms of joint degeneration can include: a painful sensation of bones rubbing together or ‘catching;’ pain and/or instability while walking or standing; aching or swelling in the knee joint or surrounding tissues. Knee pain can also occur suddenly as a result of unnatural twisting or direct trauma to the knee joint, such as accidents, falls and sports injuries. Both trauma and degeneration can cause tiny portions of bone or cartilage to break off and float around in the knee joint. This becomes problematic when the loose debris interferes with movement and causes pain in or around the joint.

Dislocating the knee cap (patella), a small triangular-shaped bone covering the front of your knee, is another common cause of knee pain. This occurs when patella slips or is forced out of place, usually to the outside of the knee. Another cause, chronic hip or foot pain, may alter the gait in such a way that unduly stresses parts of the knee and refers pain to the joint.


What is osteoarthritis?

Osteoarthritis (OA) is a chronic disease that affects millions of people. It is caused by the breakdown of cartilage or natural cushion at the end of the bones. As cartilage deteriorates, bones begin to rub against one another, causing stiffness, pain and discomfort that limit movement and range of motion. OA occurs most often in the knees, hips and hands. Over time, it can damage ligaments, menisci and muscles, and may create the need for a knee replacement or arthroplasty.


What is Rheumatiod arthritis?

Rheumatoid arthritis (RA) is an autoimmune disease that causes the body’s immune system to attack normal joint tissues, causing painful inflammation stiffness or swelling within the joint lining. The causes of RA are unknown. However, research has shown that genetic factors may predispose certain individuals to the disease, and that external or environmental factors, such as infection, can inexplicably trigger RA symptoms.

After the onset of RA, tendons become inflamed and may tear apart. Swelling can damage or destroy ligaments, joint cartilage and bone. Erosion, pain and deformity may become so severe that a joint replacement becomes necessary to restore the quality of life.


What is osteonecrosis?

Osteonecrosis, sometimes called avascular necrosis, aseptic necrosis or ischemic necrosis, refers to the temporary or permanent loss of blood supply to bone. The lack of blood causes affected portions of the bone to die and collapse. If the affected bone is near a joint, the joint surface can collapse, causing extreme pain and loss of function. Though it can occur in any bone, the ends of the femur, upper arm bone, knee bones, hip bones, shoulders and ankles are most often affected. The American Academy of Orthopedic Surgeons estimates that 10,000 to 20,000 people develop osteonecrosis each year.


What are some non-surgical treatments for knee pain?

The cause and severity of knee pain will determine how doctors treat it. Patients, caregivers and surgeons work closely to develop a treatment plan, which may include a range of non-surgical options, given alone or in combination, including:

  • Rest: reducing or avoiding activities that may irritate the knee joint allows inflammation to subside.
  • Application of ice and heat: to alternately reduce swelling, relax and loosen tissues, and stimulate blood flow to the area.
  • Stretching: stretching muscles and tendons can help relieve some symptoms of knee pain.
  • Anti-inflammatory medication: taken as prescribed, non-steroidal anti-inflammatory medicines (also called NSAIDs) can help reduce pain and swelling in the knee. The most common NSAIDs are ibuprofen and naproxen.
  • Injections: sometimes anti-inflammatory medicines called corticosteroids are injected directly into the knee joint to control pain and inflammation. A lubricating, non-steroid injection may also be given to reduce pain and irritation.
  • Supportive Aids: if walking becomes too painful, or if maintaining balance becomes difficult, doctors may recommend a cane or walker to help restore some stability and reduce the risk of falling.
  • Exercise and physical therapy: because can inactivity can actually worsen some knee conditions, therapeutic exercises such as strength, flexibility and balance training are often prescribed to improve symptoms and accelerate recovery.


What is a total knee replacement?

A total knee replacement, also called knee arthroplasty, is a procedure in which a surgeon removes damaged joint surfaces on the ends of the upper and lower leg bones (femur and tibia) and replaces them with an artificial implant or prosthesis. To provide further pain relief, the patella or knee cap may also be replaced or resurfaced at the same time. Knee replacement is today’s most common joint replacement procedure.


When is knee replacement surgery recommended?

There are several reasons why doctors recommend knee replacement surgery. Those who can benefit the most from knee replacement surgery frequently experience knee pain that:

  • Limits daily life activities, such as walking, bending and going up and down stairs
  • Continues throughout the day and night, or when resting
  • Limits the ability to move or lift the affected knee
  • Remains persistent, even with use of anti-inflammatory drugs, physical therapy, or supportive walking aids

What are some benefits of knee replacement surgery?

For most knee replacement patients, benefits can include: decreased pain, increased mobility, and an overall improvement in the quality of life.


When is a total knee replacement necessary?

A patient’s pain level and degree of disability determine whether knee replacement surgery is required, not age. Doctors typically reserve the procedure for patients whose knee pain is not alleviated by medication, physical therapy, use of supportive aids or other non-surgical treatments.


What is a “minimally invasive” knee replacement?

Minimally invasive knee replacement means that the procedure is performed through fewer and/or smaller incisions. Candidates for a minimally invasive knee replacement are typically younger, healthier and weigh less than patients who undergo a total knee replacement. Because the surgery isn’t as extensive, patients usually experience less pain and tissue trauma.

The hospital stay following a minimally invasive surgery is also shorter, with some patients returning home the next day. Recovery and rehabilitation are also quicker. Some components are the same as those used in a total knee replacement.


How long does knee replacement surgery take?

It takes an experienced surgeon about 60 to 90 minutes to complete a total knee replacement, providing there are no unexpected conditions or complications. The total time from when the patient enters the operating room, receives anesthesia, and returns to the recovery room is usually around 2 hours.


How long will a new knee implant last?

Like all medical devices, orthopedic implants have a limited life expectancy that’s affected by the patient’s body weight, age, activity level, and other factors. This makes it difficult to predict how long a particular implant will last. On average, however, most high-quality knee implants should remain viable for 10 ~ 20 years. The success of knee replacement surgery also depends on how well patients comply with the physician’s instructions during the first few weeks of recovery.


How long before I can resume daily life activities?

As with any surgery, recovery times from a knee replacement vary from patient to patient. Some people can resume some daily life activities in a few weeks, while others may take several months. Adhering to a prescribed exercise and recovery plan helps get patients back into their routine sooner, with few complications.

Upon returning home, patients are advised to stay active and be careful not to overexert. It’s always best to follow the instructions of doctors and physical therapists, but here are some general guidelines that may also be helpful.


Weight-bearing activites

Knee-replacement patients can usually put some weight on the affected leg soon after surgery, using a supportive aid like a cane, walker or crutches. These aids are often used for four to six weeks to help muscles recover and strengthen. Instructions will be given about the use of these devices, and how soon the knee can bear weight without the risk of injury or destabilizing the implant.



Most patients can begin driving an automatic shift car within four to eight weeks following a knee replacement, provided they are no longer taking narcotic pain medication.


Climbing stairs

If possible, stair climbing should be limited until adequate healing has begun. If using stairs is unavoidable, the unaffected leg should step up first, followed by the affected leg. The supportive aid will come up last. To go do down stairs, the process is reversed: place the aid on the lower step first, then the affected leg, then the unaffected leg.


Will I require physical therapy?

Yes. After a knee replacement, physical therapy plays a very important role in recovery and rehabilitation. Providing there are no complications, treatment typically begins soon after surgery, starting with simple, assisted movements and activities. After returning home from the hospital, most people receive therapy several times per week until treatment goals are attained. Some patients are referred to an outpatient physical therapist or rehabilitation hospital. Typically, physical therapists coordinate with the operating surgeon to improve range of motion, strength and weight bearing ability. They also demonstrate safe and proper movement for standing, sitting, climbing stairs and getting in and out of cars.

What activities I should avoid?

During rehabilitation, patients must be careful not to engage in activities that could aggravate or dislocate their newly implanted knee. Pivoting or twisting on the affected leg should be avoided for six to twelve months. But to prevent complications or re-injury, the operating surgeon should confirm the clinically appropriate interval. High-impact sports that involve running or jumping should be avoided. Regular, frequent, low-impact activities, such as walking, swimming, golf, hiking and biking are recommended to restore strength and mobility, and to reduce the risk of dislocation.



Fast facts

Here are some interesting facts about knee replacement surgery from American Academy of Orthopedic Surgeons (AAOS).


  • Knee replacement surgery is one of the most important orthopedic surgical advances of the twentieth century. Approximately 581,000 knee replacements are performed each year in the United States.


  • More than 90 percent of knee replacement patients experience a dramatic reduction of pain, and a significant improvement in performing every day activities.


  • Recommendations for total knee replacements are based on a patient’s pain and disability, not age. Most patients who undergo the procedure are age 60 to 80.


  • The complication rate following total knee replacement is low. Serious complications, such as a knee joint infection, occur in fewer than 2% of patients.



  • The current ten-year survival rate for most modern knee replacement systems ranges from 90% – 95%.

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