EXPERT ADVICE: Frequently Asked Questions
Knee replacement (arthroplasty)
Q: I have been experiencing knee pain for several years now, but have not yet had my knee diagnosed. Under what circumstances would I be considered for a knee replacement?
Answered by Joshua Siegel M.D.
A: Generally, knee replacement is reserved for patients over 60 years of age, however, that does not preclude younger patients with severe arthritis from undergoing knee replacement. An orthopedic surgeon will make a diagnosis using x-rays and a clinical examination. The main reason for knee replacement is intractable knee pain with degenerative end-stage arthritis, which has failed all conservative treatments, including anti-inflammatory medications, physical therapy, injections, and a trial of time.
Q: What are the different materials that can be used in joint replacement? Is one better than the other?
Answered by Joshua Siegel M.D.
A: The materials have evolved over the past several years to include high molecular weight polyethylene, a type of plastic that generally articulates with a metal component made out of titanium alloy or stainless steel. In addition, trials involving a metal-on-metal prosthesis and high-density ceramics are currently underway. There have been no documented studies showing that one material is better than another. Generally, the materials currently being used have a lifespan of approximately l5 years.
Q: I have just had a knee replacement. What should my rehabilitation include? Do I need to wear a brace?
Answered by Joshua Siegel M.D.
A: Rehabilitation for knee replacement should stress range of motion from full extension to flexion. One must understand that knee flexion obtained after knee replacement surgery is limited to about ll0-l20 degrees. It is extremely unusual for a patient to regain full range of motion after knee replacement. Braces have no bearing on patients who had total knee replacement, whose ligaments are all intact and who have no evidence of instability.
Q: Is there a certain age that is considered too old for a knee replacement? Can you be too young?
Answered by Joshua Siegel M.D.
A: There are no strict age guidelines. Each patient is taken individually based on his or her activity level and degree of pain. Generally, a patient should have worn out all of his or her conservative treatments, including anti-inflammatories, injectables, and physical therapy prior to undergoing knee replacement. However, one can become too old and too sick to undergo a knee replacement. A knee replacement may not be suitable for people with severe cardiovascular disease, as they may not withstand the stresses of surgery.
Q: What are the alternatives to knee replacement?
Answered by Joshua Siegel M.D.
A: There are many, you should discuss them with your orthopedist. Options include conservative treatment, which entails anti-inflammatory medications, physical therapy, and occasional Cortisone or other injectable materials. In addition, surgical options include arthroscopy for debridement of isolated cartilage damage. Other surgical interventions include high tibial osteotomies, which decrease the weight-bearing through the arthritic side of the joint and place the weight-bearing surface on the healthy side of the joint. Also gaining in popularity are unicompartmental arthroplasties. A unicompartmental knee replacement replaces only half of a knee, this allows the patient to regain a better range of motion, have less pain, and allow them to undergo revision surgery with a total knee arthroplasty later in life. Each one of these indications has very specific parameters. This must be discussed with your health care professional.
Q: What exactly is a unicompartmental knee replacement and should it be used over a total knee replacement?

Answered by Joshua Siegel M.D.
A: Essentially, the unicompartmental knee replacement is a half of a knee replacement. It should be limited for use in individuals who have arthritis in only one compartment of the knee as well as normal stability. Most often this happens to be on the inside portion of the knee secondary to removal of a meniscus in the distant past. Unicompartmental arthroplasties have specific indications including weight restrictions and activity modifications and need to be discussed with your health care professional.
Q: How long will my knee joint last before I experience signs of deterioration?
Answered by Joshua Siegel M.D.
A: This is totally dependent on the amount of use that this joint gets. On average most total knees last l5 years and we seem to see them lasting longer and longer as materials get better. However, a young person in his or her 40s who undergoes a total knee and pounds on it through activities with impact sports can expect to have their knee last for a lot less time than the older sedentary adult.
Q: What type of activities can I participate in after a knee replacement?
Answered by Joshua Siegel M.D.
A: Essentially, one can participate in any activities that do not entail a tremendous amount of pounding over a long period of time. These include: recreational tennis, golf, swimming, walking, bicycle riding, skiing, and other nonimpact activities. Each physician has his or her own opinion on this matter. You must discuss activities with your health care professional.
Q: My husband had a total knee replacement last year and is still experiencing pain when walking for a period of time. Is this a normal side effect of a knee replacement? Do patients experience any typical symptoms after surgery?
Answered by Joshua Siegel M.D.
A: Generally, after six to nine months, a patient with a knee replacement is extremely satisfied and has very little pain. It is not a normal side effect to have pain after knee replacement surgery. The possibilities include; occult joint infection or loosening of the prosthesis, which must be evaluated by your physician. Symptoms that are considered normal after the surgery include a limited range of motion in flexion and, occasionally, some residual thigh weakness in the quadriceps muscle. These are generally pretty rare and total knee replacement has a 95% success rate.
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