Dear Dr. Gott: Four months ago, I injured my arthritic knee while getting into a car. I thought I had twisted it or strained a ligament because it hurt so much at the time. Four days later, my knee was stiff and I could hardly move it.

At that point, I decided it was time to see my physician, who concluded that I needed a cortisone shot because I probably had fluid on my knee.

She referred me to an orthopaedist for the shot. Unfortunately, it didn't help. I was then referred for physical therapy. After only two sessions, I was told I needed to go back to the orthopaedist.

The physical therapist wouldn't tell me why but called ahead to the doctor and spoke to him directly.

When I got there, I was told I had a Baker's cyst and would need a knee replacement. I was further advised not to rush into the surgery because the cyst might improve to the point where the pain would lessen to a manageable level.

When I went back for physical therapy, I told my therapist (and another who was standing next to her) what I had been told. Both adamantly told me to not to have the surgery.

I continued with the therapy for another three sessions before I was dismissed because my therapist said she couldn't keep taking my money, as I wasn't being helped.

Now I want to know what you think about this situation. Do Baker's cysts appear suddenly, only to disappear over time? Do I really need a knee replacement?

I am an 83-year-old otherwise healthy female.

Reply: A Baker's cyst is an accumulation of joint fluid behind the knee. Most cysts do not cause symptoms, but, occasionally, large cysts may cause discomfort and/or stiffness.

In fact, most cysts are recognised only after they rupture, a process that can cause pain, swelling and bruising.

Baker's cysts can occur in anyone of any age. The most common cause in older people is arthritis.

Your cyst has probably been there for a while but was worsened by further injury.

Treatment is usually aimed at repairing the underlying cause. In your case, that would be the arthritis.

I hope you misunderstood your orthopaedist when he recommended a knee replacement. It is not appropriate therapy to treat a Baker's cyst; knee replacement would certainly help your arthritic knee, however.

Most Baker's cysts disappear on their own, but, depending on the cause and severity, it can take months or perhaps even years for that to happen.

For those that cause severe pain and interfere with normal movement, there are a few treatments available.

The most common is aspiration, in which a physician drains the cyst with a needle and syringe.

Very rarely, it may be necessary to remove the cyst surgically. This is avoided as much as possible because of the risk of damaging surrounding tissue, blood vessels and nerves located behind the knee.

I recommend you get a second opinion and start treating your arthritis, which should help resolve the cyst.

To give you related information, I am sending you a copy of my Health Report "Understanding Osteoarthritis".

Other readers who would like a copy should send a self-addressed, stamped number 10 envelope and $2 to Newsletter, PO Box 167, Wickliffe, Ohio 44092. Be sure mention the title.

Dr. Gott is a retired physician and the author of "Dr. Gott's No Flour, No Sugar Diet" and "Dr. Gott's No Flour, No Sugar Cookbook". Contact him c/o United Media, 200 Madison Avenue, fourth floor, New York, New York 10016.