Tell someone you're getting a $500 "knee job" and they might think you've got some kind of kinky habit. They might not realize you were just keeping up with the latest fashions.

As hemlines go up, up, up, so are requests for special knee-shaping operations at the offices of cosmetic surgeons.

Females who are acutely fashion-minded but lack patellas cute enough to warrant blowing a week's salary on a new Ungaro gold lame' miniskirt are contacting doctors specializing in liposuction (fat suction). In this medical procedure, fatty tissue is sucked out of the body through a cannula, a long thin plastic tube attached to a vacuum machine.

Housewives, executives, and even body-perfect models are opting for the procedure. Knee jobs and thigh lifts are the rage among European fashion models, says New York model Sharon Summerall. "The pressure to look good is so tough," says Summerall. "Skirts are so short now they just barely cover you. Everything shows when those tungsten lights flash in the studio. A lot of the girls think the surgery will be good for their jobs."

Most of the fashion designers are focusing on shorter skirts, including Yves Saint Laurent, Bruce Oldfield, Rifat Ozbek, and Katharine Hamnett. Dallas designer Michael Ballas, whose fall collection includes skirts as short as 17 inches, says he's heard of several models (none of whom would admit it) who've had their knees and thighs "sculpted" to accommodate the scantier fashions.

No one, it seems, wants to be caught with her hems down in the coming months. But revealing one's knees, no matter how much Jane Fonda-ing one's been doing, can be traumatic, these women say if those stubborn little pockets of cellulite make one's knees look more like canned hams on dowel rods than just charmingly dimpled little punctuation points on beautifully slim gams.

"I've had cellulite since the age of 10, and, even after running five miles a day, there was nothing I could do about the size of my legs," says Sharon Vannucci, 39, assistant director, Research and Development (laboratory operations), U.S. Army Corps of Engineers. The Alexandria resident had her knees done along with her hips and thighs. "I wanted to do it before I was 40, so my husband gave me the liposuction operation as an anniversary present."

Today, she's thrilled with her "new" legs. "It's easier to buy clothes now. You get tired of wearing A-line skirts your whole life."

Vannucci is one of thousands of women this year who have had the special knee operation. Liposuction is becoming one of the most popular forms of cosmetic surgery. An estimated 150,000 liposuction operations of all kinds -- for protruding abdomens, heavy thighs, hips and fannies -- are performed each year, of which a small percentage (5 percent or about 7,500) are "knee jobs," estimates liposuction surgeon Dr. Lawrence McKnelly.

But "knee jobs" are becoming increasingly popular, says McKnelly, who claims that his Alexandria practice on knees alone, has more than doubled this year, to about 50 operations. "Many women have something like a small hen's egg on the inside of the knee," he says.

It is almost exclusively women who have their knees done, says McKnelly, whose patients are women between the ages of 20 and 50. "Men mostly have love-handles done."

Dallas cosmetic surgeon James H. Fowler says he's seeing an increase, if not an actual rush, in requests for knee-shaping liposuction at his North Dallas Cosmetic Surgery Center. "Many patients are requesting liposuction on their knees and some include knee suctions with regular sculpting liposuction on the legs and buttocks," says Fowler. He says that the operation lasts one to 1 1/2 hours and is regarded as day surgery, with the patient recovering in a few days or weeks, depending on the extent of the liposuction.

Julius Newman, president of the American Academy of Cosmetic Surgeons and founder of the American Society of Liposuction Surgery, Inc., is the Philadelphia surgeon who coined the term "liposuction" back in 1982. Newman, who each week performs 10 to 12 of the procedures, also known as suction lipectomy, says he, too, has seen an increase in the number of women asking for knee and leg contouring.

"If your knees and ankles are fat, liposuction is the answer," says Newman, who is also chairman of the department of cosmetic surgery at Graduate Hospital in Philadelphia. "And if your legs are too skinny, you can fatten them up with fat recycling."

That's right. Fat recycling. That means a doctor can suck up those nasty lumps of lard and replace them wherever you actually need them. Patients are having fat implanted in their faces to fill out wrinkles and funneling it into their knees to change them from knobby to nicely rounded.

"Of all the procedures, liposuction on knees is one of the most gratifying," McKnelly says. "You can see results immediately, there's very little discomfort and the recovery time is rapid."

After the fatty tissue is sucked out through small incisions in the regions that are being sculpted, the patient then wears a girdle or other tight-fitting pressure garment for several days to allow the skin to re-adhere where the fat has been removed.

Because knee jobs require only the small, facial-quality canulas, and therefore use smaller incisions, Fowler says most patients experience only a deep soreness, like a heavy bruise, after the procedure and most return to work and normal activity (though no heavy exercise is allowed) after one day's bed rest.

"It's one of the safest techniques I do," says Newman. "In small areas it's not painful. But if you're having larger areas done, like the buttocks or the tummy, there will be more discomfort."

Liposuction removes fat cells from areas women consider to be "problem" areas, according to McKnelly, which "they can't exercise off."

But experts insist liposuction is not a substitute for dieting and exercise. "It's a contouring technique," says Newman, "and is not to be used for weight loss."

Women may be listening more to fashion than caution.

"As a model, every single day you see incredible bodies, you're surrounded by them and you start to think that perfection is the norm," says Summerall, who has appeared recently in Femme, Italian Vogue and Cosmopolitan. "Every girl is thin and stunning, with perfect breasts and tight bottoms." Although Summerall says she hasn't yet had the surgery done, "As I age and start to drop, I might change my mind."

Elaine Liner is a Dallas writer. Resources

If you're considering having your knees sculpted for the sake of new fashions, (or you just don't like the shape of your knees) it's wise to be cautious in finding a doctor. Check out the qualifications of any doctors who advertise that they perform the liposuction technique.

For information:

American Society of Liposuction Surgeons -- provides printed materials explaining the procedure and a list of certified doctors in your state, (215) 896-6677.

American Academy of Cosmetic Surgeons -- provides a referral list of qualified doctors in your city, (800) 221-9808.

A random survey of half a dozen board-certified cosmetic surgeons around the country reveals that the costs range from $500 for a simple, isolated knee job, to $5,000 for a complete lower-body sculpting including thighs, buttocks and stomach. This price generally includes the surgeon's fee and the cost of the anesthesiologist.