Oral L. Weldon, 77, was on her way to a volunteer job at the Arlington Courthouse early this year when a gust of wind knocked her to the ground, and she fractured her right hip.

Eleven days later, after surgery that replaced her hip joint with a metal ball, an ambulance carried Weldon from Arlington Hospital to the North Arlington house where she lives alone.

Weldon says she was in no shape to go home. "I could barely shuffle. And nobody comes to my house at all; at my age, all my friends have either died or moved to Florida."

Weldon, who eventually went to a nursing home, contends that a new pricing policy for Medicare, which sets fixed amounts of reimbursement for various illnesses, is the reason she was discharged from the hospital.

Arlington Hospital officials and Weldon's doctor vigorously dispute her claim, saying she was medically ready to leave and that they believed a friend would stay with her. "Medical practice goes on as usual whether the payment system is the old system or the new system," said Ruth McGoff, director of social services at the hospital.

Many doctors and health experts say, however, that medical practice is not proceeding "as usual" under the new Medicare program, known as the Prospective Payment System (PPS). They say there is ample evidence that hospitals, eager to profit on Medicare reimbursements, are sending some elderly patients home too soon. Patients discharged prematurely, they warn, may be sicker in the long run, defeating the cost-saving measures by requiring more medical resources later.

Local hospital officials, while worried about losses they foresee as a result of the pricing system, which began in some hospitals in October 1983, maintain they are not sending patients home too quickly in an effort to make money.

The effects of the new system are evident in other health care industries. Home health care agencies say their business is booming and several area nursing home administrators say that patients are arriving sooner -- and sicker -- than before.

"We're seeing sicker patients . . . it's a very frustrating problem," said Harley Tabak, administrator of Annaburg Manor Nursing Home in Prince William County.

Tabak said his staff is now treating more cancer patients, stroke patients and patients who still need intravenous feeding or have breathing tubes in their tracheas than they did previously.

"Patients have come to us sicker than before," agreed Tom Jenkins, administrator of the Manor Care Nursing Center in Arlington. "Two years ago, they would still have been in the hospital."

Doctors, health experts and advocates for the elderly have expressed concern about the new pricing for Medicare, the federal health care program for the elderly, since the system began.

Sen. John Heinz (R-Pa.), chairman of the Senate Special Committee on Aging, warned earlier this year that under the system, patients are being discharged "quicker and sicker, and some may even be discharged prematurely."

Several recent studies, the first to measure the program's impact, support their fears that the cost-cutting measures have affected medical care for the worse.

In a study by the American Medical Association, 63 percent of responding physicians stated that quality of care had deteriorated or that it would deteriorate over time if the system continued.

Proponents say there is no concrete evidence -- such as an increased mortality rate -- to indicate that medical care has worsened. "I know that's been said, but on the basis of our monitoring, we have not seen any evidence of the quality of care going down," said John Kittrell, spokesman for the Health Care Financing Administration in the Department of Health and Human Services.

The new pricing system was designed to curb the soaring costs of Medicare, the largest of the government's health programs.

In the past, hospitals were reimbursed for all costs of "reasonable" care. Under the new plan, implemented in 5,405 hospitals by September 1984, patients are sorted into 468 "diagnostic related groups," or DRGs. For each group in each part of the country there is a fixed reimbursement rate, an amount the hospital receives no matter how much the patient's care actually costs.

Hospitals in Maryland, New York, New Jersey and Massachusetts were exempt because their states already set hospital budgets or rates for all patients.

DRGs, dryly translated by one Northern Virginia nursing home administrator as "de revenue's gone," give hospitals an incentive to keep stays for Medicare patients shorter and costs low.

Technically, the new rules do not set absolute limits on the time a patient can remain in the hospital. But the reimbursement rates are based on the cost of treating an average patient, and average lengths of stay are published for each group of illnesses.

"Most hospitals are not taking those numbers as gospel," said Mary McTernan, DRG coordinator for Pennsylvania Hospital in Phildelphia.

Joseph F. Boyle, president of the AMA, said some hospitals may be turning the average lengths of stay into absolutes. "There are suggestions that the average lengths of stay for patients are interpreted as a maximum length of stay. Then the pressure really begins . . . it does become a maximum as far as that institution is concerned," he said.

A General Accounting Office report, based in part on visits to six hospitals and nursing facilities around the country, noted that "some patients are being told, improperly, that they have to leave the hospital because their Medicare coverage has run out."

According to Health Care Financing Administration statistics, Medicare patients' average length of stay has dropped since prospective pricing started.

From October 1983 to July 1984, the average length of stay for Medicare patients in all short-stay hospitals was 8.7 days, down slightly from 9.4 days during the same period the previous year. But for hospitals on the new pricing program, the length of stay from October 1983 to August 1984 was 7.5 days.

Some of the patients leaving hospitals earlier end up in nursing homes. "Because of our affiliation [with Prince William Hospital] we are trying to do everything we can to help the hospital discharge the patients as quickly as possible so the hospital will not suffer significant financial losses," said Tabak of the Annaburg Nursing Home. "That puts pressure on us because it means we are seeing patients we didn't see before."

A survey sent to state nursing home ombudsmen by the House Select Committee on Aging echoes Tabak's observations. More than 71 percent of those responding said "more or many more" people need skilled nursing care since the program began. In addition, 77 percent said patients are being discharged sicker than they were under the old system.

Other patients, discharged while they still need nurses to check their blood pressure or administer medication, have swelled the demand for home health care.

Kathy Williams, administrator of Medical Personnel Pool in Alexandria, says her caseload has more than doubled, from 25 patients to about 55, in the last six months.

"I think, in the past, a hospital might have kept some patients, even if they didn't need to be there, as a kindness, as a convenience. But society is saying, 'we can't afford to pay for that anymore,' " said McTernan of Pennsylvania Hospital.

Some hospital and nursing home officials said the program will not ultimately shave the cost of health care, but will merely shift the burden to local governments, individual patients, or Medicaid, the federal health program for the indigent.

Several local hospital officials said their hospitals fared well financially under the first year of the program, when 75 percent of the reimbursement was based on a hospital's historical cost of treatment.

But they foresee large losses by the time the system is fully implemented in 1987, when prices will be based entirely on national averages.

Robert Johnson, executive director of D.C. General Hospital, noted that the financial squeeze will be worst for urban hospitals that treat many low-income patients who may lack adequate family support or have drug or alcohol problems that complicate their illnesses. Under current rules, Johnson said, D.C. General could lose $1.1 million by fiscal year 1986 and $1.8 million the next year.

Hospital officials in Chicago, Cleveland, Minneapolis, Philadelphia and D.C. estimated that by 1987, under current PPS rules, they would lose an average of $1,000 per Medicare case. "It is a big-city problem," said Jack Ashby of the D.C. Hospital Association.

"In general, I think prospective pricing is an appropriate way of reimbursing hospitals," said Johnson. "But . . . every Medicare patient is not the same. There is a difference between basically well, elderly patients in middle America and many elderly poor in urban America."

AMA President Boyle said the problems with the new system were inevitable. The system, he argued, was launched "using theoretical models generated from reams of mathematical data that had not really been tested in a clinical setting."

While most physicians, hospital officials and taxpayers would agree that health care costs should not escalate out of control, they worry that too much emphasis on the bottom line will be dangerous.

"If cost alone becomes the factor that drives the system," Boyle said, "then it will be bad for the quality of care we will have in the future."