The auto industry's efforts to rein in employee health costs is drawing an expensive reaction, as union workers and their spouses hurry to Michigan doctors for knee replacements and other elective procedures before they lose their comprehensive medical benefits. 

Hospitals, doctors and insurers have all noticed a surge in demand for elective surgery since last year when Rick Wagoner, the chief executive of General Motors, led a public relations campaign to prepare auto workers for health care cutbacks, and Delphi, the G.M. parts supplier, filed for bankruptcy protection. Hip, knee and shoulder replacements at the Henry Ford Health System were "up 20 percent in the second half of last year and remain strong," said Robert Riney, chief operating officer of the system, the largest hospital group in the Detroit area.

"In the last six months, we've noticed a significant increase in people seeking elective surgical procedures in anticipation that they might be losing their health benefits," Mr. Riney said. He would not say how much his health system was billing the auto industry because of the last-minute rush to have elective procedures performed. 

Among smaller medical systems, the William Beaumont Hospital in suburban Royal Oak, Mich., said it had had several hundred more surgical operations of all types since Jan. 1, compared with the same period in 2005.

Mickolynn Schacher is among those determined to take advantage of generous health benefits while she can. Fearing that her husband, Ronald, an electrician at Delphi, may soon lose his health coverage, Mrs. Schacher, 56, is rushing to have artificial knees implanted while he still has full benefits under his United Automobile Workers union contract. 

"I had my right knee replaced Jan. 31 and scheduled my left knee for June 12," Ms. Schacher said. "I'm trying to get them both in before my husband retires or whatever happens." The combined cost, at McLaren Regional Medical Center in Flint, Mich., will be about $28,000. 

Her husband's company is seeking approval for drastic cuts in wages and benefits, in a three-way negotiation with the auto workers' union, General Motors and a bankruptcy judge. 

Meanwhile, under an agreement with the union in December, G.M. and Ford retirees will start paying monthly health care premiums, annual deductibles and co-payments for some services. Whether current workers take buyout packages and in many cases voluntarily give up health benefits, or hang on and risk eventually losing jobs and benefits anyway, there are no guarantees. 

"It's like a roulette wheel you bet on in Las Vegas," said Uwe E. Reinhardt, a health economist at Princeton University. "It's an agonizing decision."

General Motors is offering $140,000 to hourly employees with 10 years of service who agree to drop their health care benefits. Ford has offered $100,000 in a similar deal to workers in several of its plants. Analysts said that, depending on the worker's age, the General Motors offer might cover only about half of future health care costs for typical workers, assuming they did not find another job with at least some medical coverage.

Company and union officials have been holding meetings at 85 G.M. plants. Richard Shoemaker, a U.A.W. vice president, said workers were being told, "If you don't have a spouse that has health insurance or is covered some other way, you need to think long and hard about taking the buyout."

He added, "You can go through $140,000 with amazing quickness." 

Thus the rush to get expensive elective procedures completed while someone else is picking up most of the bill. 

Blue Cross Blue Shield of Michigan, which insures 4.7 million people, including thousands of auto workers, pays from $13,000 to $15,000 for knee or hip surgery to hospitals, on average, and typically $1,800 to $3,300 to doctors, said Helen Stojic, a Michigan Blue Cross spokeswoman. Hospitals typically receive $10,000 for shoulder surgery, while doctors' fees average $1,400.

Ms. Schacher's surgeon, Dr. Sidney N. Martin at Family Orthopedics in Flint, has seen a steady stream of patients with problems in his specialties: shoulders and knees. "We live in an area that is heavily penetrated with the sort of cradle-to-grave kind of health care that G.M. used to give people," he said "The concern they have is 'What's going to happen to me down the road?' " 

Mrs. Schacher's husband has been at Delphi for 31 years, 24 of those at General Motors before G.M. spun off Delphi as a separate company in 1999. "We're hoping that if he retires he will still have some insurance," she said. "It's more than likely we will pay much more than now."