For the vast majority of patients with debilitating knee pain, joint replacement surgery is considered an “elective” procedure.

While it’s true that one’s life doesn’t depend on it, what about quality of life? Many people hobbling about on painful knees would hardly regard the surgery as optional. Consider, for example, two people I know: a 56-year-old man passionate about tennis who can no longer run for a bus, let alone on the court, and a 67-year-old otherwise healthy woman with bone-on-bone arthritis who can’t walk without a cane or stand for more than a few minutes.

They have reason to think it may be time to replace their worn-out knees with artificial ones, an operation that is now among the most frequently performed costly medical procedures in the United States. But some leading medical economists are asking whether this surgery is being done too often or too soon on patients who have not adequately explored less invasive approaches to relieve their pain and improve their mobility.

I certainly had done due diligence before opting to have both knees replaced 14 years ago at age 63. I had wanted to wait longer, given that the life expectancy of artificial knees was then 10 to 15 years, and I would have liked Medicare to help foot the bill. I had no weight to lose and had done months of physical therapy that made me stronger but not better. I tried gel injections to no effect, and was living on anti-inflammatory drugs just to get through the day.

Finally, I was no longer willing to sacrifice many necessary and pleasurable activities, like walking to a store or visiting a museum. I couldn’t even stand up during intermission in the theater without searing pain.

To me, knee replacement surgery was a no-brainer. And I’ve had no regrets, even though I can’t kneel with comfort or bend my artificial knees as much as natural ones allowed me to do. But I can walk for miles, climb stairs easily, hike, cycle and swim. And I am happy, after more than six decades with increasingly bowed legs, to be walking on straight ones.

Still, all knee replacements are not equally successful, and some patients are no better off than they were before surgery. In addition, there’s been a steep increase in the rate of total knee replacements in younger people, raising the likelihood that years later they will need repeat procedures that are often more complicated and less beneficial.

To be sure, some surgeons advise younger patients to put off replacement surgery as long as possible because those with a life expectancy of 15 years have a much better chance of avoiding a future operation than those expected to live another 30 years, Dr. Robert H. Shmerling, rheumatologist at Beth Israel Deaconess Medical Center and Harvard Medical School, has reported. Among nearly 55,000 people who had a knee replacement, he noted, 10.3 percent needed revision surgery within 20 years, although the longevity of current knee replacements is likely to be greater thanks to better prosthetic materials and surgical techniques.

About 12 percent of adults in the United States have painful arthritic knees that limit mobility, and each year more than 640,000 have them replaced with artificial joints at a cost well in excess of $10 billion a year. The annual rate of total knee replacements doubled between 2000 and 2015, especially among people ages 45 to 64, many with significantly less severe symptoms than I had.

Now a growing number of experts are asking if all these operations are really necessary, especially those done at younger ages. Are all prospective patients giving lesser remedies a fair trial? How many knee replacements result from unrealistic patient expectations or the subtle influence of monetary gain among surgeons who perform them?

One recent study conducted by Daniel L. Riddle, a physical therapist at Virginia Commonwealth University, and two medical colleagues, for example, examined information from 205 patients who underwent total knee replacements. Fewer than half — 44 percent — fulfilled the criteria for “appropriate,” and 34.3 percent were considered “inappropriate,” with the rest classified as “inconclusive.”

Although patients with less severe pain and loss of function may still benefit from replacement surgery, the researchers suggested that their gains are likely to be smaller. “What this study does show is that the cost associated with these small changes is very high,” Riddle said. “People who are on the very severe end of the spectrum of pain and functional loss have a lot more gain to make.”

In a multicenter study reported last year of 4,498 people with arthritic knees and a second study of 2,907 people with arthritis, improvements in the quality of patients’ lives following knee replacement surgery were less than had been previously reported. Dr. Bart Ferket of the Icahn School of Medicine at Mount Sinai in New York and co-authors stated that those with the worst functional status initially had the most to gain from surgery and made the operation economically more justifiable.

“The key issue is selecting those patients most likely to benefit from surgery,” Ferket said in an interview. “At the moment, this is not optimal. Up to 20 percent of patients are not satisfied with the outcome of surgery.”

Dr. Steven Teutsch of the UCLA Center for Health Advancement said it’s important for “patients to have a clear understanding of the benefits and harms of knee replacement surgery because recovery from it is no picnic.”

A detailed discussion with the doctor should precede a decision about surgery, “and the decision should be a shared one,” Teutsch said.

So what should be tried before deciding to go under the knife? Most important are weight loss (if needed) to reduce stress on arthritic knees and exercises or physical therapy to strengthen the muscles that support these vulnerable joints and improve range of motion. One or more injections of a gel of hyaluronic acid directly into the knee joint to lubricate it can relieve pain in some patients for up to six months. Or injections of corticosteroids, which reduce inflammation, can provide more immediate relief, although these injections cannot be repeated too often lest they further damage the joint.