Factors That Influence Total Joint Surgery Success
Scientists continue to look for the best ways to help decide whether and when to undergo joint replacement surgery.
Total joint replacement (TJR), also called total joint arthroplasty, is booming in popularity, but doctors and patients are still trying to understand which patients with arthritis benefit most – as well as the best timing for these major surgeries.
The number of total knee replacements (TKR) more than tripled and the number of total hip replacements more than doubled between 1993 and 2009, according to a study published in 2014 in the Journal of Bone and Joint Surgery. And some of those surgeries may be happening too early in patients’ course of arthritis.
A 2014 study published in Arthritis & Rheumatism, for example, found that, according to the criteria used most often in the United States to help doctors decide whether a patient is ready for TKR, a full third of the procedures are “inappropriate.” Most often the factor driving the “inappropriate” determination was TKR done in people whose joint damage from osteoarthritis (OA) was classified as mild or moderate rather than severe.
But those criteria, developed in the late 1990s when both implants and surgical techniques were less successful than they are now, are outdated, says Jeffrey Katz, MD, professor of medicine and orthopedic surgery at Harvard Medical School in Boston.
“Total knee replacement is safer now, and more effective,” he says, noting this doesn’t make the decision clear-cut for doctors or patients. “Having the operation when one has a better level of preoperative function will generally lead to a better level of postoperative function. On the other hand, the implant may eventually wear out, so the earlier one has surgery the greater the risk that implant will fail and need to be [replaced] in the patient’s lifetime.”
In addition, having less severe joint damage as seen on X-ray, which often do not match people’s pain and mobility levels, was linked to worse outcomes in function a year after TKR compared with people with more advanced joint damage, according to a 2014 study published in The Bone & Joint Journal.
“People have to have something to gain to get benefits,” says Allen Riis, the study’s lead author and a scientist studying musculoskeletal disease at Research Unit for General Practice in Aalborg, Denmark. “For some people, it may be better to wait a little and try to control symptoms through other methods, including exercise, which improves pain and function. Most Danish patients with arthritis are prescribed an exercise program when they are diagnosed with OA.”
The decisions to wait or pull the TJR trigger is complex, says Dr. Katz, and must be highly individualized. “People need to ask themselves a lot of questions,” he says. “For example, how much do they fear complications? Value a higher level of function? Will they be healthy enough to have surgery in two years if they decide to defer?”
Who Benefits Most From TJR?
A study published in Arthritis & Rheumatism in 2013 may help determine which arthritis patients benefit most. Among the factors that made a difference in having a better outcome:
- high levels of pre-surgical pain
- only one “troublesome” hip or knee
- better overall health (no other health conditions)
- joint damage caused by OA as opposed to inflammatory types of arthritis
With so many people opting for TJR, “We want to make sure people have a good understanding of what this procedure is for and what it is likely to deliver,” says lead author Gillian A. Hawker, MD, the physician-in-chief of the department of medicine at Women’s College Hospital in Ontario, Canada.
The researchers followed 202 patients in Canada who had difficulty with such tasks as climbing stairs and rising from chairs, and also had “troublesome” hip or knee joints. Researchers assessed their pain and mobility before and after undergoing TJR (133 knee and 69 hip replacements).
Most patients, 93 percent, had OA and 7 percent had inflammatory arthritis, such as rheumatoid arthritis. About 83 percent had at least two “troublesome” joints (and one-third reported three or more); nearly 57 percent said they had persistent back pain; more than one-third were obese. Only 30 percent reported having no other health problems.
More than half (53.5 percent) of the participants reported “good” outcomes – defined as a clinically important improvement in pain and disability – following surgery. That number is far less than the 80 to 90 percent often touted, the researchers say.
Patients with the most pain and mobility limitations prior to surgery reported the greatest overall improvement, says Dr. Hawker, who notes the relatively low percentage of patients who experienced good results makes sense.
In people with other health problems, especially additional troublesome joints, “when you replace one joint it doesn’t result in resolution of all of your problems,” she says.