Two studies presented at the American Academy of Orthopaedic Surgeons (AAOS) annual conference this month offer new assurances to younger and older people who are considering a new hip. One study found that many hip replacements implanted in adults younger than 50 are still performing well 35 years later. Another found that undergoing hip replacement surgery at age 90 or older is relatively safe.

Arthritis is the most common cause of hip pain and disability, according to the AAOS, and a new hip can often relieve the problem. Most people who undergo hip replacement surgery are between ages 50 and 80.

Keeping Older Patients Mobile

But doctors are seeing more older patients who might benefit from the surgery. “The number of 90-year-olds has tripled over last 30 years,” says Alexander Miric, MD, assistant chief of orthopaedic surgery at Kaiser Permanente in Los Angeles and lead author of the study on hip implants in older patients. “We thought it would be interesting to see how well patients in their 90s do after hip replacement surgery.”

Past studies of this age group showed high infection and mortality rates, but they involved only a small number of patients, and some studies were decades old, says Dr. Miric. “These numbers didn’t look very encouraging, but in our own personal experience, we saw patients do very well.”

Using Kaiser’s registry of joint replacement patients, started in 2001, Dr. Miric and his colleagues identified 183 patients who were 90 or older at the time of hip replacement surgery. They found that compared to people younger than 80, these patients stayed in the hospital only about half a day longer and were not significantly more likely to develop an infection of the joint. They did have a higher mortality rate within 90 days of the surgery – 2.7 percent versus 0.2 percent – but, says Dr. Miric, “you would expect that in this age group.”