Eight out of 10 people with knee osteoarthritis are over 60. As the number of older adults increases, that of patients with “knee osteoarthritis,” a degenerative disease, is also steadily increasing. Accordingly, related medical expenses are also rising.

On Thursday, the National Health Insurance Service (NHIS) released the analysis results of the health insurance treatment status of patients with knee osteoarthritis from 2018 to 2022 using health insurance treatment data.

The number of people treated for knee osteoarthritis increased 6.7 percent from 2,874,179 in 2018 to 3,056,603 in 2022, with an average annual growth rate of 1.6 percent.

While more women than men were treated due to knee osteoarthritis, the number of treated patients was greater among men.

The number of female patients increased by 4.2 percent over five years, from 201,078 in 2018 to 209,638 in 2022, while the number of male patients increased by 12.4 percent, from 861,101 to 966,965, over the same period.

"In the case of degenerative knee osteoarthritis, women with weaker muscle strength are more prone to arthritis than men," said Park Sang-hoon, a professor of orthopedic surgery at NHIS Ilsan Hospital, explaining why there are far more female patients with knee osteoarthritis. "Osteoporosis in women that occurs after age 50 also has a significant impact."

In 2022, more than 90 percent of all knee osteoarthritis patients were older adults and those aged 50 and older. People in their 60s accounted for the largest share with 35.3 percent, followed by 26.8 percent in their 70s, 13.1 percent in their 80s and older, and 16.9 percent in their 50s.

The number of patients treated for knee osteoarthritis per 100,000 people was 5,963, a 6.0 percent increase from 2018. Those in their 70s accounted for 22,722, followed by those aged 80 or older, with 19,531, and those in their 60s, with 14,942.

Health insurance medical expenses for patients with knee osteoarthritis amounted to 1.88 trillion won ($1.42 billion) last year, an increase of 24.9 percent from 2018, with the average annual increase rate reaching 5.7 percent. Medical expenses per patient were 616,447 won, up 17.1 percent. Those in their 70s spent the most, with 854,000 won.