Knee damage increasingly found in younger adults as obesity and sports injuries rise

Knee damage and early structural changes are appearing more often in younger adults, researchers and orthopedic surgeons say, with higher body mass index and increased intensity of youth sports cited as key contributors.

A recent imaging study published in Osteoarthritis and Cartilage by researchers at the University of Oulu in Finland found signs of joint damage by age 30 in a majority of participants, many of whom had no symptoms. The Department of Health and Human Services reported a 240% increase in inpatient knee replacements among patients aged 45 to 64 between 2000 and 2017, and orthopedic surgeons say more people in their 30s and 40s are seeking care for knee problems.

The Finland study imaged 297 mostly asymptomatic participants and detected minor articular cartilage defects—primarily between the kneecap and thigh bone—in more than half of the group. Similar defects in the joint between the shin and thigh bones were found in roughly one-quarter of participants. Small bone spurs appeared in more than half the group. Investigators identified higher body mass index as the main factor associated with these early structural abnormalities.

The findings echo broader public health data: the U.S. Centers for Disease Control and Prevention estimates that more than 40% of U.S. adults are obese. "For patients who are obese and have a high BMI, it's a high load on their joints," said Dr. Ran Schwarzkopf, professor of orthopedic surgery at NYU Grossman School of Medicine. "That's more load constantly on the knees, so there's more wear and tear."

Schwarzkopf, who was not involved in the Finnish study, also pointed to a rise in traumatic knee injuries tied to more intense participation in high school and college sports. He said that in the United States, the intensity and frequency of youth athletic activity contribute to a higher rate of injuries than in some other countries. Some traumatic injuries, even when treated, can leave lasting damage because cartilage does not regenerate fully, he said, and that progressive cartilage loss can lead to osteoarthritis.

In cases where osteoarthritis and cartilage loss progress, knee replacement remains an option clinicians describe as the "ultimate treatment" for end-stage damage. HHS data showing a large increase in inpatient knee replacements for middle-aged adults suggests more patients are reaching that point earlier than in past decades.

Orthopedic specialists recommend several measures to reduce the risk of knee pain and long-term damage. Maintaining a healthy weight is the most important step to reduce load on the joints. Strengthening surrounding muscles, particularly the quadriceps and hamstrings, can provide stability and support. For people in sedentary jobs, clinicians advise incorporating substantial daily activity—about an hour on most days—and taking frequent breaks to stand and walk. Appropriate footwear can help those who spend long hours on their feet.

For those already experiencing knee pain, clinicians recommend seeking orthopedic evaluation. Nonoperative approaches such as physical therapy can restore function and reduce discomfort. When needed, arthroscopic and other less invasive surgical treatments may be considered for younger patients before proceeding to knee replacement, Schwarzkopf said. "We don't want to do knee replacements on people in their late 20s and 30s," he added.

The convergence of higher average body weight and more frequent high-intensity sports injuries appears to be changing the age distribution of knee problems, according to researchers and clinicians. The Finnish study underscores that structural changes can occur without symptoms, suggesting that clinicians and patients may need to pay closer attention to risk factors and early interventions to prevent progressive damage and disability.