Knee pain is often linked with aging, but more people in their 30s and 40s are now experiencing this issue.

With a rise in high-intensity sports participation and higher average body mass index (BMI), younger adults are increasingly facing knee problems—some even opting for surgery.

Between 2000 and 2017, inpatient knee replacements for patients ages 45 to 64 increased by 240%, according to the Department of Health and Human Services (HHS).

Early Signs of Knee Damage

A recent study in the journal Osteoarthritis and Cartilage revealed that structural changes in the knee can appear as early as age 30, often before any symptoms develop.

Researchers at Finland’s University of Oulu examined 297 participants, most without symptoms, and found joint damage in more than half. Minor cartilage defects—mainly between the kneecap and thigh bone—were present in over half the group, while a quarter showed defects between the shin and thigh bones. Small bone spurs were also detected in more than half of participants.

The study concluded that higher BMI was the strongest factor linked to these knee changes.

Obesity’s Role in Knee Problems

According to the CDC, more than 40% of U.S. adults are obese. Dr. Ran Schwarzkopf, professor of orthopedic surgery at NYU Grossman School of Medicine, agreed that higher BMI among younger Americans is a key driver of knee issues.