Knee osteoarthritis has more than doubled in prevalence since the mid-20th century after occurring at low frequencies since prehistoric times, a study has found.
Researchers from Harvard University and other centers concluded that rising levels of knee osteoarthritis—often considered an inevitable consequence of persons living longer—may be the result of modifiable risk factors, such as high body mass index (BMI), that have become more common in recent years.
Thus, they suggested, knee osteoarthritis may be more preventable than previously thought.
A Study of Skeletal Remains
The researchers studied cadaver-derived skeletal remains to investigate long-term trends in knee osteoarthritis prevalence in the United States and evaluate the effects of longevity and BMI on disease levels by comparing the prevalence among persons who lived in the 19th to early 20th centuries with persons in the late 20th to early 21st centuries. The samples included complete skeletons of persons aged 50 years and older who lived in major urban areas in the United States. They also analyzed knee osteoarthritis in a large sample of archeological skeletons of prehistoric Native American hunter-gatherers and early farmers.
Diagnosis of knee osteoarthritis was based on visual identification of the presence of eburnation on the articular surfaces of the right or left distal femur, proximal tibia, or patella.
Some key findings:
• The prevalence of knee osteoarthritis was 16% in the postindustrial sample but only 6% and 8% in the early industrial and prehistoric samples, respectively.
• The prevalence was 2.1-fold higher in the postindustrial sample than in the early industrial sample after the investigators controlled for age, BMI, and other variables.
• Females were more affected than males. After controlling for sex, knee osteoarthritis prevalence in the postindustrial sample was 2.6 times and 2 times higher than in the early industrial and prehistoric samples, respectively.
• Among postindustrial persons with knee osteoarthritis, 42% had the disease in both knees, a 2.5-fold and 1.4-fold higher proportion than in the prehistoric and early industrial samples, respectively.
Wallace IJ, Worthington S, Felson DT, et al. “Knee osteoarthritis has doubled in prevalence since the mid-20th century.” Proc Natl Acad Sci U S A. Published online before print on August 14, 2017. doi: 10.1073/pnas.1703856114