A study appearing in the Annals of Internal Medicine seeks to pinpoint the cause behind the increasing prevalence of knee pain and symptomatic knee osteoarthritis. Researchers say the study was designed to determine whether age, obesity, and change in radiographic knee osteoarthritis played a role in the trend.

The cross-sectional study reportedly utilized data from six National Health and Nutrition Examination Surveys (NHANES) between 1971 and 2004. According to researchers, the study also utilized three examination periods in the Framingham Osteoarthritis (FOA) Study between 1983 and 2005. Participants in the NHANES ranged from aged 60 years to aged 74 years. FOA study participants were aged 70 years and younger.

The NHANES participants were reportedly questioned about pain in and around the knee. FOA study participants were also questioned about knee pain and had bilateral weight-bearing anteroposterior knee radiography to define radiographic knee osteoarthritis. 

Researchers say the age- and body mass index- (BMI) adjusted prevalence of knee pain and osteoarthritis conducted during earlier examinations were compared with that of earlier examinations by utilizing the ratio of prevalence estimates. The study’s results indicate a 65% increase in age- and BMI-adjusted prevalence of knee pain among the NHANES non-Hispanic white and Mexican American male and female participants from 1974 to 1994. The FOA study indicated that the age- and BMI-adjusted prevalence of knee pain and symptomatic knee osteoarthritis doubled in female participants and tripled in male participants over 20 years. Additional results, according to researchers, indicated that there was no trend observed in the prevalence of radiographic knee osteoarthritis in FOA study participants.

Researchers acknowledge limitations within the study; yet overall results suggest that the prevalence of knee pain has increased greatly over 20 years, independent of age and BMI. The study adds that obesity accounts for only a portion of this increase. An increase in symptomatic knee osteoarthritis was reported but radiographic knee osteoarthritis did not increase.

Source: Annals of Internal Medicine