This article is intended for primary care clinicians, orthopaedists, radiologists, and other specialists who care for patients with knee pain.
The goal of this activity is to provide medical news to primary care clinicians and other healthcare professionals in order to enhance patient care.
Upon completion of this activity, participants will be able to:
As an organization accredited by the ACCME, Medscape, LLC, requires everyone who is in a position to control the content of an education activity to disclose all relevant financial relationships with any commercial interest. The ACCME defines "relevant financial relationships" as financial relationships in any amount, occurring within the past 12 months, including financial relationships of a spouse or life partner, that could create a conflict of interest.
Medscape, LLC, encourages Authors to identify investigational products or off-label uses of products regulated by the US Food and Drug Administration, at first mention and where appropriate in the content.
Medscape, LLC is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to provide continuing medical education for physicians.
Medscape, LLC designates this enduring material for a maximum of 0.25
AMA PRA Category 1 Credit(s)™
. Physicians should claim only credit commensurate with the extent of their participation in the activity.
This enduring material activity, Medscape Education Clinical Briefs, has been reviewed and is acceptable for up to 300 Prescribed credits by the American Academy of Family Physicians. AAFP accreditation begins September 1, 2011. Term of approval is for 1 year from this date. Each Clinical Brief is approved for .25 Prescribed credits. Credit may be claimed for 1 year from the date of each Clinical Brief. Physicians should claim only the credit commensurate with the extent of their participation in the activity.
Note: Total credit is subject to change based on topic selection and article length.
Medscape, LLC staff have disclosed that they have no relevant financial relationships.
AAFP Accreditation Questions
For questions regarding the content of this activity, contact the accredited provider for this CME/CE activity noted above. For technical assistance, contact [email protected]
There are no fees for participating in or receiving credit for this online educational activity. For information on applicability
and acceptance of continuing education credit for this activity, please consult your professional licensing board.
This activity is designed to be completed within the time designated on the title page; physicians should claim only those
credits that reflect the time actually spent in the activity. To successfully earn credit, participants must complete the
activity online during the valid credit period that is noted on the title page. To receive AMA PRA Category 1 Credit™, you must receive a minimum score of 70% on the post-test.
Follow these steps to earn CME/CE credit*:
You may now view or print the certificate from your CME/CE Tracker. You may print the certificate but you cannot alter it.
Credits will be tallied in your CME/CE Tracker and archived for 6 years; at any point within this time period you can print
out the tally as well as the certificates by accessing "Edit Your Profile" at the top of your Medscape homepage.
*The credit that you receive is based on your user profile.
CME Released: 12/20/2011
Valid for credit through: 12/20/2012
processing....
According to the current study by Nguyen and colleagues, frequent knee pain affects 25% of adults, and osteoarthritis is the most common cause of knee pain in adults 50 years and older. In recent years, the rate of knee replacements has surged. Rates have tripled in women in the United Kingdom and have increased 8 times in the United States among those 65 years and older.
This study of data from the National Health and Nutrition Examination Surveys (NHANES) and the Framingham Osteoarthritis (FOA) cohorts examines the changing prevalence of knee pain and knee osteoarthritis as time progresses.
The prevalence of knee pain and knee replacement surgeries has risen substantially during the last 20 years. However, the reasons for the increase remain obscure, according to a study published in the December issue of the Annals of Internal Medicine.
"A recent surge in knee replacements is assumed to be due to aging and increased obesity of the U.S. population," write Uyen-Sa D.T. Nguyen, DSc, Clinical Epidemiology Research & Training Unit, Boston University School of Medicine, and Brigham and Women’s Hospital, Boston, Massachusetts, and colleagues. However, the team's analysis suggest the rise in knee surgeries may be linked more to increasing knee pain or an increased awareness of knee pain.
"Using data from 2 community-based studies, we found that the age- and [body mass index (BMI)-]adjusted prevalence of knee pain over 20 years has increased for non-Hispanic white and Mexican American men and women and African American women," the authors write. "Adjustment for age did not substantially alter the prevalence estimate for knee pain or symptomatic knee osteoarthritis over time, whereas additional adjustment for BMI resulted in a 10% to 25% decrease in prevalence ratios."
To understand what is driving the increase in total knee replacements, Dr. Nguyen and colleagues evaluated results from 6 NHANES studies conducted between 1971 and 2004, and from 3 examination periods in the FOA Study carried out between 1983 and 2005.
"We examined whether a change in the prevalence of knee pain and symptomatic knee osteoarthritis could be attributed to age, [BMI], or radiographic knee osteoarthritis," the researchers write.
Participants in the NHANES surveys were white or black and were aged 60 to 74 years. More than 6900 people were included in that study. Participants in the FOA Study were predominately white and at least 70 years old. The number of people evaluated in the FOA Study were 902, 1132, and 671 from the 3 exam periods, respectively.
Participants in both studies were asked whether they experienced knee pain most days. In addition, participants in the FOA Study underwent bilateral weight-bearing radiographs of their knees to assess the presence and extent of osteoarthritis. Radiographs were combined with self-reported knee pain to define symptomatic knee osteoarthritis.
The researchers found that from 1974 to 1994, several ethnic groups in the NHANES study, namely, non-Hispanic white and Mexican-American men and women and black women, experienced a 65% increase in age- and BMI-adjusted knee pain.
Among FOA participants, the prevalence of age- and BMI-adjusted knee pain and symptomatic osteoarthritis approximately doubled in 20 years among women, and tripled among men.
"These increases may explain the surge in knee replacement surgeries and suggest a bigger burden of knee pain in our society than previously thought," they write.
Remarkably, the researchers saw no such trend among FOA participants in terms of the prevalence of radiographic evidence of osteoarthritis. "[T]he age- and BMI-adjusted prevalence of radiographic knee osteoarthritis did not substantially change over this same period for men (P for trend = 0.82) and actually may have decreased for women (P for trend = 0.036)," the authors write.
They conclude that even though the prevalence of knee pain, independent of increasing age and rates of obesity, has risen during the last 20 years, obesity accounted for only part of the increase.
In an accompanying editorial, Allan Gelber, MD, MPH, PhD, from Johns Hopkins University School of Medicine in Baltimore, Maryland, comments, "These findings call both the health services researcher and the treating clinician alike to action."
He adds, "This reality compels the treating physician to carefully consider, from the signs and symptoms of the patient presenting with knee pain, a broad differential diagnosis. Not all knee pain in middle-aged and older adults is the result of osteoarthritis."
The study was supported by the National Institutes of Health and an American College of Rheumatology Research and Education Foundation Rheumatology Scientist Development Award. The Framingham Heart Study was funded by the National Heart, Lung, and Blood Institute, and the FOA Study was funded by the National Institute on Aging and National Institute of Arthritis and Musculoskeletal and Skin Diseases. The authors and Dr. Gelber have disclosed no relevant financial relationships.
Ann Intern Med. 2011;155:725-732. Article abstract, Editorial