Osteoarthritis of the knee and hip are common conditions that tend to require frequent follow-up, medical therapy, and potentially expensive treatments, such as joint replacement surgery.¹ Nevertheless, relatively little is known about the prevalence of these pathologic conditions in the general population.² Estimating prevalence requires tools that allow investigators to screen a large sample drawn from the general population to identify individuals most likely to have the disease.³ Currently, investigators interested in determining the prevalence of knee or hip osteoarthritis must rely on medical histories, radiographs,^4,5 or descriptions of symptoms.⁶ Given that no single symptom can identify patients with knee or hip osteoarthritis,⁷ the most relevant symptoms are often combined to construct an algorithm that ideally has high specificity and reasonable sensitivity.³ Individuals identified as likely candidates using such screening tools must then undergo clinical examination by an experienced physician and radiography of the joint for a definitive diagnosis to be made.

As life expectancies increase, the rates of hip joint and knee replacement are expected to increase.^1-3 Although these procedures are expensive,^4-6 they also are among the most effective in terms of patient benefits. Substantial variations in the indications for a variety of surgical procedures, including hip joint and knee replacement, have been reported during the last 20 years.^7,8