Hip osteoarthritis (OA) is not always apparent on an x-ray, and new research suggests that x-rays are not a reliable way of diagnosing the condition in the majority of cases.
In a study published in the British Medical Journal, researchers evaluated the diagnostic performance of an x-ray in patients with clinical signs and symptoms of classic OA.
They assessed data from the Framingham Osteoarthritis and Osteoarthritis Initiative studies, which involved nearly 4,500 participants. In the Framingham study, only 16% of patients with hip pain had osteoarthritis that could be detected through radiographic scans, while only 21% of hips with radiographic OA had hip pain. Results of the Osteoarthritis Initiative were similar, with 9% and 24% respectively.
The researchers noted that, in both study populations, hip pain was not present in many patients with radiographic OA, and many with hip pain did not have imaging evidence of hip OA.
This suggests that many cases of hip osteoarthritis might be missed if health professionals rely solely on x-ray scans to determine whether hip pain is due to osteoarthritis.
Missing the diagnosis of hip OA has consequences, according to corresponding author Dr. Chan Kim, instructor of medicine at Boston University School of Medicine, who said that up to 10% of patients with OA do not meet adequate physical activity recommendations and are associated with having higher risk of developing heart or lung disease, diabetes, obesity and falls.
“Given these findings, patients with suspected hip OA should be treated regardless of x-ray confirmation,” Dr. Kim advised.
Dr. Katherine Free, research liaison and communications manager for Arthritis Research UK, added: “Hip pain can occur for a variety of reasons. In many cases, it could be due to a simple strain, but for some people it may be a sign of osteoarthritis. Hip osteoarthritis is a painful and debilitating condition which usually affects people from the late 40s onwards; this study highlights the need for new and improved ways to diagnose this condition.”