Half of patients who undergo knee replacement later develop OA
More than half of knees that have no or mild radiographic osteoarthritis prior to knee replacement later go on to develop the disease during the following 4 years, according to findings published in Arthritis Care and Research.
“Rates of knee replacement have more than doubled in the United States from 1999 to 2008,” Frank W. Roemer, MD, of the Boston University School of Medicine, and colleagues wrote. “In the absence of disease modifying OA drugs, further increases in knee replacement volume are projected to continue into the future due to an aging population, the obesity epidemic, the growing prevalence of sports-related knee injuries and other factors. Joint arthroplasty is commonly considered the therapy of choice for advanced symptomatic radiographic OA.”
To determine the progression of knees with no or mild radiographic OA slated to receive knee replacement surgery within 5 years, and to describe the differences in pain levels and damage on MRI between knees with no or mild forms of the disease and patients with severe conditions, the researchers drew from data in the Osteoarthritis Initiative. The initiative is a longitudinal cohort study including 4,796 participants, with the aim of identifying biomarkers associated with the onset and progression of knee OA.
In their study, Roemer and colleagues focused on 181 knees from the cohort that had received replacement surgery from baseline to 60 months. They analyzed MRI data for bone marrow lesions as well as Hoffa- and effusion-synovitis both at baseline and at the time before knee replacement. The researchers used the Western Ontario and McMaster Universities Arthritis Index (WOMAC) and Knee Injury and Osteoarthritis Outcome Score (KOOS) to assess pain. In addition, the WOMAC Activity of Daily Life and KOOS Quality of Life tools were used to determine functional status.
According to the researchers, 28.2% of the included knee had no or mild radiographic OA. Of those, 51% developed severe forms of the disease within 4 years following knee replacement. In addition, compared with those with severe forms of the disease, knees with no or mild radiographic OA demonstrated a greater likelihood for bone marrow lesions in the patellofemoral joint, both at baseline (OR = 7.92; 95% CI, 3.45-18.16) and the time before replacement (OR = 9.44; 95% CI, 4-22.28). Knees with no or mild radiographic OA were also associated with a status change of “no pain” to “pain” from baseline to the time before knee replacement (aOR = 5.48; 95% CI, 1.25-24).
Roemer and colleagues further concluded that bone marrow lesions in the patellofemoral joint were more often reported in knees with no or mild radiographic OA. In addition, worsening pain could contribute to knee replacement in those with no or mild radiographic OA.
“Our study showed that about half of the knees with no/mild tibio-femoral [radiographic OA] at baseline that underwent knee replacement during the observational period progressed to higher-grade tibio-femoral [radiographic OA] closer to the time point of surgery,” Roemer and colleagues wrote. “However, the other half of these knees did not progress to severe tibio-femoral [radiographic OA], but had evidence of patello-femoral [bone marrow lesions], which seemed to play a role in structural disease that ultimately led to knee replacement.” – by Jason Laday
Disclosure: The researchers report funding from a partnership between the NIH and Merck Research Laboratories, Novartis, GlaxoSmithKline and Pfizer. Roemer reports that he is the chief medical officer for, and a shareholder of, Boston Imaging Core Lab. See the fill study for additional researchers’ disclosures.