Researchers from Denmark studied a population of runners and ice hockey players, finding that young athletes commonly experience accumulation of excessive fluid in their sacroiliac joints, most frequently in the posterior lower ilium, or the lowest part of the spine where it connects to the pelvis. Their research was highlighted on Tuesday at the 2017 annual meeting of the American College of Rheumatology (ACR) and the Association of Rheumatology Health Professionals (ARHP).
Ulrich Weber, MD, a researcher at King Christian 10th Hospital for Rheumatic Diseases in Graasten, Denmark, and a lead author of the study, said a better understanding of how such bone marrow edema (BME) develops in healthy, active individuals may improve evaluation of magnetic resonance imaging (MRI) of the same joints in individuals with early axial spondyloarthritis (SpA).
“There is an ongoing debate about what constitutes a ‘positive sacroiliac joint MRI’ in patients with axial SpA,” he said. Although the most common definition is BME on fluid-sensitive MRI sequences, “we lack a data-driven threshold or ‘reference range’ which reliably discriminates patients with SpA from the BME ‘background noise’ in healthy individuals, or from BME seen in patients with mechanical back pain.”
Such “background noise” was the main focus of the study, as the researchers aimed to differentiate between normal variation and disease. The study sample included 20 healthy recreational runners (40% men; mean age = 27.2 years; mean BMI = 22.6) and 22 healthy professional ice hockey players (100% men; mean age = 25.9 years; mean BMI = 25.7). All participants underwent MRI scans of their sacroiliac joints: the runners before and 24 hours after a 6.2 km competitive run, and the hockey players at the end of their competitive season. Three independent, blinded readers assessed the scans for BME.
BME was found in three to four sacroiliac joint quadrants on average. The posterior lower ilium was the most affected region in all of the athletes, followed by the anterior upper sacrum.
“The presence of solely low-grade BME, especially clustered in the posterior lower ilium or anterior upper sacrum, may not be sufficient to confirm axial SpA,” Dr. Weber concluded.