Role of Magnetic Resonance Imaging in Classifying Individuals Who Will Develop Accelerated Radiographic Knee Osteoarthritis

Abstract

We assessed whether adding magnetic resonance (MR)‐based features to a base model of clinically accessible participant characteristics (i.e., serological, radiographic, demographic, symptoms, and physical function) improved classification of adults who developed accelerated radiographic knee osteoarthritis (AKOA) or not over the subsequent 4 years. We conducted a case–control study using radiographs from baseline and the first four annual visits of the osteoarthritis initiative to define groups. Eligible individuals had no radiographic KOA in either knee at baseline (Kellgren–Lawrence [KL] grade <2). We classified two groups matched on sex (i) AKOA: at least one knee developed advanced‐stage KOA (KL = 3 or 4) within 48 months and (ii) did not develop AKOA within 48 months. The MR‐based features were assessments of bone, effusion/synovitis, tendons, ligaments, cartilage, and menisci. All characteristics and MR‐based features were from the baseline visit. Classification and regression tree analyses were performed to determine classification rules and identify statistically important variables. The CART models with and without MR features each explained approximately 40% of the variability. Adding MR‐based features to the model yielded modest improvements in specificity (0.90 vs. 0.82) but lower sensitivity (0.62 vs. 0.70) than the base model. There was consistent evidence that serum glucose, effusion‐synovitis volume, and cruciate ligament degeneration are statistically important variables in classifying individuals who will develop AKOA. We found common MR‐based measures failed to dramatically improve classification. These findings also show a complex interplay among participant characteristics and a need to identify novel characteristics to improve classification. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2420–2428, 2019

Risk factors and the natural history of accelerated knee osteoarthritis: a narrative review

“…Furthermore, we used the CART analyses to explore if MR-based structural findings could help classify people at high risk for AKOA (54 people developed AKOA and 108 sex-matched Osteoarthritis Initiative participants). There is consistent evidence that age, fasting glucose concentrations, and static knee alignment were statistically important clinical factors to consider when classifying people at risk for incident AKOA [11,12]. Effusion-synovitis volume and cruciate ligament degeneration may also be statistically important for classifying people at risk for AKOA over the subsequent 4 years [11]; however, adding data from magnetic resonance imaging (e.g., quantitative effusion-synovitis, cartilage damage, bone marrow lesions; semiquantitative assessments of menisci, tendons, ligaments) failed to improve the ability to classify adults who develop AKOA over the models with only clinical measures (Table 1).…”

“…Similar to typical knee osteoarthritis, older age and body mass index (BMI) are related to AKOA onset [1,9,10]. However, two subgroups are at greater risk for AKOA: 1) individuals < 65 years of age with BMI > 32.5 kg/m 2 and 2) individuals > 65 years of age that were typically overweight or obese with BMI < 35 kg/m 2 (only 27% had BMI < 25 kg/m 2 ) [10][11][12]. Greater age and BMI may contribute to the onset of AKOA through pathways related to hyperglycemia and elevated inflammation.…”

“…Joint symptoms and effusion-synovitis during this early phase coincide with other structural alterations. For example, a possible sign that the joint experiences abnormal biomechanical loading early in the disease process is that degenerative cruciate ligaments [11,15], meniscal pathology [15], and thicker medial femoral cartilage (possibly cartilage swelling) [8] are pathologic features on magnetic resonance imaging that may discriminate people who will develop AKOA over the subsequent 2 to 4 years. These pathologic findings may be caused by abnormal arthrokinematics (e.g., laxity) or contribute to abnormal arthrokinematics that lead to local inflammation.…”

“…Going forward, it will be important to better understand the earliest phases of AKOA to develop strategies to identify people at risk for or with earlystage AKOA. The final clinical+MRI classification tree included body mass index, serum glucose concentrations, effusion-synovitis volume, presence of cruciate ligament degeneration, and coronal tibial slope angle [11] Accelerated knee osteoarthritis within the context of rapidly progressive osteoarthritis and destructive arthropathies…”

“…Both are more common among older adults and may be antedated by certain analgesic medications [45]. Furthermore, people who develop AKOA or rapid progressive osteoarthritis have early evidence of cartilage degradation followed by an extreme rate of articular cartilage loss [8,31,57] and early evidence of inflammation [11,15,16,57]. Finally, 12% of knees that develop AKOA experience attrition or subchondral fractures [8] and 35% of people who develop accelerated hand osteoarthritis develop new central erosions in other hand joints [58].…”