Description: Background Osteoarthritis (OA), a multifactorial disease causing joint degeneration, often leads to severe disability. The rising rates of disability highlight the need for implementing preventative measures at early stages of the disease, which would especially benefit subjects at high risk for OA development. Purpose To develop a risk prediction tool for moderate-severe OA (TOARP) over 8 years based on subject characteristics, knee radiographs, and MRI data at baseline using data from the Osteoarthritis Initiative (OAI). Study Type Retrospective. Subjects 641 subjects with no/mild radiographic OA (Kellgren–Lawrence [KL] 0–2) and no clinically significant symptoms (Western Ontario and McMaster Universities Arthritis Index [WOMAC] 0–1) were selected from the OAI. Field Strength/Sequence MR images were obtained using 3.0T. Assessment Compartment-specific cartilage and meniscus morphology and cartilage T 2 were assessed. Baseline subject demographics, risk factors, KL score, cartilage WORMS score, presence of meniscus tear, and cartilage T 2 were used to predict the development of moderate/severe OA (KL = 3–4 or WOMAC pain ≥5 or total knee replacement [TKR]) over 8 years. Statistical Tests Best subsets variable selection followed by cross-validation were used to assess which combinations of variables best predict moderate/severe OA. Results Model 1 included KL score, previous knee injury in the last 12 months, age, gender, and BMI. Model 2 included all variables in Model 1 plus presence of cartilage defects in the lateral femur and patella, and presence of a meniscal tear. Model 3 included all variables in Models 1 and 2, plus cartilage T 2 in the medial tibia and medial femur. Compared to Model 1 (cross-validated AUC = 0.67), Model 3 performed significantly better (AUC = 0.72, P = 0.04), while Model 2 showed a statistical trend (AUC = 0.71, P = 0.08). Data Conclusion We established a risk calculator for the development of moderate/severe knee OA over 8 years that includes radiographic and MRI data. The inclusion of MRI-based morphological abnormalities and cartilage T 2 significantly improved model performance. Level of Evidence : 2 Technical Efficacy Stage 3 J. Magn. Reson. Imaging 2017.

Description: Objective The purpose of this study was to determine the probability of structural worsening of knee cartilage and whole joint degeneration over 4–8 years based on cartilage T 2 Z-scores at baseline. Design Right knees with Kellgren-Lawrence (KL) grades of 0–2 in 587 participants from the Osteoarthritis Initiative were studied. 3T MR images were used to perform baseline cartilage T 2 quantification and assess 4-year changes in cartilage morphology (WORMS scoring) in 5 regions. Changes in joint space narrowing (JSN) and KL were assessed over 8 years. T 2 Z-scores were based on a reference database of knees without morphologic cartilage degeneration at baseline. Odds ratios for, and predicted probabilities of any worsening in WORMS cartilage, JSN and KL grade were obtained from logistic regression models. Results A one-unit increase in the baseline medial femur T 2 Z-score was associated with cartilage worsening in the same region (OR = 1.59; P  〈 0.0001) and in any region (OR = 1.37; P  〈 0.0001), and with worsening JSN (OR = 1.82; P  〈 0.0001) and KL grades (OR = 1.69; P  〈 0.0001). Predicted probabilities of worsening in knees with a medial femur T 2 Z-score from 2–4 were 38% for medial femur cartilage WORMS, 70% for any cartilage region, 28% for increasing JSN and 31% for increasing KL grade. Conclusion Knees with elevated cartilage T 2 (especially in the medial femur and those that are 2 to 4 SDs above the mean reference values) are significantly more likely to have structural worsening over 4 to 8 years. Knowing cartilage T 2 Z-scores may aid in targeting prevention efforts at early stages of osteoarthritis. Level of Evidence : 2J. Magn. Reson. Imaging 2017.