Background There are no long-term studies that describe the independent association of radiographic and magnetic resonance imaging (MRI) based markers and cartilage volume loss and knee symptoms in population-based older adults.
Objectives To describe whether radiographic (joint space narrowing (JSN) and osteophytes) and MRI-based (cartilage defects, bone marrow lesions (BMLs), meniscal tears and meniscal extrusion) measures predict long-term cartilage volume loss and knee symptoms over 10.7 years.
Methods 983 participants (mean age 62.8 years, 50% female) were randomly recruited from the local community of Tasmania and followed up at 2.6 years, 5.1 years and 10.7 years later. Osteophytes and JSN were assessed using OARSI atlas. A 1.5T MRI scan of the right knee was acquired at baseline (n=930), 2.6 years (n=399) and 10.7 years (n=484). Tibial and patellar cartilage volume was acquired using a manual segmentation method on the T1-weighted fat-saturated 3D GRE images. Cartilage defects were assessed on T1-weighted MRI using a modified Outerbridge scoring system (grade 0–4). BMLs were measured on T2-weigthed fat saturated FSE images using a modified Whole-Organ MRI scoring system (grade 0–3). Meniscal extrusion (grade 0–2) and meniscal tears (grade 0–3) were measured using the T1- and T2-weighted MRI. Analyses were performed using linear mixed-effects models for symptoms and linear regression for cartilage volume loss.
Results After adjustment for age, sex, BMI and radiographic KOA status, cartilage defects and BMLs were associated with total WOMAC score (β=4.81, p<0.01 and β=2.20, p<0.01, respectively) and subscale (pain, stiffness and function, all p<0.01) scores in a dose-response pattern. Participants who had higher grades of cartilage defects, particularly grade 3 and 4, had higher WOMAC scores and remained higher over 10.7 years (Figure 1). The association of cartilage defects was independent of BMLs, meniscal pathology and effusion-synovitis, whereas the association of BMLs was dependent on cartilage defects and meniscal pathology but independent of effusion-synovitis. Tibiofemoral cartilage volume loss (not patellar) (β=1.91, p<0.01) and meniscal extrusion (not tears) (β=3.21, p<0.01) were independently associated with total WOMAC scores and pain over 10.7 years.
Baseline cartilage defects, BMLs and meniscal extrusion were significantly associated with annual loss of tibial cartilage volume over 10.7 years (β=0.27%, p<0.01, β=0.22%, p<0.01 and β=0.28%, p<0.01, respectively) independent of other structural abnormalities.
Radiographic osteophytes (but not JSN) were significantly associated with WOMAC score (β=8.49, p<0.01) over 10.7 years after adjustment for age, sex, BMI and other structural lesions. Conversely, radiographic JSN (but not osteophytes) was significantly associated with annual tibial cartilage volume loss (β=0.28%, p<0.01) over 10.7 years. These associations were independent of MRI structural lesions.
Conclusions Baseline cartilage defects, cartilage volume loss, BMLs, meniscal extrusion, JSN and osteophytes are independent predictors of clinical and strcutural progression of knee osteoarthritis.
Acknowledgement National Health and Medical Research Council of Australia funded this study
Disclosure of Interest None declared