Joint‐adjacent Adipose Tissue by MRI is Associated With Prevalence and Progression of Knee Degenerative Changes: Data from the Osteoarthritis Initiative

Abstract

Background: Adipose tissue has recently gained interest as an independent imaging biomarker for osteoarthritis. Purpose: To explore 1) cross-sectional associations between local subcutaneous fat (SCF) thickness at the knee and the extent of degenerative changes in overweight and obese individuals and 2) associations between local fat distribution and progression of osteoarthritis over 4 years. Study Type: Retrospective cohort study. Population: 338 obese and overweight participants from the Osteoarthritis Initiative cohort without radiographic evidence of osteoarthritis. Field Strength: 3T: 3D-FLASH-WE; 3D-DESS-WE; T1w-SE; MSME. Assessment: Baseline SCF thickness was measured in standardized locations medial, lateral and anterior to the knee and the average joint-adjacent SCF (ajSCF) was calculated. Right thigh SCF cross-sectional area was assessed. Quantitative cartilage T 2 relaxation times and semi-quantitative whole organ MRI scores (WORMS) were obtained at baseline and 4-year follow-up. WORMS sum was calculated as sum of cartilage, bone marrow edema, subchondral cyst, and meniscal scores. Statistical Tests: Associations of SCF measures with baseline, and 4-year change in T 2 and WORMS were analyzed using regression models. SCF measurements were standardized using the equation. Analyses were adjusted for age, sex, physical activity, and BMI. Results: Cross-sectionally, significant associations between lateral SCF, lateral compartment WORMS and T 2 were found ( ΔWORMSsum 1SD change in lateral SCF , [95% CI]: 0.53, [0.12-0.95], P < 0.05; ΔT 2 : 0.50, [0.02-0.98], P < 0.05). Moreover, greater lateral SCF was associated with faster progression of lateral WORMS sum gradings (OR = 1.50, [1.05-2.15], P < 0.05). No significant positive associations were found for thigh SCF and WORMS sum (P = 0.44) or T 2 measurements (medial: P = 0.15, lateral: 0.39, patellar: P = 0.75). Data Conclusion: Joint-adjacent SCF thickness was associated with imaging parameters of knee osteoarthritis, both crosssectionally and longitudinally, while thigh SCF was not, suggesting a spatial association of SCF and knee osteoarthritis. Based on these findings, joint-adjacent SCF may play a role in the development and progression of knee osteoarthritis. Level of Evidence: 4 Technical Efficacy: Stage 5

Effect of weight loss on knee joint synovitis over 48 months and mediation by subcutaneous fat around the knee: data from the Osteoarthritis Initiative

“…We evaluated local SCF adjacent to the knee joint. A previous study found significant cross-sectional and longitudinal association between joint-adjacent SCF (mostly lateral) and semi-quantitative and quantitative imaging markers of knee OA [ 14 ]. How local adipose tissue around the knee – other than the IPFP – affects synovial inflammation on a cellular and cytokine level and how this is different to systemic effects of adiposity could be a focus of future investigations.…”

“…2 ). Anterior measurements were performed perpendicularly anterior to the patellar tendon at half of its length in sagittal views of 3D DESS sequences [ 14 ]. The lateral and medial tibial spine served as anatomical landmarks to choose coronal and sagittal cross-sections, respectively, for reproducible measurements.…”

“…The arithmetic mean was calculated as average joint-adjacent SCF (ajSCF). Good inter-rater and intra-rater reliability for SCF measurements were previously reported with coefficients of variation (CV) of 2.72% and 2.01%, respectively [ 14 ].

Fig.

…”

“…Beyond systemic effects of obesity, local SCF around the knee and the infrapatellar fat pad (IPFP) located in the joint capsule is of interest as being involved in the pathophysiology of knee OA [ 13 ]. A previous study found that joint-adjacent SCF played a role in the development and progression of knee OA [ 14 ]. However, the effect of local SCF on synovitis is unknown.…”

Associations between weight change, knee subcutaneous fat and cartilage thickness in overweight and obese individuals: 4-Year data from the osteoarthritis initiative

“…These studies reported that SCF thickness was significantly higher in individuals presenting with chondromalacia, 6 increases in thigh SCF over 2 years were associated with the progression of knee OA in men, 7 and greater joint-adjacent SCF levels at baseline were associated with higher odds for cartilage and meniscal structural progression over 4 years, independent of baseline BMI. 8 Thus, understanding the impact of localized adipose changes on adjacent knee joint tissue may provide novel insights OA pathogenesis, that are beyond the systemic effects of overall weight change.…”