Fat, flames and ultrasounds: the effects of obesity on pediatric joint inflammation

Abstract

The association between childhood obesity and the early appearance of joint degeneration, particularly in the infrapatellar "Hoffa's" fat pad, highlights the importance of early diagnosis and treatment. The purpose of this review is to describe the role of ultrasound imaging as a first-line imaging tool for the early detection, prevention, and follow-up of degenerative structural changes in children's joints. By combining ultrasound findings with clinical assessments and indices, healthcare providers can gain a more comprehensive understanding of obesity-related joint alterations. This integrative approach enables early therapeutic interventions, improving outcomes for affected children. Proactive management of pediatric obesity will not only improve the long-term outcomes of obesity-related joint disorders but also reduce the burden of related complications, such as osteoarthritis, in adulthood.

Keywords: Hoffa's fat pad; Joint inflammation; Metabolic syndrome; Pediatric obesity; Proinflammatory cytokines; Rheumatology; Ultrasounds.

Fig. 1

Ultrasound findings may provide a “window” for early treatment of the progression of knee osteoarthritis. Biomechanical effects of increased fat tissue surrounding the joint result in early changes in the joint, which culminate in cartilage breakdown over time

Fig. 2

Comprehensive management approach for pediatric obesity and joint inflammation

Fig. 3

US evaluation of Hoffa’s fat pad. 3 A-3 C B-mode US images of the knee on the longitudinal subpatellar scan plane, which provide an evaluation of Hoffa’s fat pad (area outlined in yellow) echostructure and echogenicity, compared to the patellar tendon (X). All patients were 9-year-old prepubescent females. 3 A Patient with higher BMI (BMI = 29.31, > 99th percentile) presents with hypoechoic fat pads with unidentifiable double-layer structures and larger fat pad areas (565.4 mm² right, 515.3 mm² left), potentially indicating increased tissue volume and altered composition due to greater mechanical or inflammatory stress. 3B,3 C Patients with lower BMIs (respectively BMI = 23.13, 95–99th percentile, 3B; BMI = 21.41, 85–95th percentile, 3 C) presented slightly hypoechoic fat pads with identifiable superficial septate (S) and deep homogeneously hypoechoic (D) layer structures and smaller fat pad areas (350.6 mm² right, 346.2 mm² left for BMI 23.13), which may reflect reduced mechanical stress and more preserved tissue characteristics. The OMERACT US semiquantitative scoring system revealed no signs of inflammation, such as effusion or hypervascularization, in any of these patients. Abbreviations: BMI, body mass index; OMERACT, Outcome Measures in Rheumatology; US, ultrasound