Echo intensity of the superficial part of the medial infrapatellar fat pad and medial meniscal extrusion are associated with knee symptoms in community-dwelling older adults

Purpose: Knee pain is a characteristic symptom of early-stage knee osteoarthritis. Recently, the association between knee symptoms and infrapatellar fat pad (IFP) degeneration has garnered attention. This study aimed to clarify the association between ultrasound-derived size and echo intensity (EI) in the IFP and knee symptoms.

Methods: A total of 163 community-dwelling older individuals (women, n = 106; age, 75.1 ± 7.0 years) participated. An ultrasound imaging device was used to assess the area and EI of the superficial and deep parts of the central, medial, and lateral IFP and presence of medial meniscal extrusion (MME) and medial tibial osteophytes. Based on the 2011 version of the Knee Society Knee Scoring System (KSS) symptoms category, the participants were classified into a symptomatic (KSS symptom score < 23, n = 74) or asymptomatic (KSS symptom score ≧23, n = 89) group. Logistic regression analyses were performed with groups as dependent variables and EI and area of the IFP as independent variables.

Results: EI of the superficial part of the medial IFP was significantly associated with knee symptoms, adjusting for age, sex, body mass index, MME, and medial osteophytes (p < 0.05). MME was also significantly associated with knee symptoms (p < 0.05). EI of the other parts, area of any parts, and medial osteophytes were not associated with knee symptoms.

Conclusion: These findings suggested the utility of evaluating EI on the superficial part of the medial IFP and MME as the articular structures associated with knee symptoms.