Department of Industrial Engineering, University of Padova, 35131 Padova, Italy; Centre for Mechanics of Biological Materials, University of Padova, 35131 Padova, Italy.
Musculoskeletal Pathology and Oncology Laboratory, Department of Surgery, Oncology and Gastroenterology (DiSCOG), University of Padova, 35128 Padova, Italy; Orthopedics and Orthopedic Oncology, Department of Surgery, Oncology and Gastroenterology (DiSCOG), University of Padova, 35128 Padova, Italy.
J Biomech. 2022 Jan;131:110931. doi: 10.1016/j.jbiomech.2021.110931. Epub 2021 Dec 23.
The infrapatellar fat pad (IFP) is an adipose tissue present in the knee that lies between the patella, femur, meniscus and tibia, filling the space between these structures. IFP facilitates the distribution of the synovial fluid and may act to absorb impulsive actions generated through the joint. IFP in osteoarthritis (OA) pathology undergoes structural changes characterized by inflammation, hypertrophy and fibrosis. The aim of the present study is to analyze the mechanical behavior of the IFP in patients affected by end-stage OA. A specific test fixture was designed and indentation tests were performed on IFP specimens harvested from OA patients who underwent total knee arthroplasty. Experiments allowed to assess the typical features of mechanical response, such as non-linear stress-strain behavior and time-dependent effects. Results from mechanical experimentations were implemented within the framework of a visco-hyperelastic constitutive theory, with the aim to provide data for computational modelling of OA IFP role in knee mechanics. Initial and final indentation stiffness were calculated for all subjects and statistical results reveled that OA IFP mechanics was not significantly influenced by gender, BMI and sample preparation. OA IFP mechanical behavior was also compared to that of other adipose tissues. OA IFP appeared to be a stiffer adipose tissue compared to subcutaneous, visceral adipose tissues and heel fat pads. It is reasonable that fibrosis induces a modification of the tissue destabilizing the normal distribution of forces in the joint during movement, causing a worsening of the disease.
髌下脂肪垫（IFP）是一种存在于膝关节的脂肪组织，位于髌骨、股骨、半月板和胫骨之间，填充这些结构之间的空间。IFP 有助于滑液的分布，并可能起到吸收关节产生的冲动作用。在骨关节炎（OA）病理中，IFP 经历了以炎症、肥大和纤维化为特征的结构变化。本研究的目的是分析终末期 OA 患者 IFP 的力学行为。设计了一种特殊的试验夹具，并对接受全膝关节置换术的 OA 患者的 IFP 标本进行了压痕试验。实验允许评估机械响应的典型特征，如非线性应力-应变行为和时变效应。机械实验的结果被实施在粘弹性超弹性本构理论的框架内，目的是为 OA IFP 在膝关节力学中的作用的计算模型提供数据。对所有受试者计算了初始和最终压痕刚度，统计结果表明，OA IFP 的力学性能不受性别、BMI 和样本制备的显著影响。OA IFP 的力学行为也与其他脂肪组织进行了比较。OA IFP 似乎比皮下脂肪、内脏脂肪组织和足跟脂肪垫更硬。纤维化导致组织不稳定，在运动过程中正常分布力，从而使疾病恶化，这是合理的。
