目的 探讨坐姿下臀部压力性损伤易发部位以及不同软组织的生物力学响应，为有效预防深层组织压力性损伤提供参考。方法 基于臀部CT扫描数据，建立坐位臀部有限元模型，包括骨骼、肌肉、脂肪和皮肤组织及坐垫模型，利用生死单元模拟组织损伤。对比实验坐垫界面压力测量数据与有限元模拟结果，验证模型有效性。模拟坐位力学状态，研究软组织的应力应变情况，分析不同软组织中的压应力及超出极限值后可能造成的损伤情况。结果 经对比坐垫模型仿真结果与实验界面压力测量结果，证明模型有效。坐位时坐骨结节下方软组织区域出现应力集中现象。其中臀大肌组织中的横向压应力峰值约为38 kPa，剪切应力峰值约为3.4 MPa；而脂肪组织中的最大压应力与峰值剪切应力均未出现在坐骨结节正下方，分别为22 kPa与4.5MPa。结论 软组织受到一定时间和大小的压力载荷作用，可能出现深层组织损伤。当保持坐姿一定时间后，应及时变换体位，以降低压力性损伤出现的概率。本研究为预防压力性损伤提供生物力学依据，具有重要的临床研究价值。
Objective To explore the prone site of pressure injury in buttock in sitting position and the biomechanical response of different soft tissues, so as to provide reference for effective prevention of deep tissue pressure injury. Methods Based on CT scan data of the buttocks, a finite element model of the buttocks in sitting position was established, including bone, muscle, fat, skin tissue and cushion model. Tissue injury was simulated using life-death elements. The pressure measurement data of the experimental cushion interface were compared with the finite element simulation results to verify the validity of the model. To simulate the mechanical state of the sitting position, the stress and strain of the soft tissue were studied, and the compressive stress in different soft tissues and the possible damage after exceeding the limit value were analyzed. Results By comparing the simulation results of the cushion model with the experimental interface pressure measurement results, the model is proved to be effective. Stress concentration occurred in the soft tissue below the ischial tuberosity in the sitting position. The peak values of transverse compressive stress and shear stress in gluteus maximus were 38 kPa and 3.4 MPa; the maximum compressive stress and shear stress in adipose tissue did not appear directly below the ischial tuberosity, which were 22 kPa and 4.5 MPa. Conclusions Deep tissue injury may occur when soft tissue is subjected to a certain time and magnitude of pressure load. When the sitting position is maintained for a certain period of time, the position should be changed in time to reduce the probability of pressure injury. This study provides a biomechanical basis for the prevention of pressure injury, which has important clinical research value.