Zhao Jiaqi, Song Xiao-Fei, Wei Xiaoxian, Mu Jiuke, Peng Peng, Yu Wenli
Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, School of Mechanical Engineering, Tianjin University, Tianjin, 300354, China.
Tianjin First Central Hospital, School of Medicine, Nankai University, Tianjin, 300192, China.
Ann Biomed Eng. 2025 Jul 19. doi: 10.1007/s10439-025-03801-3.
Waterjet is increasingly used in medicine for cutting and ablation of soft tissues due to its non-thermal damage and tissue-selective separation. However, the tissue-selective separation mechanism for cutting target tissues while protecting blood vessels under waterjet impact remains little known. In this study, the mechanical properties, dynamic responses and tissue-selective separation mechanisms of four typical soft tissues including liver, muscle, and arterial-venous blood vessels under waterjet impact were investigated.
Uniaxial tensile testing and waterjet impact testing were conducted to measure the mechanical properties and cutting responses of liver, muscle, and arterial-venous blood vessels. Based on fracture mechanics, the critical separation pressure and impact depth for these soft tissues were determined and analyzed as key controlling parameters for tissue-selective separation.
The mechanical response showed that the Young's modulus and tensile strength of blood vessels were significantly higher than those of liver and muscle tissues due to their obvious differences in tissue composition and structure, which were necessary factors for achieving tissue-selective separation. The impact depths were negatively correlated with the mechanical properties of the tissues, while the critical separation pressures were positively correlated with their mechanical properties. A sliding effect of blood vessels embedded in soft tissues was found, where the vessels slid sideways and changed position to avoid damage while target soft tissues were completely cut under waterjet impact. This indicates that the vascular sliding effect controlled by waterjet processing parameters and tissue properties is an important determination for achieving tissue-selective separation during waterjet impact.
To achieve tissue-selective separation with low damage while ensuring high efficiency, reasonable waterjet impact pressures of 2.5-3.4 MPa for liver and 3.1-3.4 MPa for muscle with the transverse speeds of 12-15 mm/s are recommended for clinical surgery. This study provides practical insights into process control and tissue-selective protection in medical waterjet applications for low-trauma cutting surgery of soft tissues.
由于水刀具有非热损伤和组织选择性分离的特点，其在医学领域用于软组织切割和消融的应用日益广泛。然而，水刀冲击下切割目标组织同时保护血管的组织选择性分离机制仍鲜为人知。本研究对肝、肌肉和动静脉血管这四种典型软组织在水刀冲击下的力学性能、动态响应及组织选择性分离机制进行了研究。
进行单轴拉伸试验和水刀冲击试验，以测量肝、肌肉和动静脉血管的力学性能及切割响应。基于断裂力学，确定并分析了这些软组织的临界分离压力和冲击深度，将其作为组织选择性分离的关键控制参数。
力学响应表明，由于血管与肝和肌肉组织在组织组成和结构上存在明显差异，血管的杨氏模量和抗拉强度显著高于肝和肌肉组织，这是实现组织选择性分离的必要因素。冲击深度与组织的力学性能呈负相关，而临界分离压力与组织的力学性能呈正相关。发现嵌入软组织中的血管存在滑动效应，即血管侧向滑动并改变位置以避免损伤，而目标软组织在水刀冲击下被完全切割。这表明由水刀加工参数和组织性能控制的血管滑动效应是水刀冲击过程中实现组织选择性分离的重要决定因素。
为在确保高效的同时实现低损伤的组织选择性分离，建议在临床手术中，肝组织采用2.5 - 3.4MPa的合理水刀冲击压力，肌肉组织采用3.1 - 3.4MPa的合理水刀冲击压力，横向速度为12 - 15mm/s。本研究为软组织低创伤切割手术的医学水刀应用中的过程控制和组织选择性保护提供了实用见解。
