A Tendon-Driven Flexible Retractor with Dynamically Adjustable Workspace for Oral and Maxillofacial Surgery

Oral and maxillofacial surgeries require precise and gentle retraction of soft tissues in confined anatomical spaces. Traditional manual retractors cause operator fatigue and inconsistent performance, while existing rigid self-retaining devices pose risks of tissue damage due to poor compliance, and flexible retractors suffer from insufficient load capacity and limited adaptability. This paper presents a tendon-driven multi-continuum retractor that integrates flexibility, adequate load-bearing capability, and a dynamically adjustable workspace. The device employs an arch-stiffened structure with five elastic beams: one active beam driven by an internal sliding cable and four passive beams hinged to adapt to the active beam’s deformation. A mechanics-based hybrid model is developed, combining a Cosserat rod model for the active beam and an Euler-Bernoulli beam model for the passive beams, to analytically describe the deformation under varying cable inputs. Leveraging this model, a pose-compensation-based automated control strategy is proposed to maintain stable contact with the mandible while resizing the retraction workspace. Comparative studies with finite element analysis, load-bearing tests, and workspace adjustment experiments validate the model accuracy and the effectiveness of the compensation strategy. The proposed retractor achieves a synergistic balance of compliance, load capacity, and spatial adaptability, demonstrating significant potential for enhancing safety and efficiency in oral and maxillofacial procedures.口腔颌面外科手术需要在有限的解剖空间内对软组织进行精确而轻柔的牵拉。传统的手动牵拉器容易导致操作者疲劳，且性能不一致，现有的刚性自锁装置因顺应性差而存在损伤组织的风险，而柔性牵拉器则负载能力不足、适应性受限。本文提出一种肌腱驱动的多连续体牵拉器，集灵活性、足够的承载能力以及动态可调节的工作空间于一体。该装置采用拱形加强结构，包含五根弹性梁：一根由内部滑动电缆驱动的主动梁，以及四根铰接的被动梁，可随主动梁的变形而调整。通过建立基于力学的混合模型，将主动梁采用Cosserat杆模型，被动梁采用欧拉-伯努利梁模型，以解析分析不同电缆输入下的变形情况。基于此模型，提出了一种姿态补偿型自动控制策略，在调整牵拉工作空间的同时，保持与下颌骨的稳定接触。通过有限元分析、承重测试和工作空间调整实验的对比研究，验证了该模型的准确性以及补偿策略的有效性。所提出的牵引器在顺应性、承载能力和空间适应性方面实现了协同平衡，展现出显著提升口腔及颌面手术安全性和效率的潜力。