Key Lab for Biomechanical Engineering of Sichuan Province, Sichuan University, Chengdu, China; Sichuan University Yibin Park, Yibin Institute of Industrial Technology, Yibin, China.
Sichuan University Yibin Park, Yibin Institute of Industrial Technology, Yibin, China; Basic Mechanics Lab, Sichuan University, Chengdu, China.
J Biomech. 2024 Nov;176:112393. doi: 10.1016/j.jbiomech.2024.112393. Epub 2024 Oct 28.
Understanding temporomandibular joint (TMJ) kinematics is essential for the clinical diagnosis and treatment of TMJ disorders. Yet, a comprehensive description of mandibular motion information in patients with anterior disc displacement (ADD) is lacking. The finite helical axis (FHA) is a mathematical model describing the motion of a rigid body in space. This model quantifies mandibular motion patterns by differentiating between rotation around the FHA and translation along it. This study aimed to compare the mandibular motion patterns between patients with ADD and asymptomatic subjects during mouth opening and closing utilizing the FHA. Ten asymptomatic subjects (2 females and 8 males, aged 19-22) and ten patients with ADD (8 females and 2 males, aged 19-57) were tracked using an optical motion tracking system for mouth opening and closing. The FHA during mouth opening and closing was determined from motion trajectory. The distance from the condylar center to the FHA (d), the angles between the FHA and the head coordinate system (θ, θ, θ), and the global fluctuation of the FHA spatial orientation (θ) were further calculated. In addition, the helical axis of each frame relative to the initial frame was computed to determine the maximum rotation angle (Θ) and maximum offset (T) of mandibular motion during mouth opening and closing. It was found that Θ, T, d, d, θ, and θ for patients with ADD differed significantly from those of asymptomatic subjects. These findings imply that the FHA effectively describes the disparities between patients with ADD and asymptomatic subjects.
了解颞下颌关节（TMJ）的运动学对于 TMJ 疾病的临床诊断和治疗至关重要。然而，对于患有前盘移位（ADD）的患者的下颌运动信息，缺乏全面的描述。有限螺旋轴（FHA）是一种描述刚体在空间中运动的数学模型。该模型通过区分 FHA 周围的旋转和沿其的平移来量化下颌运动模式。本研究旨在使用 FHA 比较 ADD 患者和无症状受试者在开口和闭口期间的下颌运动模式。使用光学运动跟踪系统对 10 名无症状受试者（2 名女性和 8 名男性，年龄 19-22 岁）和 10 名 ADD 患者（8 名女性和 2 名男性，年龄 19-57 岁）进行了跟踪，用于开口和闭口。从运动轨迹确定 FHA 期间的开口和闭口。进一步计算了从髁突中心到 FHA 的距离（d）、FHA 与头坐标系之间的角度（θ、θ、θ）以及 FHA 空间取向的全局波动（θ）。此外，计算了相对于初始帧的每个帧的螺旋轴，以确定开口和闭口期间下颌运动的最大旋转角度（Θ）和最大偏移量（T）。结果发现，ADD 患者的 Θ、T、d、d、θ 和θ 与无症状受试者有显著差异。这些发现表明 FHA 有效地描述了 ADD 患者和无症状受试者之间的差异。
