Abstract：
OBJECTIVE: The aim of this study was to calculate the stress acting on the trapeziometacarpal joint during an key pinch grip.
METHODS: We used profile X-rays of the thumb to measure the various bony and muscle lever arms. We assessed the angles of action of the muscular elements involved in the thumb column. Based on this data, we established a two-dimensional geometric model that enabled us to determine the forces at each joint level, as a function of stresses and muscular contributions. We were also able to calculate the participation of the different muscle groups in obtaining a balanced situation.
RESULTS: Our results, as a function of the degree of flexion of the interphalangeal and metacarpophalangeal joints, show a multiplying factor of 2.9-3.19 in relation to the key pinch grip force.
CONCLUSIONS: Previous studies modelling a key pinch grip are showed multiplying factors from 6 to 13 in relation to the key pinch grip force. They are not compatible with the characteristics of the polyethylene used for trapeziometacarpal prostheses, whereas numerous articles in the literature show survival rates that are more or less comparable to those of total hip prostheses. These studies required an excessive number of assumptions, which could lead to error. Our results are compatible with the results of trapeziometacarpal prosthesis and with those of a recent study measuring intra-articular trapeziometacarpal pressure in a cadaveric model. Our model allows us to test different configurations of the thumb spine depending on the degree of flexion of the interphalangeal and metacarpophalangeal joints.
METHODS: We used profile X-rays of the thumb to measure the various bony and muscle lever arms. We assessed the angles of action of the muscular elements involved in the thumb column. Based on this data, we established a two-dimensional geometric model that enabled us to determine the forces at each joint level, as a function of stresses and muscular contributions. We were also able to calculate the participation of the different muscle groups in obtaining a balanced situation.
RESULTS: Our results, as a function of the degree of flexion of the interphalangeal and metacarpophalangeal joints, show a multiplying factor of 2.9-3.19 in relation to the key pinch grip force.
CONCLUSIONS: Previous studies modelling a key pinch grip are showed multiplying factors from 6 to 13 in relation to the key pinch grip force. They are not compatible with the characteristics of the polyethylene used for trapeziometacarpal prostheses, whereas numerous articles in the literature show survival rates that are more or less comparable to those of total hip prostheses. These studies required an excessive number of assumptions, which could lead to error. Our results are compatible with the results of trapeziometacarpal prosthesis and with those of a recent study measuring intra-articular trapeziometacarpal pressure in a cadaveric model. Our model allows us to test different configurations of the thumb spine depending on the degree of flexion of the interphalangeal and metacarpophalangeal joints.
摘要：
目的：这项研究的目的是计算在按键握紧过程中作用在梯形掌关节上的应力。
方法：我们使用拇指的轮廓X射线来测量各种骨骼和肌肉杠杆臂。我们评估了拇指柱中涉及的肌肉元素的作用角度。根据这些数据,我们建立了一个二维几何模型，使我们能够确定每个关节水平的力，作为压力和肌肉贡献的函数。我们还能够计算出不同肌肉群的参与情况。
结果：我们的结果，作为指间关节和掌指关节屈曲程度的函数，显示与钥匙夹紧力相关的2.9至3.19的倍增因子。
结论：先前的模拟按键握力的研究表明，与按键握力相关的系数从6到13。它们与用于梯形掌骨假体的聚乙烯的特性不相容，而文献中的许多文章显示，存活率或多或少与全髋关节假体相当。这些研究需要过多的假设，这可能会导致错误。我们的结果与梯形掌假体的结果以及最近在尸体模型中测量关节内梯形掌压力的研究结果一致。我们的模型使我们能够根据指间关节和掌指关节的屈曲程度来测试拇指脊柱的不同构型。
方法：我们使用拇指的轮廓X射线来测量各种骨骼和肌肉杠杆臂。我们评估了拇指柱中涉及的肌肉元素的作用角度。根据这些数据,我们建立了一个二维几何模型，使我们能够确定每个关节水平的力，作为压力和肌肉贡献的函数。我们还能够计算出不同肌肉群的参与情况。
结果：我们的结果，作为指间关节和掌指关节屈曲程度的函数，显示与钥匙夹紧力相关的2.9至3.19的倍增因子。
结论：先前的模拟按键握力的研究表明，与按键握力相关的系数从6到13。它们与用于梯形掌骨假体的聚乙烯的特性不相容，而文献中的许多文章显示，存活率或多或少与全髋关节假体相当。这些研究需要过多的假设，这可能会导致错误。我们的结果与梯形掌假体的结果以及最近在尸体模型中测量关节内梯形掌压力的研究结果一致。我们的模型使我们能够根据指间关节和掌指关节的屈曲程度来测试拇指脊柱的不同构型。
