Background

The metacarpophalangeal joint has a unique morphology with a high degree of freedom. However, few studies have analyzed the kinematics of fingers owing to the rapid movement of the small bones involved. The in-vivo kinematics of metacarpophalangeal joints were analyzed by four-dimensional computed tomography (4DCT) and associated with its morphology.

Methods

The flexion motion of the fingers of bilateral hands in 10 volunteers were examined using 4DCT. Iterative surfaces were registered to trace the surface of the proximal phalanges with respect to metacarpals. Rotation angles were calculated using Euler/Cardan angles.

Findings

In the index finger, the proximal phalange supinated to a maximum flexion of 40° and then pronated, and its range of rotation was larger than the previous reports. In the other fingers, the proximal phalanges continued to supinate during flexion. The helical axis of the proximal phalange passed a point extremely close to the center point of bilateral condyles, and it moved toward the proximal and palmar directions until the middle stage of flexion and toward the proximal and dorsal directions during the late stage of flexion. The translation of the rotation axis was larger in the ring and little fingers.

Interpretation

The rotation in the index finger was larger than previously reported. The helical axes moved in the dorsal direction and proximally during the latter phase of the flexion. These results can be employed to better understand the causes of implant failure of the metacarpophalangeal joints.

中文翻译：

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三维弯曲层析成像定量分析活动性屈曲中掌指关节

背景

掌指关节具有独特的形态，具有高度的自由度。但是，由于涉及的小骨头的快速运动，很少有研究分析手指的运动学。掌指关节的体内运动学进行了三维计算机断层扫描（4DCT）分析，并与它的形态相关联。

方法

使用4DCT检查了10名志愿者的双侧手指的屈伸运动。记录迭代表面以追踪相对于掌骨的近指骨表面。使用欧拉/卡丹角计算旋转角。

发现

在食指中，近端指骨向后弯曲至最大屈曲度为40°，然后向前弯曲，其旋转范围比以前的报道要大。在其他手指中，近端指骨在屈曲过程中继续仰卧。近端趾骨的螺旋轴经过一个非常接近双侧con突中心点的点，并且它向着近端和手掌方向运动，直到屈曲中期，而在屈曲后期则向近端和背侧运动。旋转轴的平移在无名指和小指中较大。

解释

食指的旋转比以前报道的要大。在屈曲的后期，螺旋轴沿背侧方向向近端移动。这些结果可用于更好地了解掌指关节植入失败的原因。