The movement patterns of the wrist and metacarpal joints in spatial planes during typing as a foundation of possible kinematic risk factor of hand musculoskeletal disorders

Abstract

Background

Repetitive flexion and extension movements of the metacarpophalangeal (MP) joint can be a factor in the development of trigger finger because of the shear stress that occurs on the tendons and annular ligaments. Understanding the role of joint movement is crucial for gaining insight into how humans may prevent musculoskeletal disorders and related symptoms.

Purpose

This study aimed to investigate the coordination of wrist and metacarpophalangeal (MP) joint movements during the execution of a standardized typing task in the sagittal and frontal/sideways planes.

Study design

Experimental laboratory study.

Methods

Ten healthy subjects typed a task containing the sequence of letters “ryouhou” eight times, and their wrist and index finger movements were captured using a 3D motion capture system. Changes in the positions of the wrist and MP joints were calculated and compared in both planes.

Results

In the sagittal plane, the mean changes in the position of the wrist and MP joint movements for the entire group were 32.8 mm (SD 18.4 mm) and 46.6 mm (SD 17.1 mm), respectively, with MP joint movements being predominant in seven subjects. In the frontal/sideways plane, the mean changes in the position of the wrist and MP joint movements for the entire group were 30.4 mm (SD 17.6 mm) and 39.7 mm (SD 17.2 mm), respectively. Movement patterns varied among subjects: wrist joint movements were predominant in two subjects while MP joint movements were predominant in four subjects.

Conclusions

Frequent MP joint flexion/extension in the sagittal plane may increase the risk of tenosynovitis and trigger finger due to increased carpal tunnel pressure. Movement variability in the frontal/sideways plane may indicate the influence of individual anatomical factors. These findings suggest that promoting coordinated movements between the wrist and MP joints may help reduce mechanical stress and the associated risks of typing-related conditions. Understanding these movement characteristics is crucial for minimizing the development of tenosynovitis and trigger finger.