Repeated motion disorder

Repeated motion by users operating a tool or machine can lead to a group of injuries called cumulative trauma disorders or repeated motion disorders (RMDs). 

What are cumulative trauma or repeated motion disorders ... 

Cumulative trauma injuries, cumulative trauma disorders or repeated motion injuries are a family of injuries that result from repeated motion or repeated use of a tool or other equipment. Most involve inflammation of or damage to various tissues. Several may occur at the same time. The appearance of symptoms will vary from person to person, with frequency of activity, forces, and movements involved in the activity, and other factors. Factors other than repeated motion, such as age and personal differences, may contribute to the incidence of these disorders. 

Another application is analysis of repeated motions involved in many jobs. Chapter 13 discussed cumulative trauma disorders and Chapter 15 included a discussion of manual materials handling problems and controls. 

There is, however, an alternative (but still indirect) way to view these molecules. It involves studies of crystalline solids and the use of the phenomenon of diffraction. The radiation used is either X rays, with a wavelength on the order of 10 cm, or neutrons of similar wavelengths. The result of analyses by these diffraction techniques, described in this volume, is a complete three-dimensional elucidation of the arrangement of atoms in the crystal under study. The information is obtained as atomic positional coordinates and atomic displacement parameters. The coordinates indicate the position of each atom in a repeat unit within the crystal, while the displacement parameters indicate the extent of atomic motion or disorder in the molecule. From atomic coordinates, it is possible to calculate, with high precision, interatomic distances and angles of the atomic components of the crystal and to learn about the shape (conformation) of molecules in the crystalline state. 

Cumulative trauma disorder is most prevalent among people whose occupations demand the performance of the same task repeatedly. The affliction rate for cumulative trauma disorders is as high as 25% among individuals performing motion-intensive tasks with their hands [15]. 

Ergonomics is the science of fitting the job to the worker. When there is a mismatch between the physical requirements of the job and the physical capacity of the worker, work-related musculoskeletal disorders (WMSDs) can result. Workers who must repeat the same motion throughout their workday, who must do their work in an awkward position, use a great deal of force to perform their jobs, repeatedly lift heavy objects, or who face a combination of these risk factors are most likely to develop WMSDs. 

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