Tallinn University of Technology

Viive Pille defended her doctoral thesis "Development of a Model for the Prevention of Work-Related Musculoskeletal Disorders in the Upper Extremities" at the Technomedicum of Tallinn University of Technology.

Musculoskeletal disorders take the first place among the occupational diseases not only in Estonia, but in the whole world. Numerous studies in the field show that the development factors of these diseases differ somewhat depending on the specificities of the work as well as cultural environment. The doctoral thesis defended at TTÜ investigated various regions in Estonia, the sample consisted of 505 employees (office and garment industry workers and the benchmark group consisted of persons suffering from occupational diseases).

The developing of musculoskeletal disorders is associated with three main factors: physiological, psychosocial and individual. However, physiological hazards, such as repetitive hand movements like gripping, holding, working in an uncomfortable forced position and monotonous work are considered the most important factors.

"The doctoral thesis focused primarily on comparison of the causes and occurrence of the symptoms of musculoskeletal disorders in office and garment industry workers. The investigated benchmark group consisted of employees suffering from occupational diseases. The treatment of the already developed chronic overload diseases (carpal tunnel syndrome and epicondylitis) is significantly more expensive, time-consuming and more burdensome for the patient compared to alleviation of primary symptoms of general muscle pain," one of the supervisors, Professor at the Department of Business Administration Piia Tint explained.

The research showed that unfortunately muscle pains are widespread among office and garment industry workers. It also appeared that the risk level at the workplaces of sewers is higher than that of office workers (computer users), their pain spectrum is different as well. The office workers often complained of neck pain, which usually passed by itself. However, sewers had more long-lasting (with a duration of 30 days or more) pains. In addition, they complained of pain in shoulders, hands and back.

The work has outlined a three-step musculoskeletal disease evolution scheme. At the early i.e. the first stage, the the worker can recover quickly after changing working condition and after treatment. At the second stage, when the symptoms have lasted for a longer period of time, the treatment and recovery may take more time and there is a risk of development of a specific overload disease. If a musculoskeletal overload disease is diagnosed, it may be considered the third stage, which is characterised by long-lasting pains in the upper extremities, the so-called multiple region pains and potential functional impairment of joints. This means, however, that it may lead to permanent loss of work capacity.

Musculoskeletal disorders are recognized as one of the leading causes of temporary or permanent incapacity for work. Since the symptoms of the disease occur with remissions (i.e. temporary disappearance or diminution of disease symptoms), it is difficult to assess the condition of the muscles and to predict the course of the disease. Also, the results of rehabilitation suggest that the earlier treatment is started, the better the results. At the chronic stage of a disease (muscle pain lasting for more than 30 days or pain felt every day) rehabilitation is significantly less effective.

The doctoral thesis offers myotonometry (assessment of muscle tone by mechanical characteristics) as a tool for measuring the muscle tone of upper extremities and for prevention of the diseases.

Professor Tint says, "This innovative method deserves further research and application in occupational medicine for the prevention of musculoskeletal disorders and enables individual assessment of a worker's muscle condition. Myotonometric measurements can be easily conducted and repeated and they enable monitoring of the condition of the muscles under dynamic conditions in order to evaluate the effect of changes in the workload and treatment."

The supervisors of the doctoral thesis were Professor Peeter Ross, Professor Piia Tint and Professor Ruth Sepper (TTÜ).
The opponents were Professor Janis Ievinš (Riga Technical University) and Associate Professor Eda Merisalu (Estonian University of Life Sciences).

The doctoral thesis has been published in the digital collection of TTÜ library: https://digi.lib.ttu.ee/i/?6970

Kersti Vähi, TTÜ Research Administration Office