Orthopedics - Oleksa A.P. 2006

Occupational musculoskeletal disorders
Vibration disease

Vibration disease (hand-arm vibration syndrome) develops As a result of exposure to rhythmically operating pneumatic vibrating tools, impact or rotational actions (in miners, concrete workers, riveters, road builders, assembly locksmiths, etc.), as well as through the workstation (machinery, flooring, premises).

The core parameters of vibration are oscillation frequency (measured in hertz — Hz) and vibration velocity (m/s). The severity of the biological impact depends on The amount of absorbed energy, with vibration velocity being its most adequate expression. The time derivative of vibration velocity is vibration acceleration (m/s²). In industrial settings, vibration is an oscillatory process spanning a wide frequency range, and its evaluation is typically carried out across 8–10 octaves.

Vibration with a frequency of 8–16 Hz is classified as low-frequency, 31.5–63 Hz as medium-frequency, and 125–1000 Hz as high-frequency (GOST 12.1.012-78. Vibration. General Safety Requirements).

The highest risk of developing vibration disease occurs at frequencies of 16–250 Hz. The threshold of vibration velocity perception is considered to be 10¹⁴ m/s, while the pain threshold is 1 m/s.

Depending on The Nature of bodily contact, vibrations are conventionally divided into local and general. Vibration is perceived by all body Tissues, primarily the nervous and Bone Tissues, with the latter acting as an efficient conductor and resonator of vibrational energy. Sound at frequencies below 20 Hz is referred to as infrasound.

The disorder may manifest as vasoneurosis (angiodystonia), osteoarthropathy of the upper extremities, and general symptoms of vibration disease after a certain period of working with vibrating tools or under conditions of facility and equipment vibration.

Clinically, vibration-induced angioneurosis manifests through trophic-neurogenic secretory disorders, as well as vestibular and auditory disturbances. Skin discoloration and altered perspiration in the hands occur, accompanied by numbness, weakness, joint stiffness, and even finger deformities, along with heightened sensitivity to cold.

Pathological changes occur in Bones and joints. The frequency and intensity of musculoskeletal alterations generally increase with occupational tenure; however, cases occur where radiologically detectable changes emerge after just two to three years of work. Conversely, workers with long-term tenure may sometimes exhibit only minor changes. More pronounced alterations typically develop in the more heavily loaded upper extremity.

Patients complain of rapid fatigue during work, weakness in the arms, and joint pain following work shifts.

Characteristically, the pain does not subside during Sleep and is unrelated to weather changes. However, it tends to disappear while working.

The radiological presentation of Bone and joint pathology comprises several distinct elements.

The most frequent finding is single or multiple cystic radiolucencies within the spongy bone of the hand. These are located in the Carpal Bones—predominantly the capitate and lunate, and to a lesser extent the scaphoid—as well as in the epiphyseal ends and heads of the metacarpals, mainly the second and third, resulting from bone resorption. The cysts are small, comparable to a pinhead or slightly larger. As a rule, they are round with a sclerotic rim. Small sclerotic foci can also be detected radiologically, though they are usually localized at the Base of the Phalanges and may directly adjoin the cortical layer (enostosis). Clinically, these foci are asymptomatic and can only be visualized on radiographs during routine occupational screenings.

Osteonecrosis of the lunate bone is less common and is associated with occupational overloads when working with vibrating tools or with Bone Structure restructuring in the form of Looser's zones and slowly progressive "pseudofractures" that occasionally evolve into secondary pseudarthrosis.

A characteristic feature of vibration-induced injury is The Development of deforming osteoarthritis or chondromatosis-like Changes in the wrist and elbow joints, and less frequently in the shoulder and acromioclavicular joints. Chronic progressive osteoarthritis arises from prolonged microtrauma affecting all joint components, although the complete Pathogenesis of this condition remains fully unestablished to this day.

Radiographs reveal deformation of the articular ends caused by bone spurs (osteophytes) around the Joint Capsule attachments and Muscle tendons. In some cases, loose osteocartilaginous bodies (joint mice) can be identified within the joint, particularly the elbow, accompanied by relevant clinical symptoms (locking, restricted range of motion, etc.). Such changes are most commonly encountered in individuals operating pneumatic hammers (tunnelers in mines and subway construction).

Treatment for vibration disease is symptomatic. In cases of joint locking caused by loose intra-articular bodies, surgical removal is performed. Following A change in occupation, pathological bone processes may regress, but gross joint deformities remain permanent.

Prevention of vibration disease includes: 1) rotational work schedules and labor Organization—introducing additional 10–20 minute rest breaks, preventing body chilling, job combining, and prohibiting overtime work; 2) reducing hand-transmitted vibration levels (GOST 7770-72) and workstation vibration (SN 245-71). This involves The Use of personal protective equipment—special clothing (double-lined gloves, vibration-damping footwear)—as well as engineering controls (vibration damping and vibration isolation); 3) post-work therapeutic and prophylactic measures—warm hand and FOOT baths, massage, UV radiation (quartz therapy), and A balanced diet;

4) in cases of overt clinical manifestations, a change of occupation is recommended.