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Occupational Health

MSDs: Musculoskeletal Disorders at Work — Prevention and INRS Approach

MSDs are disorders of the musculoskeletal system affecting muscles, tendons and joints. They are one of the main causes of occupational diseases. INRS proposes a structured prevention approach.

IICP HSE Academy Published on 18 October 2026 7 min read 30 views
TMS — Troubles musculosquelettiques

MSDs: Work-Related Musculoskeletal Disorders — Prevention and the INRS Approach

MSDs are injuries to the musculoskeletal system affecting muscles, tendons, and joints. They represent one of the main causes of occupational diseases. The INRS proposes a structured prevention approach.

Definition

MSDs (Musculoskeletal Disorders) are conditions affecting the musculoskeletal system: muscles, tendons, ligaments, nerves, and joints. They result from an imbalance between the mechanical demands placed on the body and the tissues' capacity for recovery.

MSDs develop progressively, often insidiously, following constrained postures, repetitive gestures, or manual handling tasks. Unlike a work accident, an MSD is a disease with a professional component: it combines occupational exposure with individual factors.

Affected Areas

MSDs preferentially affect certain areas of the body:

  • Spine (back): low back pain, herniated discs
  • Shoulders: tendonitis, rotator cuff syndrome
  • Elbows: epicondylitis
  • Wrists and hands: carpal tunnel syndrome, tendonitis
  • Knees: bursitis, meniscal lesions
  • Neck and cervical spine: cervicalgia

In Morocco and internationally, the wrist and shoulder are the most frequently affected areas in industrial (assembly, packaging, garment manufacturing) and tertiary (screen-based work) sectors.

Main Causes

The risk factors for MSDs fall into several categories:

1. Biomechanical Factors

  • Constrained and prolonged postures
  • High-frequency repetitive gestures
  • Manual handling of heavy loads
  • Exerted forces (pressure, gripping)

2. Organizational Factors

  • Imposed pace, assembly line work
  • Insufficient task variability
  • Time pressure, stress
  • Shift work, atypical schedules

3. Environmental Factors

  • Cold, vibrations
  • Restricted workspace
  • Inappropriate or poorly maintained tools

4. Individual Factors

  • Age, medical history, health status
  • Lifestyle habits, intense sports

Statistics: A Public Health Priority

In France, MSDs are the leading recognized cause of occupational disease, accounting for the majority of occupational diseases compensated by the National Health Insurance (CNAMTS). Specific figures can be consulted in the annual statistics of the CNAM. In Europe, they affect millions of workers each year and represent a considerable cost in healthcare, work stoppages, and loss of productivity. In Morocco, industrial sectors (textiles, agri-food, automotive) are particularly exposed; precise Moroccan statistics must be verified with the CNSS (National Social Security Fund).

Prevention: The INRS Approach

The INRS (National Research and Safety Institute) proposes a structured MSD prevention approach in several steps:

1. Identify and assess risk situations

Identification of at-risk workstations through field observations, interviews with operators, and the use of assessment grids. Among the most widely used evaluation methods are:

  • RULA (Rapid Upper Limb Assessment): postural assessment of the upper limb
  • REBA (Rapid Entire Body Assessment): postural assessment of the entire body
  • OSRA (Occupational Repetitive Actions): INRS method for repetitive gestures

2. Act on the workstation

  • Ergonomic design: work surface height, accessibility
  • Adapted tools: counterbalances, mechanical aids, powered tools
  • Job rotation to vary demands
  • Planned recovery breaks

3. Train and involve

Training of operators in gestures and postures, raising awareness among supervisors, active participation of workers in the improvement process.

4. Monitor and sustain

Medical follow-up by the occupational physician, MSD indicators, regular reassessment of workstations.

The INRS emphasizes: MSD prevention is not limited to individual instructions (gestures and postures). It must primarily act on the organization and design of work.

Sources et références

  1. Code du travail marocain (Loi n° 65-99), Titre IV — articles 281 et suivants (principes généraux de prévention des TMS) ILO NATLEX : https://natlex.ilo.org/dyn/natlex2/r/natlex/fe/details?p3_isn=67319

  2. INRS — Troubles musculosquelettiques (TMS) : Ce qu'il faut retenir (URL vérifiée le 24/10/2026) https://www.inrs.fr/risques/tms-troubles-musculosquelettiques/ce-qu-il-faut-retenir.html

  3. INRS — Prévention des TMS (actualités) https://www.inrs.fr/actualites/tms-ed6518.html

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