This report is a review of the international definitions for musculoskeletal disorders (MSDs) and work-related musculoskeletal disorders (WRMSDs).

When discussing WRMSDs a clear definition provides a consistent foundation for developing interventions and measuring impact.

This report outlines the definition review process and how we came to define WRMSDs. It presents our preferred definition recommended for use in New Zealand.

For our one-page MSDs and WRMSDs definitions see: Definitions: Musculoskeletal disorders and work-related musculoskeletal disorders

Executive summary

Background

Musculoskeletal disorders (MSDs) have a significant effect on people all over the world. Among many definitions, MSDs refers to injuries and conditions affecting the muscles, tendons, ligaments, joints, blood vessels, and nerves. Approximately 1.71 billion people are affected by MSDs worldwide. In New Zealand MSDs make up over 30% of the overall burden of harm from work-related ill-health and injury. This equates to over 15,000 disability-adjusted life years per annum (referring to the quality and length of life lost due to injuries and illness).

There is abundant literature on work-related musculoskeletal disorders (WRMSDs) and MSDs worldwide. However, there is no universally agreed definition of WRMSDs or MSDs due to differences in terminology, diagnoses, and profession. The WorkSafe Human Factors/Ergonomics (HFE) team are tasked with leading the musculoskeletal harm reduction programme. The first step towards achieving this goal is to define WRMSDs, therefore the purpose of this report is to:

1. review the definitions of WRMSDs and MSDs,
2. define WRMSDs and MSDs for use within WorkSafe New Zealand and New Zealand.

The study reviewed international and New Zealand WRMSDs and MSDs research using Google, Google Scholar, and university library online search engines; internal WorkSafe publications; ACC internal documents; and articles from New Zealand MSDs researchers.

Findings

New Zealand MSDs definitions have typically been based on sprains and strains and discomfort, pain, and injury. More recently, the term body stressing was introduced to describe work-related injuries resulting from repetitive and strenuous work. New Zealand research groups MSDs into four categories: generic terms, body regions, task orientated terminology and exposure/hazard-related terminology. In Australia, MSDs are commonly understood as an injury or disease of the musculoskeletal system covering sprains and strains, back injuries, joint and muscle injuries, nerve, muscular and vascular disorders, soft tissue, chronic and acute pain. There are minor variances amongst various Australian states (for example, the use of body stressing injuries and manual handling injuries).

Internationally, there is no universal WRMSDs definition, and many countries use the terms MSDs and WRMSDs interchangeably. European countries have done a significant amount of research on MSDs at a national level again with no clear WRMSDs definitions (they mostly refer to MSDs). Many of the definitions are associated with muscles, tendons, and ligaments and mentioned specific regions of the body (for example, shoulders, upper arms, hands, wrists, elbows, forearms, neck, hips, legs, knees, ankles, and feet). Some definitions were typified by repetitive motion or strain injuries, cumulative trauma injuries, overuse syndrome or soft tissue disorders caused by repetitive tasks, carrying of heavy loads, vibrations, and awkward/inadequate postures. Compared to WRMSDs, MSDs definitions were much broader and included inflammatory and auto-immune conditions, some infective conditions, and fractures or bone pathologies.

There were limited (WRMSDs or MSDs) definitions in reports by international compensation authorities (the equivalent of ACC in New Zealand). Terms used to describe WRMSDs (for example, OOS and RSI) are outdated which suggests that WRMSDs definitions depend on current trends. In New Zealand, the terms OOS, RSI and DPI have had periods of popularity and continue to be used by the public.

A good practice WRMSD definition for use by WorkSafe should consider the following:

• use the term work-related musculoskeletal disorders, that may be abbreviated to WRMSDs. For more common use, musculoskeletal disorders (MSDs) is proposed as an acceptable term. However, it should be recognised that in medical circles, use of musculoskeletal disorders is inclusive of a wider range of conditions, and not all are considered work-related
• provide clarity that while MSDs and WRMSDs can have the same risk factors, WRMSDs are work-related, occurring due to exposure to risk factors at work
• include the contributing factors for WRMSDs that differentiate them from general MSDs. These include biomechanical (forces/loads, task duration/ repetition, workplace layout, vibration, and postures), work organisation, environmental, individual, and psychosocial factors
• acknowledge the distinction between acute and gradual WRMSDs and the potential for acute injuries to occur against a background of gradually acquired WRMSDs
• incorporate the terms muscles, ligaments, bones, tendons, blood vessels and nerves as they are regularly used terms to describe WRMSDs in the literature
• avoid excessive listing of body regions (for example, back, shoulder, ankle, hands etc). This not only increases the length of the definition, but it may not account for all possible body regions affected by WRMSDs
• use language that is ‘less medical’ for external facing documents (for general use). For example, using a generic and catch all term of discomfort, pain, and injury. This can be shortened to discuss discomfort and/or pain as the worker’s experience and injury when talking of recognised injuries and diagnosed conditions. Other terms such as strains and sprains or aches and pains may also be acceptable depending on the audience. It is also important to consider and include relevant words, terms and perspectives from Māori and other languages
• WorkSafe’s definition of WRMSDs should reflect the risk factors for musculoskeletal conditions, regardless of the insurance compensation framework in which we operate. Therefore, WorkSafe’s definition may differ to that of ACC.
• reference specific terms used in the Accident Compensation Act 2001 (if relevant).
• have consensus among New Zealand MSDs researchers as to the adequacy and relevance of using DPI, sprains and strains and body stressing in the definition.
• all parties with a vested or research interest in WRMSDs (for example, WorkSafe and New Zealand MSD researchers) should have an opportunity to contribute to the official WRMSD definition.