High quality trials and evidence of effective treatments for repetitive strain injury (RSI) are needed to define this controversial condition which affects millions of patients worldwide. The findings are reported in a Seminar published in this week's edition of The Lancet.
Professor Maurits van Tulder, EMGO Institute, VU University Medical Centre, Amsterdam, Netherlands and colleagues did extensive research into the prevalence, causes, symptoms, and treatments of RSI using a number of medical databases.
The authors say: "Repetitive strain injury is not one diagnosis, but is an umbrella term for disorders that develop as a result of repetitive movements, awkward postures, sustained force, and other risk factors."
Conventional definitions of RSI include specific disorders such as carpal tunnel syndrome (a twisting of the median nerve at the wrist causing pain in the wrist and hand), tendonitis of the wrist and hand, and various upper limb problems.
RSI arises frequently in adults of working age, with many people reporting strains of the hands, wrists, arms, shoulders or neck. Several countries report RSI incidence of 5-10%, although this could be as high as 40% in specific working populations.
Several hypotheses exist for how RSI occurs, but none have been supported by strong scientific evidence. One theory is that continuous contraction of muscles from long term static load with insufficient breaks could result in reduced local blood circulation and muscle fatigue. Consequently, pain sensors in the muscles could become over-sensitive, leading to a feeling of pain at lower-than-normal thresholds. Another theory is that overuse of tendons by repetitive loading causes RSI.
Diagnosis is often a difficult proposition. The authors say: "No gold standard tests for repetitive strain injury exist. In most cases, diagnosis is made on the basis of history and physical examination, including assessment of range of motion of joints, hypermobility, muscle tenderness, pain, strength, and imbalance between right and left limbs."
Doctors can also find it difficult to suggest appropriate treatment for RSI, although several studies have shown exercise to be beneficial both for providing symptom relief and improving the activities of daily living.
Other treatments such as massage or use of ergonomic keyboards at workstations are also regularly prescribed; however three separate studies into these non-proven techniques did not reduce sick leave in patients who tried them, and so none of these individual other treatments can be specifically recommended.
The authors conclude: "Strong recommendations for any therapeutic intervention cannot be made at present because many trials have small sample sizes and methodological flaws that could have led to biased results.
"This disorder will remain controversial until high-quality trials provide clear definition of repetitive strain injury and evidence of effective treatments."