Repetitive Strain Injury – Causes, Symptoms and Treatment

What is Repetitive Strain Injury

Repetitive strain injury  is a term describing patients in whom there is no discrete, objective, pathophysiology that corresponds with the pain complaints which can be related to repeated activities over a period of time.

Repetitive strain injuries, otherwise known as cumulative trauma disorders, are described as tissue damage that results from repetitive demand over the course of time. The term refers to a vast array of diagnoses, including occupational, recreational, and habitual activities.

Estimated annual incidence of upper extremity disorders at 4.5-12.7% per year.

Examples of repetitive strain injury are

• Tendinosis
• Carpal Tunnel syndrome
• De Quervain syndrome
• Thoracic outlet syndrome
• Tennis elbow
• Golfer elbow
• Trigger finger

There is an increase in repetitive strain injury of upper limb and neck after workstations required prolonged repetitive motions in a fixed posture such as computing and typewriting.

Other names for repetitive strain injury are

• Repetitive stress injury
• Repetitive motion injuries
• Repetitive motion disorder
• Cumulative trauma disorder
• Occupational overuse syndrome
• Overuse syndrome
• Regional musculoskeletal disorder

Causes of Repetitive Strain Injury

It is an injury involving  musculoskeletal and nervous systems and is thought to be by  may be caused by repetitive tasks which include

• Forceful exertions
• Vibrations
• Mechanical compression
• Sustained or awkward positions.

Repetitive strain injury tends to be associated with both physical and psychosocial stressors.

Habits

• Reading books while looking down
• Carrying heavy school/laptop bags
• Use of phone/mobile leaning onto one side
• Watching TV in incorrect position e.g. Too much to the left/right. Sleeping while watching TV
• Sleeping with head forward, while travelling
• Malpositioning limbs away from their neutral position
• Increasing duration of mouse use.

Occupational Exposure

Cyclic Activity – A job that has repetitive cycles many times a day. Labor specialization has resulted in fewer different tasks per job and is believed to be a contributing factor

Vibration – especially over long periods, has long been shown to be a factor in increasing the risk of injuries of back and wrist

RSI and Psychosocial Factors

Psychological and social factors affect repetitive strain injury complaints.

Psychological stresses in large amounts have been associated with doubled risk of the reported pain. Similarly job demands, poor support from colleagues, and work dissatisfaction have also been to shown an increase in pain.

Pathophysiology of Repetitive Strain Injury

Tissues take time to adapt to the stresses placed on them. A tissue could be subjected to various stresses like shear, tension, compression, impingement, vibration, and contraction.

If tissue do not get time to adapt due to repeated forces acting on them, mechanical fatigue results. If tissues do not get appropriate time to heal, injury can occur.

Thus, put simply, rate of injury simply exceeds the rate of adaptation and healing in the tissue. Evidence also suggests that chemical mediators are involved in the initiation and propagation of repetitive strain injuries.

Tissue level changes found in the tissues associated with repetitive stress are altered levels of prostaglandin E2 and nitric oxide. Alterations in the regulation of genes within tendons undergoing overuse have been shown in the experimental animals suggesting that overuse may cause a morphologic alteration tissue.

Clinical Presentation

Excat symptoms of overuse injury or repetitive stress injury would depend on the region involved and forces involved.

Major complaint usually is pain followed by stiffness. In upper limb, the pain can be in the arm in the arm, back, shoulders, wrists, hands, or thumbs that worsens with activity.

Sports related injuries involve the lower limb.

There are activities that worsen the pain. The patient may complaint of weakness and lack of endurance.

The symptoms tend to be diffuse and non-anatomical and uncharacteristic of any discrete pathological conditions.

The physical examination discloses only tenderness and diminished performance on effort-based tests.

Diagnostic tests like radiographs and electrophysiological studies are normal.

An enquiry should be made to rule out faulty techniques at the work. In case of athletes specific training methods, equipment, and technique must be evaluated.

A history of popping, clicking, rubbing, erythema, should be enquired.

Look for any systemic symptoms as well

On examination, tenderness and guarding are often present. Crepitus may be a finding.

Erythema and swelling raises the possibility of an acute injury or infection.

Differential Diagnoses

• Acute injuries
• Infection
• Inflammatory diseases

Lab Studies

Rarely required for diagnosis. Lab studies are done to rule out other causes.

• Complete blood count
• ESR
• Antinuclear antibody testing
• C-reactive protein
• Vit B12 levels
• Thyroid-stimulating hormone
• Metabolic panel
• Liver function tests are also used for initial evaluation.

Imaging Studies

X-rays

These would be normal in most of the cases. Fractures, bony avuslsions, stress fracture, loose bodies in joint, calcification of tendons, myositis ossificans and heterotopic ossification are findings which may be seen in different patients.

MRI

MRI is in revealing tendon, ligament, and muscle injuries, nerve compression. It is not done routinely.

Other studies

Nerve conduction studies and electromyography may be done in cases of peripheral nerve compression or injury to know about the location and severity of the injury.

Treatment of Repetitive Strain Injury

• Most repetitive strain injuries resolve with enough rest, medications and then exercises.  Repetitive strain injury can persist for years if not cared for NSAIDs are mainstays in the treatment. Muscle relaxants, opiates, corticosteroids, tricyclic antidepressants, and sleep medications have a role too.
• Braces and massage are also used as part of the treatment.
• Ergonomic adjustments of the workstation are often recommended.
• Steroid injections are frequently used in treatment of repetitive strain injuries. Steroid injections under ultrsonographic control increase accuracy and decrease the possibility.
• Physical Therapy
  • Supervised use of the injured part
  • Transcutaneous electrical nerve stimulation
  • Ultrasound/phonophoresis
  • Iontophoresis
  • Heat/cold application
  • Proper training and equipments

Surgical Management

Surgical intervention is undertaken if conservative approaches fail and if the injury is amenable to surgery. The surgery usually involves, decompression of nerves and repair of lax or failed ligaments.

Prevention

• Minimize repetitive activity
• Minimizing repetition when possible
• Use better equipments and avoiding awkward positioning are the first steps in prevention.
• Stress management techniques and coping skills
• Foot orthoses in the lower limbs
• Patient education
  • About the disease and causartion
  • Stress on preventive measures listed above
  • Deter from early return to activity

Prognosis

Most repetitive strain injuries resolve after 3-6 months. If the offending cause is not removed, recurrences are quite common.

Recovery after surgery varies with procedure.