Cumulative Trauma Disorders

Preventive Strategies

Barbara Lutz, RDH, AAS, BS

Cumulative Trauma Disorders (CTDs) are the leading work-related injuries currently reported by professionals.¹ Due to the nature of the profession, dentists present many risk factors for these disorders (eg, repetitive wrist and hand motion, awkward body postures, positioning for extended periods). These factors may result in malposition, strain, and misalignment of the musculoskeletal system, which compromises nerves, joints, and muscles. In addition, musculoskeletal disorders of the upper extremities affect the neck, shoulder, elbow, hand, wrist, and fingers, which may lead to injuries to the tendons, muscles, and nerves.² These disorders limit daily activities and may curtail a dentist’s career.

Cumulative Trauma Disorders are not caused by accidents or job-related environmental risks; rather, they develop over time.³ The US government has defined CTDs as any musculoskeletal pain associated with activities performed at work.⁴ Cumulative Trauma Disorder is not a medical diagnosis, but rather a label for pain perception. The term cumulative trauma disorder identifies a large group of conditions that result from traumatizing the body in either a minute or major way over a period of time. It is the build up of trauma which causes the disorder.  As other repetitive motions of daily life can affect an individual, controversy has emerged over the role of occupational influences in the etiology of CTDs.¹  

Causes and Considerations

The literature suggests that nerve response to injury causes structural change to connective tissues within that nerve.⁵ When pressure on an area becomes constant, vascular obstruction causes the nerves to become hypoxic.⁶ Motor skills may become impaired at the onset; this condition is, however, reversible. Without treatment, permanent damage may result, as keeping the nerve dilated causes edema and further pressure on the nerve. In addition, nerve fibers may be destroyed, leading to muscle atrophy, weakness, or loss of function. While it is true that there is no connective tissue in nerves per se, the structure of the nerve is supported by neuro filaments. The nerves can be injured by direct compression to the nerve, or by compressing the blood vessels supplying the nerves (vasa nervosa). This can result in nerve edema and swelling. With significant nerve damage the muscles loose inervation then begin to atrophy and fibrose. When muscles remain in a low-level exertion state from non-movement, they experience decreased blood flow. In rare cases, or in cases where there is occlusion or laceration of a blood vessel, this reduction in blood supply may lead to fibrosis of the muscles and result in permanent scarring.

The neck and back regions are especially susceptible to muscle strain. Extensive muscle contraction is needed to hold the head out of its neutral position; this strain puts undue stress on the spinal disks, resulting in pinched nerves and herniated disks.⁵ Certain predisposed medical conditions can also increase the risk of developing CTDs (eg, diabetes, rheumatoid arthritis, hypo- or hyperthyroid disease).⁵  

Preventive Strategies

All members of the dental team are at risk of experiencing CTD-like pain at work. Dentists, in particular, report significant neck, shoulder, and lower back pain (Figure 1).⁶ The dentist must be aware of detrimental habits that may add to his or her risk for developing CTDs. This includes being cognizant of poor body mechanics and the need to recondition himself/herself to correct posture (Table 2)⁷. Dentists should take breaks between patients and perform stretch exercises to reduce muscle tension. Schedules should also be arranged to avoid consecutive heavy patient cases.

Table 2.⁷

 Preventive Strategies

Working Position

• Avoid prolonged extensions (bending) or deviations (twisting) of the wrist
• Maintain neutral sitting position
• Keep head and shoulders relatively relaxed and straight
• Keep back straight and elbows close to sides
• Distribute body weight evenly on operator’s chair when sitting; avoid leaning to one side or the other
• Avoid working in one position for prolonged periods of time

Schedule

• Allow brief (5-10) minute breaks in the daily work schedule for relaxation, rest, and stretching exercises
• Avoid scheduling consecutive heavy of intense patient cases

Since the work environment has a profound effect on physical health, it is essential for the dentist to address how his or her surroundings may influence his or her body mechanics. It is important to keep supplies handy and the room temperature comfortable, as well as to maintain adequate room lighting. Instruments must be sharpened to decrease repetitive motion and forceful exertion during instrumentation. The addition of loupes or bifocal protective eyewear can further enhance body mechanics and assist the user in the maintenance of a neutral position. Even with excellent eyesight, dentists can miss much detail without magnification and by wearing surgical loupes not only benefits from such enhancement but prevents straining of the neck and upper/lower back.

In order to prevent the development of a CTD, the following criteria should be applied, whenever possible, to the clinician’s working position⁸:

• Head upright;
• Chin slightly tucked in;
• Feet flat on the floor;
• Shoulders relaxed and level;
• Ears positioned over the shoulders;
• Weight centered on the stool; and
• Elbows near sides

Conclusion

The development of CTDs may severely compromise the practitioner’s ability to properly execute his or her day-to-day functions. Dentists must, therefore, be conscious of the symptoms associated with these disorders, and seek treatment at the onset; diagnosis & treatment are key to effectively managing CTDs. Once the dentist has been made aware of the anatomical implications of a CTD, he or she may begin taking steps to prevent and correct its occurrence in the operatory.

*Adjunct Faculty Member, Camden County College, Blackwood, New Jersey. Administrator, Dental Arts of Southern Jersey, Voorhees, New Jersey.

References:

1. Melhorn JM. The impact of workplace screening on the occurrence of cumulative trauma disorders and workers compensation claims. J Occup Environ Med 1999;41(2):88-92.
2. Bernacki EJ, Guidera JA, Schaefer JA, et al. An ergonomics program designed to reduce the incidence of upper extremity work related musculoskeletal disorders. J Occup Environ Med 1999;41(12):1032-1041.
3. Musculoskeletal disorders and workplace factors. Accessed 4/9/13 http://www.cdc.gov/niosh/docs/97-141/pdfs/97-141.pdf  
4. Centers for Disease Control and Prevention. National Institute of Occupational Safety and Health. Ergonomics and musculoskeletal disorders. Available at: http://www.cdc.gov/niosh/topics/ergonomics/. Accessed July 1, 2008.
5. Johnson EG, Godges JJ, Lohman EB, et al. Disability self-assessment and upper quarter muscle balance between female dental hygienists and non-dental hygienists. J Dent Hyg 2003;77(6):217-223.
6. http://www.posturedontics.com/index.html Accessed 4/9/13
7. Parker, ME. Preserve your arm and hand health. Available at: http:// odontologia.uchile.cl/departamentos/restauradora/old/operatoria/operato/ doc/ergonomia%202.doc.com. Accessed March 23, 2007.
8. Nunn P. Positioning. Dimen Dent Hyg 2004;2(3):14-16.