Читать книгу Musculoskeletal Disorders - Sean Gallagher - Страница 17

LBP is a typically benign condition, though one of the most expensive conditions in industrialized countries (Mayer & Gatchel, 1988). It is associated with substantial loss in the quality of life (Punnett, 2005). LBP is characterized by pain that can range from a dull ache to a sharp, intense, and disabling pain. The focus of this pain is generally in and around the lumbar portion of the spinal column. The lumbar spine is a complex structure, consisting of vertebral bones, intervertebral discs, cartilage endplates, and nerves, and with all of these structures, there are many possible sources of pain.

LBP is often episodic, with most cases being relatively short‐lived. In fact, 40–90% of people obtain complete relief after 6 weeks (Manchikanti, 2000). LBP is often classified by duration as acute (pain lasting less than 6 weeks), sub‐chronic (6–12 weeks), or chronic (more than 12 weeks) (Koes et al., 2010). The condition may be further classified by the underlying cause as mechanical, nonmechanical, or referred pain (Manusov, 2012). While most pain is self‐limited, pain continuing after 3 months of LBP is considered chronic, as this is well beyond the 6‐ to 12‐week time period that normal connective tissues take to heal (Chawla, 2018).

Recent data suggest that approximately 38.5% of work‐related MSDs in the United States in 2016 involved the lower back (Bureau of Labor Statistics, 2018). Many occupational tasks have been associated with a higher prevalence of recurrent LBP, including lifting and/or carrying heavy weight and adoption of awkward postures such as bending, twisting, squatting, and kneeling (Amorim et al., 2019; Hoogendoorn, Poppel, Bongers, Koes, & Bouter, 1999). Exposure to whole‐body vibration in drivers (e.g., tractor drivers, taxi drivers, and helicopter pilots) appears to contribute heavily to LBP risk (Bovenzi, Schust, & Mauro, 2017), as does adoption of awkward postures when driving (Bovenzi, Schust, Menzel, Prodi, & Mauro, 2015). In the professional driving occupations cited earlier, there is also an exposure‐dependent increase in the development of degenerative changes in the spinal column, resulting in spondylolisthesis (Byeon et al., 2013; Chen, Chan, Katz, Chang, & Christian, 2004; Christ & Dupuis, 1966; Froom et al., 1984). The degenerative changes referenced earlier are thought to be due to repetitive mechanical loading and shock to the spinal column that lead to damage accumulation and degeneration (Bovenzi et al., 2017). Individual differences likely impact the effects of loading due to differences in muscle mass and strength as well as due to differences in kinematic and muscle recruitment strategies (Gallagher & Heberger, 2015; Marras et al., 2006).