Medical Utility of near Infrared Spectroscopy in Low Back Musculoskeletal Health and Disorders

Abstract

The potential application of near infrared (NIR) spectroscopy has opened doors for many research investigations related to occupational health, specifically in low back muscle research. This review addressed haemodynamic measurements of paraspinal muscles within the context of low back musculoskeletal health and disorders. Systematic online English language searches were conducted using MEDLINE, EMBASE, Science Direct and Scopus. A study was included if it was focused on NIR spectroscopy application to the back region and was also published in the English language. A study was excluded if the main focus was either on upper/lower extremity specific investigations, or the experimental protocol was ambiguous, or the measures utilised were other than spectroscopy-derived haemodynamics. In total, 37 low back studies were included in the review. Studies were mainly classified into five categories: (i) postural variation, (ii) occupational exposure, (iii) aetiology of low back disorders, (iv) analysis of adipose tissue thickness on spectroscopy-derived measurements and (v) reliability of optical spectroscopy measurements. Seventeen studies were focused on the basic (patho) physiology of the low back musculature during a variety of postural variations. Thirteen studies were specific to occupational activities, whereas 10 investigations were related to low back musculoskeletal disorders. Nine studies examined the influence of adipose tissue thickness measured at the erector spinae region on haemodynamic responses. Reliability of spectroscopy-derived responses was reported in 10 studies. This systematic review supports the need for more spectroscopy-related investigations relevant to work-related activities and specific to low back musculoskeletal disorders. Rigorous statistical analysis is needed in examining the influence of adipose tissue thickness on haemodynamic responses. Although high reliability of spectroscopy-derived responses was found in the majority of studies, to date there are no investigations that have established their reliability in the low back pain patient population. More importantly, a proper calibration technique to identify the physiological minimum in the paraspinal muscle region is still elusive. Overall, understanding injury mechanisms for low back pain and other associated musculoskeletal disorders with NIR oximeters is still in its infancy. However, with the advent of advanced optical spectroscopy systems in the last decade, the potential for innovative use of NIR oximeters in low back musculoskeletal health-related research is promising.