Exploring technology for clinical applications and analysis of factors associated with postural control in older adults with idiopathic neck pain

Abstract

Neck pain in older adults is common and has been associated with reduced postural control. However, the mechanisms underlying neck pain-related postural control deficits remain unknown. Unravelling this complex clinical phenomenon is important given the fact that older adults with balance deficits are at risk of falls. Furthermore, falls in older adults may potentially lead to serious consequences and place a burden on public health. This thesis aimed to explore new measurement tools and technique related to cervical spine impairments and postural control that may be potentially useful in research and in the clinical setting, and sought to better understand the mechanisms underpinning neck pain-related postural control deficits in older adults. Studies 1, 2 and 3 investigated the use of technology, i.e. the smart phone, the Microsoft Kinect and the Nintendo Wii Board to measure cervical range-of-motion, thoracic kyphosis and hallux flexor strength respectively. The results of study 1 showed that the Android phone was valid and reliable in the sagittal and coronal plane but not in the transverse plane. In other words, range-of-motion testing of cervical flexion and extension and lateral flexion were valid and reliable but not rotation in sitting. Study 2 demonstrated that the Microsoft Kinect was valid and reliable to measure thoracic kyphosis and could potentially bridge the gap of accessibility and ease of use in current measurement tools to regularly assess this important dimension of spinal posture. Study 3 evaluated the reliability of the Nintendo Wii Board to measure hallux flexor strength and showed that it was reliable. Because big toe strength has been previously shown to be an independent factor for balance in older adults, this newly developed device using the Nintendo Wii Board provides an affordable and reliable tool for clinic use. Studies 4, 5 and 6 were cross-sectional studies aimed to further develop our understanding of how neck pain or neck pain-related impairments may impact postural control. Specifically, study 4 explored standing postural control mechanisms using new measures of signal frequency (wavelet analysis) and complexity (sample entropy) in older adults with neck pain. This study highlighted the use of wavelet analysis to reveal new insights into postural control mechanisms and this analytical technique was then used in studies 5 & 6. However, no consistent results could be obtained when comparing the results of wavelet analysis between studies 4 and that of 5 & 6. It is clear that more research needs to be done to determine the usefulness of employing wavelet analysis in revealing mechanistic insights into postural control in older adults with neck pain. Studies 5 and 6 shed light on previously unknown factors influencing postural control in older adults with neck pain. Study 5 investigated potential differences in known predictors of postural control between older adults with and without neck pain. In particular, physical activity levels, lower limb motor and sensory function, vestibular function and visual contrast sensitivity were no different in individuals with and without neck pain. Study 6 investigated the associations of cervical spine impairments with poor postural control in older adults with neck pain. This study highlighted that neck pain moderated the relationship between static postural sway and four variables: forward head posture angles, a positive Dix-hallpike test, age and higher levels of physical activity. In addition, poor dynamic postural control was associated with greater dizziness disability, fear of movement and age. In summary, this thesis advocates the use of technology, specifically the Microsoft Kinect to measure thoracic kyphosis and the Wii Balance Board application to measure hallux flexor strength, but not the Android phone to measure seated cervical range-of- motion, in the clinical setting. There is great potential for these technologies to break the existent barriers that practitioners currently face such as affordability, inaccessibility and ease of use. Further, this thesis identified factors that contribute to neck pain-related postural control deficits. The findings suggest that the mechanisms underpinning postural control deficits in neck pain are complex and may serve as a basis for future neuro-imaging studies to explore the role of the central nervous system and its integration of somatosensory input in maintaining postural stability in older adults with neck pain. Having a greater understanding of these mechanisms is important for developing management strategies to improve postural stability and potentially reduce falls risk. Future interventional studies are also required to determine if improving head posture and vestibular function will improve standing postural stability, and if reducing dizziness and fear of movement will increase dynamic stability in older adults with neck pain.