Effects of thoracic kyphosis and forward head posture on cervical range of motion in older adults

It is unclear how age-related postural changes such as thoracic spine kyphosis influence cervical range-of-motion (ROM) in patients with cervical spine dysfunction. The purpose of this study was to explore the mediating effects of forward head posture (FHP) on the relationship between thoracic kyphosis and cervical mobility in older adults with cervical spine dysfunction. Fifty-one older adults (30 females, mean[SD]age = 66[4.9] years) with cervical spine dysfunction - that is, cervical pain with or without referred pain, numbness or paraesthesia - participated. Pain-related disability was measured using the neck disability index (NDI). Thoracic kyphosis was measured using a flexicurve. FHP was assessed via the craniovertebral angle (CVA) measured from a digitized, lateral-view photograph of each subject. Cervical ROM - namely, upper and general cervical rotation and cervical flexion - was measured by the Cervical Range-of-Motion (CROM) device. Greater thoracic kyphosis was significantly associated with lesser CVA (Spearman ρ = -0.48) whereas greater CVA was significantly associated with greater cervical flexion (Spearman ρ = 0.30) and general rotation ROM (ρ = 0.33), but not with upper cervical rotation ROM (ρ = 0.15). Bootstrap mediational analyses, adjusted for age, gender, weight and NDI, revealed significant indirect effects of thoracic kyphosis on cervical flexion and general rotation ROM through a FHP. Our results show that FHP mediated the relationship between thoracic kyphosis and cervical ROM, specifically general cervical rotation and flexion. These results not only support the justifiable attention given to addressing FHP to improve cervical impairments, but they also suggest that addressing thoracic kyphosis impairments may constitute an "upstream" approach.