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Xu et al. | Journal of Clinical and Translational Research 2023; 9(5): 340-346 343

Figure 2. The correlations between the cervical and distal spinal parameters showed an increasing trend with aging, and TIA and TS were significantly
correlated with TK, but no definite trend in correlation was detected between TIA and TK.
Abbreviations: TS: T1 slope; TIA: Thoracic inlet angle; TK: Thoracic kyphosis.
4. Discussion and lumbar alignments partially explains the trend observed with
aging between cervical and distal spinal alignments.
In recent years, an increasing number of studies has reported Furthermore, the correlations between cervical and distal spinal
the correlations between cervical and thoracolumbar pelvic parameters were compared among the different groups, and the
alignments. For instance, Lee et al. discovered factors impacting results demonstrated that the correlations between upper cervical
cervical spine sagittal balance in asymptomatic adults and spine parameters (C0-1 CA, C1-2 CA, and C0-2 CA) and distal
identified the T1 slope as a key factor [8]. At the same time, spinal parameters were all below 0.3, while the correlations
other scholars have found that C7 SVA is strongly correlated with between subaxial cervical parameters (C2-7 CA and C2-7 SVA)
C2-7 CA [5]; the C7 slope is a link between the occipitocervical and distal spinal parameters showed an increasing trend with time.
and thoracolumbar spine [9]. These results all established the To maintain the sagittal balance of the global spine, changes in the
correlations between the cervical alignments and the distal spinal thoracic and lumbar alignment require compensation through the
alignments. Our previous studies evinced that some cervical
spine parameters tend to vary with aging [7]. Meanwhile, the involvement of the cervical spine [19]. Nonetheless, this balance
interaction between cervical and distal spine alignments has also maintenance is supposed to be sufficient through subaxial cervical
been reported [10,11]. Therefore, the trends of their correlations alignment compensation and does not necessitate the involvement of
with aging, which have not been focused on so far, deserve further upper cervical alignments. Therefore, there was a weak correlation
investigation. between upper cervical spinal and distal spinal parameters.
Asymptomatic populations were stratified according to age, At the same time, the correlations between C2-7 CA and TK,
and sagittal parameters of the global spine were measured. Our C2-7 SVA and SS, as well as C2-7 SVA and C7-S1 SVA showed
study determined a gradual increase in C1-2 CA, C0-2 CA, an increasing trend with age in our study. This signified that in the
C2-7 CA, C2-7 SVA, NT, TS, TIA, TK, PT, and C7-S1 SVA elderly population, there is a strong correlation between cervical
with aging. On the contrary, a gradual decrease in LL and SS lordosis and thoracic kyphosis and between the forward translation
was noted with aging. These results are consistent with those of the cervical spine and the forward translation of the global
of Yukawa et al. [12]. Moreover, the results of cervical spine spine. These phenomena occur naturally over time, which might
parameters were also comparable to those of our previous be related to spinal degeneration and atrophy of the paravertebral
research [7], corroborating that sagittal spine parameters show a extensor. Indeed, recent studies corroborated that muscle atrophy
tendency to change with age. Notably, the loss of lumbar lordosis and spinal degeneration lead to corresponding alterations in
attributed to disk degeneration has been universally recognized spinal and pelvic alignments [20-25]. Yang [20] found a negative
as the initiator of the degenerative cascade, eventually leading correlation between the atrophy of the paravertebral extensor and
to reciprocal changes in other regions [13]. Thoracic alignments cervical sagittal parameters, while Okada [21] reported that changes
serve as a bridge between cervical and distal spinal alignments. in cervical spinal alignment contribute to the progression of disc
As individuals age, the thoracic vertebras begin to manifest degeneration at C7-T1. In other words, degeneration increased
adaptive changes, with a wedge-shaped which is narrow at the the correlation between cervical lordosis and thoracic kyphosis
front and wide at the back [14,15], resulting in physiological and that between cervical forward translation and global spine
kyphosis. Besides, earlier studies described that thoracic kyphosis forward translation. We speculate that in the youth population,
was progressively aggravated during the aging process owing well-developed cervical paravertebral extensors, intervertebral
to the accumulation of mechanical load [14,16], especially in discs, and intervertebral joints aid in supporting the head, thereby
women and elderly osteoporotic patients [17,18]. It is worthwhile maintaining the horizontal gaze and keeping the head’s central
emphasizing that thoracic kyphosis steadily worsens over time, gravity line close to the pelvis. However, following paravertebral
and lumbar lordosis concurrently decreases, leading to adaptive extensor atrophy, and intervertebral disc and intervertebral joint
adjustments in the spine, such as increased cervical lordosis and degeneration, the cervical spine not only becomes more lordotic
decreased pelvic inclination. The synergistic effect of thoracic to compensate for the increased thoracic kyphosis but also leans
DOI: http://dx.doi.org/10.18053/jctres.09.202305.23-00059