The relationship between thoracic kyphosis and age, and normative values across age groups: a systematic review of healthy adults

Abstract

Background Thoracic kyphosis is reported to increase with ageing. However, this relationship has not been systematically investigated. Peoples’ kyphosis often exceeds 40°, but 40° is the widely accepted cut-off and threshold for normality. Consequently, patients may be misclassified. Accurate restoration of kyphosis is important to avoid complications following spinal surgery. Therefore, specific reference values are needed. The objective of the review is to explore the relationship between thoracic kyphosis and age, provide normative values of kyphosis for different age groups and investigate the influence of gender and ethnicity. Methods Two reviewers independently conducted a literature search, including seven databases and the Spine Journal, from inception to April 2020. Quantitative observational studies on healthy adults (18 years of age or older) with no known pathologies, and measuring kyphosis with Cobb’s method, a flexicurve, or a kyphometer, were included. Study selection, data extraction, and study quality assessment (AQUA tool) were performed independently by two reviewers. The authors were contacted if clarifications were necessary. Correlation analysis and inferential statistics were performed (Microsoft Excel). The results are presented narratively. A modified GRADE was used for evidence quality assessment. Results Thirty-four studies (24 moderate-quality, 10 high-quality) were included (n = 7633). A positive moderate correlation between kyphosis and age was found (Spearman 0.52, p < 0.05, T5-T12). Peoples’ kyphosis resulted greater than 40° in 65% of the cases, and it was significantly smaller in individuals younger than 40 years old (x < 40) than in those older than 60 years old (x > 60) 75% of the time (p < 0.05). No differences between genders were found, although a greater kyphosis angle was observed in North Americans and Europeans. Conclusion Kyphosis increases with ageing, varying significantly between x < 40 and x > 60. Furthermore, kyphosis appears to be influenced by ethnicity, but not gender. Peoples’ thoracic sagittal curvature frequently exceeds 40°. Trial registration The review protocol was devised following the PRISMA-P Guidelines, and it was registered on PROSPERO (CRD42020175058) before study commencement.

Reference Values for 3D Spinal Posture Based on Videorasterstereographic Analyses of Healthy Adults

“…For ethical reasons, no such comparative studies based on healthy participants are available. The results presented here, however, reveal a strong functional agreement with the results derived from clinically established measurement approaches, such as X-ray or MRI/CT scans, and VRS measurements [ 33 , 34 , 39 ]. This underlines the potential of VRS to serve as a non-invasive, quick and objective alternative for spinal posture analysis in clinical practice, especially when the therapeutic focus lies in function-orientated clinical outcomes and when pre-post measurements are required.…”

“…The current study found a trend towards significant differences between young and old ( p < 0.001) and between middle and old ( p < 0.02) participants, indicating an increase in the VRS-measured parameter with increasing age. Comparable results were published in a recent systematic review based on radiography-based Cobb angle calculations [ 33 ]. The authors described an increase in thoracic kyphosis with aging but did not find that sex affected the spine parameters.…”

Standard values of the upper body posture in healthy adults with special regard to age, sex and BMI

“…Zapallá et al 56 concluded in their systematic review that kyphosis increases with age and varies significantly below 40 years and above 60 years, but not by gender 56 . Single studies could also confirm the correlation between the increase of thoracic kyphosis with age.…”

The Role of Thoracic Tilt in Identifying Thoracic Compensation and Predicting Proximal Junctional Kyphosis in Degenerative Lumbar Scoliosis

“…Previous studies mainly described thoracic compensation based on the angle of kyphosis but a mere measurement of kyphotic magnitude might be underpowered for the evaluation of thoracic compensation and the development of PJK. First, there is no consensus on the normal value of TK due to the effect of age and ethnicity 21–23 . The individual heterogeneity of normal TK ranging from 20° to 60° makes it difficult to identify hypokyphosis or hyperkyphosis 24 .…”

“…First, there is no consensus on the normal value of TK due to the effect of age and ethnicity. [21][22][23] The individual heterogeneity of normal TK ranging from 20°to 60°makes it difficult to identify hypokyphosis or hyperkyphosis. 24 Second, thoracic compensatory capacity may not manifest in kyphotic angle, only in degenerative spine.…”