Severe thoracic kyphosis in the older patient in the absence of vertebral fracture: association of extreme curve with age

Abstract

Background and purpose: Limited data exist on the natural history of thoracic kyphosis in elderly patients. The purpose of this study was to determine the statistical distribution of the thoracic kyphotic angle (TKA) measurement in older patients without vertebral body abnormalities when compared with a young population.

Methods: The TKA was measured by Cobb angle on digital lateral chest radiographs in 90 patients >65 years of age, 60 patients 51-65 years of age, 67 patients 36-50 years of age, and 63 patients 18-35 years of age. Patients with vertebral compression, vertebral body angulation, congenital anomaly, or significant scoliosis were excluded.

Results: In patients >65 years of age, average TKA was 41.9 degrees , but the distribution was unexpectedly bimodal, with a low mode at 28.3 degrees and an upper mode at 51.5 degrees (P < .001). Elderly women and men independently demonstrated a bimodal TKA distribution. Two-thirds of elderly women and half of elderly men had a TKA >40 degrees (upper mode). In young patients, average TKA was 26.8 degrees . In middle-aged patients, TKA was intermediate and nonbimodal.

Conclusion: The TKA distribution in elderly patients (>65 years) without vertebral body abnormality is unexpectedly bimodal (non-normal distribution) with a subpopulation of patients significantly more affected by extreme kyphosis. Extreme thoracic kyphosis therefore occurs independently in a large subset of people, in the absence of vertebral wedge compression. The development of extreme thoracic kyphosis might contribute to excess biomechanical stress in the spine and may identify a population at risk for future vertebral compression fracture in particular at the thoracolumbar junction.

Fig 1.

Workstation measurement of thoracic spine Cobb angle. A, Initial angles placed perpendicular to the upper vertebral endplate of T2 (black arrow) and lower vertebral endplate of T12 (white arrow) with the angle measurement function available on the Stentor workstation system. B, Cobb angle measurement obtained by angle measurement of the intersection between perpendiculars to the vertebral endplates (black arrowhead).

Fig 2.

TKA for men and women >65 years of age.

Fig 3.

TKA for men >65 years of age.

Fig 4.

TKA for women >65 years of age.

Fig 5.

Lateral chest radiograph of a 70-year-old man with an extreme thoracic kyphotic angle (65° Cobb angle) but no vertebral body compression or angulation.

Fig 6.

Age distribution for men >65 years of age.

Fig 7.

Age distribution for women >65 years of age.

Fig 8.

Lateral chest radiograph of a 77-year-old woman with degenerative disk disease and asymmetric disk height loss (white arrows) contributing to increased thoracic kyphotic angle (56° Cobb angle).