Changes in Thoracic Kyphosis and Thoracolumbar Kyphosis in Asymptomatic Korean Male Subjects Aged >50 Years: Do They Progress Above T5, T10, T12, or L2?

STUDY DESIGN: Retrospective analysis of prospectively collected data. PURPOSE: To evaluate the natural progression of segmental kyphosis in thoracic and thoracolumbar spine with advancing age. OVERVIEW OF LITERATURE: To our knowledge, the evolution of segmental thoracic kyphosis (TK) in individuals aged >50 years has not been reported. METHODS: Total 179 normal, asymptomatic Korean men were divided in to three groups (6th, 7th, and 8th decade) according to their age. Standard sagittal spinopelvic parameters, including TK and thoracolumbar kyphosis, were measured and subdivided into the following four segments: A (C7 upper end plate [UEP]-T5 UEP), B (T5 UEP-T10 UEP), C (T10 UEP-T12 lower end plate [LEP]), and D (T12 LEP-L2 LEP). These segments of the three study groups were analyzed. RESULTS: In segment B, the segmental kyphosis of group 3 (20.2°±8.0°) showed a statistically larger value than that of group 1 (15.6°±6.8°) and group 2 (16.7°±8.8°) (p=0.017). In segment C, the segmental kyphosis of group 2 (12.9°±6.5°) and group 3 (12.2°±7.1°) showed statistically larger values than that of group 1 (9.5°±6.2°) (p=0.016). The A and D segments of the three groups were not significantly different. CONCLUSIONS: Increased TK was observed in the middle (segment B) and lower (segment C) thoracic segments in normal asymptomatic male subjects with age. The results from the natural progression of segmental kyphosis with age would provide baseline reference data to help surgeons choose the optimal point of the upper instrumented vertebra level for preventing proximal junctional kyphosis.