The researchers analyzed asymptomatic volunteers’ sagittal spinal and lower extremity alignment according to age and gender norms. There was still room for growth in their knowledge of what constitutes optimal sagittal alignment. The largest multiethnic cohort of asymptomatic adult volunteers had their skeletal alignment studied as part of the Multiethnic Alignment Normative Study (MEANS). The researchers plan to analyze asymptomatic participants’ sagittal spinal and lower extremity alignment relative to age and gender norms. Prospective enrollment and retrospective analysis of asymptomatic volunteers aged 18 to 80 from 6 locations. None of the volunteers had serious back or neck discomfort, and nobody had a diagnosed spinal disease(s). All participants had a low-dose stereoradiography of their entire bodies or spines taken while standing still. The average age of the 468 participants in MEANS was 40.4±14.8 years. Thoracic kyphosis (TK) from T4 to T12 showed a mean of 37.4±10.9°. The average L1–S1 lumbar lordosis (LL) was −57.4±11.3°. There were no statistically significant LL variations between the 5 age groups. However, it was shown that there was a statistically significant difference in TK between age groups (P<0.0001). The sagittal vertical axis grew from −14.2 millimeters in young adults to 17.0 millimeters in patients aged 64 and above. T1 pelvic angle followed a similar pattern, with a mean of 5.0° in young adults and 13.7° in those over 64 years old. The odontoid-knee distance was a surrogate for the center of the head to be positioned above the knees, and it has been found to rise throughout age groups while knee flexion has remained relatively constant. For example, as people age, their sagittal alignment metrics (such as TK) gradually shift upwards. While LL decreased slightly with age, this trend was not consistent. In order to keep their heads centered over their knees in a sagittal alignment, volunteers adopted compensating strategies such as mild pelvic retroversion, knee flexion, and neck extension (odontoid-knee).
