• Zeeshan M Sardar, Meghan Cerpa, Fthimnir Hassan, Michael Kelly, Jean-Charles Le Huec, Stephane Bourret, Kazuhiro Hasegawa, Hee-Kit Wong, Gabriel Liu, Dennis HeyHwee WengHWDepartment of Orthopedic Surgery, National University Hospital (Singapore), Singapore, Singapore., Hend Riahi, and Lawrence Lenke.
• Department of Orthopedic Surgery, Columbia University Medical Center, The Och Spine Hospital at New York Presbyterian, New York, NY.
• Spine. 2022 Oct 1; 47 (19): 1372-1381.

Study DesignMulticenter Cohort.ObjectiveAssess normative values of sagittal spinal and lower extremity alignment in asymptomatic volunteers stratified by age and gender.Summary Of Background DataOur understanding of ideal sagittal alignment is still evolving. The Multiethnic Alignment Normative Study (MEANS) investigated skeletal alignment of the largest multiethnic cohort of asymptomatic adult volunteers. We aim to assess normative values of sagittal spinal and lower extremity alignment in asymptomatic volunteers stratified by age and gender.Materials And MethodsAsymptomatic volunteers between the ages of 18-80 years were enrolled prospectively and then analyzed retrospectively from six different centers. Volunteers included reported no significant neck or back pain, nor any known spinal disorder(s). All volunteers underwent a standing full-body or full-spine low-dose stereoradiograph.ResultsMEANS consisted of 468 volunteers with a mean age of 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°. LL did not show significant differences across the five age groups. TK showed a significant difference based on age ( P <0.0001). Sagittal vertical axis increased across age groups from -14.2 mm in young adults to 17.0 mm in patients >64. Similar trend was seen for T1 pelvic angle with a mean of 5.0° in young adults and 13.7° in those older than age 64. Knee flexion increased across age groups without a significant change in odontoid-knee distance which is a surrogate for the center of the head aligned over the knees.ConclusionsIn asymptomatic volunteers, sagittal alignment parameters showed a slow and steady change across age groups exemplified by an increase in TK. However, LL did not show a significant decrease across age groups. Volunteers used compensatory mechanisms such as slight pelvis retroversion, knee flexion, and neck extension to maintain an aligned sagittal posture with their head centered over their knees (odontoid-knee).Level Of Evidence3.Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.

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