When is Growth the Greatest? Spine and Total Body Growth in Idiopathic Scoliosis Through Sanders Maturation Stages 2, 3A, 3B, and 4

Background:Sanders maturation stages (SMS) 2 to 4 represent periods of rapid growth and are considered ideal candidates for growth modulation surgery, such as anterior vertebral body tethering. A detailed assessment of spine growth during these stages is essential but limited. This study aimed to clarify the differences in growth rates for spine and total body height across SMS 2, 3A, 3B, and 4, as well as to assess cumulative growth until skeletal maturity for these stages.Methods:This single-center, retrospective, case-control longitudinal study evaluated consecutive patients with idiopathic scoliosis staged SMS 2 to 4. T1-S1 spine height, total body height, and curve magnitude were measured at each visit. Monthly growth rates for spine and total body height were calculated between baseline and first follow-up visit (6-12 months). In a subset followed to skeletal maturity, cumulative spine and total body height gain were assessed. To account for height loss due to scoliosis, spine and total body height were adjusted for curve magnitude using validated formulas. Multivariate linear regression models were employed to evaluate the relationship between SMS and growth, adjusting for confounding factors.Results:A total of 517 patients (68% female) were included. Spine height growth was highest in patients at SMS 3A, approximately 1.4 times stage 2, 1.5 times stage 3B, and 1.8 times stage 4. Total body height growth rates were comparable between SMS 2 and 3A, both significantly exceeding SMS 3B and 4. Among 314 patients followed to skeletal maturity, cumulative growth in spine and total body height was greatest in patients at SMS 2.Conclusions:This study demonstrated that spinal growth was most pronounced in patients at SMS 3A, while total body height growth was greatest during SMS 2 and 3A. Less mature patients exhibited greater cumulative growth potential in both spine and total body height. These findings provide crucial insights for determining the optimal timing of growth modulation surgery.Level of Evidence:Level III Case-control study. See Instructions for Authors for a complete description of levels of evidence.