Clinical Outcomes and Risk Factors Associated with Spinal Kyphotic Deformity Following Osteoporotic Vertebral Fracture

<b>Background:</b> Osteoporotic vertebral fractures (OVFs) often lead to poor global sagittal alignment (GSA) and reduced quality of life (QOL). While pseudarthrosis and kyphotic deformities are well-known predictors of conservative treatment failure, the impact of vertebral collapse, paraspinal muscle degeneration, sarcopenia, and nutritional status on GSA remains unclear. This study investigated the relationship between these factors and GSA in patients with conservatively treated OVFs. <b>Methods:</b> This post hoc analysis of a multicenter prospective observational study included 70 patients (single OVF; age ≥ 60 years; 12-month follow-up). Radiographic parameters, paraspinal muscle degeneration, and nutritional status were assessed. GSA was categorized based on the sagittal vertical axis (SVA [mm]): normal (SVA ≤ 40), moderate (40 ≤ SVA ≤ 95), and severe (SVA > 95). Clinical outcomes were assessed using the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), Oswestry Disability Index (ODI), and visual analog scale (VAS). <b>Results:</b> At 12 months, 22.9% of patients had severe GSA and showed significantly lower JOABPEQ gait dysfunction scores (<i>p</i> = 0.01), higher ODI scores (<i>p</i> < 0.01), and reduced lower lumbar lordosis (<i>p</i> = 0.01). A higher prevalence of lower lumbar OVFs, including prior fractures, was observed in the severe group. No significant correlations were found between GSA and paraspinal muscle degeneration or nutritional status. <b>Conclusions:</b> OVFs in the lower lumbar spine significantly contributed to GSA deterioration. This indicates their critical role in sagittal alignment. Although paraspinal muscle degeneration and malnutrition are common in OVFs, their direct impact on GSA is limited. These findings highlight the need for targeted strategies to manage lumbar OVFs and prevent sagittal malalignment.