The influence of osteoporotic vertebral fractures on global sagittal alignment in elderly patients: a systematic review and meta-analysis

Abstract

Background: Thoracic kyphosis, or loss of lumbar lordosis, is often equated with osteoporosis because vertebral fractures are assumed to be a major causative factor, in addition to degeneration related to age. Despite the few studies aiming to measure the natural change in global sagittal alignment (GSA) that occurs with advancing age, the overall effect of conservatively managed osteoporotic vertebral compression fractures (OVCF) on the GSA in the elderly remains poorly understood.

Objective: To systematically evaluate the relevant literature regarding the influence of OVCF on the GSA compared to patients of similar age without fractures using the following radiological parameters: Pelvic Incidence (PI), Pelvic Tilt (PT), Lumbar Lordosis (LL), Thoracic Kyphosis (TK), Sagittal Vertical Axis (SVA) and Spino-sacral Angle (SSA).

Methods: A systematic review of the English language literature dating up until October 2022, was undertaken utilizing the PRISMA guidelines.

Results: Of a total of 947 articles, 10 studies met the inclusion criteria (4 Level II, 4 level III and 2 level IV evidence) and were subsequently analyzed. Overall, 584 patients (8 studies) of mean age 73.7 years (69.3-77.1) had acute OVCF of one or more vertebra that were managed conservatively. The male to female ratio was 82:412. Five studies mentioned the number of fractured vertebrae, with a total of 393 in 269 patients (average of 1.4 fractured vertebrae per patient). Their pre-operative radiological parameters on standing X-rays showed a mean PI of 54.8°, PT 24°, LL 40.8°, TK 36.5°, PI-LL 14°, SVA 4.8 cm, and SSA 115°. In addition, 437 patients were used as a control group with osteoporosis without fractured vertebrae, (6 studies) with an average age of 72.4 years (67-77.8) and male to female ratio of 96:210 (5 studies). They all had upright X-rays to assess their global sagittal alignments. Radiological parameters showed an average PI of 54.3°, PT 17.3°, LL 43.4°, TK 31.25°, PI-LL 10.95°, SVA 1.27 cm and SSA 125°. A statistical analysis comparing the OVCF group with the control group (4 studies), showed a significant increase in PT of 5.97° (95%CI 2.63, 9.32; P < 0.0005), a significant increase in TK by 8.28° (95%CI 2.15, 14.4; P < 0.008), an increase in PI-LL by 6.72° (95%CI 3.39, 10.04; P < 0.0001), an increase in SVA by 1.35 cm (95%CI 0.88, 1.83; P < 0.00001), and a decrease in SSA by 10.2° (95%CI 10.3, 23.4; P < 0.00001).

Conclusion: Osteoporotic vertebral compression fractures managed conservatively appear to be a significant causate factor of global sagittal imbalance.

Keywords: Conservative management; Osteoporotic fractures; Sagittal alignment; Sagittal imbalance.