Is short vertebral height always an osteoporotic fracture? The Osteoporosis and Ultrasound Study (OPUS)

Abstract

Introduction and hypothesis: Diagnosis of prevalent osteoporotic vertebral fracture is complicated by normal or developmental variation in vertebral shape or size and non-osteoporotic deformities that appear to have ‘reduced’ height. Using our visual approach, the algorithm-based qualitative method (ABQ) a vertebra with apparent “reduced” height without evidence of osteoporotic endplate depression is classified as non-osteoporotic short vertebral height (SVH). We aimed to determine whether ABQ classification of SVH represents true or false negative diagnosis of osteoporotic vertebral fracture, by testing the associations with clinical outcomes of osteoporosis or vertebral fracture. Methods: The ABQ method was used to assess spinal radiographs acquired at baseline for a subset of 904 postmenopausal women participating in the Osteoporosis and Ultrasound Study (OPUS). The sample was enriched with vertebral fracture cases. Subjects were categorized by ABQ diagnosis as (i) normal, (ii) non-osteoporotic short vertebral height (SVH) or (iii) osteoporotic vertebral fracture. Results: Women were classified by ABQ as follows: osteoporotic vertebral fracture, n = 231; SVH, n = 376 and normal, n = 297. Women with vertebral fracture were older, with lower height, weight and height loss than those classified as SVH or normal. Women with SVH were heavier and older, with greater historical height loss than normal women. Age-adjusted SD units ( z-scores) for BMD were lower than expected among women with osteoporotic vertebral fracture, but not among those with SVH. There was a significant association between diagnosis of osteoporotic vertebral fracture and history of low-trauma non-vertebral and vertebral fracture ( p < 0.001, odds ratios = 3.2 and 20.6, respectively). There was also an association between diagnosis of SVH and previous low-trauma non-vertebral fracture ( p < 0.05, odds ratio = 1.7). Conclusions: Short vertebral height without evidence of central endplate fracture in postmenopausal women is largely unrelated to osteoporosis. Quantitative morphometry should not be used alone for the assessment of vertebral fracture in clinical decision making: we recommend differential diagnosis of morphometric vertebral deformities by an expert reader to rule out non-osteoporotic deformities with short vertebral height.