Importance of identifying vertebral fracture (VF)
Osteoporosis is the most common metabolic bone disease, estimated to affect more than 200 million people worldwide (1). Osteoporosis is characterized by low bone mass and micro-arch
Importance of identifying vertebral fracture (VF)
Osteoporosis is the most common metabolic bone disease, estimated to affect more than 200 million people worldwide (1). Osteoporosis is characterized by low bone mass and micro-architectural deterioration, which leads to bone fragility and consequent increase in fracture risk. It is often termed the “silent epidemic” because clinical factors (age, lifestyle, family history, diet) are not very sensitive markers of the condition, and quite often bone loss becomes apparent only after a typical fracture has occurred.
VFs are the most common osteoporotic fracture. A VF, after minor trauma, is a hallmark of osteoporosis. Thirty to fifty percent of women and 20–30% of men experience a VF at some points in their life (2). A single atraumatic VF can lead to the diagnosis of osteoporosis. According to the National Osteoporosis Foundation 2013 clinical guide, ‘‘A vertebral fracture is consistent with a diagnosis of osteoporosis, even in the absence of a bone density diagnosis, and is an indication for pharmacologic treatment with osteoporosis medication to reduce fracture risk’’ (1). In one study of osteoporotic fractures, only 39% of individuals with a VF had a World Health Organization diagnosis of osteoporosis by dual energy X-ray absorptiometry (DXA) at the spine, only 25% by DXA of the total hip (3). Prevalent VFs increase the risk of future vertebral and non-vertebral osteoporotic fracture independent of bone mineral density (BMD) (2).
It had been reported that spinal fractures are associated with increased mortality which at year-5 is nearly identical to that from femoral neck fractures (4), though it is not clear if this is cause-and-effect or if the fracture is simply a marker for frailty (3). A low-energy occult VF, when recognized, is a sufficient indication to initiate medical osteoporosis therapy independent of BMD results. Appropriate management of osteoporosis can reduce future fracture risk. It is important to identify and report VFs accurately and clearly, so that appropriate investigation and treatment can be instigated (5). Theoretically, by mitigating anterior compressive loads, the number of occult VFs that become clinically apparent might be reduced.
Osteoporotic VFs are frequently asymptomatic. The majority are morphometric (75%), that is, clinically silent without an incident of back pain, rather than with clinical symptoms (25%) (6). Incidental osteoporotic VFs are usually under-reported on radiograph and CT (7-10). The sensitivity of axial CT images in detecting these fractures is poor, sagittal reformation is recommended to improve the detection rate (10).
VFs have an important influence on prognosis and morbidity in the osteoporotic patient (11,12). The accurate and clear reporting of VFs is essential to ensure that patients with osteoporosis receive appropriate treatment. Radiologist has an important role in the diagnosis of this disease. Exclusion of other causes of VF is crucial, in particular malignant disease. Once the diagnosis of osteoporosis is made and initiation of therapy is planned, additional BMD measurements may be useful (5).
Radiographic definitions of osteoporotic vertebral facture
The radiographic signs of osteoporotic VF include: (I) loss of self-similarity between adjacent vertebrae; (II) loss of parallelism between adjacent end-plates; (III) end-plate disruption as they are impacted into the vertebral body; (IV) fractures of vertebral cortex or end-plate characterized by cortical discontinuities; (V) buckling of the vertebral cortex, especially anteriorly (13). A number of morphometrical and radiological methods for detecting osteoporotic VF have been proposed, but there is no consensus regarding the definition of VFs (5,13-16). We feel a combined approach based on standardized radiologic evaluation by experts aided by quantitative measurement to ensure the consistence is the most appropriate approach to detect and classify VF.
Since vertebrae generally fail by compression in axial loading, these fractures are often called vertebral compression fractures. The semi-quantitative (SQ) criteria proposed by Genant et al. is commonly used for identifying VF (17). According to its criteria, a normal vertebra is defined as grade 0; 20–25% reduction in anterior, middle, and/or posterior vertebral height and 10–20% in area is defined as grade 1 deformity; a 26–40% reduction in any height and 20–40% in area is defined as grade 2 deformity; and a >40% reduction in any height and area is regarded as grade 3 deformity vertebra (Figures 1-3). A grade 0.5 is used to designate a borderline deformed. Genant et al.’s SQ approach is applied to vertebrae T4 to L4 on the spine radiograph. Visualizing T1–T3 is often limited due to overlying of the shoulders and L5 due to overlying pelvis. Osteoporotic VF above T4 is also very rare. Vertebra L5 is also subject to considerable morphologic variation between individuals, such that very often vertebral anterior height measurement is much larger than posterior height (Figure 4). Genant et al. described the impo