INFLUENCE OF SPONDYLOPATHY ON BONE DENSITOMETRY USING DUAL-ENERGY X-RAY ABSORPTIOMETRY

Spinal cord injury (SCI), as well as other neuromuscular disorders, no t only results in osteopenia but also induces various patterns of osse ous, articular, and soft tissue alterations. In the spinal column, a v ariety of abnormalities occur. To evaluate the magnitude of discrepanc y of bone densitometry results caused by spondylopathy in SCI patients , we analyzed anteroposterior (AP) radiographs of the lumbar spine [ob tained within 1 month of dual energy X-ray absorptiometry (DXA)] in 11 6 SCI patients for various manifestations of spondylopathy, and matche d the result to each vertebral level (L1, 2, 3, 4). The dataset was st ratified by individual vertebra (totally 463 vertebrae) as valid (no d emonstrable other abnormal density on plain radiograph except osteopen ia), abnormal without, and abnormal with hardware. The influence of sp ondylopathy on bone densitometry results was determined by the analysi s of variance (ANOVA) and post hoc analysis. Our results showed that 2 27 (49%) vertebrae were abnormal. Significant elevation (15%, 15%, 18% , 20%; P < 0.001-P < 0.05) of bone mineral density (BMD; g/cm(2)) was observed at all levels (L1, 2, 3, 4, respectively), particularly at th ose abnormal vertebrae without hardware compared with valid (no other abnormal density on radiograph except osteopenia (Table 1). The L4 lev el was most severely affected. We concluded that in SCI patients, owin g to various secondary progressive skeletal abnormalities, particularl y neuropathic spondylopathy, can have strongly and significantly eleva ted vertebral bone densitometry results, which can obscure underlying osteoporosis, leading to misinterpretation and underestimation of frac ture risk. DXA, although characterized by improving spatial resolution , cannot replace radiography in establishing the magnitude of this ske letal pathology. Therefore, determination of bone density in this regi on with corresponding plain radiographs is highly recommended.