Bone mineral density differences between femurs of scoliotic patients undergoing dual-energy X-ray absorptiometry

Abstract

To investigate whether a difference exists in the bone mineral density (BMD) between femurs in scoliotic patients undergoing dual-energy X-ray absorptiometry (DXA) and whether this difference is related to spine convexity. Of 1080 consecutive patients who underwent DXA, 127 had lumbar scoliosis seen at DXA. Further, after excluding 30 patients with previous osteoporotic fractures, metallic/image artefacts, soft-tissue calcifications, the BMD differences between femurs of 97 scoliotic patients (94 females; mean age 67±11 years) were analysed. Femurs were classified as ipsilateral or contralateral to the spine convexity. Least significant change was used as a threshold of measurement precision. Differences between femoral neck BMD in respect of and regardless of spine convexity were calculated for each patient. Student's t-test and Wilcoxon's signed-rank test were used to assess significance. Fifty-nine of 97 patients (61%) had left-sided scoliosis. Osteoporosis was found in 32/97 patients (33%), osteopenia in 54/97 (56%), and 11/97 (11%) had a normal T-score. Of 97 patients, 46 (47%) had ipsilateral BMD<contralateral BMD. Regardless of spine convexity, 66/97 patients (68%) had different BMD values between femurs. Among them, variation of densitometric diagnosis was seen in 29/66 patients (44%), and in 29/97 patients overall (30%). Differences in the femoral neck BMD exist between femurs of scoliotic patients undergoing DXA. Thus, bilateral femoral DXA acquisition is recommended.