Original Article
Effect of Leg Rotation on Hip Bone Mineral Density Measurements

https://doi.org/10.1385/JCD:6:4:331Get rights and content

Abstract

Bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) is widely used in the management of patients with osteoporosis. Factors, which are specific to machine or to operator, can influence the accuracy and precision of BMD estimations. We studied the effect of leg rotation by 10° either internally or externally from the standard position in a group of 50 women (average age 54.9, SD = 11.1 yr) who were free of bone active diseases or medications. External rotation of leg by 10° from the customary position increased the average BMD by 0.005, 0.003, and 0.036 g/cm2 in the femoral neck, trochanter, and Ward's area (p = 0.119, 0.309, and <0.001), respectively. Internal rotation of leg by 10° from the customary position decreased the average BMD by 0.009, 0.005, and 0.006 g/cm2 in the femoral neck, trochanter, and Ward's area (p = <0.001, 0.008, and <0.001), respectively. The number of subjects qualified for the diagnosis of osteoporosis based on the T-scores (equal to or below –2.5) of the femoral neck and trochanter did not change significantly in three different positions (18% in the customary position and after the external rotation and 14% after the internal rotation). A significant change in the femoral neck BMD (defined as 2.77 × precision error) was seen in 12% of subjects after the internal rotation and 8% after the external rotation. Our data emphasize the need for proper positioning of the hip during DXA scanning. Malrotation of the hip can be an important confounding factor when interpreting serial BMD values.

References (10)

There are more references available in the full text version of this article.

Cited by (40)

  • MRI-based assessment of proximal femur strength compared to mechanical testing

    2020, Bone
    Citation Excerpt :

    The present study had comparable results to those studies, with an average age of 76 and an average failure load of 3300 N, thus suggesting that MRI-derived FEA of the proximal femur would be sensitive enough to evaluate age-related changes in bone quality. It is important to note that, although the referenced DXA correlation values seem relatively close to those from QCT FEA, DXA scans of cadaveric specimens are performed in well-regulated settings which control for the soft tissue thickness and the scanning location [61–63]. This effectively reduces errors in DXA's quantifications and produces correlations which are vastly superior to what they would be in vivo, whereas the MRI- and QCT-derived methods would be more robust [63].

  • Quality in dual-energy X-ray absorptiometry scans

    2017, Bone
    Citation Excerpt :

    The difference in BMD with differences in rotation was generally greater in the femoral neck as compared to the total hip. Lekamwasam and Lenora studied the effects of 10° of internal or external rotation on hip BMD in 50 women using a Norland Eclipse XR scanner (Norland Corp, Fort Atkinson, WI) [101]. There was a significant change in the femoral neck (2.77 × precision error) in 12% of subjects after internal rotation and in 8% after external rotation.

  • Effect of Clothing on Measurement of Bone Mineral Density

    2016, Journal of Clinical Densitometry
View all citing articles on Scopus
View full text