Bone Mineral Density of Opposing Hips Using Dual Energy X-Ray Absorptiometry in Single-Beam and Fan-Beam Design

Abstract

Bone densitometry focuses on bone mineral area density (BMD in g/cm2) of the proximal femur and spine in anterior-posterior (AP) projections. Artifacts, such as osteoarthritis and osteophytic calcifications (OC) influence spine BMD, especially in AP scans. If only two sites are measured, as is usual in clinical practice, there may be advantages to measuring both femora rather than one femur and the spine. This would not be useful, however, if there was strong symmetry between the two sides. Furthermore, fan beam (FB) techniques have become available for measuring BMD with less data acquisition time. We compared densitometry of opposing femora in 421 patients (369 women, mean age 59.0 +/- 4.8; 52 men, mean age 56.9 +/- 7.4) using dual-energy X-ray absorptiometry (DXA): both single-beam (SB) and FB modes were evaluated. The precision errors in vivo (short- and midterm) of total BMD were 0.7% for both SB and FB. The total BMD and BMC of the left hip (0.817 +/- 0.124 g/cm2, 31. 3 +/- 6.4 g) were significantly (P < 0.001) higher (2-3%) than the corresponding values of the right hip (0.801 +/- 0.125 g/cm2, 30.3 +/- 6.3 g) in both SB and FB (left BMD 0.802 +/- 0.117 g/cm2, BMC 30. 0 +/- 6.2 g versus right BMD 0.795 +/- 0.117 g/cm2, BMC 29.3 +/- 6.3 g) modes. However, BMD of the femoral neck and Ward's triangle were not significantly (P > 0.05) different between the two sides. The FB results were generally 2% lower than SB results. There were highly significant (P < 0.001) correlations (r > 0.9) between both hips using both SB and FB. For diagnostic procedures and longitudinal studies, one should consider that there are bilateral differences of femur BMD, as well as differences between FB and SB scan modes.

Bone mineral density of the proximal femur after unilateral cementless total hip replacement

“…We, like Svendsen [21], did not find a statistically significant difference in the bone density of the left femur compared to the right. We found an increase of 3.7% of the left compared with the right in our small sample, while Franck found a statistically significant increase of the left compared to the right of 2% in a large sample of more than 400 patients [5].…”

“…Osteodensitometry has for many years been an established procedure for measuring changes in bone mineral density in the spine, femoral neck, distal radius and calcaneus [5,8,23]. During the last few years it has become possible to measure periprosthetic bone density following total hip replacement very accurately [2,12,17].…”

“…No consideration has however been given to the extent to which the non-operated hip can be used as a reference in retrospective studies. This is clearly important as there are intraindividual bone density differences [5,13,21] and the changes depend upon hip pathology [7,18]. In addition, one of the authors has previously reported an apparent increase in bone density directly following uncemented total hip replacement of up to 20% [17], which suggests difficulty in interpreting results.…”

Scanning both Hips and the Lumbar Vertebrae in Men Identifies More Patients with Osteoporosis than Scanning One Hip and the Lumbar Vertebrae

“…Arguments for scanning both hips include the differences between the left and right T-scores observed in some patients who may result in the patient being classified differently if one or both hips are scanned [1][2][3][4][5], and being able to follow up patients who fracture one hip or undergo hip replacement. Arguments against scanning both hips include the good correlation that exists between the BMD of both hips [6][7][8][9][10][11], unnecessary exposure to radiation and the time taken to perform the scan. On the other hand, exposure to radiation is now so small as to be negligible, and the time factor is no longer an issue with modern densitometers, many offer the ability of scanning both hips without repositioning the patient.…”

The prevalence of significant left–right hip bone mineral density differences among black and white women

“…However, a few studies report disagreement between opposing hip subregion BMD [11][12][13]. These reports lead some to suggest BMD measurement in both hips to reduce the chances of missing osteoporosis.…”