Measurement of distal forearm bone mineral density: can different forearm segments be used interchangeably ?

DEXA sensitivity analysis in patients with adult spinal deformity

BACKGROUND

Adult spinal deformity (ASD) is a debilitating condition that commonly requires surgical intervention. However, ASD patients may also present with osteoporosis, predisposing them to surgical complications and failure of instrumentation. As a result, proper detection of low bone mineral density (BMD) is critical in order to ensure proper patient care. Typically dual-energy x-ray absorptiometry (DEXA) scans are performed on the hip and spine. Unfortunately, in ASD patients, the latter is often inaccurate PURPOSE: In this study, we consider the value of obtaining a forearm DEXA scan in addition to a hip scan in patients suffering from ASD and osteoporosis in order to accurately detect low BMD.

STUDY DESIGN

Retrospective study.

PATIENT SAMPLE

Patient data between 2016 and 2018 from a single academic medical center was utilized. Two hundred eighty-six patients met the initial search criteria.

OUTCOME MEASURES

No outcomes measures related to self-reporting, physiology, or functionality were evaluated in this study. Primary outcome measures analyzed included T-scores across various anatomic locations and diagnoses relating to low bone density (ie, osteopenia and osteoporosis).

METHODS

This retrospective study examines patients that underwent DEXA studies between 2016 and 2018 and were previously diagnosed with both osteoporosis and adult spinal deformity. For each patient, age, gender, body mass index, and smoking history were noted, as well as whether there was long-term prednisone use. T-scores from both the forearm and hip were recorded and analyzed. Diagnoses from hip DEXA scans were compared with those obtained from forearm scans to identify which region was more sensitive in detecting low BMD. From this data, the frequency of a missed diagnosis, due to reliance on hip or spine T-scores for detection of low BMD, was extrapolated. No external funding source was received in support of this study.

RESULTS

Two hundred eighty-six patients matched the initial search criteria. Only 68% had one T-score value. However, 24.8% of patients had data for both the hip and forearm, whereas 7.1% had data for the forearm, hip, and spine. Among the 85 patients with more than one anatomical site of study, the forearm was more sensitive than the hip in its ability to detect osteopenia or osteoporosis 41.2% of the time. A two-tailed t test showed no statistically significant difference between hip T-scores and forearm T-scores. However, for more than 17% of patients, the forearm allowed clinicians to detect osteoporosis or osteopenia in a setting where using only the hip data would have missed such a diagnosis.

CONCLUSIONS

Clinicians need to ensure they survey at least two locations when conducting DEXA studies before precluding a diagnosis of osteopenia or osteoporosis. All ASD patients being evaluated for low bone density should receive DEXA scans that survey at least the hip and the forearm. Misdiagnoses can be costly in the setting of ASD. They occur frequently when only a single hip scan is relied upon to assess BMD.

Forearm bone mineral density in postmenopausal former users of depot medroxyprogesterone acetate

BACKGROUND

The aim of the study was to compare the bone mineral density (BMD) of postmenopausal women who had used depot-medroxyprogesterone acetate (DMPA) or a copper intrauterine device (IUD) as a comparison group until menopause.

STUDY DESIGN

BMD was measured using dual-energy X-ray absorptiometry at the nondominant forearm for up to 3 years following menopause in 135 women aged 43-58 years: 36 former DMPA users and 99 former IUD users.

RESULTS

Mean duration of use was (mean+/-SEM) 9.4+/-3.8 and 14.7+/-6.2 years for the DMPA and IUD groups, respectively. One year after menopause, mean distal radius BMD was 0.435 and 0.449 in DMPA and IUD users, respectively, and 0.426 and 0.447 at 2-3 years following menopause. Ultra-distal BMD was 0.369 and 0.384 in DMPA and IUD users, respectively, at 1 year, and 0.340 and 0.383 at 2-3 years.

CONCLUSIONS

At 1 and 2-3 years following menopause, no significant differences were observed in the BMD of postmenopausal women aged 43-58 years, who had used DMPA or an IUD until menopause.

Whole bone geometry and bone quality in distal forearm fracture

Fracture of the distal radius is a sentinel for future increased risk of other "osteoporotic" fractures, in which the peak age for incidence of distal radius fracture is 5 to 10 years before that for spine and hip fractures. Mean bone mineral density (BMD) of the distal radius was lower in patients with osteoporosis compared with age- and sex-matched normal subjects. However, it has been shown that to predict the strength of the distal radius at the site where fractures occur requires more than measurement of bone mineral content (BMC) or BMD. Only moderate correlations have been found between forearm sites, which may be a result of differences in bone composition between sites. Different forearm sites may be used interchangeably for diagnostic purposes, but the prognostic value is not known. Using the distal radius as a screening tool for identifying individuals at risk of "osteoporotic" fracture shows that forearm site selection and accuracy of measurement can be important confounders in group studies.Improving resolution of computed tomography (CT) scanners has enabled quantitation of cortical bone density and cortical thickness. These measurements have enabled the mechanism of bone loss in the distal radius to be elucidated and show that, after menopause, bone loss is primarily through thinning of the cortex. CT imaging allows the precise localization of bone changes in individuals and should be of value in the assessment of the severity of osteoporosis. It also shows that this technology has the potential to determine the efficacy of therapeutic interventions. A concerted effort has been made to elucidate the interrelationships between the amount of bone and the geometry and that clinical imaging of BMC and/or cross-sectional area in the radius would provide improved prediction of an individual's risk of fracture.The technological tools are available, in the clinic, to accurately measure the 3-dimensional (3D) geometry of the distal radius and the amount of bone. In addition, the cortical and cancellous bone compartments can be analyzed separately. This capability, along with the easy accessibility of the distal radius to clinical imaging modalities, provides an excellent framework for longitudinal prospective studies to determine morphologic risk factors for osteoporotic fractures of the distal radius.

Cortical and trabecular bone at the forearm show different adaptation patterns in response to tennis playing

Bone responds to impact-loading activity by increasing its size and/or density. The aim of this study was to compare the magnitude and modality of the bone response between cortical and trabecular bone in the forearms of tennis players. Bone area, bone mineral content (BMC), and bone mineral density (BMD) of the ulna and radius were measured by dual-energy X-ray absorptiometry (DXA) in 57 players (24.5 +/- 5.7 yr old), at three sites: the ultradistal region (50% trabecular bone), the mid-distal regions, and third-distal (mainly cortical bone). At the ultradistal radius, the side-to-side difference in BMD was larger than in bone area (8.4 +/- 5.2% and 4.9 +/- 4.0%, respectively, p < 0.01). In the cortical sites, the asymmetry was lower (p < 0.01) in BMD than in bone area (mid-distal radius: 4.0 +/- 4.3% vs 11.7 +/- 6.8%; third-distal radius: 5.0 +/- 4.8% vs 8.4 +/- 6.2%). The asymmetry in bone area explained 33% of the variance of the asymmetry in BMC at the ultradistal radius, 66% at the mid-distal radius, and 53% at the third-distal radius. The ulna displayed similar results. Cortical and trabecular bone seem to respond differently to mechanical loading. The first one mainly increases its size, whereas the second one preferentially increases its density.

Impact of using the ultradistal radius region of interest on diagnostic classification

World Health Organization (WHO) criteria using T-scores for classifying patients as normal, osteopenic, or osteoporotic are based on bone mineral density (BMD, g/cm2) of the lumbar spine and hip and bone mineral content (BMC) (BMC, g) at the distal and midradius. There is no consensus on whether other forearm regions of interest (ROIs) can be used with the WHO criteria. Because the ultradistal radius region of interest (UDR) has a greater ratio of trabecular to cortical bone than midshaft portions of the radius, it is possible that more patients would be classified as osteoporotic if the UDR is measured. The objective of this study was to determine the prevalence of osteoporosis when using T-scores from the UDR in addition to PA lumbar spine, proximal femur (hip), and the radius 33% ROI. Retrospective data were obtained from three centers with differing patient demographics, thus reducing bias as a result of patient characteristics. Data were used only from patients who had a spine, hip, and forearm scan on the same day. Central dual-energy X-ray absorptiometry (DXA) systems included a GE Lunar DPX-L, DPX IQ, and Prodigy and a Hologic Delphi. Hologic data were for the ultradistal radius + ulna ROI (UDRU). Diagnostic classification (using the WHO T-score criteria) was made excluding and including the UDR and UDRU T-scores, in addition to lumbar spine (L2-L4 or L1-L4), hip (femoral neck, greater trochanter, or total), and the radius 33% ROI. The lowest T-score from any ROI determined the classification. For all GE Lunar patients (n = 409 women; age range: 20-96 yr), the distribution of normal, osteopenic, osteoporotic not using the UDR was 94 (23%), 170 (42%), and 145 (36%), respectively. The distribution when using the UDR was 67 (16%), 137 (33%), and 205 (50%), respectively. The difference in the ratio of normal + osteopenic versus osteoporotic when excluding and including the UDR T-scores was significant (p < 0.0001; two-tailed Fisher's exact test). For all Hologic patients (n = 153 women; age range: 44-93 yr), the distributions were 32 (21%), 66 (43%), and 55 (36%) not using and 31 (20%), 64 (42%), and 58 (38%), respectively, using the UDRU (not statistically significantly different). The group mean T-scores were lowest for the UDR compared to the spine and hip with GE Lunar but not Hologic patients.

Prediction of fracture in nursing home residents

OBJECTIVES

To investigate cross-validated methods of identifying patients at increased risk of fracture in nursing homes using readily available data.

DESIGN

Prospective cohort study with 18 months of follow-up.

SETTING

Forty-seven randomly selected nursing homes in Maryland.

PARTICIPANTS

One thousand four hundred twenty-seven white female nursing home residents aged 65 and older were followed for fracture for 18 months after baseline assessment.

MEASUREMENTS

Fracture ascertained by physician note or x-ray from chart abstraction; demographic and baseline data extracted from the Minimum Data Set (MDS).

RESULTS

Exploratory analyses on a random subset (67%) of the data (development sample) identified variables that might be important in predicting subsequent fracture and included variables for how the resident moved between locations in her room or adjacent corridor (mobility), age, weight, height, independence in eating and dressing, urinary incontinence, resistance to care, falls in the previous 6 months, a dementia score, and other activities of daily living. A simple scoring algorithm derived from a subset of these MDS variables showed good sensitivity (.70) but low specificity (.39) in the random validation sample.

CONCLUSION

A scoring algorithm developed in more than 1,400 white females from 47 nursing homes in the state of Maryland shows high sensitivity for identifying women at increased risk for fracture and may be useful in targeting fracture prevention programs.