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CTXA Hip—An Extension of Classical DXA Measurements Using Quantitative CT

<div><p>Bone mineral density (BMD) estimates for the proximal femur using Dual Energy X-ray Absorptiometry (DXA) are currently considered the standard for making a diagnosis of osteoporosis in an individual patient using BMD alone. We have compared BMD results from a commercial Quantitative CT (QCT) BMD analysis system, “CTXA Hip”, which provides clinical data for the proximal femur, to results from DXA. We have also used CTXA Hip to determine cortical and trabecular contributions to total BMD. Sixty-nine patients were scanned using 3D QCT and DXA. CTXA Hip BMD measurements for Total Hip and Femoral Neck were compared to DXA results. Twenty-two women were scanned at 0,1,2 years and CTXA Hip and DXA results analyzed for long-term reproducibility. Long-term reproducibility calculated as root-mean-square averages of SDs <i>in vivo</i> was 0.012 g/cm² (CV = 1.8%) for CTXA Total Hip and 0.011 g/cm² (CV = 2.0%) for CTXA Femoral Neck compared to 0.014 g/cm² (CV = 2.0%) and 0.016 g/cm² (CV = 2.7%), respectively, for DXA. The correlation of Total Hip BMD CTXA vs. DXA was R = 0.97 and for Femoral Neck was R = 0.95 (SEE 0.044 g/cm² in both cases). Cortical bone comprised 62±5% (mean ± SD) of total hipbone mass in osteoporotic women. CTXA Hip provides substantially the same clinical information as conventional DXA and in addition provides estimates of BMD in separate cortical and trabecular bone compartments, which may be useful in evaluation of bone strength.</p></div

Effect of Body Mass Index on Blood Transfusion in Total Hip and Knee Arthroplasty.

Perioperative blood management remains a challenge during total hip arthroplasty (THA) and total knee arthroplasty (TKA). The purpose of this study was to systematically examine the relationship between body mass index (BMI) and perioperative blood transfusion during THA and TKA while attempting to resolve conflicting results in previously published studies. The authors retrospectively evaluated 2399 patients, 896 of whom underwent THA and 1503 of whom underwent TKA. Various outcome variables were assessed for their relationship to BMI, which was stratified using the World Health Organization classification scheme (normal,/m(2); overweight, 25-30 kg/m(2); obese, \u3e30 kg/m(2)). Among patients undergoing THA, transfusion rates were 34.8%, 27.6%, and 21.9% for normal, overweight, and obese patients, respectively (P=.002). Among patients undergoing TKA, transfusion rates were 17.3%, 11.4%, and 8.3% for normal, overweight, and obese patients, respectively (P=.002). Patients with an elevated BMI have decreased rates of blood transfusion following both THA and TKA. This same cohort also loses a significantly decreased percentage of estimated blood volume. No trends were identified for a relationship between BMI and deep venous thrombosis, pulmonary embolism, myocardial infarction, discharge location, length of stay, 30-day readmission rate, and preoperative hemoglobin level. Elevated BMI was significantly associated with increased estimated blood loss in patients undergoing THA and those undergoing TKA. There was a statistically significant trend toward increased deep surgical-site infection in patients undergoing THA (P=.043). Patients with increased BMI have lower rates of blood transfusion and lose a significantly smaller percentage of estimated blood volume following THA and TKA. [Orthopedics.2016; 39(5):e844-e849.]

Summary of Long-Term <i>In Vivo</i> Precision, CTXA vs. DXA, in Osteoporotic Subjects.

<p>Summary of Long-Term <i>In Vivo</i> Precision, CTXA vs. DXA, in Osteoporotic Subjects.</p

Correlation of area BMD for CTXA and DXA for femoral neck region of interest.

<p>Correlation of area BMD for CTXA and DXA for femoral neck region of interest.</p

Correlation of CTXA Hip and DXA BMD Results (Site 1, Manchester; Site 2, Schenectady).

<p>Correlation of CTXA Hip and DXA BMD Results (Site 1, Manchester; Site 2, Schenectady).</p

CTXA proximal femur ROI positions.

<p>CTXA projected image with standard regions of interest used for BMD calculations (femoral neck, trochanter, intertrochanter, and Total Hip as sum of these three regions). Position of femoral neck box and intertrochanter limit line at base of lesser trochanter, and rotation of femoral neck axis, are adjustable by user. Ward's Triangle ROI is displayed but not used in comparisons.</p

Correlation of area BMD for CTXA and DXA for total hip region of interest.

<p>Correlation of area BMD for CTXA and DXA for total hip region of interest.</p

QA study axial image.

<p>Completed ROI placement in axial CT slice of quality assurance and CT calibration reference phantoms positioned for QA studies.</p