Horizon dxa system

In this retrospective cohort study, we reviewed 94 patients with low-trauma hip fractures (45 with trochanteric fractures, 49 with femoral neck fractures) treated at a single medical institution in Japan for 9 months from April 2020. We performed bipolar hip arthroplasty (BHA) or open reduction and internal fixation (ORIF) for hip fractures and ORIF for trochanteric fractures. YAM in the nonfractured femoral neck was measured by using the Horizon DXA System bone densitometer (Hologic Inc., Marlborough, MA). This was because the femoral neck is a consistently significant predictor of hip fractures, and the discriminant power was better than that measured at the lumbar spine [9 (link)].
Patients comprised 76 women and 18 men with a median age of 88 years (range, 61–105 years). The median YAM was 54% (47%–67%); 77 patients had a YAM <70%, and 17 patients had a YAM >70%. The median body mass index (BMI) was 19.8 kg/m² (range, 12.5–30 kg/m²). In accordance with the American Society of Anesthesiologists Physical Status (ASA-PS) scale, 51 cases were classified as grade II and 43 cases were classified as grade III. Chronic diseases, namely, diabetes mellitus (DM) and hypertension (HT), were also evaluated; 14 patients had DM, and 59 had HT. This retrospective study was approved by the Kyushu Central Hospital review board (approval number: 21–1).

Radiological imaging included preoperative DEXA and pre- and postoperative QCT scanning. The Horizon DXA system (Hologic, Inc., Marlborough, MA, USA) was used to assess the areal bone mineral density in the proximal femur. The SOMATOM Force 196-slice dual-source CT scanner (Siemens Healthineers, Forchheim, Germany) was used to assess the 3D geometry as well as the volumetric density distribution and allow for the designing of specimen-specific positioning guides (see Section 2.3). The following parameters were used in QCT scanning: Dual-energy scanning mode, tube A and tube B: voltage: 150 and 100 kV, intensity: 220 and 460 mAs, respectively. Collimation was 196 × 0.6 mm, rotation time 500 ms and pitch-factor 0.5. QCT imaging sequences were reconstructed at a slice thickness of 0.6 mm and position increment of 0.4 mm using the Qr69 kernel and an iterative reconstruction mode (ADMIRE) at strength 3. QCT scanning was performed in the described manner, pre- and postoperatively, after metal removal (see Section 2.4).

Following preparation, all specimens underwent radiological assessment for bone mineral density (BMD) and morphology. The Horizon DXA system (Hologic, Inc., Marlborough, MA, USA) was used to assess the bone mineral density (g/cm²) of the proximal femur. QCT image sequences were acquired with the SOMATOM Force 128-slice dual-source CT scanner (Siemens Healthcare GmbH, Erlangen, Germany) with the following parameters for tube A and tube B: voltage: 120 and 150 kV, intensity: 270 and 540 mAs, respectively. QCT image sequences were reconstructed at a slice thickness of 0.6 mm and position increment of 0.4 mm using the Qr69 kernel and the ‘Bone’ window.
Images were segmented and postprocessed for preoperative planning and creation of drill guides (see Experimental Setup) using Mimics Research 21.0 and 3-Matic Research 13.0 (both Materialise NV, Leuven, Belgium). Cortical width (mm) was measured at 12 sites (6 on medial and 6 on lateral side) along the axis of the implant in the coronal plane.

Grip strength and fat-free mass (FFM) measurements were used to assess muscle strength. Grip strength was measured three times each using a DynamoMeter (Smedley, TTM; Tokyo, Japan) at 8, 16, and 24 weeks, with the maximum value recorded. FFM was calculated at 24 weeks as follows: FFM = body weight − fat mass (FM), where FM was measured using dual-energy X-ray absorptiometry (DXA; Hologic Horizon DXA System, United States).