DXA-based Bone Strain Index: A New Tool to Evaluate Bone Quality in Primary Hyperparathyroidism

Presentation Format: Oral presentation.

Purpose or Learning Objective: Primary hyperparathyroidism (PHPT) is associated with impaired bone quality and increased fracture risk. Reliable tools for the evaluation of bone quality parameters are not yet clinically available. The bone strain index (BSI) is a new metric for bone strength based on finite element analysis from the lumbar spine (LS) and femoral neck (FN) dual X-ray absorptiometry images. Our aim was to assess the LS, FN, and total hip (TH) BSI in PHPT compared with controls.

Methods or Background: This cross-sectional study consisted of 50 subjects with PHPT and 100 control subjects. We measured bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA) at the LS (L1–L4), TH, FN, and nondominant forearm (one-third distal radius). For BSI analysis, raw data from the DXA image were sent to a separate workstation with BSI software. BSI computation was determined by dividing each vertebra of the lumbar scan into several triangles following the contour provided by DXA software mapping. Vertebral fracture (VF) assessment was done using DXA or plain radiographs (for patients with scoliosis and severe arthrosis), by applying Genant's semiquantitative method.

Results or Findings: FN BMD and one-third distal radius BMD were lower in the PHPT group than in controls (FN: 0.633 ± 0.11 versus 0.666 ± 0.08; p < 0.05; radius 0.566 ± 0.07 versus 0.625 ± 0.06; p < 0.001). The trabecular bone score (TBS) and T-score adjusted for TBS were lower in patients with PHPT compared with controls (TBS: 1.24 ± 0.11 versus 1.29 ± 0.09; p < 0.001; T-score TBS − 2.4 ± 1.05 versus − 1.8 ± 1.02; p = 0.002). BSI was significantly higher at LS (2.28 ± 0.59 versus 2.02 ± 0.43; p = 0.003), FN (1.72 ± 0.41 versus 1.479 ± 0.35; p = 0.002), and TH (1.51 ± 0.33 versus 1.36 ± 0.25; p < 0.001) in PHPT. Only LS-BSI was associated with VF (odds ratio: 3.09; 95% confidence interval, 1.004–9.55; p = 0.04) in PHPT.

Conclusion: The BSI analysis was a significant independent predictor of a subsequent refracture. BSI, a DXA-derived bone quality index, is impaired in PHPT and may help identify PHPT subjects at high risk of fractures.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
03 June 2021