Table 1.
Interventional thresholds for bone strength [35] (in newtons, N) and BMD (in dimensionless DXA-equivalent T-score units for the hip or mg/cm3 for the spine). A patient is considered at high risk of fracture if any measurement falls within the italicized entries. The bone strength thresholds were developed based on a statistical correspondence between BMD and bone strength, measured in hundreds of patients in cohorts independent of those used for their prospective validation. The BMD thresholds are based on established guidelines. See Appendix C for further details and the related validation studies
| Classification | Women | Men | ||
|---|---|---|---|---|
| Hip | Spine | Hip | Spine | |
| Fragile bone strength | ≤ 3000 N | ≤ 4500 N | ≤ 3500 N | ≤ 6500 N |
| Low bone strength | > 3000 to < 4000 | > 4500 to < 6000 | > 3500 to < 5000 | > 6500 to < 8500 |
| Normal bone strength | ≥ 4000 | ≥ 6000 | ≥ 5000 | ≥ 8500 |
| Osteoporosis | ≤ − 2.5 | ≤ 80 mg/cm3 | ≤ − 2.5 | ≤ 80 mg/cm3 |
| Low bone mass (osteopenia) | > − 2.5 to < − 1.0 | > 80 to < 120 | > − 2.5 to < − 1.0 | > 80 to < 120 |
| Normal bone mass | ≥ − 1.0 | ≥ 120 | ≥ − 1.0 | ≥ 120 |
The strength thresholds were developed and validated for measurement by VirtuOst. Strength is reported to ± 10 N, BMD T-score to ± 0.1 unit, and volumetric BMD to ± 1 mg/cm3. For the overall fracture risk classification (see text), a patient is classified as being at: high risk if testing test positive for fragile bone strength or (BMD-defined) osteoporosis or both, at either the hip or spine; not increased risk if both bone strength and BMD are in the normal range at all measured sites; or increased risk otherwise