Vnitr Lek 2010, 56(7):764-770

Femur strength index versus bone mineral density: new findings (Slovak epidemiological etudy)

J. Wendlová

Osteology Unit, Derer's University Hospital and Policlinic Bratislava, Slovakia, head Ass. Prof. Jaroslava Wendlová, MD, PhD.

Patients and methods:
We analysed the data in the sample (n = 3,215) of East Slovak women with a primary or secondary osteopenia, osteoporosis and with risk factors for osteoporosis, aged 20-89 years, median 59 years, 95% C. I. (59.31; 60.07) obtained from dual energy X-ray absorptiometry device (Prodigy-Primo, GE, USA). Measured variables: 1. left proximal femur: T-score total hip, FSI (femur strength index), 2. lumbar vertebrae L₁-L₄: BMD (bone mineral density).

Objectives:
1. To estimate and to compare an expected frequency of pathological FSI < 1 and T-score total hip ≤ -2.5 SD values in the East Slovak female population. 2. To estimate expected frequency of women with: FSI < 1 and T-score total hip ≤ -2.5 SD (Group A), FSI < 1 and T-score total hip from interval from -1,0 till -2.5 SD (Group B), FSI < 1 and T-score total hip > -1.0 SD (Group C) in the East Slovak female population. 3. To determine, if FSI variable value is a significant predictor of BMD variable values in lumbar vertebrae.

Results:
1. In the East Slovak female population we can expect 14.54% of women with FSI values < 1 and 6.25% of women with osteoporosis in the total hip area according to T-score. 2. For the group A we can expect the mean value (μ) from interval (1.41; 2.36) %, for the group B from interval (4.50; 6.03) % and for the group C from interval (6.76; 8.55) %. 3. Between FSI and BMD L₁-L₄ variable values there is not a statistically significant dependence, because FSI variable is quantitative and qualitative different variable from BMD variable.

Conclusion:
The measurement of FSI variable values may discover a higher percentage of women with a probability of femoral neck fracture by fall than the measurement of BMD variable value in the total hip area. Patient with osteopenia or normal BMD measured in the total hip area may sustain a femoral neck fracture by fall, when she has pathological value of FSI, i.e. she has adverse values of geometric variables of proximal femur (biomechanically unfavourable proximal femur configuration). FSI variable value is not a significant predictor of BMD variable values in lumbar vertebrae L₁-L₄.

Keywords: osteoporosis; femur strength index (FSI); bone mineral density (BMD); femoral neck fracture; dual energy X-ray absorptiometry (DXA); lumbar vertebrae

Received: May 12, 2010; Published: July 1, 2010  Show citation