Women with previous stress fractures show reduced bone material strength

Abstract

Background and purpose — Bone fragility is determined by bone mass, bone architecture, and the material properties of bone. Microindentation has been introduced as a measurement method that reflects bone material properties. The pathogenesis of underlying stress fractures, in particular the role of impaired bone material properties, is still poorly understood. Based on the hypothesis that impaired bone material strength might play a role in the development of stress fractures, we used microindentation in patients with stress fractures and in controls.Patients and methods — We measured bone material strength index (BMSi) by microindentation in 30 women with previous stress fractures and in 30 normal controls. Bone mineral density by DXA and levels of the bone markers C-terminal cross-linking telopeptide of type-1 collagen (CTX) and N-terminal propeptide of type-1 procollagen (P1NP) were also determined.Results — Mean BMSi in stress fracture patients was significantly lower than in the controls (SD 72 (8.7) vs. 77 (7.2); p = 0.02). The fracture subjects also had a significantly lower mean bone mineral density (BMD) than the controls (0.9 (0.02) vs. 1.0 (0.06); p = 0.03). Bone turnover—as reflected in serum levels of the bone marker CTX—was similar in both groups, while P1NP levels were significantly higher in the women with stress fractures (55 μg/L vs. 42 μg/L; p = 0.03). There was no correlation between BMSi and BMD or bone turnover.Interpretation — BMSi was inferior in patients with previous stress fracture, but was unrelated to BMD and bone turnover. The lower values of BMSi in patients with previous stress fracture combined with a lower BMD may contribute to the increased propensity to develop stress fractures in these patients.

Assessment of Bone Health in Patients With Type 1 Gaucher Disease Using Impact Microindentation

“…Whether this finding implies an increased risk of fracture cannot be firmly established because no clear international reference values have yet been published. However, the average value in our patients is lower than those associated with fragility fracture or previous stress fracture in other studies using the same technique. Bone turnover biomarkers are not currently used in clinical practice because studies to date have produced inconsistent results .…”

Feasibility and tolerability of bone impact microindentation testing: a cross-sectional, population-based study in Australia

“…In this study, we did not observe a correlation between BMSi and age, corresponding to two studies by Duarte Sosa et al in which no association was detected between age and BMSi in 42 Norwegian and 46 Spanish women18 and among 30 women with previous stress fractures and 30 normal controls 19. By contrast, an inverse association between age and BMSi has been reported for 90 patients (male and female) with low bone mass, (r=−0.539; p<0.001) and in a case–control study of 48 patients with acromegaly and 44 controls (male and female), there was a positive association for patients with acromegaly (r=0.291, p=0.045) and an inverse relationship for the controls (r=−0.457, p=0.002) 20.…”

Clinical experience with microindentation in vivo in humans

“…Mean BMSi in a group of women with stress fracture was significantly lower than in controls [28]. The fracture group also had a significantly lower mean BMD than the controls.…”

“…The discrepancies between BMD and fracture risk are important when comparing Scandinavian and Mediterranean women; here again, lower BMSi can account for at least a part of the increased fracture rates in Norwegians[19]. Stress fractures, another clinical situation where bone fragility is not explained by bone density, also are associated with deterioration in BMSi[28].Altogether, the evidence supports the idea that, independently of BMD, tissue-level properties captured by RPI may help to explain the increased fragility of bone. Returning to the classical definition of osteoporosis[3], elements other than BMD are relevant for bone health.…”