pQCT bone strength index may serve as a better predictor than bone mineral density for long bone breaking strength

Abstract

Bone mineral density (BMD) is commonly used to predict osteoporotic fracture risk without considering the geometry of the bone. However, geometric parameters are also important in determination of bone strength. An index including both material and geometric properties may be therefore more relevant in prediction of fracture risk. We studied the correlation between parameters measured by noninvasive peripheral quantitative computed tomography (pQCT) and bone bending strength of the diaphysis of 45 fresh goat humeri and 27 femora. Multislice pQCT was used for measuring volumetric diaphyseal cortical BMD, total BMD, diaphyseal and cortical cross-sectional area (CSA), and cross-sectional moment of inertia (CSMI) and their derived bone strength indices (BSIs), including BSI(CSMI) (cortical BMD x CSMI) and BSI(CSA) (cortical BMD x cortical CSA). Conventional dual-energy absorptiometry (DXA) was also conducted to measure areal BMD of diaphysis for comparison. Ultimate fracture load was obtained via three-point bending test. Results showed that for femora, fracture load was correlated better with BSI(CSA) ( r = 0.697, P < 0.001) than cortical BMD ( r = 0.304, P > 0.05) and total BMD ( r = 0.387, P > 0.05) measured using pQCT and areal BMD ( r = 0.612, P < 0.001) measured using DXA. For humeri, fracture load was also correlated with BSI(CSA) ( r = 0.579, P < 0.001) but not with other pQCT parameters including cortical BMD and total BMD ( r = 0.282 and 0.305, respectively; P > 0.05, both). The best correlation was found with areal BMD measured by DXA ( r = 0.760, P < 0.001). In conclusion, pQCT noninvasive BSI(CSA) derived from cortical BMD (material) and its cortical CSA (bone geometry or distribution) may serve as an important noninvasive index for predicting long bone bending strength. The bending strength was also predicted by bone mass (areal BMD) measured by DXA, an integration of bone mineral and geometry. Further clinical studies are needed to validate the predictive value of BSI in long bone osteoporotic fracture.

A Comparison of Micro-CT and Dental CT in Assessing Cortical Bone Morphology and Trabecular Bone Microarchitecture

“…Several scholars have adopted QCT or pQCT to measure the morphology parameters of the femur [2], [3], [5], [34], and proved that QCT and pQCT can provide not only bone densitometric parameters as DXA does, but also bone geometric parameters for accurately predicting bone strength. However, scant studies have involved the use of dental CT for measuring the cortical bone morphology parameters of long bone diaphysis.…”

“…Bone strength is affected by both geometric parameters and densitometric parameters. However, DXA provides only areal BMD information [3], [4], and does not include geometric parameters, such as size and shape. Although quantitative computed tomography (QCT) can provide both geometric and densitometric parameters [2], [5], the clinical application of this technique is not extensive because of the cost and high radiation dosage.…”

Age and Sex Differences in Estimated Tibia Strength: Influence of Measurement Site

“…These data can then be used to calculate section moduli and 2 nd moments of inertia to provide information about resistance to fracture from bending and torsional loading. pQCT-assessed bone variables have been shown to strongly predict breaking strength (6–8). Polar strength strain index (SSI), a cortical-weighted section modulus, is the most commonly reported pQCT strength variable.…”

“…Polar strength strain index (SSI), a cortical-weighted section modulus, is the most commonly reported pQCT strength variable. The term bone strength index (BSI) has been used both interchangeably with SSI and as a separate measure of compressive strength at distal tibia sites using a different equation from SSI (6,8–11). Polar, maximum and minimum moments of inertia (Ip, Imax, Imin) values are sometimes reported in mechanical loading studies (9,12,13), and recently, the use of bone strength-to-bone mass ratios were proposed as an indicator of mechanostat effectiveness (14).…”

In VivoStudy on the Pharmacological Interactions between a Chinese Herbal Formula ELP and Antiresorptive Drugs to Counteract Osteoporosis

“…This unmatched observation might be due to the fact that biomechanical properties of bone depend not only on material and architectural factors, but also the geometric parameters of cortical bone on mid-shaft of long bone [23]. Fracture load was correlated better with BSI (CSA) (a bone strength index including the cortical BMD and the cross-sectional area) of the bone than cortical BMD or total BMD alone in mid-shaft femur and humerus of goats.…”