Laterality and grip strength influence hand bone micro-architecture in modern humans, an HRpQCT study

Abstract

It is widely hypothesized that mechanical loading, specifically repetitive low-intensity tasks, influences the inner structure of cancellous bone. As such, there is likely a relationship between handedness and bone morphology. The aim of this study is to determine patterns in trabecular bone between dominant and non-dominant hands in modern humans. Seventeen healthy patients between 22 and 32 years old were included in the study. Radial carpal bones (lunate, capitate, scaphoid, trapezium, trapezoid, 1st, 2nd and 3rd metacarpals) were analyzed with high-resolution micro-computed tomography. Additionally, crush and pinch grip were recorded. Factorial analysis indicated that bone volume ratio, trabeculae number (Tb.N), bone surface to volume ratio (BS.BV), body weight, stature and crush grip were all positively correlated with principal components 1 and 2 explaining 78.7% of the variance. Volumetric and trabecular endostructural parameters (BV/TV, BS/BV or Tb.Th, Tb.N) explain the observed inter-individual variability better than anthropometric or clinical parameters. Factors analysis regressions showed correlations between these parameters and the dominant side for crush strength for the lunate (r² = 0.640, P < 0.0001), trapezium (r² = 0.836, P < 0.0001) and third metacarpal (r² = 0.763). However, despite a significant lateralization in grip strength for all patients, the endostructural variability between dominant and non-dominant sides was limited in perspective to inter-individual differences. In conclusion, handedness is unlikely to generate trabecular patterns of asymmetry. It appears, however, that crush strength can be considered for endostructural analysis in the modern human wrist.

Keywords: grip strength; human; laterality; trabecular bone; wrist.

Figure 1

Three‐dimensional (3D) segmentation of wrist bones prior to volume of interest (VOI) analysis.

Figure 2

Volume of interest (VOI) in capitate (non‐dominant side on left, dominant side in right) on patient 2. Trabeculae are thicker (Tb.Th 0.35 mm vs. 0.31 mm) on the right sample, and bone volume fraction BV/TV is higher (37.3% vs. 30.9%).

Figure 3

Variables correlations on principal component analysis (PCA) on PC1 (x‐axis) and PC2 (y‐axis) per bone studied. The explanation of the variance per PC (58% for PC1 and 20% for PC2) is meant for all the bones studied.

Figure 4

Variables correlations on principal component analysis (PCA) on PC1 (x‐axis) and PC2 (y‐axis) for dominant and non‐dominant sides. Dots indicate dominant and triangles indicate non‐dominant. The explanation of the variance per PC (58% for PC1 and 20% for PC2) is meant for all the bones studied.