Relationship of side dominance and ultrasonographic measurements of pronator quadratus muscle along with handgrip and pinch strength

Aims: We ascertained effects of hand dominance in both right and left-handed volunteers on the thickness and cross sectional area (CSA) of pronator quadratus (PQ) muscle as measured by the axial and sagittal views of ultrasound imaging. Secondly, we also aimed to document the extent of the relationship between the PQ measurements and handgrip. Materials and methods: Healthy adults from the volunteer medical staff were included in the study. Handedness was assessed via The Flinders Handedness survey. The sonographic appearance of the PQ was evaluated on sagittal and axial images for both hands. CSA of PQ muscle was digitally drawn and calculated on the axial plane. Handgrip was measured by using adjustable-handle dynamometer. Results: Eighty-nine healthy volunteers were included (54 right and 35 left-handed). Significant difference was detected between dominant and non-dominant hands in CSA and muscle thickness in both right and left-handed volunteers (p<0.05). These measurements were correlated with the handgrip strength (p<0.05, r=0.55, and r=0.43 for right-handed volunteers, r=0.67 and r=0.48 for left-handed volunteers, respectively). There were also significantly high correlations between the measurements of CSA and PQ thickness of the corresponding extremity in both right-handed and left-handed volunteers (p<0.05). Conclusions: A statistically significant difference exists between dominant and non-dominant hands in CSA and muscle thickness measured by US in both right and left handed volunteers, and this is correlated with handgrip strength. Hand dominance should be considered to compare healthy and affected sites during US of PQ while investigating for occult fractures of distal forearm or PQ atrophy due to anterior interosseous nerve injury