Table 1 Quality assessment tool adapted from National Institute of Health (NIH) Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies

 1. Was the research question or objective in this paper clearly stated?

 2. Was the study population clearly specified and defined?

 3. Were all the subjects selected or recruited from the same or similar populations (including the same time period)? Were inclusion and exclusion criteria for being in the study prespecified, rigorous, and applied uniformly to all participants?

 4. Was the protocol for image acquisition clearly defined (including the type of machine and appropriate transducer range > 10 MHz)?

 5. Was the protocol for analyzing the outcome measure clearly defined?

 6. Was the outcome measure collected and analyzed by a qualified person?

 7. Were the outcome assessors blinded to the exposure (or health) status of participants?

 8. Were key potential confounding variables measured and adjusted statistically for their impact on the relationship between exposure(s) and outcome(s) (e.g., gender, hand-dominance)

Quality rating (good, fair, or poor)

Rater #1 initials:

Rater #2 initials:

Additional comments (If poor, please state why):