Fig. 4.

Representative indentation results and illustration of analysis methods. (A) The normal force is plotted versus indentation depth for a central femoral aspect sample at the indentation rates of 1, 10, and 100 μm/s. The line represents the best fit to Hertz model for each measurement. The effective modulus for the fit is given with the corresponding uncertainty and coefficient of determination (R²). The data shown for 1 μm/s was the worst fit in the study. (B) The normal force is plotted versus indentation depth for the five locations at one meniscus under a commanded indentation rate of 10 μm/s. Only data from 50 to 100 μm depth (indicated by thin solid lines) were used in the fitting and analysis.