FIG. 5.
Experimental reaction force (RZ) from indentation testing of a 4 mm diameter chondral plug from the trochlear groove of a juvenile bovine knee. Indentation tests were performed at rates of (A) 0.05%/s, (B) 0.25%/s, (C) 0.50%/s, and (D) 1.00%/s on the same sample. Results from the FEBio parameter optimization at each loading rate showed that (E) the estimated Young's modulus was lower for fits to experimental data acquired at 1.00%/s, while (F) the value of ksi increased for fits to data acquired at 0.05%/s. The permeability (G) was the most variable parameter. (H) Calculation of % error showed that error was reduced when optimizations were performed on the second or third step of the indentation test.