Table 2.
Comparison of Impact Characteristics Delivered Using a Spring-Loaded Impactor on Bovine Cartilage In Vitro and Lapine Cartilage In Vivoa
| Impact area (mm2) | Time to peak (ms) | Peak force (N) | Normalized peak impact stress (MPa) | Maximum displacement (%) | Spring potential energy (J) | Loading rate to peak force (×103 N/s) | Average stress rate (×103 MPa/s) | Average strain rate (×103 %/s) | |
|---|---|---|---|---|---|---|---|---|---|
| In vitro (adult bovine articular cartilage) | 12.6 ± 2.7 | 0.47 ± 0.02 | 453.52 ± 82.1 | 36.05 ± 5.62 | 38.55 ± 3.54 | 0.27783 | 970.44 ± 81.81 | 77.14 ± 5.62 | 82.50 ± 3.54 |
| In vivo (adult lapine articular cartilage) | 1.39 ± 0.11 | 0.32 ± 0.04 | 236 ± 95.2 | 169 ± 68.4 | 21.5 ± 4.5 | 0.27783 | 737.5 ± 182 | 528.1 ± 69 | 67.2 ± 4.6 |
a
Impacts delivered using a 9-mm spring compression setting (0.28 J) and a mass of 220 g. In vitro: adult bovine patellofemoral groove articular cartilage without subchondral bone. In vivo: adult lapine articular cartilage of the medial femoral condyle.