Table 3.
The differences between the new results using the in vitro ATT data minus 3 mm and the in vitro ATT data plus 3 mm as inputs and the results using the original in vitro data as inputs during tuning of the knee-ligament parameters
| Subject | Inputs of in vitro ATT data | Percentage change (%) | ATT | ACL force | MCL force | ||||
|---|---|---|---|---|---|---|---|---|---|
| Stiffness | Zero load length | R 2 | RMS error (mm) | R 2 | RMS error (N) | R 2 | RMS error (N) | ||
| Healthy | Plus 3 mm | 1.85 (4.00) | −0.15 (1.67) | 0.628 | 1.10 | 0.863 | 212.8 | 0.852 | 191.6 |
| Minus 3 mm | −1.59 (6.69) | −1.26 (7.17) | 0.888 | 0.48 | 0.973 | 78.8 | 0.933 | 201.8 | |
| ACL-deficient | Plus 3 mm | 2.80 (6.38) | −1.32 (2.60) | 0.970 | 2.36 | – | – | 0.800 | 150.1 |
| Minus 3 mm | −2.71 (3.53) | 0.16 (1.94) | 0.966 | 0.59 | – | – | 0.746 | 54.2 | |
Average percentage change of the calculated stiffness and zero load length of the ligament bundles were reported with standard deviations in parentheses to show the influence of different ATT inputs on the tuned ligament parameters. Coefficient of determination (R 2) and RMS error between the new results of ATT, ACL force, and MCL force during stance phase and the original results were reported to show the influence of different tuned knee–ligament parameters on the knee biomechanics. In this sensitivity study we chose to use the knee joint model with 4° of tibial slope as an example