Table 2 Peak and mean equivalent stress (Von Mises) at the patellar and the trochlear cartilage are shown in the healthy knee and the trochleodysplastic knee “preoperative” and after simulated surgery at different flexion angles. “Welch’s t-test.
Healthy knee | « Preoperative » | « 0.5x mean » | « mean » | « 1.5x mean » | |
|---|---|---|---|---|---|
Flexion angle [°] | Peak Patella /Trochlea [mPa] | Peak Patella /Trochlea [mPa] | Peak Patella /Trochlea [mPa] | Peak Patella /Trochlea [mPa] | Peak Patella /Trochlea [mPa] |
30 | 0.844/ 1.027 | 0.94/ 0.939 | 1.719/ 1.141 + 82%/ + 22% | 1.985/ 1.636 + 111%/ + 74% | 1.359/ 1.608 + 45%/ + 71% |
45 | 0.724/ 0.945 | 1.302/ 1.381 | 1.433/ 1.948 + 10%/ 41% | 1.395/ 1.795 + 7%/ + 30% | 1.623/1.923 + 25%/ + 39% |
60 | 0.893/ 0.834 | 0.919/ 1.06 | 1.238/ 1.293 + 35%/ + 22% | 1.16/ 1.338 + 26%/ + 26% | 1.336/ 1.57 + 45%/ + 48% |
75 | 1.002/ 0.905 | 0.975/ 1.067 | 1.025/ 1.208 + 5%/ + 13% | 0.989/ 1.36 + 1%/ + 27% | 0.979/ 1.204 + 0%/ + 13% |
All angles | 0.87 (SD 0.12)/ 0.93 (SD 0.08) | 1.03 (SD 0.18)/ 1.11 (SD 0.19) | 1.35 (SD 0.31)/ 1.5 (SD 0.28) | ||
Significance | P = 0.167*/ P = 0.123* vs. healthy | P = 0.073*/ P = 0.024* vs. preoperative | |||
Flexion angle [°] | Mean Patella /Trochlea [mPa] | Mean Patella /Trochlea [mPa] | Mean Patella /Trochlea [mPa] | Mean Patella /Trochlea [mPa] | Mean Patella /Trochlea [mPa] |
30 | 0.46/ 0.43 | 0.5/ 0.47 | 0.49/ 0.5 −2%/ + 6% | 0.62/ 0.74) + 24%/ + 57% | 0.62/ 0.7 + 24%/ + 49% |
45 | 0.43/ 0.41 | 0.55/ 0.59 | 0.64/ 0.69 + 16%/ + 16% | 0.63/ 0.74 + 15%/ + 25% | 0.66/ 0.72 + 20%/ + 22% |
60 | 0.42/ 0.41 | 0.47/ 0.52 | 0.55/ 0.62 + 17%/ + 19% | 0.56/ 0.65 + 19%/ + 25% | 0.61/ 0.67 + 30%/ + 29% |
75 | 0.43/ 0.46 | 0.46/ 0.52 | 0.52/ 0.61 + 13%/ + 17% | 0.51/ 0.63 + 10%/ + 21% | 0.51/ 0.57 + 10%/ + 9% |
All angles | 0.43 (SD 0.02)/ 0.43 (SD 0.02) | 0.49 (SD 0.04)/ 0.52 (SD 0.05) | 0.58 (SD 0.06) / 0.65 (SD 0.07) | ||
Significance | P = 0.041*/ P = 0.01* vs. healthy | P = 0.02*/ P = 0.006* vs. preoperative | |||