Higher contact pressure of the lateral tibiofemoral joint in lateral extra-articular tenodesis with tensioned graft in external rotation than in neutral rotation: A biomechanical study

Objective To determine the mean contact pressure, peak contact pressure, and mean contact area of the lateral tibiofemoral joint in lateral extra-articular tenodesis (LET) with tension on the graft in tibial neutral and external rotation. Methods A total of eight Thiel's embalmed cadaveric knees were prepared and divided into two groups (4 knees in each group): the LET-NR group (lateral extra-articular tenodesis tension in neutral rotation) and (2) the LET-ER group (lateral extra-articular tenodesis tension in external rotation). Each knee was prepared according to the corresponding technique. A hydraulic testing system (E10000, Instron) simulates an axial load of 735 N for 10 seconds in each group. Results The LET-ER group exhibited a statistically significant higher peak contact pressure compared to the LET-NR group. The peak contact pressure values in the LET-NR and LET-ER groups were 702.3 ± 233.9 kPa and 1,235.5 ± 171.4 kPa, respectively ( p = 0.010, 95% CI, −888.0–−178.5). The mean contact pressure values in the LET-NR and LET-ER groups were 344.9 ± 69.0 kPa and 355.3 ± 34.9 kPa, respectively ( p = 0.796, 95% CI, −105.1–84.2). The mean contact area values in the LET-NR and LET-ER groups were 36.8 ± 3.1 mm2 and 33.3 ± 6.4 mm2, respectively ( p = 0.360, 95% CI, −5.2–12.2). Conclusions The peak contact pressure of the lateral tibiofemoral joint is greater in LET when the graft is tensioned in external rotation than in neutral rotation. However, no statistically significant difference in the mean contact pressure or the mean contact area was observed between the two groups. Level of evidence III.