Background

Changes in knee kinematics from internal tibial torque under tibiofemoral compression force have been studied, but the potentially stabilizing effects of external tibial torque have not been reported. We hypothesized that for a given knee flexion angle, 1) external torque would significantly reduce anterior tibial translation, internal tibial rotation, and valgus tibial rotation before and after sectioning the anterior cruciate ligament and 2) changes in kinematics from applied external torque would be significantly greater with the cruciate cut.

Methods

A robotic test system was used to flex intact human knees continuously from 0° to 50° under 200 N compression, without and with 5 Nm external torque. Tests were repeated after cruciate section.

Findings

With the cruciate intact, external torque had no significant effect on anterior translation, and significantly reduced internal and valgus rotations at all flexion angles. With the cruciate cut, external torque significantly reduced anterior translation beyond 25° flexion, significantly reduced internal rotation at all flexion angles, and significantly reduced valgus rotation beyond 15° flexion. Although external torque had no significant effect on anterior translation with the ACL intact, external torque produced relatively large decreases in anterior translation with the cruciate sectioned (−11.6 mm at 50° flexion). Reductions in valgus rotation from applied external torque were significantly greater for cruciate deficient knees beyond 25° flexion.

Interpretation

We conclude that external tibial torque may be important for controlling the abnormal kinematics associated with an anterior cruciate ligament deficient knee, and possibly help stabilize the knee during in vivo activities.

中文翻译：

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施加的外部胫骨扭矩导致的膝部运动学变化：稳定前交叉韧带不足的膝关节的含义

背景

研究了在股骨股骨压力下膝关节运动学与胫骨内部扭矩的关系，但尚未报道外部胫骨扭矩的潜在稳定作用。我们假设对于给定的膝盖屈曲角度，1）外部扭矩将显着减少前十字韧带切开前后的胫骨前平移，胫骨内旋转和外翻胫骨旋转； 2）施加的外部扭矩引起的运动学变化将显着十字形切割效果更好。

方法

使用机器人测试系统，在200 N的压力下，从0°到50°连续弯曲完整的人类膝盖，没有或没有5 Nm的外部扭矩。十字形切片后重复测试。

发现

十字交叉完好无损时，外部扭矩对前平移无明显影响，并且在所有屈曲角度均显着减少了内外翻旋转。通过十字形切口，外部扭矩可显着减小前屈超过25°屈曲的前平移，显着降低所有屈曲角度的内旋，并显着减少超过15°屈曲的外翻旋转。尽管外部扭矩对ACL完整的前移没有显着影响，但在十字形截面处（50°屈曲时为-11.6 mm），外部扭矩在前移中产生了相对较大的减小。对于超过25°屈曲的膝关节严重不足的膝关节，外加外扭矩对外翻旋转的抑制作用明显更大。

解释

我们得出结论，外部胫骨扭矩对于控制与前交叉韧带缺陷型膝关节相关的异常运动学可能很重要，并可能有助于在体内活动期间稳定膝关节。