Biomechanics Research Laboratory, Steadman Philippon Research Institute, Vail, Colorado, USA.
Am J Sports Med. 2012 Jan;40(1):170-8. doi: 10.1177/0363546511423746. Epub 2011 Oct 13.
The anterior cruciate ligament (ACL) has been well defined as the main passive restraint to anterior tibial translation (ATT) in the knee and plays an important role in rotational stability. However, it is unknown how closely the ACL and other passive and active structures of the knee constrain translations and rotations across a set of functional activities of increasing demand on the quadriceps.
Anterior tibial translation and internal rotation of the tibia relative to the femur would increase as the demand on the quadriceps increased.
Controlled laboratory study.
The in vivo 3-dimensional knee kinematics of 10 adult female patients (height, 167.8 ± 7.1 cm; body mass, 57 ± 4 kg; body mass index [BMI], 24.8 ± 1.7 kg/m(2); age, 29.7 ± 7.9 years) was measured using biplane fluoroscopy while patients completed 4 functional tasks. The tasks included an unloaded knee extension in which the patient slowly extended the knee from 90° to 0° of flexion in 2 seconds; walking at a constant pace of 90 steps per minute; a maximum effort isometric knee extension with the knee at 70° of flexion; and landing from a height of 40 cm in which the patient stepped off a box, landed, and immediately performed a maximum effort vertical jump.
Landing (5.6 ± 1.9 mm) produced significantly greater peak ATT than walking (3.1 ± 2.2 mm) and unweighted full extension (2.6 ± 2.1 mm) (P < .01), but there was no difference between landing and a maximum isometric contraction (5.0 ± 1.9 mm). While there was no significant difference in peak internal rotation between landing (19.4° ± 5.7°), maximum isometric contraction (15.9° ± 6.7°), and unweighted full knee extension (14.5° ± 7.7°), each produced significantly greater internal rotation than walking (3.9° ± 4.2°) (P < .001). Knee extension torque significantly increased for each task (P < .01): unweighted knee extension (4.7 ± 1.2 N·m), walking (36.5 ± 7.9 N·m), maximum isometric knee extension (105.1 ± 8.2 N·m), and landing (140.2 ± 26.2 N·m).
Anterior tibial translations significantly increased as demand on the quadriceps and external loading increased. Internal rotation was not significantly different between landing, isometric contraction, and unweighted knee extension. Additionally, ATT and internal rotation from each motion were within the normal range, and no excessive amounts of translation or rotation were observed.
This study demonstrated that while ATT will increase as demand on the quadriceps and external loading increases, the knee is able to effectively constrain ATT and internal rotation. This suggests that the healthy knee has a safe envelope of function that is tightly controlled even though task demand is elevated.
前交叉韧带（ACL）已被明确为膝关节中前胫骨平移（ATT）的主要被动约束，并在旋转稳定性中发挥重要作用。然而，尚不清楚 ACL 和膝关节的其他被动和主动结构在多大程度上限制了在一系列对股四头肌需求不断增加的功能活动中的平移和旋转。
随着股四头肌需求的增加，前胫骨平移和胫骨相对于股骨的内旋会增加。
对照实验室研究。
使用双平面荧光透视术测量 10 名成年女性患者（身高 167.8 ± 7.1cm；体重 57 ± 4kg；体重指数[BMI]24.8 ± 1.7kg/m2；年龄 29.7 ± 7.9 岁）的体内 3 维膝关节运动学，当患者从 90°缓慢伸展至 0°屈曲时，患者完成 4 项功能任务。任务包括在不受重的情况下进行膝关节伸展，患者以 2 秒的时间从 90°伸展至 0°屈曲；以每分钟 90 步的恒定速度行走；在 70°屈膝的最大努力等长膝关节伸展；从 40cm 的高度跳下，患者跳下箱子，着地，然后立即进行最大努力的垂直跳跃。
着陆（5.6 ± 1.9mm）产生的峰值 ATT 明显大于行走（3.1 ± 2.2mm）和无重全伸展（2.6 ± 2.1mm）（P <.01），但着陆和最大等长收缩（5.0 ± 1.9mm）之间没有差异。虽然着陆（19.4° ± 5.7°）、最大等长收缩（15.9° ± 6.7°）和无重全膝关节伸展（14.5° ± 7.7°）之间的峰值内旋没有显著差异，但每个动作产生的内旋都明显大于行走（3.9° ± 4.2°）（P <.001）。每个任务的膝关节伸展扭矩均显著增加（P <.01）：无重膝关节伸展（4.7 ± 1.2N·m）、行走（36.5 ± 7.9N·m）、最大等长膝关节伸展（105.1 ± 8.2N·m）和着陆（140.2 ± 26.2N·m）。
随着股四头肌和外部负荷需求的增加，前胫骨平移明显增加。着陆、等长收缩和无重膝关节伸展之间的内旋没有显著差异。此外，每个运动的 ATT 和内旋都在正常范围内，没有观察到过度的平移或旋转。
本研究表明，尽管随着股四头肌和外部负荷的增加，ATT 会增加，但膝关节能够有效地限制 ATT 和内旋。这表明健康的膝关节具有安全的功能范围，即使任务需求增加，也能得到有效控制。
