Accurate assessment of 3D tibio-femoral kinematics is essential for understanding knee joint functionality, but also provides a basis for assessing joint pathologies and the efficacy of musculoskeletal interventions. Until now, however, the assessment of functional kinematics in healthy knees has been mostly restricted to the loaded stance phase of gait, and level walking only, but the most critical conditions for the surrounding soft tissues are known to occur during high-flexion activities. This study aimed to determine the ranges of tibio-femoral rotation and condylar translation as well as provide evidence on the location of the centre of rotation during multiple complete cycles of different gait activities.

Based on radiographic images captured using moving fluoroscopy in ten healthy subjects during multiple cycles of level walking, downhill walking and stair descent, 3D femoral and tibial poses were reconstructed to provide a comprehensive description of tibio-femoral kinematics.

Despite a significant increase in joint flexion, the condylar antero-posterior range of motion remained comparable across all activities, with mean translations of 6.3–8.3 mm and 7.3–9.3 mm for the medial and lateral condyles respectively. Only the swing phase of level walking and stair descent exhibited a significantly greater range of motion for the lateral over the medial compartment. Although intra-subject variability was low, considerable differences in joint kinematics were observed between subjects. The observed subject-specific movement patterns indicate that accurate assessment of individual pre-operative kinematics together with individual implant selection and/or surgical implantation decisions might be necessary before further improvement to joint replacement outcome can be achieved.

准确评估3D胫股运动学对于理解膝关节功能至关重要，但它也为评估关节病变和肌肉骨骼干预的有效性提供了基础。但是，到目前为止，健康膝盖的功能运动学评估大多仅限于步态的负荷姿势阶段和仅水平行走，但是已知在高屈曲活动中会发生周围软组织最关键的情况。这项研究旨在确定胫骨股骨旋转和con突平移的范围，并提供关于不同步态活动的多个完整周期中旋转中心位置的证据。

基于在十个健康受试者中通过水平透视，下坡步行和楼梯下降的多个周期中使用移动荧光镜拍摄的影像学图像，重建了3D股骨和胫骨位姿，以提供胫股运动学的全面描述。

尽管关节屈曲明显增加，但all突前后运动范围在所有活动中均保持可比性，内侧和外侧mean的平均平移分别为6.3–8.3 mm和7.3–9.3 mm。仅水平行走和楼梯下降的摆动阶段在内侧隔室上方显示了较大的运动范围。尽管受试者内部的变异性较低，但受试者之间的关节运动学差异却很大。观察到的特定于受试者的运动模式表明，在进一步改善关节置换结果之前，可能需要对各个术前运动学以及各个植入物的选择和/或手术植入的决定进行准确的评估。