Abstract Human patellae (kneecaps) are thought to act as gears, altering the mechanical advantage of knee extensor muscles during running. Similar sesamoids have evolved in the knee extensor tendon independently in birds, but it is unknown if these also affect the mechanical advantage of knee extensors. Here, we examine the mechanics of the patellofemoral joint in the helmeted guineafowl Numida meleagris using a method based on muscle and tendon moment arms taken about the patella's rotation centre around the distal femur. Moment arms were estimated from a computer model representing hindlimb anatomy, using hip, knee and patellar kinematics acquired via marker‐based biplanar fluoroscopy from a subject running at 1.6 ms−1 on a treadmill. Our results support the inference that the patella of Numida does alter knee extensor leverage during running, but with a mechanical advantage generally greater than that seen in humans, implying relatively greater extension force but relatively lesser extension velocity.

中文翻译：

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头盔珍珠鸡的髌骨（膝伸肌籽骨）在陆地运动过程中的传动效应

摘要 人类髌骨（膝盖骨）被认为充当齿轮，在跑步过程中改变膝伸肌的机械优势。类似的籽骨在鸟类的膝伸肌腱中独立进化，但尚不清楚这些是否也会影响膝伸肌的机械优势。在这里，我们使用基于肌肉和肌腱力臂的方法检查头盔珍珠鸡 Numida meleagris 髌股关节的力学，该方法是围绕髌骨绕股骨远端的旋转中心获取的。力矩臂是根据代表后肢解剖结构的计算机模型估计的，使用通过基于标记的双平面透视从在跑步机上以 1.6 ms-1 运行的受试者获得的髋、膝和髌骨运动学。