Clark A L, Herzog W, Leonard T R
The University of Calgary, Faculty of Kinesiology, Human Performance Laboratory, 2500, University Drive NW, AB, T2N 1N4, Calgary, Canada.
J Biomech. 2002 Jan;35(1):53-60. doi: 10.1016/s0021-9290(01)00165-8.
The purpose of this study was to determine contact area and mean and peak pressures in the healthy feline patellofemoral joint over the complete range of possible applied force. Furthermore, we wanted to improve upon the repeatability of previous measurements while maximizing the physiological relevance of the results obtained. The patellae and femora were secured in a loading frame approximating an in situ loading configuration. Low- and medium-grade Fuji film was used to assess patellofemoral contact area and pressure distribution, respectively. Constant force was applied to the patellofemoral joints for 2s (short duration trials) or 5min (long duration trials). For the short duration trials, contact area was shown to increase logarithmically with the force applied. In contrast, mean and peak pressures increased linearly with force. Furthermore, the rate of increase of peak pressure with force was approximately three times greater than that of mean pressure. For the long duration trials, contact area increased up to 33% compared to the short duration trials. This effect could no longer be detected with our approach after an unloading period of 5-10s. Increasing contact area is one mechanism that the feline patellofemoral joint may use to regulate the pressures experienced by the cartilage as the force applied to the joint increases. The attenuation of external forces inside a joint is achieved by the specific geometry of the articulating surfaces and the viscoelastic properties of the articular cartilage. It likely represents a natural protection of joints to high external load magnitudes.
本研究的目的是确定在健康猫的髌股关节整个可能施加力的范围内的接触面积、平均压力和峰值压力。此外，我们希望提高先前测量的可重复性，同时使所获得结果的生理相关性最大化。将髌骨和股骨固定在一个近似原位加载配置的加载框架中。分别使用低等级和中等等级的富士胶片来评估髌股关节的接触面积和压力分布。对髌股关节施加恒定力2秒（短时间试验）或5分钟（长时间试验）。对于短时间试验，接触面积显示出随施加的力呈对数增加。相比之下，平均压力和峰值压力随力呈线性增加。此外，峰值压力随力的增加速率大约是平均压力的三倍。对于长时间试验，与短时间试验相比，接触面积增加了33%。在5 - 10秒的卸载期后，我们的方法不再能检测到这种效应。随着施加到关节的力增加，猫的髌股关节可能通过增加接触面积这一机制来调节软骨所承受的压力。关节内部外力的衰减是通过关节表面的特定几何形状和关节软骨的粘弹性特性来实现的。这可能代表了关节对高外部负荷量的一种自然保护。
