目的:根据我们最近的研究,这表明往复滑动接触中的软骨疲劳破坏是由周期性压缩力引起的,不是来自周期性的摩擦力,我们假设滑液(SF)的主要功能作用是降低周期性压缩负荷引起的关节软骨疲劳破坏率。
方法:通过将玻璃透镜滑向浸入成熟牛SF的未成熟牛软骨胫骨平台条,来测量由于重复压缩载荷引起的软骨疲劳破坏率,磷酸盐缓冲盐水(PBS),或SF/PBS稀释液(50%SF和25%SF;对于所有四种浴条件,n=8)。经过24小时的往复滑动(5,400次循环),对样品进行目视评估,如果观察到损坏,测试终止;否则,测试持续72小时(16,200个循环),与解决方案每天刷新。
结果:PBS组中的所有八个样品在24小时后都表现出物理损伤,平均最终表面粗糙度为Rq=0.210±0.067mm。SF组在24小时后没有显示损伤;然而,八个样本中有两个在72小时后受损,产生显著低于PBS组的平均表面粗糙度(Rq=0.059±0.030mm;p<10-4)。对于其余的群体,在72小时时,50%SF组中八个样本中的一个受损,25%SF组中八个样本中有五个受损。
结论:结果强烈支持我们的假设,显示测试浴中SF量的减少会导致软骨经受往复滑动接触的疲劳破坏率增加。
OBJECTIVE: Based on our recent study, which showed that cartilage fatigue failure in reciprocating sliding contact results from cyclical compressive forces, not from cyclical frictional forces, we hypothesize that a major functional role for synovial fluid (SF) is to reduce the rate of articular cartilage fatigue failure from cyclical compressive loading.
METHODS: The rate of cartilage fatigue failure due to repetitive compressive loading was measured by sliding a glass lens against an immature bovine cartilage tibial plateau strip immersed in mature bovine SF, phosphate-buffered saline (PBS), or SF/PBS dilutions (50% SF and 25% SF; n = 8 for all four bath conditions). After 24 h of reciprocating sliding (5400 cycles), samples were visually assessed, and if damage was observed, the test was terminated; otherwise, testing was continued for 72 h (16,200 cycles), with solution refreshed daily.
RESULTS: All eight samples in the PBS group exhibited physical damage after 24 h, with an average final surface roughness of Rq= 0.210 ± 0.067 mm. The SF group showed no damage after 24 h; however, two of eight samples became damaged after 72 h, producing a significantly lower average surface roughness than the PBS group (Rq=0.059 ± 0.030 mm; p < 10-4). For the remaining groups, at 72 h, one of eight samples was damaged in the 50% SF group, and five of eight samples were damaged in the 25% SF group.
CONCLUSIONS: The results strongly support our hypothesis, showing that decreased amounts of SF in the testing bath produce increased rates of fatigue failure in cartilage that was subjected to reciprocating sliding contact.