John can't run anymore because his knee joint was injured in a race.

他的膝关节在某次赛跑中受伤因此不再跑步了。

Surgery can repair damaged hip and knee joints, but spinal surgery is typically considered risky and is rarely performed.

外科手术可以修复损毁的骶髂关节和膝关节，但通常认为脊柱手术的风险很大，因此很少进行。

It's been found that a one pound weight loss can equal a 4 pound reduction in knee joint stress.

研究发现，体重减轻 1 磅相当于膝关节压力减轻 4 磅。

Synthetic knee joints may give off particles as they’re worn down, causing immune cells to inflame around these fragments.

合成膝关节在磨损时可能会释放出颗粒，导致这些碎片周围的免疫细胞发炎。

Well that's what these girls were doing, except they were cracking their knee joints, which sounds a little painful.

好吧，这就是这些女孩所做的， 除了她们的膝关节开裂，这听起来有点痛。

They would, what we would call " crack" certain parts of their body – their toes and especially their knee joints.

他们会，我们称之为“裂开”他们身体的某些部位——他们的脚趾，尤其是他们的膝关节。

They started each session collecting a blood sample, and a bit of synovial fluid, the natural lubricant inside the knee joint.

他们在每次训练开始时采集血样和少量滑液，滑液是膝关节内的天然润滑剂。

The idea is that when you run, the flexible, tough tissue that cushions your knee joints, called cartilage, takes a pounding.

这个想法是， 当你跑步时，缓冲膝关节的柔韧、坚韧的组织（称为软骨）会受到冲击。

By looking at the articulations, that is where two bones are in contact with one another like at this knee joint.

通过观察关节，这就是两块骨头相互接触的地方，就像这个膝关节一样。

When I went for a walk, I didn't leak join fluid from my knees, " joint fluid." Why was menstruation so different?

当我去散步时， 我没有从膝盖漏出关节液，“关节液” 。 为什么月经如此不同？