Sentence:  I seized the rack and made a western style flying mount just in time , one of my <WSD>knees</WSD> mercifully landing on my duffel bag - and merely wrecking my camera , I was to discover later - my other knee landing on the slivery truck floor boards and - but this is no medical report . 
Meaning of the word marked with <WSD> tags:  hinge joint in the human leg connecting the tibia and fibula with the femur and protected in front by the patella