這個膝蓋問題怎麽用英語向醫生描述？（偶爾左膝會突然一軟一麻，不能承重，但瞬間就恢複正常，不疼。）

偶爾左膝會突然一軟一麻，不能承重，但瞬間就恢複正常，不疼. 有時運動前發生，有時運動後發生。

Occasionally my left knee got numb in a sudden and that knee cannot carry my body weight. I had to shift all my body weight to my right knee. 

But only after a few seconds, the left knee issue disappears. My left knee would work normally then. 

I do not feel pain in the whole process. Sometimes this happens before a workout, sometimes after a workout. 

Just these days this happend more often than before, which alerted me. 

謝謝！