I have severe intermittent knee pain upon bending i am a 39 year woman who is in good physical shape it can last for 3 days and then completely disappear it does not come on with any specific cause it just tends to happen i have seen a sports medicine phy

Meniscus tear: Its possible to have an unstable meniscus tear that flips into the joint intermittently when the knee is bent. It may cause a sense of locking or catching in addition to pain. At most times it is painless. Work with an MRI may not reveal a tear if the meniscus is flipped back to it's normal position. It a difficult diagnosis. A careful work mus be done.

Patellofemoral?: If the pain is in the front of the knee it may be patellofemoral syndrome and you would benefit from physical therapy.

Many possibilities: Meniscus tears can give a similar picture as well. You need an exam from an orthopaedic surgeon and then you can pinpoint the problem.

Meniscus Tear: Is a possibility. Other thing to consider are patellofemoral pain, synovitis or a symptomatic plica. It depends where it hurts in you knee. If it is in the back or sides it is typically a meniscus. If it is in the front it is most commonly related to patellofemoral pain.