Hurt at work, left knee, horizontal meniscus tear. right knee, oblique tear medial meniscus . do i need surgery ?

Meniscus Tear: With that kind of specific knowledge your must have had an MRI of your knees. Without a knowledge of your symptoms and exam of your knees it is impossible to know wether you need surgery or not. The simple presence of a tear without any corresponding symptoms or exam specific to that area would not need surgery. Either would minimal or mild symptoms which resolve with rest and no surgical care