Knee pain for decade and no particular injury or accident. mri said chondromalacia patella and medial posterior meniscus horizontal tear with mild joint fluid effusion. need diagnosis/name of disease. is it permanent? surgery recommended?

First, you describe wear and tear "chondromalacia", and an injury to at least one meniscus. Would consult with an orthopedic surgeon. Surgery is not always the approach, as a steroid injection and a series of hyaluronic acid injections might be preferred approaches. Physical therapy definitely should be commenced.

Very young for this problem. You could have a biomechanical problem causing abnormal wear of the he joint cartilage. If you have “flat”feet or muscle imbalance or rotation at the hip can be involved.