Outer lateral cartilage of knee is reduced so pain in the lateral knee, what can be best treatment, what should be done?

Not clear . Not clear your question orthopedic injuries are usually help by rest for a couple of weeks and splinting. You can restate your question. Seen orthopedist for specific diagnosis and treatment.
What is wrong. What do you mean by the lateral cartilage is red uced.Have you seen a doctor and had an MRI already.Did you have Knee injury I su ggest you either see your primary care doctor or an orthopedic specialistto find out what is wrong and treated appropriately Meanwhile rest the knee and use an ace bandage or knee brace.And if recent injury put ice on it Good Luck.