I had cartolige symptoms in high school and now my doctor says i will need a knee replacement if i keep running. is this true?

If : There is no cartilage left in the joint your doctor is preparing you for it. There are some "cushioning injection that are new but discuss with your orthopedic surgeon.

Knee Cartilage: If you had cartilage removal surgery 10, 20 or even 30 years ago, its very likely you will develop a degree of arthritis in your knee. High impact activities (running/jumping) hasten the demise of this joint surface possibly leading to the need for joint replacement. Weight control, dietary modifications, and a low-impact cardio program with periodic steroid injections to manage symptoms.