Does knee clicking indicate a lack of knee cartilage?

No: Knee clicking or "crepitus" can be caused by a torn cartilage, ganglion cyst, patella chondromalacia, synovitis, swelling (also known as an "effusionn"), or knee laxity. Some normal knees click. Clicking is a nonspecific finding that can be associated with both normal and abnormal knees.

Not necessarily: Most knees make noise. While it can sometimes indicate pathology, without injury or pain, it is usually harmless.