Well, without a clinical evaluation it would be difficult to determine the cause of the pain. Meniscal tears often do not heal well and could be a constant source of discomfort; while other possibilities that may need to be considered include inflammations, arthritis, bursitis, tendonitis, cyst formation, injuries to the internal knee ligaments, chondromalacia patellae, loose bodies, patellar dislocation, nerve impingement/ compression, neuropathy, vascular issues, bone growths/ tumours etc; just to name a few. It would be best to consult an orthopedician for a detailed evaluation. After a specific cause is identified, it can be managed accordingly.
Hope this is helpful.