Occasional knee pain may be related to the following causes: 1. There may be patellar tenderness. Patellar chondromalacia refers to the gradual destruction of the articular cartilage on the medial side of the patella, resulting in pain around the patella and a tenderness in the leg. In the early stages, this pain may be mild and paroxysmal.2. There may be a condition of osteoarthritis. Patients can simply interpret osteoarthritis as excessive wear and tear of the knee joint, which gradually causes pain, deformity and limited movement of the knee joint due to excessive destruction of the knee cartilage and subarticular bone. In the early stages, this pain can be manifested as pain at rest and paroxysmal pain. 3. There may be meniscus-related damage. Meniscus injuries are often due to long-term wear and tear, or transient trauma, resulting in different parts of the meniscus with different degrees of rupture. If the injury is mild, the pain may be occasional. 4. The condition may be caused by inflammation of the joint inside the knee joint, such as synovitis inside the knee joint due to cold, which may cause occasional pain in the early stages and an increase in fluid inside the joint.