Knee pain is usually not a standalone condition. Being the center joint in the lower limb, abnormal loading from the hip or ankle/foot will always alter the loading on the knee joint. When the knee is aligned ideally, the force going through the knee does not cause injury. But, when there is a combination of forces from multiple directions, such as compression and gliding or twisting, the knee is predisposed to early degeneration.
Studies have shown that the majority of patients with knee pain also have weakness in their hip muscles and core control. Over time, abnormal balancing and movement strategies will be adopted.