These days, many published articles are indicating the weakness in the hip muscles may be an indirect cause of knee pain such as patellofemoral stress syndrome (PFSS) or iliotibial band friction syndrome (ITBS). The gluteus medius, or G-med, is an important muscle in the side of your hip, and weakness here may be a cause of hip and knee pain.
If you are having knee pain, you may be referred to a physical therapist to help with the problem. Be sure that your PT checks the strength of your gluteus medius muscle. This muscle is responsible for hip abduction and rotation.