There are many conditions in the more upper or proximal regions of the body that may be related to foot posture.
Abnormal foot posture may cause changes in the alignment of the leg that subsequently result in rotational changes at the hip and pelvis. For example, flat feet may cause the leg to excessively rotate so that the knee cap faces inwards. This may cause the muscles around the hip and lower back that externally rotate the leg to overwork as compensation in an attempt to maintain forward facing alignment. These rotational changes may also increase torque at the knee resulting in knee pain and overuse of the muscles surrounding the knee.
Another relatively common finding is a leg length difference resulting in un-levelling of the pelvis and muscle strain of the hips and lower back.
Your podiatrist will be able to determine whether your knee, hip and/or lower back problems are related to your foot posture and manage this pain with treatments such as Orthotics and heel lifts.