Last week we ended our discussion looking at how poor posturing loads various portions of the body. We will continue to see how this posturing impacts thoracic spine on down to the foot.
Two common alignment issues that we see in a postural assessment are supination (in relation to position of the calcaneous) resulting in pes cavus (in relation to the position of the medial arch) of the foot and pronation resulting in pes plantus of the foot. The position we most often observe in athletics however is calcaneal pronation resulting in pes plantus. This may present bilaterally but in many cases will present with an asymmetrical pattern, meaning that it will be much more pronounced on one side versus the other or be present on one side and not present at all on the other. In cases that present asymmetrically, we often see much greater dysfunction during sports performance and/or increased injury potential on the side with the most pronounced pronation. This can result in the athlete being plagued with injuries along the kinetic chain on the side with the greatest magnitude of pronation. When the calcaneous falls into excessive pronation in a closed kinetic chain the result is genu valgum at the knee, adduction at the hip and pelvic asymmetry. Although many believe this is the “main cause” of pathokinematics, research has shown us that proximal weakness in the hip and core can also result in pronation and pes plantus at the foot and ankle. In fact, pronation and pes plantus can be caused by a multitude of factors including weakness of the posterior tibialis, intrinsics of the foot on the plantar aspect, hypermobility of the plantar fascia or calcaneous, or proximal weakness in the hips and core.