Massage & Bodywork

MARCH | APRIL 2019

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92 m a s s a g e & b o d y w o r k m a r c h / a p r i l 2 0 1 9 technique CLINICAL EXPLORATIONS Posterior Tibial Tendon Dysfunction By Whitney Lowe 1 Lower extremity overuse disorders are painful and can be debilitating. In this article, we look at the function of the posterior tibialis in lower extremity biomechanics and pain conditions. Specifically, we look at a condition called posterior tibial tendon dysfunction. The posterior tibialis plays a crucial role in many foot disorders, but can be overlooked because the muscle is not easily accessible to palpation. ANATOMY Foot problems often result from dysfunctional biomechanics. Absorbing and distributing the load and ground reaction forces from walking or running puts a heavy demand on the lower extremity. One of the most important stabilizing muscles of the lower extremity is the posterior tibialis (PT), also called tibialis posterior. It lies deep within the posterior compartment of the leg and, as a result, is difficult to reach. It is the deepest of the posterior compartment muscles and originates from the interosseous membrane, posterolateral tibia, and posteromedial fibula (Image 1). Its distal attachment spans across the bottom surface of the foot and has branches that insert into most of the foot bones, including the second, third, and fourth metatarsals; intermediate and lateral cuneiforms; cuboid; and calcaneus (Image 2). The PT tendon is the largest and most anteriorly situated of the three tendons that course around the medial ankle and through the tarsal tunnel. There is a region of reduced vascularity where the tendon bends around the medial malleolus. This decreased blood supply makes the tendon prone to overuse injury. In addition, the PT changes its angle of pull from vertical to horizontal as it courses around the medial side of the ankle, causing increased friction on the tendon, which can play a role in degenerative changes. The other two tendons from the deep posterior compartment are the flexor hallucis longus and flexor digitorum longus. The flexor retinaculum holds these three tendons in place around the medial ankle. The flexor retinaculum also forms the roof of the tarsal tunnel, and the tendons share the narrow tunnel space with arteries, veins, and nerves. When damaged or dysfunctional, local inflammation of the PT tendon can also cause vascular and nerve compression (tarsal tunnel syndrome) in this region. BIOMECHANICS The PT is the main inverter of the foot. However, the majority of load on the muscle-tendon unit occurs not from forceful inversion, but from eccentrically resisting eversion as an eccentric "brake" during the weight-bearing portion of the gait cycle. There is a complex pattern of movement involving the foot, ankle, and leg that occurs when we are walking and running. There are three main stages (or phases) of the gait cycle. The foot strikes the ground with the outside of the heel first (heel-strike phase). Then, the foot's bottom surface makes Location of posterior tibialis. Image is from 3D4Medical's Complete Anatomy application.

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