INJURY TIBIALIS POSTERIOR DYSFUNCTION BY KAREN HANKEY, BSC (HONS)

INTRODUCTION Tibialis posterior pain is a common injury often caused by a direct kick to the tibialis posterior tendon in contact sports such as football or, more often, by overuse in runners. The tibialis posterior tendon plays an important role in providing support to the medial arch of the foot, and so its correct functioning is vital. Many athletes continue training through apparently minor discomfort, but an untreated problem can lead to biomechanical problems throughout the kinetic chain or, in the worst-case scenario, to serious rupture and a subsequent collapse of the arch.

ANATOMY

The tibialis posterior muscle arises from the upper third of the tibia and interosseous membrane. It passes posteriorly around the medial malleolus, with the insertion into the navicular, cuneiforms, cuboid and metatarsals (see fig.1). The muscle’s main action is to combine plantarflexion with inversion. It also acts as a synergist with both tibialis anterior and the peroneii to balance the ankle. However, in addition to this, Norris states that pathology within tibialis posterior is likely in patients who hyperpronate (1). This must mean that the tibialis posterior muscle plays a part in forefoot pronation. Kohls-Gatzoulis and colleagues support this by stating that tibialis posterior is the primary muscle to provide dynamic stabilisation to the medial arch and therefore causes arch elevation (2).

MECHANISM OF INJURY During the walking cycle, there are three distinct parts: heel-strike, forefoot loading and toe-off. Forefoot pronation

TENDON REQUIRES THE USE OF DIFFERENTIAL DIAGNOSIS TO ASCERTAIN THAT THE PROBLEM IS ASSOCIATED WITH THE TIBIALIS POSTERIOR MUSCLE

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INITIAL DISCOMFORT ON PALPATION OF THE

online See animation Figure 1: Anatomy of tibialis posterior

occurs within this cycle just after heel strike; the forefoot then needs to supinate during push-off.

Pronation occurs during heel-strike

to allow a more open-packed position of the mid-foot, so that it can better adapt to the surface underneath. However, the amount of pronation that occurs needs to be controlled because excessive pronation may result in alterations of tibial, femoral, pelvic and lumbar alignment.

During the push-off phase of gait, the medial arch requires elevating. Kohls-Gatzoulis and colleagues suggests that this causes the mid- tarsal joints to lock, which in turn adds rigidity to the hind- and mid- foot (3). This allows efficient use of gastrocnemius during the gait cycle. Lake and colleagues state that

sports involving rapid changes of direction can also contribute to tendon dysfunction (4). This is probably due to the repeated microtrauma causing fibrotic changes in the muscles (2,3). Biomechanical issues are not the only cause of tibialis posterior dysfunction. As with most tendons, a direct contusion to the area may cause damage to the tendon fibres and local inflammation. In this case, if the problem is treated quickly and effectively, then long-term effects may be reduced. However, if the problem is left untreated, then the patient will alter their biomechanical state, which may in turn weaken the tibialis

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TIBIALIS POSTERIOR DYSFUNCTION

The tibialis posterior tendon plays an important role in providing support to the medial arch of the foot. The likely cause of problems in this tendon is overuse, although they can be caused by trauma. Failure to treat can lead to serious long-term problems. Anatomy, diagnosis and treatment are discussed.

BOLD HEAD TIBIALIS POSTERIOR DYSFUNCTION