Dysfunction, rupture, or injury of the posterior tibial tendon causing a flexible pes planovalgus deformity; Stage II PTTD (11, 12, 13 and 14)

Rheumatoid arthritis without appreciable inflammatory arthritis of the talonavicular or subtalar joint

Peroneal spasticity arising from childhood

Talocalcaneal or calcaneonavicular coalition combined with or after resection of the coalition

Painful accessory navicular and attenuated function of the posterior tibial tendon or after failed Kidner procedure

Shortening of the lateral column due to a traumatic injury of the midfoot, impaction-compression fracture of the cuboid or anterior process of the calcaneus, and/or disruption of the calcaneocuboid joint

Primary osteoarthritis of the calcaneocuboid joint and a short lateral column

Salvage of an overcorrected equinocavovarus deformity (clubfoot)

The surgeon must assess the constituent deformities of the AAFD with the patient standing.

Anteroposterior and lateral radiographs with the patient in full weight bearing must be obtained.

A supple flatfoot corrects by inverting the calcaneus through the subtalar joint and plantarflexing and adducting the navicular through the talonavicular joint.

Forefoot varus must be correctable. The metatarsals must derotate in the coronal plane when the calcaneus is held in a neutral position.

Hindfoot valgus, manifested as lateral deflection of the heel relative to the ankle, is best appreciated while viewing the patient from behind (Fig. 20.1A). The leg must also be visualized to determine if valgus tilting of the ankle contributes to the deformity.

Radiographically, hindfoot valgus can be measured from a hindfoot alignment view using a technique described by Saltzman (15).

Midfoot abduction also may be assessed from this vantage point. Qualitatively, the amount of midfoot abduction can be determined by the “too many toes” sign (Fig. 20.1A). Increasing abduction allows a greater number of lesser toes to be seen from behind. From this posterior view, the arch is absent and replaced with a prominence created by a plantarflexed and uncovered head of the talus in contact with the floor.

Midfoot abduction observed as lateral deviation of the foot may be seen while viewing the patient from the front (Fig. 20.1B).

Abduction is quantified radiographically by measuring the talonavicular uncoverage angle on a weight-bearing anteroposterior x-ray of the foot (Fig. 20.2A) (16, 17 and 18). Recently, stage II PTTD has been subdivided into three categories with stage IIB signifying that significant midfoot abduction comprises the flatfoot (19). A revised classification scheme offers that lateral column lengthening is warranted when the AAFD demonstrates uncoverage of talonavicular joint exceeding 40% of the articulation. Lateral incongruity of the talonavicular joint as measured by the angle created by lateral subluxation/rotation of the navicular relative to the lateral talar neck has been advanced as a reliable radiographic indicator of the presence of a stage IIB deformity and the need for a lateral column lengthening.

Forefoot varus represents the combined effect of supination of the foot and elevation of the medial column to maintain a compensated, plantigrade foot during weight bearing in the presence of hindfoot valgus.

The flexibility of forefoot varus in pes planovalgus can be evaluated dynamically by asking the patient to externally rotate the knee while standing. In flexible forefoot varus, as the heel inverts toward the midline, the arch returns and the first metatarsal head maintains contact with the floor. During this maneuver, the patient corrects their forefoot varus by derotating the foot and plantarflexing the first ray through active contraction of the posterior tibial and peroneus longus muscles. With fixed forefoot varus, the first metatarsal lifts off the floor, and the arch does not return because the joints along the medial column do not move with muscle contraction. The presence of fixed forefoot varus indicates that realignment and stabilization of the medial column must accompany a lengthening of the lateral column during reconstruction to achieve a plantigrade foot.

Radiographically, forefoot varus can be quantified by measuring the talo-first metatarsal angle on the lateral weight-bearing view (Fig. 20.2B).

Equinus contracture. The Silfverskiöld test will determine the origin of an equinus contracture (20). If ankle equinus resolves with knee flexion, the contracture is isolated to the gastrocnemius. If equinus does not change whether the knee is flexed or extended, then the Achilles tendon is contracted. Isolated contractures are corrected with a recession of the gastrocnemius, while a lengthening of the Achilles is necessary for a combined contracture of the triceps surae (Fig. 20.3).

Peroneus brevis contracture. In severe abduction or anatomical shortening of the lateral column, the peroneus brevis tendon becomes contracted. A lengthening or transfer of this tendon to the peroneus longus is required to allow full correction of an abducted midfoot.

Posterior tibial tendon dysfunction

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