The flatfoot may or may not be symptomatic. Pain coincides variably with the severity or progression of the deformity. Patients may report arch, medial ankle, heel, or pretibial pain. Patients may also report lateral ankle pain due to lateral impingement (sinus tarsi and fibular-calcaneal), which is seen over time as the deformity progresses. When symptoms are present, patients frequently report a dull achy pain at the medial arch or medial ankle. They also may describe a feeling of "muscle weakness" or fatigue with exercises or standing for long periods of time.
The clinical examination should include a generalized overview of the foot type, a gait analysis, and an examination of the foot and ankle in both weight bearing and non–weight bearing. There is a variable spectrum of presentation from flexible to rigid. Upon inspection, the foot may have an arch while non–weight bearing but flattens with weight bearing. The arch may reconstitute with toe walking, hallux dorsiflexion at the first MTP joint (activation of the Windlass Mechanism), or hanging the foot in plantarflexion. Upon weight bearing and gait analysis, there may be collapse of the medial longitudinal arch, the "too many toes" sign, valgus hindfoot deformity, and forefoot abduction. Examination should include an evaluation of the ankle joint and subtalar joint range of motion. In a flexible deformity, the examiner can passively correct the deformity to a plantigrade foot. In a rigid deformity, the examiner cannot correct the deformity. The heel cord can have a contracture (ankle joint equinus) with lateral deviation of the Achilles with weight bearing. Severe Achilles contracture is associated with midfoot breakdown.
If the patient reports pain in the medial ankle or of pain during the examination posterior to the medial malleolus, posterior tibial tendon dysfunction should be strongly suspected. Examination should include a single heel raise, with the heel raising off the ground and inverting (Figure E4–8). If patients are unable to perform the single heel raise or if there is pain with this motion, the posterior tibial tendon is weak and inflamed. The posterior tibial tendon's strength should be examined by manual muscle testing by positioning the foot in plantarflexion and full inversion. If the patient is unable to maintain this foot position when the examiner applies an eversion force, the posterior tibial tendon is underpowered.
Single heel raise examination with the heel raised off the weight-bearing surface. The patient may or may not be able to perform the single heel raise or will be in pain while performing the single heel raise. Also shown is the posterior tibial dysfunction with the heel not being in rectus or an inverted state. (Used, with permission, from C. Parks, DPM.)
Plain radiographs are used to determine the severity of a flatfoot deformity or to rule out other mimicking conditions. Weight-bearing anteroposterior, oblique, and lateral radiographs of the foot are the most useful images (Figure E4–9). On weight-bearing anteroposterior view of the foot, the following will be evaluated: talar head coverage, increased talocalcaneal angle, cuboid-abduction angle, and talar-first metatarsal axis. The oblique view is to help rule out a tarsal coalition. Another view called the Harris-Beath view can help rule out a tarsal coalition. A weight-bearing lateral radiograph of the foot can evaluate for decrease in calcaneal inclination angle, increased talar declination angle, increased first metatarsal declination angle, anterior break in the Cyma line, and the Meary angle.
A weight-bearing lateral radiograph of a foot. Visible here is a decreased calcaneal inclination angle, increased talar declination angle, increased first metatarsal declination angle, anterior break of the Cyma line, and incongruent Meary angle. (Used, with permission, from C. Parks, DPM.)
MRI in later stages of this deformity may show a varying amount of posterior tibial tendon degeneration and arthritic changes in the talonavicular, subtalar, and tibiotalar joints.