Flexible Flatfoot
1. Definition—Anatomic variation
a. Congenital physiologically normal foot shape with valgus alignment of the hindfoot, supination of the forefoot, a low or depressed longitudinal arch, and no contracture of either the gastrocnemius or the entire triceps surae (Figure 5-30).
b. The arch elevates and the hindfoot valgus changes to varus with toe-standing and with the Jack toe-raise test (see Assessment Principle #9, Figures 3-6A, B and 3-7, Chapter 3).
c. The ankle dorsiflexes at least 10° above neutral with the subtalar joint inverted to neutral (locked) and the knee extended, based on the Silfverskiold test (see Assessment Principle #12,Figure 3-13, Chapter 3)
2. Elucidation of the segmental deformities
a. Forefoot—supinated
b. Midfoot—neutral or abducted
c. Hindfoot—valgus/everted
d. Ankle—plantar flexed (equinus)
3. Imaging
a. None
4. Natural history
a. Gradual elevation of the longitudinal arch in most children through normal growth and development from birth until early adolescence (see Basic Principle #4, Figure 2-1, Chapter 2)
b. For those flatfeet that remain flat, comfort and function are equal to that of feet with average height longitudinal arches
5. Nonoperative treatment
a. None indicated for the typical asymptomatic physiologic flexible flatfoot
b. For activity-related diffuse nonspecific foot/ankle/leg pain, prescribe over-the-counter, cushioned, semirigid arch supports (Figure 5-31). These are contraindicated if the gastrocnemius or entire triceps surae is contracted (see Flexible Flatfoot with Short (Tight) Achilles or Gastrocnemius Tendon, this chapter).
6. Operative indications
a. None
7. Operative treatment with reference to the surgical techniques section of the book for each individual procedure
a. Not applicable.
Flexible Flatfoot with Short (Tight) Achilles or Gastrocnemius Tendon
1. Definition—Deformity
a. Congenital physiologically normal foot shape with valgus alignment of the hindfoot, supination of the forefoot, a low or depressed longitudinal arch, and contracture of either thegastrocnemius or the entire triceps surae (see Figure 5-30).
b. The arch elevates and the hindfoot valgus changes to varus with toe-standing and with the Jack toe-raise test (see Assessment Principle #9, Figures 3-6A, B and 3-7, Chapter 3)
c. The tendo-Achilles or gastrocnemius tendon is contracted, thereby limiting ankle dorsiflexion—accurately tested with the subtalar joint in neutral alignment and the knee extended (see Assessment Principle #12, Figure 3-13, Chapter 3).
Figure 5-31. Over-the-counter inexpensive firm, but not rigid, shoe inserts/arch supports.
Figure 5-32. Flatfoot (with mild midfoot adductus) x-rays. A. Standing AP of a flatfoot with abduction at the talonavicular joint. B. Standing lateral of a flatfoot with a sag at the talonavicular joint and a low calcaneal pitch.
2. Elucidation of the segmental deformities
a. Forefoot—supinated
b. Midfoot—neutral or abducted
c. Hindfoot—valgus/everted
d. Ankle—plantar flexed (equinus)
3. Imaging
a. Standing AP, lateral, (and oblique) of the foot (Figure 5-32).
b. AP, lateral, and mortis of the ankle
4. Natural history
a. Pain under the head of the talus and/or impingement-type pain in the sinus tarsi area in many/most cases occurring with, or exacerbated by, weight-bearing (Figure 5-33)
b. It is unknown whether the heel cord contracture is congenital or developmental
5. Nonoperative treatment
a. Heel cord stretching exercises performed with the subtalar joint inverted to neutral and the knee extended (see Management Principle #5, Figure 4-1, Chapter 4)
b. Soft, cushioned FLAT orthotics/shoe inserts (Figure 5-34)
Figure 5-33. A. FFF-STA with most weight-bearing pain under the medial midfoot due to forced plantar flexion of the talus caused by the heel cord contracture. B. There may also be pain in the sinus tarsi area due to impingement of the lateral process of the talus with the beak of the calcaneus. Lateral hindfoot pain can also be caused by impingement of the soft tissues between the calcaneus and the tip of the lateral malleolus. C. The finger points to the focal site of pain and tenderness. D. Callused skin under the head of the talus (circled).
Figure 5-34. Flat over-the-counter gel shoe insert for a FFF-STA. This design provides extra cushioning without increasing pressure under the plantar flexed talar head. A firm or hard elevated arch support causes increased pressure under the rigidly plantar flexed talar head and amplifies the pain. That design is, therefore, contraindicated. A. Bottom view. B. Top view.
6. Operative indications
a. Failure of prolonged nonoperative treatment to relieve the pain under the head of the talus and/or in the sinus tarsi area (Figure 5-33)
7. Operative treatment with reference to the surgical techniques section of the book for each individual procedure
a. Combination of procedures
i. Calcaneal lengthening osteotomy (see Chapter 8) with medial soft tissue plications (see Chapter 7)
ii. Gastrocnemius recession (see Chapter 7) or tendo-Achilles lengthening (see Chapter 7), based on the result of the Silfverskiold test (see Assessment Principle #12, Figure 3-13,Chapter 3), and
iii. Possible medial cuneiform (plantar flexion) plantar-based closing wedge osteotomy (MC-PF-CWO) (see Chapter 8)—perform this if rigid forefoot supination deformity is identified intraoperatively after the hindfoot deformity is corrected
b. Isolated gastrocnemius (see Chapter 7) or tendo-Achilles lengthening (see Chapter 7), based on the result of the Silfverskiold test (see Assessment Principle #12, Figure 3-13, Chapter 3).
i. Perform this rarely, except perhaps in very young children with FFF-STA with “mild” valgus/eversion deformity. With “moderate” and “severe” eversion deformities, this could lead to lever arm dysfunction (see Basic Principle #7, Figure 2-10, Chapter 2) and unacceptable weakness in push-off and jumping. Unfortunately, there are no meaningful definitions for “mild,” “moderate,” and “severe” valgus/eversion.