CONGENITAL DEFORMITIES OF THE FOOT

Congenital clubfoot (talipes equinovarus) is a hereditary foot deformity of unproven etiology. It affects males more

often than females and may be unilateral or bilateral. It is often
associated with other conditions, such as myelodysplasia,
arthrogryposis, and congenital hip dysplasia. Pathologic changes seen
in clubfoot include bony deformity, particularly of the talus (short
neck, medial deviation of the neck, abnormal articular surface of the
head) and soft-tissue contracture (muscle, tendon sheath, capsule,
ligament, skin) (14).
Externally, the clubfoot is smaller than the normal foot. There is
equinus of the ankle, varus and internal rotation of the heel,
accompanied by adduction, supination, and cavus of the midfoot. The
calf is atrophic and smaller in circumference than the opposite calf.
The leg lengths are generally equal. Internally, the deformity is most
clearly defined as a rotational subluxation of the
talocalcaneonavicular joint complex, with the talus in plantar flexion
and the talocalcaneonavicular (subtalar) complex in medial rotation and
inversion (20). There is controversy over
whether the soft tissue or bony changes are the primary cause of the
disorder, although nonoperative and surgical treatment both address the
soft-tissue portion of the deformity with the expectation that at least
some of the bony abnormalities will remodel. Regardless of the form of
treatment, the resultant foot will be smaller and less mobile, and the
calf relatively atrophic, when compared with a normal limb.

Management of the congenital clubfoot is initially
nonoperative and, if possible, should begin on the first day of life.
Serial manipulation of clubfoot and maintenance of correction with
casting is a skill that all orthopaedic surgeons dealing with children
should develop (15,26).
It is essential to correct the midfoot adductus and hindfoot varus in
the casts before you make any attempt to address the equinus. We have
concern that overly aggressive attempts at dorsiflexion may damage the
talus, and we often abandon casting once progression of the correction
into dorsiflexion stops.

When casting fails, surgical release is indicated. The
need for and the exact timing of the surgery depends on the severity of
the clubfoot. We normally make a decision to treat surgically by 3–4
months of age. Surgery, however, can be timed so that the postoperative
casting is completed at about the time the child begins to bear weight
on the foot. Some surgeons prefer operative treatment at a much younger
age, but there is also literature support for postponing surgery up to
1 year of age or beyond, if the surgeon feels technically more able to
operate on a larger foot (33). In children with syndromes, delay of surgery until a year of age or beyond is often desirable or necessary.

Stress dorsiflexion lateral radiographs of an
incompletely corrected clubfoot reveal inadequate dorsiflexion of the
os calcis or parallelism of the talar and calcaneal axes.
Anteroposterior (AP) views show medial deviation of the first
metatarsal axis relative to the talar axis, a function of subluxation
of the talonavicular joint (the navicular ossification center itself
does not appear for several years, and its position must be inferred);
the axes of the talus and calcaneus likewise become parallel because
the external rotation of the subtalar joint is lost. Most of the angles
described for evaluation of clubfoot are based on radiographs of older
children, and they date from an era when treatment was nonoperative and
involved prolonged casting. We have not found radiographs to be helpful
in determining which children should have early surgery; the decision
is made more easily on clinical grounds.

The aim of surgical treatment is to release soft-tissue
restraints on proper positioning of the tarsal bones. The exact
surgical procedure can be tailored to the residual deformity of the
foot at the completion of casting. The usual surgical release always
includes posterior structures (tendo Achillis, posterior tibial tendon,
calcaneofibular ligament, posterior ankle, subtalar capsulotomy, and,
sometimes, long toe flexors). If significant midfoot deformity remains
(medial talonavicular subluxation), release the medial talonavicular
joint and the tendon sheaths of posterior tibial, flexor digitorum
longus (FDL), and flexor hallucis longus (FHL) muscles. Some clubfeet
have significant medial subluxation of the calcaneocuboid joint,
requiring capsular release (2,21).
The medial subtalar capsule can be partially or completely released to
correct hindfoot varus. These releases allow the talus to be
dorsiflexed into neutral position, the navicular to be abducted and
rotated onto the true axial head of the talus, and the os calcis to be
brought out of varus and into lateral rotation under the talus to
reduce the subtalar joint. Hold the reduction with pin fixation in a
cast until the soft tissues heal.

Although surgeons have recognized for years that
posterior and medial releases are necessary to correct clubfoot, recent
attention to the posterolateral ankle structures (fibulocalcaneal
ligament and peroneal sheaths) has emphasized the importance of
correction of internal rotation of the subtalar joint if full correction of the clubfoot is to be achieved (20,21,22,28,29,32).
The exact incision used may not be important, but it must provide
adequate exposure of these structures or the correction is incomplete.
We prefer the Cincinnati circumferential subtalar incision (or portions
of it), because it gives the fullest visualization of the entire
midfoot and hindfoot, including the posterolateral region; you can use
portions of this incision for more limited releases (8).
Because tarsal bones are largely cartilaginous in the small child, they
are inevitably deformed at the time of reorientation, and the
correction must be maintained for at least 3–4 months to allow
remodeling. Many children require further bracing for a year or more to
maintain position during walking.

Tailor the operative procedure to the deformity. If the
releases performed are overly aggressive, the result may be an
overcorrected clubfoot when the child becomes older. There are good
methods that have been developed to later

improve
undercorrected feet or relapsed feet, but there are no good secondary
procedures that adequately deal with the overcorrected clubfoot.
Although our initial feeling was that complete correction of a clubfoot
was necessary in most cases, the long-term follow-up of many of our
earlier patients with clubfoot has led us to temper these beliefs. In
the mild and moderate clubfoot, we now favor a more limited release of
posterior structures, which generally leads to better foot function as
the child matures.

Rarely, cavus foot is idiopathic and seen in infancy.
Cavus is a common component or residuum of clubfoot. However, isolated
cavus or cavovarus deformity usually develops insidiously with growth
and is a sign of occult neuromuscular disease. Some of the more common
associated disorders are listed in Table 167.1.

Because the orthopaedic surgeon is often the first
physician to recognize the deformity, it is important to do a careful
neurologic examination and initiate necessary ancillary studies (e.g.,
electromyography, muscle enzyme studies, spine radiographs, and spine
magnetic resonance imaging) and obtain appropriate consultation before
attempting treatment.

Cavus is generally progressive until growth stops.
Orthotic management is never successful; the deformity is either
accepted or treated surgically. The mainstay of treatment is triple
arthrodesis (see Chapter 115), but dorsal
wedge osteotomy may be appropriate in selected cases. There is usually
associated hindfoot varus. Determine whether hindfoot varus is fixed by
the Coleman block test (Fig. 167.9). This test
differentiates between rigid varus, which must be surgically treated by
triple arthrodesis, and varus secondary to first metatarsal depression,
which is flexible and corrects once the medial column cavus has been
corrected using midfoot dorsal wedge osteotomy.

If cavus is severe and disabling in a young child,
plantar release and metatarsal osteotomies can successfully temporize
while the foot matures. However, bony procedures at maturity (after age
11 or 12 years) almost always are required, even after earlier
soft-tissue release.

Polydactyly is a hereditary foot deformity inherited
with an autosomal dominant pattern. The most common form is postaxial
duplication of the fifth digit. Less common is preaxial duplication of
the great toe. Rarest is middle toe duplication. Both preaxial and
postaxial polydactyly may be associated with syndromes, which you
should look for. The hand is often involved as well; when this is the
case, the foot deformities are usually more severe than the hand
deformities in that the duplications are more proximal. Generally, it
is desirable to treat polydactyly of the toes because untreated
patients experience difficulty with fitting shoes. In addition, extra
digits, even though asymptomatic, can subject a child to ridicule from
peers (9,25,35).

Bunions, or hallux valgus deformities, are relatively common problems in children and adolescents (6,7,31).
The incidence is unknown. It occurs much more commonly in girls than
boys. Ill-fitting shoes have been implicated as a causative factor in
adult hallux valgus, but the association of shoe wear with juvenile
hallux valgus is unclear. There is often a positive family history. The
deformity is usually bilateral. The age of onset may be as young as 10
years of age.

The general indications for surgical intervention are
problems with shoe wear and dissatisfaction with the cosmetic
appearance of the foot. Despite the fact that surgical intervention is
noted to have a high failure rate, most reports on the correction of
juvenile hallux valgus have presented the results of a single, specific
technique of surgical reconstruction. We agree with Coughlin (6)
that the operative procedure to correct juvenile hallux valgus must be
customized to the specific deformities in the foot. Surgical correction
prior to epiphyseal closure is controversial. Whereas there is rarely a
rush to perform surgery to correct the deformities of juvenile hallux
valgus, the notion that surgery performed on a patient with an open
epiphysis is contraindicated has not been substantiated.

In assessing the patient with juvenile hallux valgus,
obtain an AP weight-bearing radiograph of the foot. Measure the
following: (a) the hallux valgus angle, (b) the first-to-second
intermetatarsal angle, (c) the distal metatarsal articular angle, and
(d) the first metatarsophalangeal joint congruency (the relationship of
the articular surface of the base of the proximal phalanx to the
articular surface of the 1st metatarsal) (Fig. 167.14, Fig. 167.15).

Operative procedures to correct juvenile hallux valgus can be grouped into four categories:

These procedures are covered in more detail in Chapter 112.
No one standard operation is suited for all juvenile patients with
hallux valgus. Versatility is the surgeon’s most important asset when
treating the juvenile bunion. It is important not to stretch the
indications for a particular technique to correct the deformity.

Tarsal coalition (9,23)
is a congenital fusion between two or more of the tarsal bones. The
coalition can be a true bony fusion, or a cartilaginous or fibrous
connection. The overall incidence of tarsal coalitions is unknown, but
many are inherited with an autosomal dominant pattern. Many tarsal
coalitions are not symptomatic and therefore go unrecognized. The most
common symptomatic tarsal coalitions occur between the calcaneus and
the talus, and between the calcaneus and the navicular. Complex
coalitions also accompany fibular hemimelia and proximal femoral focal
deficiency, but these rarely require treatment.

Pain is the principal presenting symptom, occurring when
the coalition or bar begins to ossify. The usual age of onset is the
second decade of life. The most common clinical finding is restriction
of subtalar motion. The hindfoot

is
in valgus, and the patient may experience peroneal muscle spasm
exhibiting in a rigid flatfoot. An attempt to invert the hindfoot,
especially as a rapid maneuver, causes an increase in pain.

For radiographic evaluation, take AP, lateral, and
oblique radiographs of the foot. The best radiographic view to detect a
calcaneonavicular bar is the 45° oblique view (Fig. 167.17A).
A lateral radiograph of the foot or of the ankle will usually
demonstrate the so-called anteater nose sign, which is elongation of
the anterosuperior aspect of the calcaneus as it is directed toward the
navicular.

A talocalcaneal bar is much more difficult to
demonstrate on plain radiographs. Oblique subtalar (Harris) views can
be helpful, but often the best study to demonstrate a medial subtalar
coalition is a computerized tomographic examination. When done in the
coronal plane, this study usually successfully demonstrates
talocalcaneal coalition.

The treatment of a symptomatic tarsal coalition is
initially conservative. Start with 4–6 weeks of immobilization in a
short-leg walking cast. If this and other conservative measures fail,
consider resection of the tarsal coalition if the child is still young,
particularly when some subtalar motion is present. Results are
generally favorable with resection of calcaneonavicular tarsal
coalitions. The results are less predictable with tarsal coalitions
between the talus and calcaneus. The presence of symptoms for many
years and advanced degenerative changes on midfoot radiographs are
contraindications for resection of the coalition. In such cases, triple
arthrodesis may be appropriate.

Congenital vertical talus (CVT), also know as congenital
convex pes valgus, is a complex, rare, foot deformity that is resistant
to conservative treatment. There is a continuum from a relatively mild,
flexible form (oblique talus) to a rigid, severe deformity
characterized by a plantar-flexed talus, hindfoot equinus, and dorsal
dislocations of the talonavicular and calcaneocuboid joints. The heel
is always in rigid valgus. There are contractures of the Achilles
tendon, peroneus tertius, long-toe extensors, and tibialis anterior
muscle (Fig. 167.18). Lateral roentgenographs
taken in full dorsi- and plantarflexion differentiate the more flexible
oblique talus from the severe variety; oblique talus exhibits severe
deformity in dorsiflexion but a relatively normal relation between the
talus and calcaneus in full plantar flexion (16).

In more than 80% of cases, CVT is associated with other
anomalies and syndromes (Marfan’s syndrome, arthrogryposis, multiple
pterygium syndrome), genetic abnormalities (trisomy 13–15, trisomy 18),
or neuromuscular defects (myelomeningocele) (16).
Unless the cause of the anomaly is clear, perform a thorough
neuromuscular and genetic workup. Many children with CVT who would
otherwise be candidates for surgery are wheelchair bound and can be
treated by protecting the foot with a soft tennis shoe.

When indicated, treatment of rigid CVT is always
surgical. Most experts recommend preliminary casting to mobilize the
skin, but casting does not correct the bony deformity. Single-stage
correction usually involves mobilization and reduction of all subluxed
joints, internal fixation, and appropriate soft-tissue repair with
transfer of the anterior tibial tendon to the neck of the talus to
maintain dorsiflexion of the talus and minimize heel valgus (16,30).

The other commonly used approach is a two-stage method, with the procedures spaced 6–8 weeks apart (5).
In this approach, first reduce the dorsally dislocated midfoot through
an anterior incision, and lengthen contracted toe extensors and
anterior tibialis muscles. Stabilize the subtalar joint in appropriate
position with a subtalar bone block. Six weeks later, release the
posterior ankle and subtalar joints, lengthen the heel cord, and
reconstruct the anteriorly displaced posterior tibial muscle to support
the talar head and neck. Whereas many surgeons attempt correction by
soft-tissue means, this approach (using a subtalar fusion) can be
highly effective in difficult cases.

Seimon (27) has described
correction of deformities in CVT with a single dorsolateral
longitudinal incision and a percutaneous posterior release. This
procedure has been used with excellent success in patients under the
age of 2 years.

Surgery is ideally done at 4–6 months of age, although accompanying anomalies and illnesses often require postponement

to age 1 year or later. After the age of 2 to 5 years, reduction is
difficult unless the foot is decompressed by navicular excision (3).
Partial talectomy and decancellation of the tarsal bones may be
required. Triple arthrodesis may be necessary in neglected or severe
cases, and it may be necessary in maturity even when surgery early in
life has corrected the gross deformity. This is especially true when
tarsal bones are excised, leading to late degenerative arthritis.

Do not miss associated anomalies and conditions.
Misdiagnosis can lead to a poor outcome or, worse, a serious
complication when there is serious associated systemic disease or other
disorders.

Precise, careful surgical technique is necessary to
avoid neuromas from inadvertently cutting superficial sensory nerves,
more serious injury to the main neurovascular bundles and tendons, and
skin sloughs. In small feet, magnifying loupes are quite helpful.

Avoid incomplete correction or overcorrection,
particularly the latter as it is more difficult to correct, by careful
preoperative planning.