The bones of the foot are assigned to the following three anatomical divisions: the forefoot (metatarsals and phalanges); the midfoot (the cuneiforms, cuboid and scaphoid); and the hindfoot (talus and calca- neus). As discussed in the next section in more detail, this division has also functional implications.
The three cuneiform bones articulate with the base of the first three metatarsals, while the cuboid, located on the lateral side of the foot, articulates an- teriorly with the base of the 4th and 5th metatarsals, and posteriorly with the calcaneus. The navicular bone is sited transversely, with the three cuneiforms anterior, and the talus posterior to it. There can be a number of accessory ossification centers in the feet, the most common and best known of which are the sesamoids (located near the heads of the meta- tarsals), the os tibialis externum (located near the tuberculum of the scaphoid), and the os trigonum (situated near the dorsal process of the talus). These accessory ossicles occasionally simulate fractures and can be responsible for symptoms, including pain and local tenderness (Lawson 1985).
The primary ossification centers for the meta- tarsals appear at about the 9th to 10th week of gesta- tion, while those for the phalanges are evident be- tween the 9th and 15th weeks of gestation. The cuboid ossifies at the end of gestation or within the 1st month after birth and the third cuneiform at about the 5th postnatal month, while ossification of the other cuneiforms and the navicular bone takes place during the 2nd to 3rd year of life. Ossification in the calcaneus begins around the 24th week of ges- tation with the appearance of one or two primary centers that rapidly coalesce into a single center, while ossification of the talus becomes apparent shortly afterwards, around the 30th gestational week. Thus, the ossification centers for the talus, cal- caneus, cuboid (usually), metatarsals, and phalanges are present at birth. The apophysis of the calcaneus, located behind its posterior margin, begins to ossify
at about the middle of the first decade and progress- es over time until complete fusion is attained well in- to the second decade. A secondary ossification cen- ter appears in the dorsal process of the talus around the 5th–6th year of age, and it fuses with the body of the talus between the 16th and 20th years. If it per- sists beyond this period it is referred to as the os trigonum.
The ossification of the navicular bone, cuboid and cuneiforms is often irregular in children who are healthy and have no evidence of local disease in the feet. Several other anatomical variations occur in the feet, including pseudoepiphyses, cone-shaped epi- physes, ivory epiphyses, and partite epiphysis of the proximal phalanges of the great toes. Cone-shaped epiphyses in the feet are more common than those in the hands and usually have no clinical significance except for a possible association with premature epi- physeal fusion and shortening of the involved toe (Silverman 1993). Lack of epiphyseal centers in the middle phalanges of the toes and distal sympha- langism are also common findings in otherwise nor- mal children. The anatomical skeletal variations are discussed in detail in various excellent textbooks (Köhler and Zimmer 1968; Keats and Anderson 2001).
References
Keats TE, Anderson MW. Atlas of normal roentgen variants that may simulate disease. Mosby, New York, 2001 (7th ed.) Köhler A, Zimmer EA. Borderlands of the normal and early pathology in skeletal roentgenology. Grune & Stratton, New York, 1968
Lawson JP. Symptomatic radiographic variants in extremities.
Radiology 1985; 157: 625–31
Silverman FN. The bones: normal and variants. In: Silverman FN, Kuhn JP (eds.) Caffey’s pediatric X-rays diagnosis. An integrated imaging approach. Mosby, St. Louis, 1993 (9th ed.), pp. 1465–529
Alessandro Castriota-Scanderbeg, M.D.
Clubfoot and Other Foot Deformities
At birth, the normal infant’s foot is proportionately longer and thinner than that of the older child, and the joints of the ankle and foot display a wide range of motion. The foot can be dorsiflexed so far that the top of the foot touches the tibia anteriorly, and flexed in the plantar direction so far that the dorsum of the forefoot is parallel with the tibia. The anterior part of the foot must be flexible enough to be moved into 45°
of adduction or abduction. Although the newborn’s feet may appear to be in abnormal positions, there is no need for concern if the feet can be moved through the range of motion described above. Such ‘position- al’ foot configurations resolve spontaneously (Watts 1987).
In contrast, there are several other situations in which the deformity of the foot is progressive. In the interests of a better understanding of the complexi- ties of these foot malformations, a brief discussion of
the elementary foot anomalies, with reference to the pertinent terminology, is useful (Freiberger et al.
1970). As stated previously, dividing the foot into a posterior (hindfoot) and an anterior (forefoot) por- tion is beneficial to the understanding of the foot anomalies.
A key element in the evaluation of the normal and abnormal hindfoot alignment is to assess the rela- tionship between the talus and the calcaneus (Ozonoff 1979; Resnick 1995). In a normal situation, on an anteroposterior (AP) radiograph the talar axis intersects the 1st metatarsal or falls just medial to it and the navicular bone is situated directly opposite the head of the talus. The calcaneal axis points to the 4th or 5th metatarsal bone, and the resulting talocal- caneal angle (angle of Kite) measures approximately 35° in adults (Resnick 1995) and in the range of 20–40° in normal children (Simons 1977). On a later- al (LL) radiograph, the talar axis is directed along the axis of the 1st metatarsal bone as it slopes gently in a
Fig. 7.1 a–c. Drawings of a normal foot (a, c) and hind- foot varus (b), with lines and angles commonly used to evaluate clubfoot and flatfoot deformities. For the explana- tion, see the text. (Reprinted, with permission, from Si- mons 1977)
a b
c
plantar direction from posterior to anterior. The cal- caneus is slightly dorsiflexed, and the resulting talo- calcaneal angle varies between 35° and 55° (Simons 1977) (Fig. 7.1 a–c). In the hindfoot varus deformity, the talocalcaneal angle measured on the AP projec- tion is narrower, as the calcaneus has shifted medial- ly under the talus (it is generally assumed that the position of the talus relative to the lower leg is rela- tively fixed and that a change in the relative positions of the talus and the calcaneus reflects a movement of the latter bone) (Resnick 1995). The long talar axis falls laterad to the 1st metatarsal, and the navicular bone is displaced medially in relation to the talus. In the LL projection, the talus and the calcaneus lie more nearly horizontal and parallel to each other (Fig. 7.2 a, b). This foot deformity occurs in some paralytic disorders and as a component of the equinovarus foot deformity, as discussed below. In hindfoot valgus, the talocalcaneal angle on the AP projection is increased, the long talar axis falling me- dial to the 1st metatarsal. The calcaneus is abducted, while the navicular bone and the remaining tarsal bones are displaced lateral to the talus. On the LL projection, the talus is tilted into a more vertical position, so that its long axis and that of the 1st metatarsal are angled in the plantar direction (Fig.
7.3). This deformity occurs in flatfoot, metatarsus varus, congenital vertical talus, and certain congeni- tal and neurological deformities of the foot. In hind- foot equinus, the lateral projection shows the calca- neus flexed in a plantar direction, so that the angle between the long axis of the calcaneus and that of the tibia is greater than 90° (Fig. 7.2 b). This defect oc- curs as an element in talipes equinovarus and verti- cal talus, and is associated with various neuromuscu- lar disorders. As opposed to the defect described
Fig. 7.2 a, b. Hindfoot varus deformity. a In a female newborn:
anteroposterior projection of the foot, showing severe varus deformity of the hindfoot with superimposition of the talus and calcaneus. The long axis of the talus projects a long way laterally to the 1st metatarsal. The navicular bone is not ossi- fied, but its abnormal position on the medial aspect of the midfoot can be inferred from the location of the 1st metatarsal base. Note severe adduction of the forefoot (metatarsus varus).
bIn a male newborn: on the lateral projection the talus and calcaneus are more nearly parallel than normal owing to plan- tar flexion of the calcaneus (hindfoot equinus). Delayed ossifi- cation of the cuboid was observed
Fig. 7.3. Hindfoot valgus deformity in a male newborn. Later- al projection. Note plantar flexion of the anterior aspect of the talus, which appears more vertically oriented than normal a
b
above, in calcaneal hindfoot the calcaneus is dorsi- flexed, so that its anterior end has a higher position.
This deformity occurs in association with cavus foot.
Abnormalities of the forefoot alignment are also easily established on the AP and LL foot projections taken during weight-bearing. In normal individuals the metatarsals converge proximally on the AP radi- ograph, overlapping at their bases. On the LL projec- tion, the 5th metatarsal is located in the most plantar position and the remaining metatarsals are superim- posed. In forefoot valgus (abducted), on the AP view the metatarsals are seen to deviate in a lateral direc- tion and are approximately parallel in their orienta- tion. Furthermore, they look wide open and display a lesser degree of basal overlapping (Fig. 7.4). In the LL projection, the metatarsal bones are often arranged in a ladder-like fashion with the 1st metatarsal locat- ed in the most plantar position. A forefoot valgus is seen in flatfoot. In forefoot varus (adducted), the fore- foot on the frontal projection appears to be nar- rowed, with increased convergence at their bases and a greater degree of basal overlapping. On the LL view, the metatarsal bones are also arranged in a ladder- like fashion, but with the 1st metatarsal located in the most dorsal position. This foot deformity occurs in talipes equinovarus and metatarsus varus. The term cavus foot (pes cavus) is applied to a deformity char- acterized by an abnormally increased longitudinal
plantar arch. The calcaneus is dorsiflexed (calcaneal hindfoot deformity), and the metatarsals are plantar flexed and in valgus, thus resulting in a deepened plantar arch. The deformity can occur as an isolated congenital malformation, but is frequently associat- ed with neuromuscular disorders, such as spinal dys- raphia, cerebral palsy, poliomyelitis, the Charcot- Marie-Tooth type of peroneal muscular atrophy, and other conditions. The term flatfoot (pes planus) des- ignates a common condition in which the hindfoot is in valgus and the forefoot is abducted. The talus has an orientation closer than normal to vertical, while the calcaneus and metatarsals are aligned horizontal- ly, accounting for flattening of the plantar arch. The calcaneus fails to support the anterior portion of the talus, which therefore slips in a medial and plantar direction. There is a continuum extending from the physiological flatfoot of infancy through varying de- grees of hindfoot valgus to the severe ‘rocker-bottom’
foot deformity with vertical talus and everted fore- foot. In contrast to congenital vertical talus, in flexi- ble flatfoot the calcaneus is not in equinus and the navicular bone retains its normal position. Moreover, a full range of motion is present at the level of the subtalar joint. The condition is not painful and some- times improves or resolves spontaneously (Sullivan 1999). This foot deformity is also a frequent manifes- tation of disorders with joint laxity, such as the Ehlers-Danlos syndromes, Marfan syndrome, and metatropic dysplasia.
The elementary foot changes delineated above can occur in variable combinations in more complex foot deformities, some of which, talipes equinovarus, metatarsus adductus, and vertical talus, are discussed at length in this chapter. Other foot deformities that can be regarded as the counterparts of similar de- fects in the hands, including deficiency or segmenta- tion defects, great toe abnormalities, and acro-osteo- lysis, have been reviewed in Chapter 6 when appro- priate and will not be included here.
References
Freiberger RH, Hersh A, Harrison MO. Roentgen examination of the deformed foot. Semin Roentgenol 1970; 5: 341 Joseph B. Congenital distal humeral dysplasia: a case report.
Pediatr Radiol 2003; 33: 7–10
Ozonoff MB: Pediatric orthopedic radiology. W.B. Saunders Company, Philadelphia, Philadelphia, 1979
Resnick D. Additional congenital or heritable anomalies and syndromes. In: Resnick D (ed.) Diagnosis of bone and joint disorders. W.B. Saunders Company, Philadelphia, 1995 (3rd ed.), pp. 4311–6
Fig. 7.4. Forefoot valgus in a 4-year-old girl with congenital dysplasia of the humerus. Note abduction of the forefoot, with lateral deviation of the metatarsals and lack of basal overlap.
(From Joseph 2003)
Simons GW. Analytical radiography of club feet. J Bone Joint Surg Br 1977; 59: 485–9
Sullivan JA. Pediatric flatfoot: evaluation and management.
J Am Acad Orthop Surg 1999; 7: 44–53
Watts HG. The bones and joints: orthopedic problems. In:
Behrman RE, Vaughan VC (eds.) Nelson textbook of pedi- atrics. W.B. Saunders Company, Philadelphia, 1987 (13th ed.), pp. 1343–6
Clubfoot/Metatarsus Adductus
䉴
[Talipes equinovarus/metatarsus varus]
Clubfoot and metatarsus varus are two common con- genital foot deformities that share certain features:
specifically, the forefoot is adducted and in varus in both conditions. In fact, metatarsus adductus is a component of the more complex talipes equinovarus deformity; this is why these conditions are discussed together.
Although the term clubfoot is loosely applied to a number of congenital foot anomalies, an equino- varus deformity is the most common type, account- ing for up to 95% of all cases. Thus, the term ‘club- foot’ is used synonymously with ‘talipes equino- varus,’ referring to a complex foot deformity in which the ankle is in equinus, the hindfoot is in varus, and the mid- and foreparts of the foot are adducted and in varus (Fig. 7.5). Up to seven basic combinations of deformities are thought to occur in talipes equino- varus (Simons 1978). This malformation can occur as an isolated finding in an otherwise normal child;
in association with other defects, such as tibial hemimelia and tibiofibular diastasis (Gilsanz et al.
1983); or in the context of a syndrome or neuromus- cular disease. Isolated talipes equinovarus (OMIM 119800) has a prevalence of approximately 1 in 1000 live births in Caucasians (Bleck 1993), a male-to-fe- male ratio of 2:1, and a bilateral distribution in 55%
of cases. Its genetics is complex, and only partially understood. A mixed model seems likely, with a ma- jor gene behaving as a dominant and an additional contribution of multifactorial inheritance (Palmer 1964; Wang et al. 1988). However, a study conducted in clubfoot patients of New Zealand Polynesian ex- traction suggests that the best genetic model is a sin- gle dominant gene with 33% penetrance and 0.9%
predicted gene frequency (Chapman et al. 2000). It is currently believed that the malformation results from failure of the spontaneous ‘rotation-elevation’
mechanism, which should be activated between the 9th and 10th weeks of normal fetal development.
Several possible factors can interfere with embryonic
development. A faulty intrauterine position, abnor- malities of the central nervous system or the vascular system, retracting fibrosis and muscular imbalance, anomalous tendon insertion, and defective connec- tive tissue with ligamentous laxity have all been im- plicated as potential mechanisms in the development
Fig. 7.5. Talipes equinovarus in a 1-month-old baby boy. Ob- serve severe hindfoot varus, with superimposed talar and cal- caneal centers. Neither the cuboid nor the navicular bone is os- sified, but the abnormal position of the latter bone can be in- ferred from the location of the 1st metatarsal base. Note also severe adduction of the forefoot (metatarsus varus), with a concave medial border and convex lateral border
Fig. 7.6. Schwartz-Jampel syndrome in a 7-year-old boy. Note varus deformity of the hindfoot, the talar axis projecting later- ad to the 1st metatarsal. The metatarsals are adducted, while the phalanges, especially the proximal phalanx of the great toe, are in valgus. Note also deformation of the tarsal cuneiforms.
(Reprinted, with permission, from Mastroiacovo et al. 1990)
of clubfoot (Ozonoff 1979; Somppi 1984; Ippolito and Ponseti 1980; Ponseti and Campos 1972; Victoria- Diaz and Victoria-Diaz 1984; Seringe 1999). Most of the osteoarticular malformations involve the talus, the calcaneus, and the navicular bone, at which sites articular stiffness is experienced as a secondary phe- nomenon once soft tissue retractions are established.
The talus is smaller than normal, with a flattened ta- lar dome and a neck that is dislocated in a medial and plantar direction (Ippolito 1995). As a result, the ar- ticular surface between the talus and the navicular bone faces medially, with the subtalar surface tilted in varus, equinus, and medial rotation. The calcaneus is mildly hypoplastic and is displaced under the talus into varus, equinus, and internal rotation. The cuboid may be either hypoplastic or totally unossified. Mat- uration of the navicular bone, which normally ossi- fies in the 2nd or 3rd year of life, is often delayed.
Significant talonavicular and calcaneocuboid joint malalignment results, the navicular bone and the cuboid being displaced medially, with medial angu- lation of the talonavicular and calcaneocuboid joints (Ippolito 1995; Simons 1995). The cuneiform and metatarsal bones follow the medial displacement of the cuboid and navicular bone and deviate inward in adduction. The diagnosis of clubfoot is based on clin- ical examination at birth, which makes it possible to
establish the degree of severity by assessing re- ducibility, the presence of skin creases, and the de- gree of muscular atrophy. Early treatment by either manipulation and casting or surgery is critically im- portant, as untreated cases are associated with fur- ther stiffening in the abnormal position and second- ary changes in osseous development. Extensive sur- gical release procedures are now avoided owing to their frequent complications, such as recurrence, overcorrection, severe stiffness, and pain (Cummings et al. 2002). It is now recognized that the mainstay of treatment is serial manipulation and cast immobi- lization, followed as appropriate by minimally inva- sive surgical procedures (Ponseti and Compos 1972).
Severe equinovarus deformity of the foot is a cardi- nal manifestation of arthrogryposis multiplex con- genita (OMIM 108110). As discussed elsewhere in this book, arthrogryposis is currently regarded as a birth defect consisting in multiple nonprogressive joint contractures of prenatal onset, whose etiology includes more than 150 syndromic and nonsyn- dromic conditions. The clinical phenotype therefore varies according to the underlying disorder. How- ever, talipes equinovarus, ulnar deviation of the hand, carpal or tarsal fusions, hip dislocation, patella malposition and dislocation, and scoliosis are com- mon to all types (Hall 1985). Talipes equinovarus also occurs in several other disorders with joint con- tracture, including multiple pterygium syndrome (OMIM 265000), Schwartz-Jampel syndrome (OMIM 255800) (Fig. 7.6), and Pena-Shokeir syndrome (OMIM 208150, 214150). Among the skeletal dysplasias, club- foot is a prominent manifestation of diastrophic dys- plasia (OMIM 222600), an autosomal recessive short- limb dwarfism (Lamy and Maroteaux 1960) with clubbed hands and feet, ovoid 1st metacarpal and metatarsal, deformed tarsal and carpal bones, and typical hitch-hiker thumbs (Fig. 7.7). Additional manifestations include short tubular bones with metaphyseal widening and epiphyseal distortion, flexion contracture of hips and knees, progressive joint dislocation and restriction of movement, kyphoscoliosis, and malformed ears with calcified pinnae. Severe clubfoot deformity, rhizomelic limb shortening, and atlantoaxial instability are features common to both diastrophic and pseudodiastrophic dysplasia (OMIM 264180), a lethal disorder with mul- tiple dislocations (Burgio et al. 1974). Some unique changes in the lumbar spine (marked lumbar scolio- sis, severe platyspondyly with tongue-like vertebral projections) and in the hands (multiple interpha- langeal and metacarpophalangeal joint dislocations, normal 1st metacarpal) allow for the radiographic differential diagnosis against diastrophic dysplasia.
Fig. 7.7. Diastrophic dysplasia in a 6-year-old boy (patient 3 in Part 2, Fig. 37). Note severe equinovarus deformity of the right foot, with hindfoot varus, medial subluxation of the navicular bone, and metatarsus adductus. Note also metaphyseal widen- ing, severe epiphyseal distortion, and proximally placed short 1st metatarsal with increased distance between great toe and second toe. Similar changes were apparent in the left foot (not shown)
Equinovarus deformity of the feet is also a frequent manifestation of the autosomal dominant campomel- ic dysplasia (OMIM 114290), a disorder with bowing and angulation of the long bones, small thorax and scapulas, underdeveloped cervical vertebrae, large head, small facies, small hands, dislocatable hips, and slender ribs and clavicles with lateral hooks (Hall and Spranger 1980). In lethal atelosteogenesis type II (de la Chapelle syndrome, OMIM 256050), features include a small thorax with short ribs, micromelia, bowed long bones, small hands, cleft palate, and equinovarus deformity of the feet (Greally et al.
1993). Talipes equinovarus can also occur in the con- text of conditions with joint laxity, such as spondy- loepimetaphyseal dysplasia with joint laxity (OMIM 271640). Kyphoscoliosis at birth, cleft palate, congen- ital heart disease, and a specific facial dysmorphism are additional manifestations (Hall et al. 1998). In the caudal regression syndrome (OMIM 182940), sacral agenesis and spinal cord disruption lead to such dis- turbances as spine instability, bladder dysfunction, underdevelopment of the lower limbs with contrac- ture deformities, hip dislocations, and talipes equino- varus (Guidera et al. 1991). In acromelic frontonasal dysplasia (OMIM 603671) the craniofacial manifesta- tions of frontonasal dysplasia are associated with central nervous system malformations and limb de- fects, including tibial hypoplasia/aplasia, talipes equinovarus, and preaxial polydactyly of the feet (Toriello et al. 1986). In mesomelic dwarfism, Niever-
gelt type (OMIM 163400), the unique appearance of the shanks, with abnormally thick and short, trian- gle-shaped tibias and short fibulas, is sometimes as- sociated with an atypical form of bilateral clubfoot with a prominent equinus component.
Metatarsus adductus is the designation for a de- formity characterized by inward deviation of the forefoot, with a concave medial border, convex later- al border, and high longitudinal arch. The hindfoot is normal in mild cases, and is in valgus alignment in severe cases (Fig. 7.8). The deformity is less severe than in talipes equinovarus, in which it is also a com- ponent. It has an estimated prevalence of 1 in 1000 live births, occurs with equal frequency in males and females, and is bilateral in 50% of cases. Its natural course, at least in mild to moderate cases, is one of spontaneous correction in the early years of life. Ma- nipulation and casting are usually required in more severe cases, whereas surgery is confined to the rare instances of persistent problems after conservative treatment and cases in which the deformity is main- tained by an aberrant tendon insertion. Metatarsus adductus is clearly different from simple metatarsus primus deformity, a condition characterized by ad- duction of the 1st metatarsal only, with angulation of the 1st metatarsophalangeal joint and hallux valgus (Silverman 1993). Based on the presence or absence of associated anomalies of the midfoot and hindfoot, four varieties of metatarsus adductus have been recognized: (1) simple metatarsal adductus (adduc- tion of the metatarsals alone); (2) complex metatar- sal adductus (forefoot adduction + abnormal align- ment of the midfoot); (3) simple skewfoot deformity (forefoot adduction + hindfoot valgus); (4) complex skewfoot (forefoot adduction + abnormal alignment of the midfoot + hindfoot valgus) (Berg 1986). Al- though the etiology of this foot deformity is un- known, the genetic components are undeniable, as demonstrated by the occurrence of simple metatar- sus adductus (metatarsus varus, OMIM 156520) in nine persons in four generations of one family, with male-to-male transmission (Juberg and Touchstone 1974). Based on the findings of a histological study, it has been suggested that a primary abnormality of the medial cuneiform with misalignment of the 1st metatarso-cuneiform joint is the single most critical factor in the development of metatarsus adductus (Morcuende and Ponseti 1996). Metatarsus adductus occurs in Carpenter syndrome (acro-cephalo-poly- syndactyly type II, OMIM 201000), together with pre- axial polydactyly, partial syndactyly, and short/ab- sent middle phalanges of toes, and it can be a compo- nent of Down syndrome (OMIM 190685) and of the
Fig. 7.8. Metatarsus adductus in a male newborn. Note varus deformity of the forefoot, with a concave medial border and convex lateral border. The metatarsal bones converge more than normal at their bases. The hindfoot is not affected, talo- calcaneal alignment being normal
heterozygous form of Grebe chondrodysplasia (OMIM 200700). A severe form of metatarsus adductus has been described in three sibs in association with mi- crocephaly, minor facial anomalies reminiscent of the Brachmann-de Lange syndrome, developmental delay, and unusual dermatoglyphics (Brachmann-de Lange-like facial changes with microcephaly/meta- tarsus adductus/developmental delay, OMIM 112370) (Halal and Silver 1992).
Radiographic Synopsis
AP and LL weight-bearing projections. Conventional radiography is used to establish possible surgical indications and to evaluate residual deformities at follow-up studies. CT scanning and MRI provide, respectively, 3D image reconstruction and visualiza- tion of the unossified cartilage.
In talipes equinovarus, on the AP view, the talocal- caneal angle is decreased (<15°), the talar axis points lateral to the base of the 1st metatarsal, and the nav- icular bone is displaced medially to the talus; on the LL projection, the talar and calcaneal axes lie closer to the horizontal and in severe cases are parallel to each other.
In metatarsus adductus, on the AP view the fore- foot is narrowed, with increased convergence and overlapping of the metatarsal bases (Petterson and Ringertz 1991; Resnick 1995). On the LL projection, the 1st metatarsal lies further dorsally than normal.
1. Talipes equinovarus; tarsal synostosis; multiple joint contractures (arthrogrypotic disorders) 2. Talipes equinovarus; ovoid 1st metatarsal; short
tubular bones, with wide metaphyses and distort- ed epiphyses; small, deformed tarsal bones (dias- trophic dysplasia)
3. Talipes equinovarus; preaxial polydactyly; tibial hy- poplasia/aplasia (acromelic frontonasal dysplasia) 4. Metatarsus adductus; preaxial polydactyly with
partial syndactyly; short/absent middle phalanges of toes (Carpenter syndrome)
Associations
• Aarskog syndrome
• Adams-Oliver syndrome
• Aminopterin/methotrexate embryopathy
• Amniotic band sequence
• Amyoplasia
• Arthrogrypotic disorders (including distal arthro- gryposis)
• Bloom syndrome
• Brachmann-de Lange-like facial changes with microcephaly/metatarsus adductus/developmen- tal delay
• Campomelic dysplasia
• Catel-Manzke syndrome
• Caudal regression syndrome
• Cephaloskeletal dysplasia (Taybi-Linder syndrome)
• Cerebro-costo-mandibular syndrome
• Chondrodysplasia punctata, X-linked
• Chondroectodermal dysplasia (Ellis-van Creveld)
• Chromosomal abnormalities (4p-, 9p-, 13q-, 18q-, 3q+, 4p+, 9p+, 10q+, triploidies, trisomy 9 mosaic, trisomy 13 and 18, XXXXX, XXXXY)
• Contractural arachnodactyly, congenital (Beals syndrome)
• De Lange syndrome
• Diastrophic dysplasia
• Down syndrome
• Dubowitz syndrome
• Ehlers-Danlos syndrome
• Fanconi pancytopenia syndrome
• Faulty intrauterine positioning
• Femoral-facial syndrome
• Freeman-Sheldon syndrome
• Gardner-Silengo-Wachtel syndrome
• Hecht syndrome (trismus pseudocamptodactyly)
• Hydrolethalus syndrome
• Homocystinuria
(pes planus or cavus, everted feet)
• Humerospinal dysostosis
• Kuskokwim syndrome
• Larsen syndrome
• Limb-body wall complex
• Marden-Walker syndrome
• Marinesco-Sjögren syndrome
• Meckel syndrome
• Melnick syndrome
• Meningomyelocele
• Mesomelic dwarfism, Nievergelt type
• Mietens-Weber syndrome
• Möbius syndrome
• Mucopolysaccharidoses
• Multiple pterygium syndrome (Escobar syndrome and lethal form)
• Myotonic dystrophy
• Nager syndrome
• Nail-patella syndrome
• Noonan syndrome
• Pena-Shokeir syndrome
• Potter syndrome
• Roberts-SC phocomelia syndrome
• Schinzel-Giedion syndrome
• Schwartz-Jampel syndrome
• Sickle syndrome
• Smith-Lemli-Opitz syndrome
• Spondyloepiphyseal dysplasia congenita
• Spondyloepimetaphyseal dysplasia with joint laxity
• Stickler syndrome
• Thrombocytopenia-radial aplasia syndrome (TAR)
• Tibial aplasia-ectrodactyly syndrome
• VATER association
• Weaver syndrome
• Williams syndrome
• Zellweger syndrome
References
Berg EE. A reappraisal of metatarsus adductus and skewfoot.
J Bone Joint Surg Am 1986; 68: 1185–96
Bleck EE. Club foot. Dev Med Child Neurol 1993; 35: 927–31 Burgio GR, Belloni C, Beluffi G. Nanisme pseudodiastrophi-
que: étude de deux soeurs nouveau-nées. Arch Fr Pediatr 1974; 31: 681–96
Chapman C, Stott NS, Port RV, Nicol RO. Genetics of club foot in Maori and Pacific people. J Med Genet 2000; 37: 680–3 Cummings RJ, Davidson RS, Armstrong PF, Lehman WB. Con-
genital clubfoot. Instr Course Lect 2002; 51: 385–400 Gilsanz V, Teitelbaum G, Condon VR. Clubfoot deformity and
tibiofibular diastasis.AJR Am J Roentgenol 1983; 140: 759–61 Greally MT, Jewett T, Smith WL Jr, Penick GD, Williamson RA.
Lethal bone dysplasia in a fetus with manifestations of atelosteogenesis I and boomerang dysplasia. Am J Med Genet 1993; 47: 1086–91
Guidera KJ, Raney E, Ogden JA, Highhouse M, Habal M. Caudal regression: a review of seven cases, including the mermaid syndrome. J Pediatr Orthop 1991; 11: 743–7
Halal F, Silver K. Syndrome of microcephaly, Brachmann-de Lange-like facial changes, severe metatarsus adductus, and developmental delay: mild Brachmann-de Lange syn- drome? Am J Med Genet 1992; 42: 381–6
Hall BD, Spranger JW. Campomelic dysplasia. Further elucida- tion of a distinct entity. Am J Dis Child 1980; 134: 285–9 Hall CM, Elcioglu NH, Shaw DG. A distinct form of spondy-
loepimetaphyseal dysplasia with multiple dislocations.
J Med Genet 1998; 35: 566–72
Hall JG. Genetic aspects of arthrogryposis. Clin Orthop 1985;
194: 44–53
Ippolito E, Ponseti IV. Congenital club foot in the human fetus.
A histological study. J Bone Joint Surg Am 1980; 62: 8–22 Ippolito E. Update on pathologic anatomy of clubfoot. J Pediatr
Orthop B 1995; 4: 17–24
Juberg RC, Touchstone WJ. Congenital metatarsus varus in four generations. Clin Genet 1974; 5: 127–32
Lamy M, Maroteaux P: Le nanisme diastrophique. Presse Med 1960; 68: 1977–80
Morcuende JA, Ponseti IV. Congenital metatarsus adductus in early human fetal development: a histologic study. Clin Orthop 1996; 333: 261–6
Ozonoff MB. Pediatric orthopedic radiology. W.B. Saunders Company, Philadelphia, 1979
Palmer RM. Hereditary clubfoot. Clin Orthop 1964; 33: 138–46 Petterson H, Ringertz H. Measurements in pediatric radiology.
Springer-Verlag, London, 1991, p. 80-1
Ponseti IV, Campos J. Observations on pathogenesis and treat- ment of congenital clubfoot. Clin Orthop 1972; 84: 50–60
Resnick D. Additional congenital or heritable anomalies and syndromes. In: Resnick D (ed.) Diagnosis of bone and joint disorders. W.B. Saunders Company, Philadelphia, 1995 (3rd ed.), pp. 4311–6
Seringe R. Congenital equinovarus clubfoot. Acta Orthop Belg 1999; 65: 127–53
Silverman FN. Chest wall, diaphragm, and pleura. In: Silver- man FN, Kuhn JP (eds.) Caffey’s pediatric X-rays diagnosis.
An integrated imaging approach. C. V. Mosby Company, St.
Louis, 1993 (9th ed.), p. 1841
Simons GW. Analytical radiography and the progressive ap- proach in talipes equinovarus. Orthop Clin North Am 1978;
9: 187–206
Simons GW. Calcaneocuboid joint deformity in talipes equino- varus: an overview and update. J Pediatr Orthop B 1995; 4:
25–35
Somppi E. Clubfoot. Review of the literature and an analysis of a series of 135 treated clubfeet. Acta Orthop Scand Suppl 1984; 209: 1–109
Toriello HV, Radecki LL, Sharda J, Looyenga D, Mann R. Fron- tonasal “dysplasia”, cerebral anomalies, and polydactyly:
report of a new syndrome and discussion from a develop- mental field perspective. Am J Med Genet 1986; 2: 89–96 Victoria-Diaz A, Victoria-Diaz J. Pathogenesis of idiopathic
clubfoot. Clin Orthop 1984; 185: 14–24
Wang J, Palmer RM, Chung CS. The role of major gene in club- foot. Am J Hum Genet 1988; 42: 772–6
Vertical Talus
䉴
[Rocker-bottom foot deformity]
Congenital vertical talus is a rare foot deformity characterized by two fixed deformities, equinus of the hindfoot with a vertical talus and dislocation of the talonavicular joint with dorsiflexion of the fore- foot at the midtarsal level (Badelon et al. 1984). When the heel is held in marked equinus and the forefoot everted a convex plantar surface of the foot results, which is the reason for the designation ‘rocker-bot- tom deformity.’ The deformity may go unrecognized at birth owing to its deceptive resemblance to con- genital flexible flatfoot, a benign condition requiring no treatment in the majority of cases (Sullivan 1999).
The key clinical element in the differential diagnosis is loss of motion at the subtalar joint in congenital vertical talus, which is unambiguous proof of a fixed deformity (Greenberg 1981). In fact, the talus is locked in plantar flexion by the navicular bone, which is displaced dorsally between the cuneiform and the neck of the talus. On clinical palpation, the head of the talus can be perceived as a hard mass under the sole of the foot. The diagnosis is facilitated by radiographic demonstration of the vertical orien- tation of the talus with talonavicular joint dislocation and equinus deformity of the calcaneus (Salo et al.
1992). In addition, radiography rules out other causes
of rigid flatfoot that can simulate vertical talus, in particular tarsal coalition (Hefti and Brunner 1999).
Although direct X-ray visualization of the unossified navicular bone is lacking in infants, altered articular relationships at the midtarsal level can be inferred from dorsal migration of the ossified cuneiforms.
Early recognition of congenital vertical talus is mandatory, since prompt surgical treatment yields satisfactory results whereas delayed or inadequate treatment is associated with persistent deformity and significant complications, including avascular necro- sis of the body of the talus, premature osteoarthritis, pain, and gait disturbances (Napiontek 1995; Duncan and Fixsen 1999; Mazzocca et al. 2001; Zorer et al.
2002). Current treatment strategies include one-stage open reduction of the talonavicular dislocation com- bined with posterior release and subtalar arthrodesis to correct for and maintain the equinus deformity of the hindfoot (Wirth et al. 1994; Ogata et al. 1979).
Congenital vertical talus can occur as an isolated condition or as part of a malformation syndrome (Fig. 7.9) or generalized disorder, notably arthrogry- posis and myelomeningocele (Hamanishi 1984; West- cott et al. 1992; Specht 1975).
Vertical transmission for the isolated form of con- genital vertical talus (rocker-bottom foot, OMIM 192950) has been reported in a Honduran family (Stern et al. 1989). Nine members of the family over three generations were affected in all. There was in- complete penetrance in one woman with two affected children. Unilateral and bilateral involvement was seen, ranging widely in severity. On the basis of these observations, it was suggested that isolated congenital vertical talus might be inherited as an autosomal dominant trait with variable expression and incom- plete penetrance.An affected mother and son were de- scribed in another kindred (Hamanishi 1984). Con- genital vertical talus occurs in association with bilater- al symmetrical subtotal atresia of the external auditory canal in Rasmussen syndrome (OMIM 133705) (Rasmussen et al. 1979). When fully ex- pressed, the syndrome features increased interocular distance, epicanthal folds, congenital exotropia, con- vergent strabismus, low-set nasal bridge, abnormal ex- ternal ears with hypoplastic lobes and overfolded he- lices, dysplastic dental enamel, short 5th fingers, ab- normal thumb position, pyloric stenosis, congenital hip dislocation, and umbilical hernia (Julia et al. 2002).
Digitotalar dysmorphism (OMIM 126050) is a syn- dromic association of flexion of fingers with ulnar de- viation and bilateral vertical talus (Sallis and Beighton 1972; Stevenson et al. 1975). Moderate short stature may be an additional finding (Dhaliwal and Myers 1985). There is a close similarity between this disorder and distal arthrogryposis type I (OMIM 108120), an autosomal dominant condition with variable expres- sion, which is characterized by a distinct positioning of the hands (tightly clenched fists, with thumb adduc- tion and medially overlapping fingers at birth, fol- lowed by striking ulnar deviation of fingers and camp- todactyly in adulthood) and bilateral foot deformities (calcaneovalgus, equinovarus, or a combination of the two). Contractures at other joints, especially the hips, knees, and shoulders, are variably associated (Hall et al. 1982). Similarities in the limb phenotype (flexion and ulnar deviation of fingers in the hands, and talipes equinovarus or vertical talus in the feet) are also rec- ognized in Freeman-Sheldon syndrome (whistling face syndrome, OMIM 193700) (Fig. 7.10), which can in fact be regarded as a form of distal arthrogryposis type I (Bamshad et al. 1996) associated with a charac- teristic facial morphology (small mouth giving a
Fig. 7.9. Chromosome 4p trisomy syndrome in a male new- born. Note bilateral vertical talus with rocker-bottom foot de- formity. The talar axis is oriented vertically, and the calcaneus is in marked equinus (plantar flexion). The forefoot is everted, contributing to the convex deformity of the plantar foot. The navicular bone is not yet ossified, but its cartilaginous nucleus is likely to be displaced dorsally, putting it in close proximity to the talar neck
Fig. 7.10. Freeman-Sheldon syndrome in a 16-year-old patient (also seen in Part 2, Fig. 47.5 a, b). Note abnormal plantar flex- ion of the talus, with dorsal subluxation of the navicular bone.
The calcaneus is in mild equinus, and the forefoot is dorsally flexed
‘whistling’ appearance, deep-sunken eyes with hyper- telorism, and retraction of the alae nasi). The idea of a link between distal arthrogryposis type I and the Free- man-Sheldon syndrome is further supported by the occurrence of both disorders in the same pedigree (Klemp and Hall 1995) as well as by the existence of in- termediate forms (Krakowiak et al. 1998).
Radiographic Synopsis
LL and AP, weight-bearing projections.
Conventional radiography is used to confirm the diagnosis, rule out other causes of rigid flatfoot, guide the surgical treatment, and evaluate residual deformities at follow-up studies. CT scanning and MRI provide, respectively, 3D image reconstruction and visualization of the unossified cartilage.
On the AP view, severe heel valgus and forefoot abduction are seen, the navicular bone and remain- ing tarsal bones being located lateral to the talus. The talocalcaneal angle is increased, with the talar axis passing medial to the 1st metatarsal. The LL view shows that the talus is plantar flexed to such an extent that is almost vertical, while the calcaneus is in mild equinus. The navicular bone is displaced dorsally, with talonavicular dislocation. The forefoot is dorsi- flexed at the midtarsus.
Associations
• Caudal regression syndrome
• Chromosome trisomy syndromes (4p, 13, 18)
• Congenital vertical talus, isolated form
• De Barsy syndrome
• Digitotalar dysmorphism
• Distal arthrogryposis
• Freeman-Sheldon syndrome
• Multiple pterygium syndrome (Escobar syndrome)
• Neural tube defects
(myelomeningocele, spina bifida)
• Neuromuscular disorders (e.g., myotonic dystrophy)
• Rasmussen syndrome
References
Badelon O, Rigault P, Pouliquen JC, Padovani JP, Guyonvarch J.
Congenital convex clubfoot: a diagnostic and therapeutic study of 71 cases. Int Orthop 1984; 8: 211–21
Bamshad M, Jorde LB, Carey JC. A revised and extended classi- fication of the distal arthrogryposes. Am J Med Genet 1996;
65: 277–81
Dhaliwal AS, Myers TL. Digitotalar dysmorphism. Orthop Rev 1985; 14: 90–4
Duncan RD, Fixsen JA. Congenital convex pes valgus. J Bone Joint Surg Br 1999; 81: 250–4
Greenberg AJ. Congenital vertical talus and congenital calca- neovalgus deformity: a comparison. J Foot Surg 1981; 20:
189–93
Hall JG, Reed SD, Greene G. The distal arthrogryposes: delin- eation of new entities. Review and nosologic discussion.
Am J Med Genet 1982; 11: 185–239
Hamanishi C. Congenital vertical talus: classification with 69 cases and new measurement system. J Pediatr Orthop 1984;
4: 318–26
Hefti F, Brunner R. Flatfoot. Orthopade 1999; 28: 159–72 Julia S, Pedespan JM, Boudard P, Barbier R, Gavilian-Cellie I,
Chateil JF, Lacombe D. Association of external auditory canal atresia, vertical talus, and hypertelorism: confirma- tion of Rasmussen syndrome. Am J Med Genet 2002; 110:
179–81
Klemp P, Hall JG. Dominant distal arthrogryposis in a Maori family with marked variability of expression. Am J Med Genet 1995; 55: 414–9
Krakowiak PA, Bohnsack JF, Carey JC, Bamshad M. Clinical analysis of a variant of Freeman-Sheldon syndrome (DA2B). Am J Med Genet 1998; 76: 93–8
Mazzocca AD, Thomson JD, Deluca PA, Romness MJ. Compar- ison of the posterior approach versus the dorsal approach in the treatment of congenital vertical talus. J Pediatr Orthop 2001; 21: 212–7
Napiontek M. Congenital vertical talus: a retrospective and critical review of 32 feet operated on by peritalar reduction.
J Pediatr Orthop B 1995; 4: 179–87
Ogata K, Schoenecker PL, Sheridan J. Congenital vertical talus and its familial occurrence: an analysis of 36 patients. Clin Orthop 1979; 139: 128–32
Rasmussen N, Johnsen NJ, Thomsen J. Inherited congenital bilateral atresia of the external auditory canal, congenital bilateral vertical talus and increased interocular distance.
Acta Otolaryngol 1979; 88: 296–302
Sallis JG, Beighton P. Dominantly inherited digito-talar dys- morphism. J Bone Joint Surg Br 1972; 54: 509–15
Salo JM, Viladot A, Garcia-Elias M, Sanchez-Freijo JM, Viladot R. Congenital flat foot: different clinical forms. Acta Orthop Belg 1992; 58: 406–10
Specht EE. Congenital paralytic vertical talus. An anatomical study. J Bone Joint Surg Am 1975; 57: 842–7
Stern HJ, Clark RD, Stroberg AJ, Shohat M. Autosomal domi- nant transmission of isolated congenital vertical talus. Clin Genet 1989; 36: 427–30
Stevenson RE, Scott CI Jr, Epstein MJ. Dominantly inherited ulnar drift. Birth Defects Orig Art Ser 1975; XI(5): 75–7 Sullivan JA. Pediatric flatfoot: evaluation and management.
J Am Acad Orthop Surg 1999; 7: 44–53
Westcott MA,Dynes MC,Remer EM,Donaldson JS,Dias LS.Con- genital and acquired orthopedic abnormalities in patients with myelomeningocele. Radiographics 1992; 12: 1155–73 Wirth T, Schuler P, Griss P. Early surgical treatment for congeni-
tal vertical talus.Arch Orthop Trauma Surg 1994; 113: 248–53 Zorer G, Bagatur AE, Dogan A. Single stage surgical correction of congenital vertical talus by complete subtalar release and peritalar reduction by using the Cincinnati incision.
J Pediatr Orthop B 2002; 11: 60–7
Tarsal Abnormalities
The tarsal bones are involved to a significant extent in a number of disorders, many of which are dis- cussed at different points throughout this book. They usually behave in a similar manner to carpal bones, as explained in Chapter 6 (sections headed “Carpal Abnormalities” and “Acro-osteolyses”). The charac- teristic features of two important tarsal defects are briefly reviewed below.
Tarsal Synostosis
䉴
[Congenital fusion of two or more adjacent tarsal bones]
Many of the general concepts relating to carpal syn- ostosis are also applicable to tarsal synostosis, in- cluding those that refer to the pathogenetic mecha- nisms involved and the terminology. Indeed, congen- ital tarsal fusion results from a failure of joint formation (Jack 1954), so that the term ‘synostosis’
seems to be the most appropriate. ‘Fusion’ best de- scribes the acquired forms of tarsal coalition that can arise in response to infection, various arthritides, trauma, and surgical fixation, but is often also used to designate congenital joint fixation.
Tarsal coalition may be an isolated defect, or it may occur as part of a wider malformation spec- trum, which often encompasses multiple bony fu- sions, particularly fusion in the carpus. These disor- ders are reviewed in the section entitled “Carpal Syn- ostosis” in Chapter 6 and also elsewhere in this book.
In the current section, the discussion is focused on the specific characteristics of the various forms of isolated tarsal coalition, with the emphasis on their radiographic appearance.
Tarsal coalitions are uncommon entities, with an overall incidence in the general population lower than 1% (Stormont and Peterson 1983). However, the increasing use of more sensitive diagnostic proce- dures is likely to show that the real incidence of this entity is higher than this (Solomon et al. 2003). Ap- proximately 90% of tarsal coalitions involve the cal- caneonavicular (50%) or talocalcaneal (40%) joint (Stormont and Peterson 1983). Talonavicular coali- tions are far less common (Fig. 7.11), followed in or- der of decreasing frequency by calcaneocuboid, cubonavicular, and navicular-1st cuneiform joint coalitions (Palladino et al. 1991; Kumai et al. 1996;
Gregerson 1977). Occasionally, a double union in one foot is observed (Wheeler et al. 1981; Bhalaik et al.
2002; Clarke 1997). More extensive or ‘bizarre’ (e.g., cuneiform–metatarsal) fusions are typical of certain malformation syndromes, such as Apert syndrome (OMIM 101200), the oto-palato-digital syndrome type I (OMIM 311300), the hand-foot-genital syn- drome (OMIM 140000), and the mesomelia-synos- toses syndrome (OMIM 600383).
Tarsal fusion is bilateral in approximately 50% of cases (Perlman and Wertheimer 1986), and the union can be osseous or fibrocartilaginous, escaping direct radiographic visualization in the latter case. The pathogenesis is unknown, although a genetic form of isolated tarsal fusion (OMIM 186850) unassociated with carpal fusion, and displaying an autosomal dominant inheritance and high penetrance, has long been reported (Leonard 1974). Clinical symptoms consist primarily in foot and ankle pain, restricted motion, and rigid pes planus with calcaneus valgus (Perlman and Wertheimer 1986; Cowell and Elener 1983; Pachuda et al. 1990). However, symptoms vary according to the extent of tarsal fusion and the type of bones involved, and it is not uncommon for there to be no symptoms at all (Conway and Cowell 1969).
A sequence of sprains or other minor injuries usual- ly precedes the onset of symptoms (Bohne 2001), which is variable but usually does not occur before the 2nd decade, by which time the fibrous and carti- laginous tissue components have undergone ossifica- tion (Cowell and Elener 1983; Conway and Cowell 1969; Lahey et al. 1988). Calcaneonavicular coalitions typically ossify sooner than do talocalcaneal coali- tions and therefore manifest earlier in childhood (Cowell and Elener 1983). Pain is likely to be second- ary to structural changes at the boundaries of the in- volved bones via free nerve endings in the perios-
Fig. 7.11. Talonavicular coalition. Note bony fusion between the talus and navicular bone. Deformity of the apposing sur- faces of talus and calcaneus is also apparent. (Reprinted, with permission, from Resnick 1995)
teum (Kumai et al. 1998) and is worsened by contin- ued activities. As an effect of altered biomechanics in the foot, joint degeneration is a common complica- tion. Peroneal spastic flatfoot, or peroneal spasm, consisting of adaptive peroneal shortening to adjust for the heel valgus and to maintain the subtalar joint
in the least painful position, also frequently compli- cates the course of tarsal coalition.
Calcaneonavicular fusion, the most common type, is often bilateral and can be either asymptomatic or associated with rigid flatfoot. This type of tarsal coalition can be overlooked on standard projections, but is easily demonstrated on 45° internal oblique X-ray projections, either by direct visualization of the bony bar extending between the calcaneus and navicular bone or by identification of indirect signs of fibrocartilaginous union, such as approximation of the two bones and changes of their bony surfaces (Fig. 7.12 a, b). Talocalcaneal coalition is more com- mon in males than in females, and is bilateral in about one quarter of all cases. Fusion of this type oc- curs almost invariably at the middle subtalar facet joint (Fig. 7.13) between the talus and sustentaculum tali (the subtalar articulation consists, in fact, of an anterior, middle, and posterior facet joint) (Sartoris and Resnick 1985). Occasionally, coalition of the anterior (Fig. 7.14) or posterior (Fig. 7.15) subtalar joint is seen (Lee et al. 1989). Radiographic confirma- tion of this type of tarsal coalition can be extremely difficult, owing to the complex orientation of the sub- talar joint. Fortunately, a number of secondary radi- ographic signs, including talar beaking, rounding of the lateral process of the talus, narrowing of the pos- terior subtalar joint space, failure to visualize the
Fig. 7.12 a, b. Calcaneonavicular coalition. a Observe the ap- proximation of the osseous surfaces of the calcaneus and nav- icular bone (arrows) on the medial oblique view. Mild abnor- malities are apparent at the calcaneocuboid joint. b Note com- plete osseous coalition (solid arrows) on the medial oblique
view. Observe the bony excrescences at the talonavicular joint space (arrowheads) and hypoplasia of the distal aspect of the talus (open arrow). (Reprinted, with permission, from Resnick 1995)
b a
Fig. 7.13. Talocalcaneal coalition (middle facet) in a 19-year- old woman. There is a prominent talar beak (curved arrow) and a positive “C” sign (arrows). Note also flatfoot associated in this case with middle facet joint coalition. The C sign may not be related to the talocalcaneal coalition; it does sometimes occur in simple flatfoot. (From Brown et al. 2001)
middle subtalar joint, and ball-and-socket ankle joint may indirectly suggest the diagnosis (Sartoris and Resnick 1985). These secondary findings are thought to develop in response to an alteration caused in the biomechanics of the midfoot by the coalition. Talar beaking, for example, results from dorsal subluxation of the navicular bone, which is due in turn to subta- lar rigidity, with periosteal elevation at the insertion of the talonavicular ligament and subperiosteal bone
proliferation (Resnick 1984). However, the talar beak, which is best identified on lateral X-ray projections, is by no means pathognomonic for talocalcaneal coalition, as it can also occur in diffuse idiopathic skeletal hyperostosis, acromegaly, and rheumatoid arthritis (Resnick 1984). Broadening of the lateral process of the talus, another indirect sign that is eas- ily identified when both feet are examined for com- parison, occurs in about 50–60% of cases of talocal- caneal coalition and is possibly related to a valgus angulation of the calcaneus (Resnick 1995). The ball- and-socket appearance of the tibiotalar joint, that is to say increased convexity of the proximal talar artic- ular surface with concomitant increased concavity of the distal end of the tibia, is probably related to an adaptation of the ankle joint to compensate for the loss of the inversion and eversion function caused by the talocalcaneal coalition (Pappas and Miller 1982;
Takakura et al. 1986). Ball-and-socket ankle joint also occurs in association with other congenital anom- alies, such as genu valgum deformity and fibular hemimelia, and with acquired disorders of the mid- foot, including osteoarthritis (Dennis et al. 1987). An additional indirect radiographic finding, the ‘C sign’
(a C-shaped line formed on lateral projection by the medial outline of the talar dome in combination with a prominent inferior outline of the sustentaculum tali), has been proposed as a reliable indicator of talocalcaneal coalition by Lateur et al. (1994), a view questioned by others who believe rather that the C sign is specific, though not sensitive, for flatfoot de- formity (Brown et al. 2001) (Fig. 7.13). If all the above radiographic signs fail to demonstrate tarsal fusion, cross-sectional imaging techniques must be used (Emery et al. 1998; Newman and Newberg 2000).
Talonavicular coalition is an uncommon type of isolated tarsal fusion that may reveal autosomal dominant (Callis 1974) or recessive (Zeide et al. 1977) hereditary transmission and an association with anomalies of the little finger (Callis 1974). Patients may be symptom-free or have varying degrees of pain (Bonk and Tozzi 1989) or peroneal spasm (Cowell and Elener 1983). When present, symptoms usually start at the age of 5 years. On physical exami- nation, limitation of motion at the subtalar joint and a bony prominence on the dorsal surface of the mid- foot at the level of the navicular bone may be ob- served. The osseous fusion between the talus and navicular bone, like variable malformation of the ap- posing surfaces of the talus and calcaneus, are usual- ly readily apparent on lateral projections.
Treatment of a painful tarsal coalition is initially conservative, with orthotics, casting, anti-inflamma-
Fig. 7.14. Talocalcaneal coalition (anterior facet) in a 5-year- old girl. Note the bony bridge between the talus and calcaneus at the anterior subtalar joint. The middle and posterior facets are wide open. This is an uncommon type of subtalar coali- tion: the talus is markedly deformed, with flattening of the ta- lar dome and hypoplasia of its posterior portion
Fig. 7.15. Talocalcaneal coalition (posterior facet) in an 18- year-old man. Note poorly defined posterior facet (arrow) and normal middle facet joint (arrowheads). This is an uncommon type of subtalar coalition, occurring posterior to the susten- taculum tali. (From McNally 1999)
tory medications, or physical therapy (Kumar et al.
1992; Olney and Asher 1987). Patients who fail to re- spond to a conservative therapy are treated with surgical resection of the bony bridge and interposi- tion of fat or tendon, whereas triple arthrodesis is reserved for symptomatic recurrences, multiple coalitions, and advanced degenerative changes (Scranton 1987; Wilde et al. 1994).
Radiographic Synopsis
AP, LL, 45° medial-oblique projections are often suffi- cient to diagnose most calcaneonavicular and talon- avicular coalitions. Penetrated axial view with vary- ing degrees of beam angulation (Harris-Beath), oblique views, and plain tomography may be neces- sary to diagnose talocalcaneal coalitions; however, this approach is now largely replaced by cross-sec- tional imaging, especially CT using the coronal scan- ning plane. In all types of tarsal coalitions, CT and MRI with multiplanar reconstruction give an accu- rate depiction of the actual site and extent of joint in- volvement, the presence of nonosseous union, and secondary changes and are therefore invaluable in surgical planning (Newman and Newberg 2000;
Wechsler et al. 1994).
1. With osseous coalition, a bony bar extending all or part of the way across the gap between the calca- neus and navicular bone (45° internal oblique view); fibrous or cartilaginous coalition, close ap- proximation of the two bones, with irregularity and sclerosis of their surfaces, and elongation of the anterosuperior portion of the calcaneus (‘anteater nose’ appearance on LL view); hypopla- sia of the head of the talus (calcaneonavicular coalition).
2. Direct visualization of the fusion at the middle subtalar facet joint is difficult; indirect signs include a dorsal talar beaking, broadening and rounding of the lateral process of talus, narrowed posterior subtalar joint, nonvisualization of the middle facet, ball-and-socket ankle joint, C-sign (talocalcaneal coalition).
Associations
• Acquired causes
(trauma, infection, arthritides, surgery)
• Antley-Bixler syndrome
• Apert syndrome
• Arthrogryposis multiplex congenita
• Coxa vara/patella aplasia/tarsal synostosis
• Crouzon syndrome
• Ehlers-Danlos syndrome
• F syndrome
• Hand-foot-genital syndrome
• Hereditary symphalangism
• Humeroradial/multiple synostosis syndrome
• Ischiopatellar dysplasia
• Mesomelia-synostosis syndrome
• Mesomelic dysplasia, Kantaputra
• Mesomelic dysplasia, Nievergelt
• Mitral regurgitation/conductive deafness/fusion of cervical vertebrae and carpal/tarsal bones
• Multiple synostosis syndrome
• Nevoid basal cell carcinoma (Gorlin syndrome)
• Oto-palato-digital syndrome (type 1)
• Pfeiffer syndrome
• Second metatarsal/metacarpal syndrome
• Spondylo-carpo-tarsal synostosis syndrome
• Tarsal/carpal/digital synostosis
• Tarsal/carpal coalition syndrome
• Turner syndrome
References
Bhalaik V, Chhabra S, Walsh HP. Bilateral coexistent calcaneon- avicular and talocalcaneal tarsal coalition: a case report.
J Foot Ankle Surg 2002; 41: 129–34
Bohne WH. Tarsal coalition. Curr Opin Pediatr 2001; 13: 29–35 Bonk JH, Tozzi MA. Congenital talonavicular synostosis. A re- view of the literature and a case report. J Am Podiatr Med Assoc 1989; 79: 186–9
Brown RR, Rosenberg ZS, Thornhill BA. The C sign: more spe- cific for flatfoot deformity than subtalar coalition. Skeletal Radiol 2001; 30: 84–7
Challis J. Hereditary transmission of talonavicular coalition in association with anomaly of the little finger. J Bone Joint Surg Am 1974; 56: 1273–6
Clarke DM. Multiple tarsal coalitions in the same foot.
J Pediatr Orthop 1997; 17: 777–80
Conway JJ, Cowell HR. Tarsal coalition: clinical significance and roentgenographic demonstration. Radiology 1969; 92:
799–811
Cowell HR, Elener V. Rigid painful flatfoot secondary to tarsal coalition. Clin Orthop 1983; 177: 54–60
Dennis DA, Clayton ML, Ferlic DC. Osteoarthritis associated with a ball-and-socket ankle joint. A case report. Clin Orthop 1987; 215: 196–200
Emery KH, Bisset GS 3rd, Johnson ND, Nunan PJ. Tarsal coali- tion: a blinded comparison of MRI and CT. Pediatr Radiol 1998; 28: 612–6
Gregerson HN. Naviculocuneiform coalition. J Bone Joint Surg Am 1977; 59: 128–30
Jack FA. Bone anomalies of the tarsus in relation to “peroneal spastic flat foot”. J Bone Joint Surg Br 1954; 36: 530–42 Kumai T, Tanaka Y, Takakura Y, Tamai S. Isolated first naviculo-
cuneiform joint coalition. Foot Ankle Int 1996; 17: 635–40 Kumai T, Takakura Y, Akiyama K, Higashiyama I, Tamai S.
Histopathological study of nonosseous tarsal coalition.
Foot Ankle Int 1998; 19: 525–31
Kumar SJ, Guille JT, Lee MS, Couto JC. Osseous and non-os- seous coalition of the middle facet of the talocalcaneal joint. J Bone Joint Surg Am 1992; 74: 529–35
Lahey MD, Zindrick MR, Harris EJ. A comparative study of the clinical presentation of tarsal coalitions. Clin Podiatr Med Surg 1988; 5: 341–57
Lateur LM, van Hoe LR, van Ghillewe KV, Gryspeerdt SS, Baert AL, Dereymaeker GE. Subtalar coalition: diagnosis with the C sign on lateral radiographs of the ankle. Radiology 1994;
193: 847–51
Lee MS, Harcke HT, Kumar SJ, Bassett GS. Subtalar joint coali- tion in children: new observations. Radiology 1989; 172:
635–9
Leonard MA. The inheritance of tarsal coalition and its rela- tionship to spastic flat foot. J Bone Joint Surg Br 1974; 56:
520–6
McNally EG. Posteromedial subtalar coalition: imaging ap- pearances in three cases. Skeletal Radiol 1999; 28: 691–5 Newman JS, Newberg AH. Congenital tarsal coalition: multi-
modality evaluation with emphasis on CT and MR imag- ing. Radiographics 2000; 20: 321–32
Olney BW, Asher MA. Excision of symptomatic coalition of the middle facet of the talocalcaneal joint. J Bone Joint Surg Am 1987; 69: 539–44
Pachuda NM, Lasday SD, Jay RM. Tarsal coalition: etiology, diagnosis, and treatment. J Foot Surg 1990; 29: 474–88 Palladino SJ, Schiller L, Johnson JD. Cubonavicular coalition.
J Am Podiatr Assoc 1991; 81: 262–6
Pappas AM, Miller JT. Congenital ball-and-socket ankle joints and related lower-extremity malformations. J Bone Joint Surg Am 1982; 64: 672–9
Perlman MD, Wertheimer SJ. Tarsal coalitions. J Foot Surg 1986; 25: 58–67
Resnick D. Talar ridges, osteophytes, and beaks: a radiologic commentary. Radiology 1984; 151: 329–32
Resnick D. Additional congenital or heritable anomalies and syndromes. In: Resnick D (ed.) Diagnosis of bone and joint disorders. W.B. Saunders Company, Philadelphia, 1995 (3rd ed.), pp. 4294–301
Sartoris DJ, Resnick DL. Tarsal coalition. Arthritis Rheum 1985; 28: 331–8
Scranton PE. Treatment of symptomatic talocalcaneal coali- tion. J Bone Joint Surg Am 1987; 69: 533–8
Solomon LB, Ruhli FJ, Taylor J, Ferris L, Pope R, Henneberg M.
A dissection and computer tomograph study of tarsal coalitions in 100 cadaver feet. J Orthop Res 2003; 21: 352–8 Stormont DM, Peterson HA. The relative incidence of tarsal
coalition. Clin Orthop 1983; 181: 28–36
Takakura Y, Tamai S, Masuhara K. Genesis of the ball-and- socket ankle. J Bone Joint Surg Br 1986; 68: 834–7
Wechsler RJ, Schweitzer ME, Deely DM, Horn BD, Pizzutillo PD. Tarsal coalition: depiction and characterization with CT and MR imaging. Radiology 1994; 193: 447–52 Wheeler R, Guevera A, Bleck EE. Tarsal coalitions: review of
the literature and case report of bilateral dual calcaneonav- icular and talocalcaneal coalitions. Clin Orthop 1981; 156:
175–7
Wilde PH, Torode IP, Dickens DR, Cole WG. Resection for symptomatic talocalcaneal coalition. J Bone Joint Surg Br 1994; 76: 797–801
Zeide MS, Wiesel SW, Terry RL. Talonavicular coalition. Clin Orthop 1977; 126: 225–7
Multiple Calcaneal Ossification Centers
䉴
[Duplicate/triplicate calcaneus, or stippled calcaneus]
As anticipated, ossification in the calcaneus begins at approximately the 24th week of gestation with the ap- pearance of one or, more commonly, two primary centers that rapidly coalesce into a single center: a lat- eral center, appearing slightly earlier and located be- tween the retrotrochlear eminence and the lateral process of the tuber, and a central ossific center situ- ated in the anterior third of the cartilaginous calca- neus in relation to the sustentaculum tali (Meyer and O’Rahilly 1976). Occasionally, these two centers fail to fuse and persist as separate centers for some months after birth, thus resulting in ‘duplication’ or, more rarely, triplication of the calcaneus. When fusion be- tween the original ossification centers is incomplete a bifid calcaneus results (Kohler and Zimmer 1970). Al- though a bipartite (duplicated) calcaneus can occur as a variant in otherwise normal children, it is gener- ally associated with distinct skeletal dysplasias and syndromes, including the thanatophoric dysplasia and the short-rib dysplasia groups (Cormier-Daire et al. 2001), and also Larsen syndrome (Latta et al. 1971).
Interestingly, calcaneal duplication seems to occur in thanatophoric dysplasia type I (OMIM 187600) (Fig. 7.16) but not in type II (OMIM 187601) (Cormi- er-Daire et al. 2001). These two thanatophoric dyspla- sia disorders are characterized by platyspondyly, short limbs, and a small characteristically formed pelvis. However, curved femurs are predominantly observed in type I, while straight femurs and severe cloverleaf skull are more typical of type II. Duplica- tion of the calcaneus can be regarded as an addition- al distinctive radiographic feature that can be helpful in the differential diagnosis (Cormier-Daire et al.
2001). The short-rib (with or without polydactyly)
dysplasia group encompasses several disorders with
narrow thorax and short ribs, micromelia, multivis-
ceral involvement, and autosomal recessive inheri-
tance (Lachman 1997). These disorders are differenti-
ated on the basis of the radiologic and histological
findings, as discussed elsewhere in this book. Dupli-
cation or triplication of the calcaneus has been ob-
served in short-rib polydactyly syndrome type I
(Saldino-Noonan, OMIM 263530) and type III (Ver-
ma-Naumoff, OMIM 263510), chondroectodermal dys-
plasia (Ellis-van Creveld, OMIM 225500), and asphyxi-
ating thoracic dysplasia (Jeune syndrome, OMIM
208500) (Fig. 7.17), but not in short-rib polydactyly
syndrome type II (Majewski, OMIM 263520) or type
IV (Beemer-Langer, OMIM 269860) (Cormier-Daire et al. 2001). Therefore, duplicated calcaneus could be an additional feature allowing discrimination among the different entities in this dysplasia group. Multiple calcaneal ossification centers, in combination with ac- cessory carpal bones, have been reported as a specific feature of Larsen syndrome (OMIM 150250, 245600) (Latta et al. 1971). A duplicate calcaneus resulting from delayed coalescence of the primary ossification centers is also a feature in children with brachydacty- ly, type A6 (Osebold-Remondini syndrome, OMIM 112910), a condition combining hypoplasia/aplasia of middle phalanges, mesomelic limb shortening, mild short stature, capitate-hamate fusion, and normal in- telligence (Osebold et al. 1985).
Another mechanism by which multiple ossifica- tion centers may appear in the calcaneus is through evolution from epiphyseal stippling. This abnormal ossification pattern, which is typical of the heteroge- neous group of chondrodysplasia punctata disorders (OMIM 118650, 118651, 215100, 215105, 222765, 302950, 302960, 600121, 602497), has been reviewed in Chapter 5 (section “Stippled Epiphyses”). In contrast to the aforementioned disorders, in which duplica- tion/triplication of the calcaneus results from delayed coalescence of the primary ossification centers, in the disorders subsumed under the general name of chon- drodysplasia punctata the radiographic pattern con- sists in multiple punctate calcifications in the cal- caneal area, which eventually coalesce into calcified clods and subsequently disappear in the early years of life (Fig. 7.18). At microscopic level, stippling corre- sponds to calcification of aberrant cysts resulting from mucoid degeneration of the cartilaginous matrix (Rasmussen and Reimann 1973). Stippling in the cal- caneus similar to that of chondrodysplasia punctata also occurs in several apparently unrelated disorders, including Zellweger syndrome (cerebro-hepato-renal syndrome, OMIM 214100), various embryopathies (warfarin, phenytoin, alcohol), rubella infection, vita- min K epoxide reductase deficiency, GM1 gangliosido- sis, and Down syndrome (Silverman 1993).
Radiographic Synopsis
1. Duplicate/triplicate calcaneus in infancy, with subsequent fusion of the individual nuclei into a single bone (normal variation, thanatophoric dys- plasia group, short-rib dysplasia group, Larsen syndrome)
2. Stippled calcaneus, described as ‘spattered paint’
or ‘cluster of pearls’ (chondrodysplasia punc- tata, Down syndrome, Zellweger syndrome, em- bryopathies, rubella infection)
Fig. 7.16. Thanatophoric dysplasia, type I. Close-up of the an- kle region of a fetus with typical features of the disease, show- ing apparent triplication of the calcaneus. (From Cormier- Daire et al. 2001)
Fig. 7.17. Asphyxiating thoracic dysplasia in a newborn.
Close-up lateral view of the ankles and feet showing the ossifi- cation center for the talus lying above a duplicated calcaneus.
(Cormier-Daire et al. 2001)
Fig. 7.18. Chondrodysplasia punctata, X-linked in a 4-year-old child. Note multiple unfused ossification centers in the calca- neus, with residual stippling in several tarsal areas. (From Cormier-Daire et al. 2001)
