Clubfoot Metatarsus Adductus

► [Talipes equinovarus/metatarsus varus]

Clubfoot and metatarsus varus are two common congenital 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, accounting for up to 95% of all cases. Thus, the term 'clubfoot' is used synonymously with 'talipes equinovarus,' 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 neuromuscular disease. Isolated talipes equinovarus (OMIM 119800) has a prevalence of approximately 1 in 1000 live births in Caucasians (Bleck 1993), a male-to-female 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 major 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 extraction suggests that the best genetic model is a single 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

Valgus Angulation The Hindfoot

Fig. 7.5. Talipes equinovarus in a 1-month-old baby boy. Observe severe hindfoot varus, with superimposed talar and calcaneal centers.Neither the cuboid nor the navicular bone is ossified, but the abnormal position of the latter bone can be inferred 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. 7.5. Talipes equinovarus in a 1-month-old baby boy. Observe severe hindfoot varus, with superimposed talar and calcaneal centers.Neither the cuboid nor the navicular bone is ossified, but the abnormal position of the latter bone can be inferred 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

Primus Metatarsus Adductus

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)

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)

development. A faulty intrauterine position, abnormalities of the central nervous system or the vascular system, retracting fibrosis and muscular imbalance, anomalous tendon insertion, and defective connective tissue with ligamentous laxity have all been implicated as potential mechanisms in the development

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 widening, 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)

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 phenomenon once soft tissue retractions are established. The talus is smaller than normal, with a flattened talar dome and a neck that is dislocated in a medial and plantar direction (Ippolito 1995). As a result, the articular 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. Maturation of the navicular bone, which normally ossifies 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 clinical examination at birth, which makes it possible to establish the degree of severity by assessing re-ducibility, the presence of skin creases, and the degree of muscular atrophy. Early treatment by either manipulation and casting or surgery is critically important, as untreated cases are associated with further stiffening in the abnormal position and secondary changes in osseous development. Extensive surgical 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 immobilization, followed as appropriate by minimally invasive surgical procedures (Ponseti and Compos 1972). Severe equinovarus deformity of the foot is a cardinal manifestation of arthrogryposis multiplex congenita (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. However, talipes equinovarus, ulnar deviation of the hand, carpal or tarsal fusions, hip dislocation, patella malposition and dislocation, and scoliosis are common to all types (Hall 1985). Talipes equinovarus also occurs in several other disorders with joint contracture, 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, clubfoot is a prominent manifestation of diastrophic dysplasia (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 multiple 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 widening, 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)

Varus Deformity
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

Equinovarus deformity of the feet is also a frequent manifestation of the autosomal dominant campomelic 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 context of conditions with joint laxity, such as spondy-loepimetaphyseal dysplasia with joint laxity (OMIM 271640). Kyphoscoliosis at birth, cleft palate, congenital 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 disturbances as spine instability, bladder dysfunction, underdevelopment of the lower limbs with contracture deformities, hip dislocations, and talipes equino-varus (Guidera et al. 1991). In acromelic frontonasal dysplasia (OMIM 603671) the craniofacial manifestations of frontonasal dysplasia are associated with central nervous system malformations and limb defects, 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, triangle-shaped tibias and short fibulas, is sometimes associated with an atypical form of bilateral clubfoot with a prominent equinus component.

Metatarsus adductus is the designation for a deformity characterized by inward deviation of the forefoot, with a concave medial border, convex lateral 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 component. 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. Manipulation 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 maintained by an aberrant tendon insertion. Metatarsus adductus is clearly different from simple metatarsus primus deformity, a condition characterized by adduction 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 (adduction of the metatarsals alone); (2) complex metatarsal adductus (forefoot adduction + abnormal alignment 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). Although the etiology of this foot deformity is unknown, the genetic components are undeniable, as demonstrated by the occurrence of simple metatarsus 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 preaxial polydactyly, partial syndactyly, and short/absent middle phalanges of toes, and it can be a component of Down syndrome (OMIM 190685) and of the heterozygous form of Grebe chondrodysplasia (OMIM 200700). A severe form of metatarsus adductus has been described in three sibs in association with microcephaly, minor facial anomalies reminiscent of the Brachmann-de Lange syndrome, developmental delay, and unusual dermatoglyphics (Brachmann-de Lange-like facial changes with microcephaly/metatarsus adductus/developmental delay,OMIM 112370) (Halal and Silver 1992).

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Responses

  • JEWEL SENN
    Is metatarsus adductus critical?
    7 years ago
  • ensio kemppi
    Is metatarsus adductus genetic?
    7 years ago

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