A 6-month-old boy has the deformities shown in the photograph above. There are no associated syndromes. His parents would like to have more children and inquire about the risk for similar deformities. The risk for development of this deformity in future offspring is closest to

(A) 0%
(B) 5%
(C) 10%
(D) 25%
(E) 50%

The correct response is Option A.

This 6-month-old boy has amniotic constriction band syndrome, a congenital hand deformity that manifests as intrauterine amputation of the digits. Amniotic constriction band syndrome has no known genetic transmission and is considered to be an intrauterine accident. Although there are several theories regarding the cause of this condition, it is believed to be related to rupture of the amniotic membrane caused by oligohydramnios; when this occurs, the digits and/or extremities are constricted by amniotic tissue bands created from the edges of the ruptured amniotic sac. Amniotic bands may result in amputations, not only of the fingers (as in this patient) or the extremities, but sometimes other parts of the body. The degree of constriction is variable and is classified according to its severity.

Amniotic constriction band syndrome is the fourth most common congenital anomaly of the hand; only polydactyly, syndactyly, and trigger thumb occur more frequently. Currently, its incidence is estimated at approximately 1 in 5000 to 15,000 births, with variations among different ethnic groups.

Anomalies frequently associated with amniotic constriction band syndrome include club foot, cleft lip and/or palate, craniofacial defects, hemangioma, and meningocele.

In this infant, appropriate management of the hand deformity is deepening of the web space using a standard dorsal flap followed by full-thickness skin grafting.

References
1. Doyle JR. Constriction ring reconstruction. In: Blair WF, ed. Techniques in Hand Surgery. Baltimore, Md: Williams & Wilkins; 1996:1106-1111.
2. Ezaki M. Amnion disruption sequence. In: Green DP, Hotchkiss RN, Pederson WC, eds. Operative Hand Surgery. 4th ed. New York, NY: Churchill Livingstone, Inc; 1999;1:429-431.
3. Upton J. Congenital anomalies of the hand and forearm. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;8:5373-5378.
4. Wiedrich TA. Congenital constriction band syndrome. Hand Clin. 1998;14:29-37.

During embryologic development of the hand, which of the following structures is most likely to affect normal differentiation of the limb?

(A) Apical ectodermal ridge
(B) Fourth branchial cyst
(C) Germinal matrix
(D) Second branchial cleft
(E) Wolffian ridge

The correct response is Option A.

The apical ectodermal ridge is the critical structure that defines the growth and differentiation of the new limb during embryologic development; if the apical ectodermal ridge were to be surgically removed, the developing limb would be truncated. The apical ectodermal ridge arises from the Wolffian ridge, which protrudes from the main trunk of the embryo. A zone of polarizing activity determines the anterior-posterior morphology of the limb.

The upper extremities begin to develop during the first four weeks of gestation. By the completion of the fifth week, the hand becomes a recognizable structure. As the apical ectodermal ridge becomes flattened, the hand appears initially as a paddle. Each of the phalanges is then formed by a process of physiologic cell death that occurs within the web spaces. The digits become defined by the end of the eighth week, and fingernails can be identified by 17 weeks’ gestation.

References
1. Daluiski A, Yi SE, Lyons KM. The molecular control of upper extremity development: implications for congenital hand anomalies. J Hand Surg. 2001;26A:8-22.
2. McCarroll HR. Congenital anomalies: a 25-year overview. J Hand Surg. 2000;25A:1007-1037.
3. Watson S. The principles of management of congenital anomalies of the upper limb. Arch Dis Child. 2000;83:10-17.

A 6-year-old girl has camptodactyly of the small finger of the right hand. The deformity has not improved with splinting and passive stretching exercises. On physical examination, there is loss of 20 degrees of terminal extension of the proximal interphalangeal (PIP) joint that is unaffected by flexion of the metacarpophalangeal joint.

Which of the following is the most appropriate management?

(A) Observation
(B) Injection of a corticosteroid into the PIP joint
(C) Release of the lumbrical tendon
(D) Release of the superficialis tendon
(E) Zancolli-lasso procedure

The correct response is Option A.

In this 6-year-old girl with camptodactyly who has a loss of 20 degrees of extension of the proximal interphalangeal (PIP) joint, observation is most appropriate. Surgical correction is rarely required in patients who have lost less than 30 degrees of extension. Minimal extension deficits that require operative management can be corrected by transferring the lumbrical tendon into the central slip.

In patients who have a terminal extension deficit of 30 degrees or more, surgical release of the abnormal lumbrical and superficialis tendons is most likely to improve the deformity. Release of the attachment of the accessory collateral ligaments to the volar plate may also be necessary. Full-thickness skin grafts or local skin flaps can be used to cover the resultant volar skin deficits. However, the patient should be informed of the likelihood for a residual flexion deformity, especially if there are abnormalities of the articular joint surfaces on preoperative radiographs.

Corticosteroids should not be injected into the affected joints of patients with camptodactyly. In the Zancolli-lasso procedure, slips of the flexor digitorum superficialis tendon are looped through the A2 pulley. This technique is appropriate for correction of digital clawing associated with ulnar palsy in a patient who demonstrates improved extension of the PIP joint with flexion of the metacarpophalangeal joint.

References
1. Ezaki M, Kay SP, Light TR, et al. Congenital hand deformities. In: Green DP, Hotchkiss RN, Pederson WC, eds. Operative Hand Surgery. 4th ed. New York, NY: Churchill Livingstone, Inc; 1999;1:325-551.
2. McFarlane RM, Curry GI, Porte AM, et al. The anatomy and treatment of camptodactyly of the small finger. J Hand Surg. 1992;17A:35-44.

Q174
PIC

A 10-month-old infant with simple, complete syndactyly involving the third web space of the left hand undergoes reconstruction using a dorsal flap and multiple full-thickness skin grafts. A postoperative photograph is shown above. Which of the following is the most appropriate next step in management?

(A) Wound cleansing using dilute peroxide and application of antibiotic ointment daily
(B) Application of soft dressings and an elastic wrap
(C) Application of a short arm splint
(D) Application of a short arm cast
(E) Application of a long arm cast

PIC

The correct response is Option E.

In infants and children who undergo reconstructive procedures for correction of syndactyly, the most appropriate management postoperatively is application of a long arm cast. The success of the procedure depends on adequate immobilization of the entire upper extremity following surgery. When applying the cast, the elbow must be flexed before padding and fiberglass material are applied in order to prevent restriction or pressure in the antecubital region. Flexion of the cast at the elbow will prevent the dressings around the skin grafts and flaps from becoming loosened.

The photograph above shows the properly applied above-elbow cast of a patient who has undergone syndactyly reconstruction. All of the fingertips are visible, but the fingers are immobilized securely. This infant previously underwent two reconstructive attempts that were unsuccessful because of improper postoperative immobilization. The third procedure, involving release of severe contractures of the digits followed by repeat full-thickness skin grafting, was successful because the arm was immobilized correctly.

If the arm is not immobilized, the skin grafts and flaps will ultimately fail, and significant wound problems will occur. Soft dressings do not provide the needed immobilization. Short arm splints and casts frequently become dislodged in infants in children because of their high level of activity and the problems associated with fitting a short arm device to the cone-shaped forearm of a young child.

References
1. Ezaki M. Syndactyly. In: Green DP, Hotchkiss RN, Pederson WC, eds. Operative Hand Surgery. 4th ed. New York, NY: Churchill Livingstone, Inc; 1999;1:426.
2. Upton J. Congenital anomalies of the hand and forearm. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;8:5292.

A 3-year-old boy has total absence of the long and ring fingers of both hands. This finding is most consistent with which of the following conditions?

(A) Camptodactyly
(B) Clinodactyly
(C) Ectrodactyly
(D) Macrodactyly
(E) Polysyndactyly

The correct response is Option C.

This 3-year-old boy has ectrodactyly, a partial or total absence of the fingers that suggests a central hand deficiency. Central hand deficiencies can be classified as typical or atypical. Patients with typical central hand deficiencies have absence of the third ray (infrequently the second ray, rarely the fourth ray). The finding is often bilateral. Other anomalies, including cleft lip and palate, congenital heart disease, and significant deformities of the upper and lower extremities, can be associated. Syndactyly and foot involvement are common. The inheritance is familial.

In contrast, a patient with atypical central hand deficiency usually has several deficient rays unilaterally. This deficiency is commonly known as symbrachydactyly and is the opposite of true cleft hand. Inheritance is nonfamilial. Other anomalies, such as syndactyly and foot involvement, are uncommon. Affected patients typically have digital nubbins that are best removed at birth. Functional hand grasp can be increased through surgical manipulation of the web space or osteotomies.

Camptodactyly is a nontraumatic flexion deformity of the proximal interphalangeal joint, usually bilateral and involving the small finger.

Patients with clinodactyly have either radial or ulnar angulation of the digit, usually the small finger, at the distal interphalangeal joint. In severe clinodactyly, a delta phalanx is common.

Macrodactyly involves overgrowth of one digit or hand segment. Overgrowth appears to be under neurotrophic control. Correction is either reduction or ablation.

Polysyndactyly is a type of complicated syndactyly, in which polydactyly and syndactyly are seen in association.

References
1. Dobyns JH, Wood VE, Bayne LG. Congenital hand deformities. In: Green DP, ed. Operative Hand Surgery. New York, NY: Churchill Livingstone, Inc; 1993;1:251-548.
2. Flatt AE. The Care of Congenital Hand Anomalies. Saint Louis, Mo: CV Mosby Co; 1977.
3. Upton J. Congenital anomalies of the hand and forearm. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;8:5213-5398.

Q190
PIC

A 9-month-old infant has the deformity shown in the photograph above. The pregnancy and delivery were uncomplicated; the infant’s development is otherwise normal. Which of the following is the most likely diagnosis?
(A) Brachysyndactyly
(B) Camptodactyly
(C) Clinodactyly
(D) Ectrodactyly
(E) Syndactyly

The correct response is Option E.

Syndactyly is a common congenital hand anomaly, occurring in one of every 2500 neonates. Familial inheritance ranges from 10% to 40%, and boys are twice as likely as girls to be affected. Syndactyly can be simple or complex and complete or incomplete. Patients with simple syndactyly have fusion of the skin of adjacent digits. In complex syndactyly, the skin and bones are fused. Complete syndactyly encompasses the entire web space. In patients with incomplete syndactyly, only part of the web space is fused.

Based on the clinical photograph alone, incomplete syndactyly can be diagnosed in this infant because the entire web space is not involved. However, because there are no additional radiographs, a diagnosis of simple or complex syndactyly cannot be determined.

Although most infants with syndactyly undergo release before 18 months of age, some surgeons have performed surgery as early as 6 weeks of age.

Infants with brachydactyly have short, fused digits. Camptodactyly is characterized by curvature of a digit in its plane of flexion; in contrast, clinodactyly describes deviation of the digit in the plane of the hand. Patients with ectrodactyly have partial or total absence of the digits.

References
1. Ezaki M, Kay SP, Light T, et al. Congenital hand deformities. In: Green DP, Hotchkiss RN, Pederson WC, eds. Operative Hand Surgery. 4th ed. New York, NY: Churchill Livingstone, Inc; 1999;1:325-551.
2. Smith P, Laing H. Syndactyly. In: Gupta A, Kay SP, Scheker LR, eds. The Growing Hand. London: Mosby - Year Book, Inc; 2000:225-230.

Q197
PIC

A 7-month-old infant has the deformity shown in the photographs above. Which of the following is the most likely mode of inheritance of this deformity?

(A) Autosomal dominant
(B) Autosomal recessive
(C) Sporadic
(D) X-linked dominant
(E) X-linked recessive

The correct response is Option A.
This 7-month-old infant has a typical, or true, cleft hand deformity, which is most commonly inherited as an autosomal dominant condition. However, cleft hand may also occur as a spontaneous mutation, as it did in this patient whose family members were unaffected.

Typical cleft hand deformity is classified as a longitudinal deficiency because it involves dysplasia of the central portion of the hand. This anomaly is stratified into five categories, based on the degree of ray absence and hypoplasia of the thumb space. Characteristics include a V-shaped cleft, suppression of the central digit, and sometimes minor syndactyly of the ulnar border digits.

In contrast, atypical cleft hand is sporadic and is included in the teratologic sequence of symbrachydactyly. Affected patients have a broad, flat cleft hand with finger nubbins containing nail remnants.

Because typical cleft hand may be associated with several syndromes, any infant who exhibits this anomaly should be evaluated for cardiac, pulmonary, musculoskeletal, ocular, and renal defects. EEC syndrome, involving ectrodactyly, ectodermal dysplasia, and cleft lip/palate, is most frequently associated. Many patients with typical cleft hand deformity also have clefting of the feet (as does this patient), which results from localization of the split hand foot gene (SHFM1) to chromosome 7q21.

The degree of deformity of typical cleft hand varies greatly. Although most patients adapt and ultimately function quite well, surgical reconstruction is often recommended for functional as well as cosmetic reasons. The Snow-Littler procedure, which involves transposition of a palmar-based cleft flap with the index ray to close the cleft and create a useful first web space, is an appropriate reconstructive option.

References
1. Kay SP. Cleft hand. In: Green DP, Hotchkiss RN, Pederson WC, eds. Operative Hand Surgery. 4th ed. New York, NY: Churchill Livingstone, Inc; 1999;1:402-413.
2. Netscher DT. Congenital hand problems. Hand Clin. 1998;25:544.
3. Upton J. Congenital anomalies of the hand and forearm. In: McCarthy JG, ed. Plastic Surgery. Philadelphia, Pa: WB Saunders Co; 1990;8:5267-5273.