Radial Deviation Distal Phlanx Pediatric Radial Deviation Distal Phlanx Syndrome

• Digital lengthening is difficult and requires frequent monitoring to avoid potential complications.

• On-top plasty requires extensive neurovascular dissection to prevent vascular compromise of digit.

• Toe-to-hand transfer in the congenitally anomalous hand is difficult.

Amniotic Bands Radiograph
Figure 79—2. Radiographs of both hands with aphalan-gia long and ring fingers, absent middle index, and radial deviation small distal interphalangeal joint.

Diagnostic Studies

Radiographs of both hands revealed several abnormalities of the left hand (Fig. 79—2). The thumb appeared normal in size and bony configuration. The fingers had normal metacarpals with considerable deficiencies at the phalangeal level. The index digit had a metacarpophalangeal joint with a remnant of proximal phalanx. The long and ring fingers had no phalanges. The small digit had normal-appearing joints and radial deviation ofthe distal interphalangeal joint.

Differential Diagnosis

Constriction band syndrome Hypoplastic digits Brachydactyly Poland's syndrome

Constriction band syndrome is a result of entrapment of developing embryonal tissue by fetal lining and can affect the upper extremity in a variety of ways. Mild band formation can cause simple constriction rings that are merely a cosmetic deformity. Severe bands can cause autoamputation of the digits, which requires treatment similar to severe hypoplasia. The diagnosis of constriction band requires the presence of a constriction band either in the hand or elsewhere. Brachydactyly usually refers to a shortened digit with the normal complement of bones and is a specific form of hypoplasia. Poland's syndrome is usually sporadic in occurrence and combines hand hypoplasia with chest wall abnormalities. The most common hand anomaly is symbrachydactyly (syndactyly combined with brachydactyly), and the typical chest abnormality is ipsi-lateral absence of the sternocostal portion of the pectoralis major muscle.

Diagnosis

Digital Hypoplasia

Hypoplasia can result from numerous anomalies including failure of formation, failure of differentiation, undergrowth, or constriction band syndrome. Hypoplastic digits is a general term that reflects deficiencies of the thumb and/or fingers. Thumb hypoplasia is often associated with preaxial longitudinal deficiencies (i.e., radial clubhand) and classified as a specific entity. The terminology for hypoplastic fingers is confusing and inconsistent. The term hypoplastic digits is best reserved for fingers that cannot be specifically classified (e.g., brachydactyly) or secondary to a known cause (e.g., amniotic bands or posttraumatic).

Nonsurgical Management

The initial treatment of digital hypoplasia is nonoperative. The child needs to be evaluated and the parents educated about this congenital anomaly. The emotional distress of the parents should be addressed during the initial visits. We attempt to explain to the parents that most congenital anomalies occur during weeks 4 and 8 of gestation as the developing limb bud grows. The defect most likely affected the covering of the limb (apical ectodermal ridge), which caused a malformation of the underlying structures. This abnormality may have occurred prior to their knowledge of the pregnancy. In addition, the cause of the vast majority of congenital abnormalities is unknown, and we will likely never know what resulted in most congenital anomalies. We also stress that the parents treat the child as normal as possible, as the child does not know he or she is different and will be highly adaptive in achieving those tasks necessary for function. These adaptive maneuvers should not be discouraged during the developmental stages, as the child attempts to achieve bimanual and prehensile function.

Children with varying degrees of hypoplastic digits in the same hand may be able to achieve good functional pinch and grasp. This is especially true if the thumb is normal and another digit is available to act as a post. In this child, the thumb was able to oppose the small digit for oppositional pinch and grasp (Fig. 79—3). These movements were easily performed despite symphalangism (proximal interpha-langeal joint ankylosis) and clinodactyly (radial deviation of the distal interpha-langeal joint) of the small finger. Children who are this functionally adept are not surgical candidates.

Pediatric Callotasis Hand
Figure 79—3. (A) Oppositionalpinch between thumb and small digit despite aphalangia of index and long and small finger symphalangism. (B) Functional grasp between hypoplastic digits and thumb.

Surgical Management

Surgery for digital hypoplasia should not improve appearance and supplant function. Hypoplastic digits with short proximal phalanges and intact metacarpophalangeal joints have good potential for function. The shortened digits can be used for crude grasp and have normal sensibility. Many children with severe hypoplasia are very capable of daily function. The child should be evaluated during activities to assess functional handicap with regard to grasp, pinch, and release.

Lengthening of the digits can be done to augment function and can be achieved by nonvascularized toe phalanx transfer, distraction osteogenesis, bone grafting, on-top plasty, or toe-to-hand transfer. Phalangeal transfer is most commonly performed in hands without phalanges (aphalangia) and can use any of the toes as a donor (see Case 75, Transverse Deficiency of the Digits). The phalanx is harvested in an extraperiosteal fashion and placed within the recipient finger. There must be an adequate skin tube of the finger to accept the toe phalanx. Otherwise the bone will disrupt the blood supply to the skin and result in tip necrosis. Any hypoplastic tendons are sutured to the phalanx. The results of toe phalangeal transfer are somewhat disappointing with mild growth only for a few years.

Distraction osteogenesis is applicable to the hand but not without inherent risks. The metacarpal is more suitable to lengthening compared with the phalanges, which are extremely difficult to distract. The small size of the phalanges and little tolerance for traction make phalangeal lengthening complicated. Distraction is performed slowly at 1 mm per day with careful monitoring of the pin sites and status of the soft tissues. Contracture formation requires therapy and may require slowing of the lengthening rate. Radiographs are taken weekly to monitor callus formation, and the lengthening rate is adjusted if there is insufficient callus or early consolidation. In general, distraction osteogenesis can almost double the length of the bone, and the fixator must remain in place for three times the duration of the lengthening to allow for bony consolidation. In addition, the regenerate bone is prone to fracture and must be protected for months after fixator removal.

Bone grafting can be used to increase the length of a hypoplastic digit. This technique is most useful at the time of first web space reconstruction. For example, excision of a hypoplastic index metacarpal will increase the first web space, and a portion of the bone can be used to augment the adjacent thumb or long finger as an intercalary graft (Fig. 79—4). The recipient digit must have ample skin to accommodate the acute increase in length. Excessive pressure along the lengthened digit results in skin necrosis at the tip.

Hypoplastic Thumb
Figure 79—4. Postoperative radiograph of hypoplastic hand and digits treated by index metacarpal resection to increase first web space. The resected metacarpal was used as an intercalary bone graft to increase thumb
Hand Microsurgery Adult Clinodactyly

Figure 79—5. (A) A 2-year-old boy with hypoplastic index and thumb. (B) Index proximal phalanx dissected on its neurovascular pedicle in preparation for on-top plasty. (C) Placement of the index proximal phalanx on top of the thumb and first web space reconstruction.

Top Plasty

On-top plasty is a neurovascular transfer of a hypoplastic digit on top of another digit to increase length and augment function. This technique is also most useful during first web space reconstruction (Fig. 79-5A). This technique is difficult and requires extensive dissection of the neurovascular pedicle to obtain sufficient length for distal placement on the recipient digit (Fig. 79-5B). On-top plasty can provide considerable length and enhanced function without the risks of free tissue transfer (Fig. 79-5C).

The microsurgical transfer of a toe to the hand is an additional option to treat the congenitally deficient limb. Toe-to-hand transfer is best used in the monodactylous hand or in the hand without fingers (adactylous hand). The advantages of this technique are the potential for continued growth, the addition of functional joints, the prospect of active motion, and the possibility of normal sensation. The disadvantages include the potential loss of the transferred toe and the difficulty of the procedure. However, as the technical details of toe-to-hand transfer for congenitally deficient hands become more refined, this procedure will become available to more children.

Suggested Readings

Flatt AE. The Care of Congenital Hand Anomalies, 2nd ed. St. Louis: Quality Medical Publishing; 1994:149-179.

Goldberg NH, Watson HK. Composite toe (phalanx and epiphysis) transfers in the reconstruction of the aphalangic hand. J Hand Surg [Am] 1982;7:454-459.

Ireland DC, Takayama N, Flatt AE. Poland's syndrome. A review of forty-three cases. J Bone Joint Surg [Am] 1976;58A:52—58.

James MA, Durkin RC. Nonvascularized toe proximal phalanx transfers in the treatment of aphalangia. Hand Clin 1998;14:1-15.

Kay SP, Wiberg M. Toe to hand transfer in children. Part 1: technical aspects. J Hand Surg [Br] 1996;21B:723-734.

Kay SP, Wiberg M, Bellow M, Webb F. Toe to hand transfer in children. Part 2: functional and psychological aspects. J Hand Surg [Br] 1996;21B:735-745.

Kozin SH, Thoder JJ. Congenital anomalies of the upper extremity. In: Baratz ME, Watson AD, ImbrigliaJE, eds. Orthopaedic Surgery: The Essentials. New York: Thieme; 1999:657-673.

Pennsler JM, Carroll NC, Cheng LF. Distraction osteogenesis in the hand. Plast ReconstrSurg 1998;102:92-95.

Seitz WH Jr, Froimson AI. Digital lengthening using the callotasis technique. Orthopedics 1995;18:129-138.

Vilkki SK. Advances in microsurgical reconstruction of the congenitally adactylous hand. Clin Orthop 1995;314:45-58.

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Responses

  • asmara
    When was radial deviation first diagnosed?
    4 years ago

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