Pediatric Hand Deficiencies

Krister Freese MD, FAAOS

Rashmi Agarwal MD

Dr. Freese or an immediate family member serves as a board member, owner, officer, or committee member of the Pediatric Orthopaedic Society of North America. Neither Dr. Agarwal nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter.

This chapter is adapted from Langer JS: Pediatric hand deficiencies, in Krajbich JI, Pinzur MS, Potter BK, Stevens PM, eds: Atlas of Amputations and Limb Deficiencies: Surgical, Prosthetic, and Rehabilitation Principles, ed 4. American Academy of Orthopaedic Surgeons, 2016, pp 843-854.

ABSTRACT

Congenital hand deficiencies and abnormalities present unique diagnostic and therapeutic challenges. Each patient requires an individual approach to manage specific priorities including increasing function, pain reduction, and improved aesthetics. Common deficiencies include symbrachydactyly, syndactyly, longitudinal deficiencies, and polydactyly. Improved basic knowledge of pediatric hand deficiencies will aid surgeons and clinicians in choosing the optimal treatment strategy for their patients.

Introduction

The birth of a child with an upper limb deficiency may elicit many confusing parental emotions. Medical professionals should address parental concerns and expectations in a compassionate, honest, and forthright manner. Parents may grieve that their infant is not the perfect child that they had anticipated or voice anger that prenatal evaluations did not detect their child’s hand difference. Many parents feel an intense need to do something, either surgical or prosthetic, to make their child normal and whole. Conflicting advice from well-meaning friends and relatives may contribute to parental stress.

Despite frequently voiced parental concerns, a recent self-concept scale study demonstrated that overall, children with congenital anomalies possessed equal self-concept to healthy children.¹ Interestingly, children with more mild anomalies had worse scores than children with more severe anomalies.

As infants begin to explore their environment, they learn to use their unique physical capabilities to their best advantage. Deficits in function will be augmented through the use of the other hand, or if needed feet. The child’s growing awareness of their abnormality is usually the result of comments from playmates, siblings, or well-meaning adults. The child usually does not become self-conscious until approximately the age of 6 or 7 years. Peer pressure may cause the child with a unilateral abnormality to conceal the hand in a pocket or to reject an otherwise successful prosthesis.

Other points of psychological stress occur during adolescence when concerns arise over attractiveness. Feelings may be further complicated by impending marriage and the prospect of offspring with similar abnormalities. Access to knowledgeable genetic counseling is essential, particularly at that time. Increased use of patient-reported outcomes measures has allowed for improved evaluation of subjective measures not normally available to clinicians. The PROMIS score especially has demonstrated utility in the congenital hand cohort without evidence of a ceiling effect. Early studies have demonstrated decreased function, however low scores for depression, anxiety, and pain. Qualitative studies looking at the psychosocial effects of congenital hand differences have also become of increasing interest—there is a high stress level in the patient cohort as well as the parents, regarding the functional deficits, hand appearance, social interactions, and emotional reactions.²

Upper Limb Kinesiology

The hand allows children to explore their environment and to manipulate objects within that environment. The hand should be able to maneuver in space under volitional control and should be able to reach the body and the area in front of the body. Using both visual and tactile clues, a child must be able to aim the hand so that it can precisely approach an object. The object is then grasped by the closing fingers and adducting the thumb. The hand must also be capable of releasing the object from its grasp.

The two major types of grasp are precision prehension and power prehension.³ Precision prehension is used
to hold relatively small objects with modest force, whereas power prehension is used to hold larger objects, often with greater force. In precision prehension, the object is secured between the distal phalanx of the thumb and the index finger or within the thumb, index, and middle fingers. The fingers are usually extended at the interphalangeal joints, and the metacarpophalangeal (MCP) joints are partially flexed. The object itself usually does not contact the palm.

The three most common forms of precision grasp or pinch are palmar pinch, lateral pinch, and tip pinch. With palmar pinch, the flat palmar pads of the thumb and fingers secure opposite sides of the object being grasped. With lateral pinch, the palmar surface of the thumb’s distal phalanx is brought against the radial border of the index finger. Because this posture is often used to grasp and twist a key, this pattern is also known as key pinch. Tip pinch provides contact with the distal end of the distal phalanx of the thumb with the distal phalanx of the index or of the index and middle fingers. Tip pinch is used to pick up small objects such as a pin or a dime from a tabletop.

Power prehension involves the ulnar digits (most often the ring and little fingers), whereas the radial digits (the index and middle fingers) are used primarily in precision prehension. The hand also plays an important role in nonprehensile activities. These activities usually involve the transmission of force through the terminal portion of the limb to another object. Nonprehensile activities include keyboarding or button pushing, pushing open a swinging door, or throwing a punch. The hand may also be used to cradle or hold objects against the chest or to support objects such as a tray. Congenitally anomalous hands without prehensile capability are often used with great dexterity to perform these nonprehensile functions.

Prostheses

A purely cosmetic prosthesis to conceal the abnormality may be some parents’ first choice but may ultimately prove to be a hindrance. Any decision-making process should include a frank discussion of poor outcomes when a cosmetic prosthesis covers the sensate skin of an anomalous hand should be openly discussed. Although a cosmetic upper limb prosthesis may facilitate rehabilitation after a traumatic amputation, it is usually an impediment to a child with congenital amputation who possesses a mobile hand and wrist, even without fingers. Cosmetic prostheses may become a source of conflict between parent and child if the child regards the prosthesis as an obstacle rather than an aid. The child may feel that the prosthesis functions only to please parents who are embarrassed by their appearance. If a prosthesis is to be successfully integrated into the child’s life, it must help the child either accomplish otherwise impossible activities or perform meaningful activities with greater facility.

Prostheses have not yet been designed to replicate sensation, leading to limited utility for children with unilateral conditions. If the affected side is able to function as a helper hand for the unaffected side, especially with wrist motion and/or at least one functional digit, a prosthesis may be more of an obstruction than an aid. Some prosthesis designs may augment the single-digit hand, allowing for a surface to pinch again, such as an opposition paddle or a partial hand prosthesis.

On occasion, the removal of a functionless part may facilitate prosthetic fitting. Approximately 50% of individuals with congenital lower limb amputations require surgical revision before prosthetic fitting, whereas only approximately 10% of congenital anomalous upper limbs fit for prostheses require surgical revision.⁴ Consultation between the surgeon and prosthetist helps the surgeon understand which anomalies will obstruct prosthetic donning and wear. Portions of the affected limb that are useful for prehension without a prosthesis should never be amputated.

A recent advancement in prosthetic care is three-dimensional prosthetic printing, which provides a low-cost alternative to traditional cosmetic or functional prosthetic devices.⁵^,⁶ This patient driven and family-driven modality gives the child or family the ability to easily customize and alter the prosthesis and may aid in the emotional adjustment to their disability. These prostheses can be lightweight, durable, and easily replaced as a child grows and has different needs. Cooperation between clinicians and engineers has led to multiple designs available online as open-source blueprints, which can be used and modified to fit a specific child’s desired function. This area will continue to grow and develop as the technology continues to advance.

Clinical Presentation

Although congenital upper limb abnormalities are increasingly diagnosed by prenatal ultrasonography, they typically are first diagnosed at birth. Identification of congenital limb anomalies on prenatal ultrasonography has been cited as low as 30% and as high as 80%, with significant variation based on the type of malformation.⁷^,⁸^,⁹ Parents often have a deep need to understand the nature of their child’s abnormality and the potential treatments available. Early consultation with experienced physicians and therapists is helpful for most families. In some cases, a prenatal consultation with a congenital hand surgeon can provide the family with insight into their child’s condition.

Classification

The Oberg, Manske, and Tonkin (OMT) classification of congenital anomalies of the hand and upper limb was proposed in 2010 as a replacement for the Swanson International Federation of Societies for Surgery of the Hand classification system. The OMT system uses increasing knowledge of molecular and developmental pathways, and relates them to clinically relevant anomalies. It separates malformations from deformations and dysplasias. Malformations are subdivided according to the axis of formation and differentiation and involvement of the whole limb or the hand plate alone. It has been updated twice, in 2014 and 2020, with the most recent version shown in Table 1.¹⁰ The classification has demonstrated high intraobserver reliability and substantial interobserver agreement.

Conditions in which body parts are absent are referred to as failures of formation. These have been classified by etiology in the modified Swanson/International Federation of Societies for Surgery of the Hand system (Table 2). In most patients, the anatomic border between normal tissue and absent elements is indistinct and gradual; a blend of dysplastic and hypoplastic tissue typically forms a transition zone that may extend the entire length of the limb. One exception is amniotic band syndrome, where there is highly localized intrauterine trauma to the growing limb and there may be an abrupt transition from normal tissue to absent elements (Figure 1). In these limbs, the anatomy proximal to the area of abnormality is usually normal.

Conditions in which the absence is most intense in the distal portion of the limb are usually referred to as terminal deficiencies (Figure 2). The entire limb, including the chest, must be evaluated to fully understand these abnormalities. Distal anomalies involving the hand, such as syndactyly, may be associated with chest abnormalities in children with Poland syndrome.

Symbrachydactyly

The most common forms of terminal limb deficiency are related to the symbrachydactyly sequence of abnormalities.¹¹^,¹²^,¹³ The term symbrachydactyly literally refers to a hand with syndactyly of short fingers. Manifestations may be as mild as slightly shortened middle phalanges or as severe as a very short forearm segment with digital nubbins protruding from its distal end. Children with intermediate forms may have only a thumb or only a thumb and little finger with small nubbins representing the undeveloped fingers. Mild hypoplasia of the ipsilateral humerus is common, as is dysplasia or hypoplasia of the forearm. When multiple digits are involved, the central three digits are usually the most profoundly affected. Many patients with symbrachydactyly have primitive digits, often termed nubbins. These bud-like, incompletely formed digits often include small fingernails. In many instances, digital flexor and
extensor tendons insert into the nubbin, enabling children to move the tip of the digit proximally (Figure 3). Some characteristic patterns of digital absence have been noted and are summarized in Table 3.

TABLE 1 Oberg, Manske, and Tonkin Classification 2020

Malformations
1. Entire upper limb: abnormal axis formation (early limb patterning)
  1. Proximodistal axis
    1. Brachymelia
    2. Symbrachydactyly spectrum (with ectodermal elements)
      1. Poland syndrome
      2. Whole limb excluding Poland syndrome (various levels: humeral to phalangeal)
    3. Transverse deficiency (without ectodermal elements)
      1. Amelia
      2. Segmental (various levels: humeral to phalangeal)
    4. Intersegmental deficiency (phocomelia)
      1. Proximal (humeral: rhizomelic)
      2. Distal (forearm: mesomelic)
      3. Proximal plus distal (hand to thorax)
    5. Whole limb duplication/triplication
  2. Radioulnar (anterior-posterior) axis
    1. Radial longitudinal deficiency
    2. Ulnar longitudinal deficiency
    3. Ulnar dimelia
    4. Radiohumeral synostosis
    5. Radioulnar synostosis
    6. Congenital dislocation of radial head
    7. Forearm hemiphyseal dysplasia, radial (Madelung deformity), or ulnar
  3. Dorsoventral axis
    1. Ventral dimelia
    2. Dorsal dimelia
  4. Unspecified axis
    1. Shoulder
      1. Undescended (Sprengel)
      2. Abnormal shoulder muscles
    2. Upper to lower limb transformation
2. Hand plate: abnormal axis differentiation (late limb patterning/differentiation)
  1. Proximodistal axis
    1. Brachydactyly
    2. Symbrachydactyly (with ectodermal elements)
    3. Transverse deficiency (without ectodermal elements)
    4. Cleft hand (split hand foot malformation)
  2. Radioulnar (anterior-posterior) axis
    1. Radial longitudinal deficiency, hypoplastic thumb
    2. Ulnar longitudinal deficiency, hypoplastic ulnar ray
    3. Radial polydactyly
    4. Triphalangeal thumb
      1. Five-finger hand
    5. Ulnar dimelia (mirror hand)
    6. Ulnar polydactyly
  3. Dorsoventral axis
    1. Dorsal dimelia (palmar nail)
    2. Ventral dimelia (hypoplastic/aplastic nail)
  4. Unspecified axis
    1. Soft tissue
      1. Cutaneous (simple) syndactyly
    2. Skeletal
      1. Osseous (complex) syndactyly
      2. Clinodactyly
      3. Kirner deformity
      4. Synostosis/symphalangism
    3. Complex
      1. Syndromic syndactyly (eg, Apert hand)
      2. Synpolydactyly
3. Not otherwise specified
Deformations
1. Constriction ring sequence
2. Not otherwise specified
Dysplasias
1. Variant growth
  1. Diffuse (whole limb)
    1. Hemihypertrophy
    2. Aberrant flexor/extensor/intrinsic muscle
  2. Isolated
    1. Macrodactyly
    2. Aberrant intrinsic muscles of hand
2. Tumorous conditions
  1. Vascular
    1. Hemangioma
    2. Malformation
    3. Others
  2. Neurological
    1. Neurofibromatosis
    2. Others
  3. Connective tissue
    1. Juvenile aponeurotic fibroma
    2. Infantile digital fibroma
    3. Others
  4. Skeletal
    1. Osteochondromatosis
    2. Enchondromatosis
    3. Fibrous dysplasia
    4. Epiphyseal abnormalities
    5. Pseudarthrosis
    6. Other
3. Congenital contracture
  1. Arthrogryposis multiplex congenita
    1. Amyoplasia
    2. Distal arthrogryposis
    3. Other
  2. Isolated
    1. Camptodactyly
    2. Thumb in palm deformity
    3. Other
4. Syndromes

Reproduced with permission from Goldfarb CA, Ezaki M, Wall LB, Lam WL, Oberg KC: The Oberg-Manske-Tonkin (OMT) classification of congenital upper extremities: Update for 2020. J Hand Surg Am 2020;45(6):542-547. © 2020 by the American Society for Surgery of the Hand.

TABLE 2 Modified Swanson/International Federation of Societies for Surgery of the Hand Classification

Type	Description
I	Failure of formation of parts (arrest of development)
II	Failure of differentiation (separation) of parts
III	Duplication
IV	Overgrowth (gigantism)
V	Undergrowth (hypoplasia)
VI	Congenital constriction band syndrome
VII	Generalized skeletal abnormalities

FIGURE 1 Photographs demonstrating early congenital amniotic rupture sequence with amputation and syndactylization of the index, middle, ring, and little fingers. A, Palmar view demonstrating interdigital sinuses. B, Dorsal view. C, AP radiograph showing tapering of the distal end of the proximal phalanx of the ring finger.

The symbrachydactyly sequence is relatively uncommon, occurring in approximately 0.6 per 10,000 live births. Boys are more frequently affected than girls (73%). Only 7% have been associated with other anomalies and 7% have an associated family history. The left upper limb is involved more often than the right upper limb (67%).¹⁴^,¹⁵

When the right side is involved, a diagnosis of Poland syndrome should be considered. Though most cases of
isolated symbrachydactyly involve the left side, 61.1% of Poland syndrome patients have symbrachydactyly on the right side. Poland syndrome involves the unilateral absence or hypoplasia of the pectoralis major muscle with associated symbrachydactyly.

FIGURE 2 Dorsal (A) and palmar (B) photographs of a terminal transverse deficiency characterized by persistent digital nubbins without bony phalangeal elements.

FIGURE 3 Radiographs demonstrating the variable morphology of unilateral symbrachydactyly. A, Five-digit-type hand with biphalangeal thumb and biphalangeal fingers (left) is smaller than the contralateral, normal hand. B, Four-digit-type hand with four biphalangeal digits and one digital nubbin. C, Three-digit-type hand includes a narrowed syndactylized web between the biphalangeal thumb and biphalangeal ring finger. D, Two-digit-type hand shows limited ossification of the distal phalanx within the nubbin index, middle, and ring fingers. E, Monodigital-type hand consists of a widely abducted thumb metacarpal. F, Carpal-type hand with five soft-tissue nubbins. G, Wrist disarticulation-type hand with a single digital nubbin.

Imaging Studies

Radiographs of the entire upper limb should be obtained usually between 1 and 2 years of age. Earlier radiographs are unlikely to change management and should be avoided. The limb will grow in proportion to the contralateral side. Radiographs of young children may underestimate the extent of bone formation, particularly in syndactylized fingers. Portions of the anomalous fingers and carpus often include unossified cartilage.

Classification

The original classification groups symbrachydactyly under three categories: I, failure of formation; II, failure of differentiation; and V, undergrowth. This has since been revised in the OMT classification to consider the condition to be a malformation in the failure of axis formation/differentiation of the entire limb and hand plate. The most useful classification is based on the number of functional digits as that may help guide treatment—adactylous, monodactylous, bidactylous versus multidigit.

TABLE 3 Classification of Common Types of Digital Absence

Type of Hand	Characteristics
Symbrachydactyly
Five digits with biphalangeal thumb	All fingers triphalangeal Incomplete simple syndactyly of the index, middle, and ring fingers
Five digits with biphalangeal thumb	Biphalangeal index, middle, and ring fingers Triphalangeal little finger Incomplete simple syndactyly of the index, middle, and ring fingers
Five digits with biphalangeal thumb	Monophalangeal index, middle, and ring fingers
Three digits with biphalangeal thumb	Nubbin index and middle fingers Monophalangeal ring finger Biphalangeal little finger
Two digits with monophalangeal thumb	Nubbin index, middle, and ring fingers Monophalangeal little finger
Monodigital with monophalangeal thumb	Nubbin index, middle, ring, and little fingers
Aphalangeal
Adactylous with five metacarpals	Five nubbins
Adactylous with two metacarpals	Thumb metacarpal Little finger metacarpal Digital nubbins
Carpal	Digital nubbins No metacarpals or phalanges Mobile carpus
Wrist disarticulation level	Digital nubbins No wrist motion No carpal, metacarpal, or phalangeal elements
Short transradial level	Extremely short forearm Digital nubbins
Reproduced from Light TR: Hand deficiencies, in Smith DG, Michael JW, Bowker JH, eds: Atlas of Amputations and Limb Deficiencies: Surgical, Prosthetic, and Rehabilitation Principles, ed 3. American Academy of Orthopaedic Surgeons, 2004, p 857.