The Congenital Hand Anomaly Team
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A pediatrician team leader
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Specialists on normal and abnormal child development
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Geneticists
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Social worker and social services personnel
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Occupational and physical therapists
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An orthotics and prosthetics group
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A congenital hand surgeon
Radial Club Hand
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At least 40% of children with radial club hand have some associated medical problem.
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Early stretching and orthotic intervention can aid in decreasing the severity of contracture and ease future surgical procedures.
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A radial gutter orthosis is recommended for daytime use.
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Centralization can be performed at 6 to 12 months.
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Thumb procedures are often performed at 2 to 5 years.
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Distraction of the forearm can be considered for some cases at 8 to 12 years.
Hypoplastic Thumb
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Thumb hypoplasia is often associated with radial hypoplasia.
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Stability of the thumb carpometacarpal (CMC) joint helps determine whether the thumb is salvageable.
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Pollicization is recommended for most thumbs with an unstable CMC joint.
The surgical treatment and rehabilitation of children with congenital hand deformities has substantially changed over the past 30 years. Advancements in free tissue transfer, bony reconstruction, and rehabilitation have allowed for the restoration of prehensile grasp and improved cosmesis in many children, but many defects still pose significant challenges for the hand surgeon and therapist. Fortunately, children have a tremendous ability to adapt, and many will thrive despite significant physical impediments. Occupational therapy, in many cases, is all that is required for affected children to perform the activities of daily living which will, in turn, provide them with independence in their daily activities. This chapter provides general guidelines for the surgeon’s and therapist’s interaction with patients and families, followed by an overview of the most common congenital abnormalities and the surgeon’s and therapist’s role in the management of these abnormalities.
Incidence and Initial Interaction with the Patient
Assembling a Team
Congenital upper extremity anomalies occur in 0.2% of live births, but only 10% of diagnosed congenital hand anomalies are serious enough to warrant surgical intervention. Children with congenital hand differences may have associated anomalies which will often take precedence over the treatment of upper limb problems. The management of the hand must often be coordinated between the evaluations of many other specialists. It is often most convenient for patients and their families if the pediatric specialists are grouped close together within a specialized clinic or within the same medical facility. For this reason, the treatment of most congenital hand anomalies should be performed by hand surgeons and therapists at pediatric surgical centers, where physicians and therapists familiar with the treatment of these children are on staff. The health-care team involved with the care of the child should include
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A pediatrician team leader
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Normal and abnormal child development specialist
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Geneticists
- 4
Social worker and social services
- 5
Occupational and physical therapists
- 6
An orthotics and prosthetics group
- 7
A congenital hand surgeon
Therapy and care of these children is a team effort, as no one health-care provider can hope to grasp the full spectrum of the patient’s problem within a single office visit. Occupational therapists, often through repeated therapy sessions, gain the best assessment of the child’s ongoing hand function, needs for improved hand function, and means of adaptation. This information is often best brought to the surgeon’s attention through team meetings or patient care conferences prior to the initiation of any surgical intervention. The goals for children with congenital hand and upper limb anomalies are to optimize the child’s ability to orient the hand in space, provide sensate skin coverage to working digits, and provide grasping power and precision pinch.
Initial Physical Examination
Evaluation of the infant or child with a congenital anomaly can be difficult, as compliance with the physical exam is often limited. We have found it much easier to provide the child with age-appropriate toys and to assess the child’s functional capabilities as he or she plays. Careful examination will also allow the care provider to observe for compensatory patterns of activity, with the affected and unaffected extremity. Laying hands on the child is necessary to demonstrate joint laxity or stiffness, joint contractures, and skin deficiencies, which determine the surgical intervention and orthotic regimen; however, this is often best reserved until late in the interview process when the child has gained some familiarity with the physician. A complete musculoskeletal examination should attempt to assess the entire affected and normal limb from thorax to fingers. The physician and therapist should focus on the following:
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Active range of motion (AROM)
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Passive range of motion (PROM)
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Manual muscle testing of upper extremity
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Observation of prehensile patterns
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Sensory testing
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Stereognosis
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Two-point discrimination in older children
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Consideration of wrinkle test or ninhydrin test for younger children where a peripheral nerve injury is suggested
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Often in cases of musculoskeletal impairment (hemiplegia, arthryrogryposis, and cerebral palsy—discussed in detail elsewhere) a functional or dynamic electomyogram may be considered to better assess muscle groups and the child’s volitional control of these muscle groups. Bilateral radiographs are obtained for almost all children to asses the affected and normal side and to evaluate the severity of disease and to rule out any anomalies on the “normal” side. MRI is usually reserved for soft tissue mass, ligamentous injuries, or examination of the presence or absence of soft tissue structures. Its use is very limited due to the necessity of sedating the child for these procedures.
Overall assessment should also include an evaluation of other common musculoskeletal abnormalities, such as hip dysplasia and scoliosis. Abnormalities in facial development, lower limb development, hair growth, tooth development, and skin pigmentation should all be noted since these may be signs of a genetic syndrome or other generalized skeletal dysplasia. Evaluation of developmental progress should also be noted to assure the surgeon and therapist that the child is keeping pace with general developmental milestones.
For straightforward problems, an initial consultation may be all that is necessary before establishing a treatment plan; more commonly, however, additional visits are required for the surgeon and therapist to fully determine the patient’s limitations and establish the need for any surgical intervention. Parents also benefit from hearing the surgical and therapy plan several times so they absorb the information and form their own questions. Each visit should include an explanation of the defect, its expected effect on development, plans for intervention, timing, and alternatives to treatment. Finally all parents wish to know if this defect can be passed to other children. Often these questions should be referred to a pediatric geneticist following a full genetic analysis.
Social Acceptance
A child with a developmental anomaly can create considerable stress for the parents and care givers. Parents can often feel guilty and confused about the exact cause of their child’s deformity; they may often fear that something they did during pregnancy caused their child’s condition. In addition, significant anxiety exists about future peer pressure and chiding that the child may experience on entering school. Often, the most important thing that parents can be told is that the child’s anomaly is not their fault. Helping parents work through their guilt allows them to begin to accept their child’s difference and to develop an optimistic outlook regarding the child’s future.
From our experience, some of the best means of helping parents and children cope with these complex issues is through the use of support groups and peer groups established independently or through specific institutions. Information about many of these groups can be obtained through the Internet. Excellent resources for parents and physicians include the following:
www.assh.org—Look under the title of “congenital hand differences.”
www.helpinghandsgroup.org—This nonprofit support group is made up of parents who have children with upper limb differences and who are concerned with the challenges facing the child and the entire family.
www.limbdifferences.org—This is an online resource for family and friends of children with limb differences. This site aims to provide practical information as well as emotional support.
www.acpoc.org—Association of Children’s Prosthetic Orthotic Clinics (ACPOC). ACPOC is an association of professionals who are involved in clinics that provide prosthetics and orthotic care for children with limb loss or orthopedic disabilities.
www.superhands.us—Superhands is a forum for learning about children who have hand or upper limb differences.
Finally the physician should be careful about how he or she describes the child’s congenital hand difference. It is best to use terms such as congenital hand difference rather than offensive terminology such as “lobster-claw hand” or “club hand.” Children with congenital hand anomalies may have an obvious and visible difference in arm and hand appearance. Children that are most socially adjusted are those that can explain why their hand is the way it is; the surgeon and therapist can help the child formulate that response.
Upper Limb Congenital Anomalies
Development
Four weeks after fertilization the upper limb bud develops on the lateral wall of the developing embryo. The limb develops from the migration of ectodermal and mesodermal tissue. The migration of these tissues is orchestrated through a specialized component of the ectoderm called the apical ectodermal ridge (AER). The AER is found in the leading edge of the limb bud and coordinates the differentiation of the underlying mesoderm ( Fig. 128-1 , online). The limb develops in a proximal-to-distal direction. Results from Summerbell and colleagues have shown that injury or removal of the AER results in a truncated limb.
The anterior–posterior axis (radioulnar relationship) of the hand is regulated by proteins produced in the posterior portion of the limb bud. The specialized tissue that produces these proteins has been named the zone of polarizing activity, or ZPA. The specific protein signals produced in this portion of the limb bud are controlled by groups of genes, which are referred to as the sonic hedgehog genes. Ventral and dorsal differentiation is thought to be under the influence of bone morphogenic proteins as well as the Wnt (wingless type) signaling pathway. Wnt protein expression has been identified in the dorsal ectoderm. Expression of the Wnt protein results in a transformation in the mesoderm, causing it to form dorsal bony structures.
Gross development is completed by the eighth week, with all limb structures being present. Thus, it is during the brief time span of the fourth to eighth week of development that the majority of congenital defects are initiated. Injuries to the AER during this period have permanent effects on all development distal to the zone of injury. Historically, congenital deformities were thought to result solely from external teratogens, such as irradiation; certain infections; excessive hormone ingestion; and medications such as thalidomide, phenytoin, and warfarin; however recent research has shown that many genetic defects are inherited or develop thorough genetic mutations or growth factor receptor abnormalities. Developmental deformities initiated after the eighth week of development are usually the result of external trauma to the limb bud from amniotic bands; uterine wall pressure; or vascular insults.
Classification
Attempts have been ongoing since the 1800s to uniformly classify all congenital upper limb anomalies. Three major classification schemes are used for developmental abnormalities: the embryologic, teratologic, and anatomic classification schemes. The embryologic scheme is the most widely accepted classification scheme and has been accepted by both hand surgery and orthotic–prosthetic groups worldwide. Within this schema each limb deformity is classified according to its most predominant anomaly ( Box 128-1 ). No classification system is perfect, and many have argued that this classification system does not categorize all defects. Ongoing genetic analysis has also shown that many defects, although appearing clinically unique, originate from common abnormalities in limb development; an example of this can be seen in cases of central polydactyly, syndactyly, and central hand deficiency, which in animal models have been shown to develop from a common insult.
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Failure of formation of parts
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Transverse
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Longitudinal
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Failure of differentiation of parts
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Soft tissue
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Skeletal
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Tumorous conditions
- a
- 3
Duplication
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Whole limb
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Humeral
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Radial
- d
Ulnar
- e
Digit
- a
- 4
Overgrowth
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Undergrowth
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Congenital constriction band syndrome
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Generalized skeletal abnormalities
A brief note should be made about the teratologic classification scheme. The teratologic scheme classifies anomalies on the severity of their phenotypic expression. This classification scheme, although not practical for classifying all congenital anomalies, is very helpful in classifying specific defects according to severity, for example, grade I (mild) to grade V (severe), and is used frequently within the upper extremity. The teratologic classification scheme is used to describe radial aplasia and thumb hypoplasia described in the following sections.
Specific Congenital Upper Limb Anomalies
Failure of Formation of Parts
Transverse Deficiencies
Transverse deficiencies describe congenital amputations at various levels of the upper limb. They are classified according to the last remaining bony segment ( Fig. 128-2 , online). These occur at a incidence of one in every 30,000 births. The most common transverse deficiency is through the proximal third of the forearm. Transverse deficiencies are most commonly unilateral and are sporadic in nature. The differential diagnosis for transverse deficiency can include amniotic band syndrome. Amniotic band syndrome may be differentiated from transverse deficiency by the presence of banding in other extremities or fingers and is not commonly a unilateral finding. Patients with true transverse deficiencies present with well-padded amputation stumps.
Surgical intervention for unilateral cases is seldom required, and most children are fitted for a prosthesis. Substantial controversy surrounds the optimal age for the initial fitting of a prosthesis. It has been our practice to fit children as early as 6 months with a passive prosthesis ( Fig. 128-3 ). This helps with balance during the child’s transition from sitting to walking as well as prosthetic acceptance. Active body-powered prostheses, including voluntary opening and closing prostheses, may be introduced between 15 months and 2 years. Myoelectric prostheses may be considered at 3 to 5 years of age and may be preferred for school use as they are visually more acceptable; however, voluntary opening devices remain the most common form of prosthesis.
Acceptance of a prosthesis varies, with rejection rates ranging from 10% to 32%. Studies from the Netherlands have found that children tend to reject a prosthesis either within 3.5 years of prosthesis initiation or after 13.5 years of prosthetic use. This later time period tends to correspond with puberty. Studies from Davids and colleagues have shown that initial prosthetic fitting prior to the age of 3 years in conjunction with occupational therapy may help in promoting long-term use of prosthetic devices. Functional grading and quality of life questionnaires, when assessed in these children, are found to be near normal regardless of whether they wear a prosthesis.
The therapist’s major role in children with transverse deficiency begins at the age of 3 or 4 years; at this age children often need help in learning to use their prosthesis with tasks such as dressing, tying shoelaces, and using buttons and zippers. Children with more proximal amputations (above the elbow) have an increased reliance on their prosthesis and are more likely to become consistent users, whereas children with distal amputations are more likely to have prosthetic devices that are custom-molded to aid in specific activities such as sports or for playing musical instruments ( Fig. 128-4 ). Most children should be seen every 6 months to evaluate how the prosthesis is fitting and for resizing. As the child grows, annual evaluation is still needed for prosthetic maintenance.
Longitudinal Intercalary Deficiencies
Phocomelia
Phocomelia is the absence of a portion of the extremity with continued distal rudimentary development of the hand. Phocomelia most commonly occurs bilaterally and was associated with perinatal ingestion of thalidomide in Europe during the 1960s, when this medication was given to pregnant women as a sedative during their first trimester. Three major types of phocomelia are classified according to their intermediate segment. In type I—the most severe—the hand is attached directly to the shoulder. In type II, the forearm and hand attach directly to the shoulder. In type III the forearm is absent and the hand attaches to the humerus ( Fig. 128-5 ).
The hand is usually underdeveloped and often lacks the development of a thumb. Strength in the hand is decreased but some degree of prehension is still possible. Surgical intervention is rarely indicated. Patients are treated with prostheses and often adapt to performing many functions with their feet. Shoes that can be easily removed should be encouraged in these children since prehensile function with their feet is often superior to that obtained with their hands. Prosthetics are reserved for children with some hand function who are capable of activating terminal devices. Such prosthetics are difficult to suspend from the patients’ hypoplastic shoulders, but are often valuable for school activities, including writing at a desk, using scissors, and holding books open.
Surgery is usually reserved for the separation of syndactylized digits. Functional shortness of the limb is the primary problem. The hand may be incapable of reaching the face for eating or may not be long enough for self-dressing and toileting. Therapists may recommend extended tools to help a child perform self-care tasks more easily. Distraction-lengthening using external distracters may aid in increasing the length of the humerus, which may aid in the fitting of some prosthetics.
Radial Deficiency
Radial deficiency can manifest as a spectrum of deformity ranging from minimal wrist impairment to wrist, thumb, and elbow impairment. The incidence of radial deficiency has been estimated to be 1 in 30,000 to 1 in 100,000 births. Unilateral and bilateral cases are felt to occur at a similar frequency; however, bilateral cases occur more frequently in males at a ratio of 3:2. Most cases of radial deficiency are associated with hypoplasia or aplasia of the thumb as well, further complicating hand function.
Associated anomalies and skeletal syndromes are extremely common with radial hypoplasia ( Box 128-2 , online) and must be excluded prior to any type of surgical intervention. Most important is to identify any associated hematologic or cardiac abnormality because these are often life-threatening. Commonly associated syndromes include the thrombocytopenia/absent radius syndrome (TAR syndrome), Holt–Oram syndrome, Fanconi’s anemia, and the VACTERL association (a mnemonic for V ertebral anomalies, A nal atresia, C ardiac anomalies, T racheo e sophageal fistula, R enal anomalies, and L imb abnormalities, which includes the finding of radial deficiency). The cardiac defects most frequently encountered in these children are atrioseptal and ventriculoseptal defects. Associated medical problems have been noted in 40% of children with unilateral involvement and in 77% of children with bilateral involvement. Fanconi’s anemia does not manifest at birth, but may be identified in infancy with genetic screening, which will allow for close hematologic monitoring during the child’s development. This condition is often fatal if not treated with a bone marrow transplant. Due to the high number of associated defects, many children with radial hypoplasia require specialized cardiac monitoring while undergoing general anesthesia and thus may require all surgical procedures be conducted in a specialized pediatric center capable of monitoring them during the perioperative and postoperative period.
VACTERL association
Thrombocytopenia/absent radius (TAR syndrome)
Fanconi’s anemia
Holt–Oram syndrome (hand and heart syndrome)
Acrofacial dysostosis (Nager’s syndrome)
Mandibular dysostosis (Treacher Collins’ syndrome)
Cornelia de Lange’s syndrome
Ventriculoradial dysplasia
Klippel–Feil syndrome
VACTERL, V ertebral anomalies, A nal atresia, C ardiac anomalies, T racheo e sophageal fistula, R enal anomalies, and L imb abnormalities.
Radial aplasia is classified into four types based on severity ( Fig. 128-6 ).
Type I: Type one deficiency typically manifests with a minimally shortened radius compared with the ulna. Elbow function is normal. Thumb hypoplasia may or may not be present. Surgical management of the wrist in these cases is rare, and surgery, if necessary, is usually directed toward improving any abnormalities in thumb function.
Type II: The radius is short and the ulna is often bowed toward the radius. The hand and wrist deviate toward the deficient radius. Radial hypoplasia usually extends into the wrist and thumb ray, evident by an absent scaphoid and underdeveloped thumb. Orthotic intervention and stretching are often recommended in these children at an early age to attempt to limit the amount of radial deviation of the wrist. Surgery in these cases consists of procedures to correct radial-ward bowing of the ulna and to stabilize the wrist on the ulna.
Type III: The radius is hypoplastic with absence of the distal and middle thirds. Often it is difficult to identify type III deformities when the child is very young as the proximal radial remnant may not have fully ossified. The wrist progressively moves into a pronated, flexed, and radially deviated posture. Thumb ray and radial carpal hypoplasia are often present. Children with this grade of deformity often have a fibrous anlage, which extends from the distal radial remnant to the carpus. This anlage must be released to allow for correction of the carpal misalignment. Children with this deformity usually undergo a centralization or radicalization procedure to stabilize the wrist on the ulna bone. If the third metacarpal is centered over the distal ulna, the procedure is called centralization ; if the index metacarpal is centered over the distal ulna, it is called radialization ( Figs. 128-7 and 128-8 ).
Figure 128-7
A, Nine-month-old child with a left-sided type IV radial hypoplasia. Severe radial deviation of the wrist is present. B, Initial treatment begins with daily stretching and orthotic positioning. C, Positioning is performed at night and during nap time. D, At 2 years of age this child underwent soft tissue distraction for 6 weeks followed by wrist centralization. Part D shows the appearance of the limb 3 years following centralization surgery. Index finger pollicization was performed 1 year after centralization procedure.
Figure 128-8
A, Posteroanterior radiographs of a child with type II radial hypoplasia. Notice the mild bowing of the ulna. B, The patient underwent a centralization procedure with corrective osteotomy of the ulna, resection of the fibrous anlage, and centralization of the carpus on the ulna. The pin in this child remained in place for 12 weeks.
Type IV: Type 4 deformities represent complete absence of the radius. Traditionally this is felt to be the most common presentation of radial deficiency, however Upton has recently stated that the type III deformity is the most common. With the type 4 deformity ulnar bowing is present, and overall ulnar growth is usually limited to no more than 60% of the contralateral side. Elbow motion is often restricted. In these children the thumb is often absent and the index and long fingers often lack full ROM and may also be hypoplastic. The one exception to this phenomenon occurs in the TAR syndrome, where the thumb is always present but has variable function. Most children with type 4 hypoplasia undergo a wrist centralization procedure. In many cases, wrist centralization is preceded by soft tissue distraction for a period of 4 to 6 weeks, which substantially facilitates the centralization procedure (see Fig. 128-7 ).
Therapy and Surgical Options for Type 2-3-4 Radial Deficiency
Stretching and orthotic intervention for radial deficiencies can start shortly after birth. The goal is to reduce the hand/carpus onto the distal ulna and prevent contracture of the wrist in radial deviation. The stretching protocol consists of progressive longitudinal distraction, ulnar deviation, and extension with stabilization of the ulnocarpal joint. The wrist is stretched as close to neutral as possible, using gentle but firm passive stretching. Directing the parents to perform the stretches with each diaper change provides an easy schedule to remember, with a forearm-hand/wrist orthosis maintained at all other times. Any improvement in ROM achieved through exercises can make future surgical correction less complex (see Fig. 128-7 ).
In addition to stretching, a radial gutter orthosis, which leaves the thumb and fingers free, is recommended during the day to maintain the correction obtained from passive manipulation. Patients with a shortened forearm and those with elbow extension limitations may require an orthosis above the elbow. Once passive motion is achieved, use of a day orthosis is discontinued and it is worn only during the night and for periods of rapid growth.
As infants, these children may have decreased weight-bearing through the involved upper extremity and therefore limited crawling abilities. Children with severe deformities often have hypoplastic or stiff index fingers as well. Prehension activities are accomplished through the use of the small finger. These children may need adaptive techniques or devices, such as a universal cuff to hold toys, to maximize function and achieve success in developmental activities. Therapeutic activities are encouraged to improve AROM of the extremity through reaching, weight-bearing, and play activities. Therapists should also monitor and engage the child in fine-motor activities as they develop.
Centralization and radialization have become accepted treatment options for children with type 2 to 4 deformities. The goal of these procedures is to provide wrist stability while increasing the functional length of forearm by placing the wrist on the distal end of the ulna. These procedures also help to improve the alignment of the flexor tendons. A temporary pin is placed across the ulnocarpal joint to stabilize the hand and wrist on the ulna (see Fig. 128-8B ). The pin remains for a variable period of time depending on surgeon preference. During these procedures the remaining radial tendons are often transferred to the ulnar aspect of the carpus in an attempt to rebalance the wrist and prevent recurrent contractures. Restoring muscle imbalance is very important for preventing recurrence of deformity. Recurrence of radial deviation of the wrist as the child grows has been associated with the amount of correction obtained at the initial surgery and the age at the time of initial surgery.
Postsurgical therapy for children undergoing radialization and centralization procedures includes full-time use of a protective orthosis for 4 weeks following cast removal. The orthosis may be removed for hygiene and three to five times a day for ROM exercises. To help maintain the correction and minimize further ulnar bowing, use of a rigid night orthosis may be indicated until skeletal maturity.
The timing for surgical intervention in children with radial deficiency is a matter of some debate, but in general wrist centralization is often performed between 6 to 12 months of age so the child will have a stable wrist for bimanual activities as well for aiding in early ambulation. Additional procedures for thumb deficiency are usually performed before the child enters preschool at 2 to 5 years. Finally, distraction-lengthening of the shortened forearm may be elected at 8 to 12 years of age.
Thumb Deficiency
Thumb deficiency is often seen as a terminal extension of radial deficiency. Thumb hypoplasia is a condition that encompasses a spectrum of clinical presentation, ranging from mild hypoplasia of the thumb to complete absence or aplasia of the thumb. The sex distribution for thumb hypoplasia appears to be equal. Bilateral involvement tends to predominate in more than 60% of patients, followed by the right thumb involvement (21–27%), and then left thumb involvement (12–15%).
Hypoplasia of the thumb has been classified by Blauth into five grades. Grade I is a normal-appearing thumb; however, it is smaller in proportion to the contralateral thumb. In grade II, there is metacarpophalangeal (MCP) joint insufficiency with joint laxity. The first metacarpal is adducted, and the MCP joint is radially deviated due to ulnar collateral ligament laxity. There is often a tight first webspace. In grade III deficiency, there is hypoplasia of the proximal portion of the first metacarpal, the degree of which can vary. Grade IV represents total aplasia of the metacarpal with underdeveloped thumb phalanges; this is also referred to as a floating thumb, or pouce flottant . Grade V manifests as total absence of the thumb ( Fig. 128-9 , online).
Manske modified the Blauth classification to describe thumbs with hypoplastic metacarpals but stabile carpometacarpal (CMC) joints as type IIIA thumbs, and those with an unstable CMC joint are classified as type IIIB ( Table 128-1 , online). This classification scheme is very practical for surgeons, since type IIIB thumbs are usually not amenable to surgical correction. These children are best treated with removal of the IIIB thumb and pollicization of the index finger, whereas type IIIA thumbs can be improved following attempts at stabilization of the CMC and MCP joints. The most common type of thumb hypoplasia (based on Manske’s classification) is type V, representing over 33% of cases; this is followed by Manske type IV (15–19%), type III (16–20%), type II (13%), and finally Manske type I (2–4%). The reported incidence of type I, and perhaps Manske type II, may be an underestimation because many of these children may not seek surgical treatment.
| Type I | Minimal shortening and narrowing |
| Type II |
|
| Type III |
|
| Type IV | Floating thumb, or pouce flottant |
| Type V | Absent thumb |
Treatment options range from observation to pollicization of the index finger, and typically are determined by the severity of the thumb hypoplasia. Type I thumbs require no treatment. For children with type II and IIIa hypoplasia, video-taped play sessions allow the surgeon and therapist to evaluate thumb function and the incorporation of the thumb into the activities of daily living. Spontaneous use of the hand in a semistructured play session may uncover areas of weakness and compensations, such as difficulties with large grasp when picking up a can. Areas of concern are identified, and the therapist can provide the surgeon with treatment suggestions to maximize functional use. Type II thumbs usually benefit from stabilization of the MCP joint, centralization of the flexor and extensor mechanism. Hypoplasia of the thenar muscles may limit thumb opposition. Preoperative hand therapy in these children should include strengthening available muscles for grasp, release, and pinch. The hypoplastic thumb may be thinner and shorter than the contralateral side; in such cases a custom thumb abduction orthosis can provide improved function and stability. A rigid thumb abduction orthosis may be indicated if the CMC joint is unstable as well. If pinch and grasp function is still limited following therapy, tendon transfers (opponensplasty) may be performed to improve oppositional strength.
Type IIIa thumbs benefit from MCP joint stabilization, tendon centralization, first webspace deepening, and opponensplasty (see Table 128-1 ). Opponensplasty in these children usually involves the transfer of the superficialis flexor to the ring finger or the transfer of the abductor digiti minimi (Huber’s transfer). The transferred tendons are attached to the MCP joint to provide additional pinch and grip strength. The superficialis transfer has been found to be more powerful than the abductor digit minimi transfer. In addition the tendon end of the superficialis, when passed over or through the MCP joint, can serve to reconstruct the deficient MCP joint ulnar collateral ligaments ( Fig. 128-10 ). If the abductor digiti minimi muscle transfer is chosen for oppositional transfer, a tendon graft (palmaris longus) can be used to reconstruct the ulnar collateral ligament. When multiaxial instability of the thumb MCP joint is present, joint fusion or chondrodesis can be used for joint stabilization.
