Hand - Limbs - Congenital Flashcards
A 6 year old boy is brought to the office because of enlargement of the index and long fingers that has been progressing since infancy. A photograph of the fingers is shown. He has not had pain. Two point discrimination is 6 to 8 mm in the affected digits. Which of the following is the most appropriate treatment?
A) Administration of thyroid supplements
B) Radiation therapy to the fingers
C) Ray amputation of the index finger
D) Surgical debulking and epiphysiodesis
E) Systemic administration of oral corticosteroids
The correct answer is option D.
The photograph shows a case of macrodactyly of both the index and long fingers. This deformity is caused by the development of a lipomatous hamartoma usually within the digital nerves with resulting overgrowth of the hand and fingers within the distribution of the tumor. If the affected fingers are sensate, then debulking procedures, in addition to epiphysiodesis (premature closure of the growth plates), at the distal interphalangeal, proximal interphalangeal, and metacarpophalangeal joints may slow progression of the disease process. Epiphysiodesis should be performed when the fingers are at the adult length.
Radiation and thyroid supplementation are not known to affect the growth of such tumors and carry significant side effects. The affected digits are often insensate and stiff with cold intolerance. When indicated by painful, functionally massive overgrowth, amputation is an option, although generally not initially. Systemic administration of corticosteroids is the treatment for some forms of congenital hemangiomas.
A newborn child is brought to the office because of the hand deformity shown in the photograph and the radiograph. Which of the following is the most appropriate classification for this deformity?
A ) Duplication
B ) Failure of differentiation
C ) Failure of formation: longitudinal
D ) Failure of formation: transverse
E ) Overgrowth
The correct response is Option B.
Approximately one in 600 infants is born with a congenital difference of the upper limb. The American Society of Surgery of the Hand and International Federation of Societies for Surgery of the Hand developed a unified classification system to help reduce the confusion from the previous system of Greek and Latin prefixes.
Classification of Congenital Hand Differences Type/Description
I Failure of formation of parts IA Transverse (eg, amelia, more distal amputations) IB Longitudinal (eg, phocomelia, radial dysplasia) II Failure of differentiation (separation) of parts (eg, synostosis, syndactyly, contracture,
camptodactyly, trigger digits, clinodactyly) III Duplication (eg, polydactyly, triphalangeal thumb) IV Overgrowth (eg, macrodactyly) V Undergrowth (eg, hypoplastic thumb) VI Constriction band syndrome VII Generalized skeletal deformities (eg, dystrophic dwarfism)
The photograph shows the hand of a newborn child with a simple syndactyly, which is a conjoining of the adjacent fingers. This syndactyly would be classified as a failure of differentiation. Surgical treatment would be performed in a staged procedure, avoiding separating adjacent web spaces for fear of devascularizing a finger. Separation is usually delayed until the child is one year old; however, earlier separation may be needed to separate the small and ring finger syndactyly, if there is a significant difference in the digital length. Surgical repair of the deformity involves multiple skin flaps from the adjacent fingers, along with full-thickness skin grafting. Releases should be performed before the child is of school age.
A 7-month-old male infant with complete syndactyly is evaluated for surgical release. Which of the following is the most appropriate technique for reconstruction of the web space?
A) Coverage with a distally based zigzag flap
B) Coverage with a dorsal rectangular flap
C) Coverage with a volar triangular flap
D) Full-thickness skin grafting
E) Split-thickness skin grafting
The correct response is Option B.
The most appropriate technique for reconstruction of the web space in patients with complete syndactyly is coverage with a dorsal rectangular flap.
In patients with compete syndactyly, separation does not typically result in sufficient skin to resurface both digits entirely. Reconstruction of the web space is a priority and is typically achieved with a proximally-based dorsal rectangular flap. Interdigitating skin flaps are designed, and skin grafts are placed to replace skin deficiency. Full-thickness skin grafts are preferred to split-thickness skin grafts because of the decreased likelihood of contracture; however, these grafts are not typically placed in the web space.
A newborn male is brought to the tertiary multidisciplinary referral center for evaluation of anorectal malformation, tracheoesophageal fistula and absent right thumb. Which of the following associated VACTERL diagnoses is the best predictor of inpatient mortality?
A) Aniridia with brain stem hypoplasia
B) Anomalies of spine or vertebrae
C) Cardiac disease
D) Renal or urinary anomaly
E) Tracheal stenosis with stridor
The correct response is Option C.
Anomalies of the spine or vertebrae (V), anorectal malformations (A), congenital cardiac anomalies (C), esophageal atresia/tracheoesophageal fistula (TE), renal and urinary abnormalities (R), and limb lesions (L) frequently co-occur and are recognized as VACTERL anomalies. VACTERL association is typically diagnosed in the presence of at least three characteristic features in the absence of evidence for an overlapping condition, and is estimated to occur in approximately 1 in every 10,000 to 40,000 live births. The presence of either anorectal malformation or esophageal atresia alone generally triggers a workup for associated VACTERL diagnoses because of their significant impact on morbidity and mortality. For example, in a large cohort of children undergoing surgical repair of anorectal malformations, Lautz et al. found associated VACTERL diagnoses including congenital heart disease in 40.4%, renal or internal urinary disease in 34.7%, spinal or vertebral anomalies in 31.4%, esophageal atresia/tracheoesophageal fistula in 7%, and limb defects in 5.6%. The most common limb defects in VACTERL association include poorly developed or missing thumbs, or underdeveloped forearms and hands, polydactyly, syndactyly, and reduction deformities of the lower limb.
Independent predictors of mortality in any patient with VACTERL association include congenital heart disease (greatest for those who require cardiac surgery than those with a diagnosis but no operation), birthweight < 2 kg, and black race. Of note, the association between cardiac disease and higher mortality has been reproduced in several studies.
Aniridia, brain stem hypoplasia, and tracheal stenosis with stridor are not primary characteristics of VACTERL association.
A 3-month-old male infant is brought to the clinic by his parents for evaluation of craniofacial and hand anomalies. Genetic testing confirms an FGFR2 abnormality consistent with Apert syndrome. Which of the following hand anomalies is most likely in this infant?
A) Camptodactyly
B) Clinodactyly
C) Ectrodactyly
D) Macrodactyly
E) Syndactyly
The correct response is Option E.
The hand anomaly most associated with Apert syndrome is syndactyly.
Apert syndrome, or acrocephalosyndactyly, is a syndrome resulting from a defect in chromosome 10q, the site of the fibroblast growth factor-2 receptor. This syndrome consists of coronal craniosynostosis, mid face hypoplasia with retrusion, and syndactylies of the hands and feet. These may be type I (syndactyly of digits 2–4 with a free thumb; “spade hand”), type II (syndactyly of digits 2–4 with a simple syndactyly of the thumb; “mitten hand”), or type III (complex syndactyly of all digits with complex thumb syndactyly; “rosebud hand”).
The other choices are not typically associated with Apert syndrome. Camptodactyly is a fixed-flexion deformity of the proximal interphalangeal (PIP) joint(s), most commonly the little finger. Macrodactyly involves the localized overgrowth of bone and soft tissue. Clinodactyly is congenital deviation of a digit in the radioulnar plane. Ectrodactyly refers to a split-hand/split-foot malformation.
Hematologic evaluation is indicated before surgical intervention for which of the following conditions?
A) Atypical cleft hand
B) Constriction band syndrome
C) Radial hypoplasia
D) Small finger polydactyly
E) Thumb duplication
Correct answer is option C.
Radial aplasia and hypoplasia are associated with several syndromes including VACTERL (vertebral, anal, cardiac, tracheoesophageal, renal/radial, limb), Holt Oram, TAR (thrombocytopenia absent radius), and Fanconi anemia. Both TAR syndrome and Fanconi anemia are contraindications for early surgical intervention until the underlying hematologic abnormalities have stabilized or been corrected.
The other congenital disorders listed tend to occur sporadically or familially and are not associated with specific hematologic abnormalities.
A 5-year-old boy presents with Blauth/Manske Grade IIIa hypoplasia of the thumb, with narrowing of the first web space, hypoplastic thenar muscles, an unstable metacarpophalangeal joint, and a stable carpometacarpal (CMC) joint. Examination shows weakness of grasp of his toys and utensils, and he has failed a 6-month course of therapy. Which of the following is the most appropriate surgical approach to improving the patient’s grasp?
A) Abductor digiti minimi transfer
B) Free great toe transfer
C) Fusion of the thumb interphalangeal joint
D) Pollicization of the index finger
E) Thumb CMC ligament reconstruction with tendon interposition arthroplasty
The correct response is Option A.
Blauth developed the classification for thumb hypoplasia, which consists of five grades. Manske expanded the classification system by expanding the definition of grade III into grade IIIa, which has a carpometacarpal (CMC) joint, and grade IIIb, which does not:
Blauth I thumbs have minimal shortening and narrowing, and they do not require surgical treatment.
Blauth II thumbs have narrowing of the first web space, hypoplastic thenar muscles, and an unstable metacarpophalangeal (MCP) joint. They are best treated with reconstruction.
Blauth/Manske IIIa thumbs have type II features, extrinsic tendon abnormalities, and metacarpal hypoplasia with a stable CMC joint. They do well with reconstruction.
Blauth/Manske IIIb thumbs have type IIIa features plus partial metacarpal aplasia and CMC joint instability. Because of the additional complexity of CMC joint reconstruction, thumb ablation and pollicization is generally recommended.
Blauth IV thumbs are often referred to as pouce flottant, or floating thumb. There is a neurovascular bundle coursing through the stalk of skin connecting the thumb to the hand, and these thumbs have few rudimentary bony or soft-tissue structures. These thumbs are best treated with ablation and pollicization.
Blauth V dysplasia demonstrates absence of the thumb and require pollicization.
Blauth II and Blauth/Manske IIIa reconstructive options include the abductor digiti minimi (ADM or Huber) transfer and the flexor digitorum superficialis (FDS) transfer. There is no clear indication of the superiority of one over the other. The use of the ADM diminishes the power of abduction of the small finger but provides some thenar bulk. It is a better pronator of the thumb. The FDS transfer removes a flexor from the ring finger, perhaps decreasing grip strength, and fails to provide any bulk to the thenar eminence. The FDS is superior in providing palmar abduction but pronates less effectively. When additional tissue is needed to stabilize the MCP joint, the FDS can also be used to reconstruct the MCP joint as part of the transfer.
Aside from pollicization, additional reconstructive options for Blauth IIIb-V dysplasia include second toe-to-hand transfer with metatarsalphalangeal (MTP) joint arthrodesis if parents and patients decide to keep a five-digit hand. Due to the level of aplasia, harvest of the MTP joint is necessary for anatomic reconstruction. The second and third toes are best used for this level of reconstruction due to the ability to harvest the MTP joint. The great toe cannot be used, as harvest of the MTP joint of the great toe will lead to gait and balance issues. Fusion of the thumb interphalangeal joint and thumb CMC ligament reconstruction and tendon interposition arthroplasty do not address any or all of the issues with the thumb dysfunction.
A 2-year-old girl with VATER syndrome (involving vertebral, anal, tracheoesophageal, radial, and renal defects) has total absence of the left radius (type IV radial club hand). Which of the following is the most appropriate management for stabilization of the wrist?
(A) Ablation of the ulna
(B) Centralization of the ulna
(C) Lengthening of the ulna
(D) Shortening of the ulna
(E) Straightening of the ulna
The correct response is Option B.
This 2-year-old girl has complete absence of the left radius (type IV radial club hand) involving an absence of the thumb associated with type IV radial dysplasia. The most appropriate management is centralization of the ulna into the carpus followed by pollicization of the index finger. Total absence is the most common radial deficiency. Radial dysplasia is seen in as many as one in 55,000 births; boys and girls are affected equally. This deformity is frequently bilateral; preaxial hypoplasia or aplasia is common, and the radial artery is usually absent. The thumb may be hypoplastic and is in fact absent in nearly half of all affected persons. A common radial muscle mass is noted. The wrist is angulated radially from 30 degrees to 90 degrees, the carpus articulates with the radial border of the distal ulna, and the scaphoid and trapezium are usually absent. In addition to VATER syndrome, conditions associated with radial dysplasia include Holt-Oram syndrome and TAR (thrombocytopenia-absent radius) syndrome.
Although centralization of the carpus is a technically difficult procedure, it has been shown to be successful in many patients with radial dysplasia. This technique aligns the hand over the distal ulna, resulting in improved hand function. Following centralization, pollicization of the index finger will help with grasping of large objects.
Corrective closing wedge ulnar osteotomy is often necessary for patients who have ulnar bowing of greater than 35 degrees. Other techniques such as ulnar lengthening, shortening, or ablation will not correct the alignment of the hand and wrist in relation to the forearm.
A neonate is born with unilateral edema of the arm. During the ensuing day, there is worsening edema and bullae formation. Which of the following is the most appropriate next step in management of this patient?
A) Administration of intravenous antibiotics and elevation of the arm
B) Compartment release
C) Continued observation and dressing change
D) Debridement and skin grafting
E) Treatment in a hyperbaric chamber
The correct response is Option B.
Compartment release should be performed early and urgently. The other treatments above may play a role in secondary treatment. Volkmann’s ischemia is not rare and awareness of the diagnosis is important. The sentinel lesion of neonatal compartment syndrome is bullous formation on the dorsum of the hand or arm. Etiology is often in utero and can be amniotic bands, umbilical cord loops, forceps extraction, oligohydramnios, preeclampsia, and excessive maternal weight. Diastolic pressures in neonates are usually 40 mmHg or less. Small increases in compartment pressure are therefore not tolerated well. The six P’s of compartment syndrome, which include pain, paresthesias, pulselessness, pallor, paralysis, and pressure, will not be seen in the neonate. The three A’s, which precede the six P’s in children, are agitation, anxiety, and increasing analgesic requirements; and will not be seen in the neonate.
A male newborn has the isolated congenital deformities of the left hand shown in the photographs. Which of these surgical options may improve the function of the hand?
A) Amputation of the long, ring, and small fingers
B) Full-thickness matrix grafting
C) Phalangeal lengthening of the small and ring fingers
D) Radial metacarpal lengthening of the index and long fingers
E) Toe-to-hand transplantation
The correct answer is option C.
The patient described has an isolated congenital anomaly of the left hand known as shortened fingers or brachydactyly. The most functional improvement is to lengthen the small and ring fingers to facilitate power grip and opposition. One method is nonvascularized toe phalanx grafting; another is distraction lengthening. This procedure should be performed when the patient is between 8 and 12 months of age.
Amputation would not add to the patient’s function. Full-thickness matrix grafting is for reconstruction of the nail matrix complex. Lengthening the second and third metacarpals would not address the functional deficit. The patient’s thumb appears to be quite functional, so toe-to-hand transplantation is not appropriate.
A 2-year-old boy with VATER syndrome is brought to the office for evaluation because his parents are concerned that the thumb of the right hand appears small and weak. Physical examination shows weakness of intrinsic function of the right thumb. The flexor pollicis longus flexion crease is absent and the thenar eminence is flat. The left hand, including the thumb, appears normal. The patient uses a pincer-type motion between the right index and long fingers to pick up small objects. The ulnar collateral ligament at the metacarpophalangeal joint of the right thumb is lax. There is no gross dislocation at the carpometacarpal joint of the right thumb, but 6 mm of passive dorsoradial mobility is noted. An x-ray study and photograph are shown. Which of the following is the most appropriate management?
A) Amputation of the thumb and pollicization of the index finger
B) Flexor digitorum sublimis opponensplasty and ulnar collateral ligament stabilization
C) Huber transfer and ulnar collateral ligament stabilization
D) Tendon graft reconstruction of the flexor pollicis longus and ligament stabilization
E) Observation and occupational therapy until the child is age 4 to 5 years, followed by reassessment of function
The correct response is Option A.
The child described has a classic Blauth Type IIIB hypoplastic thumb. Although the carpometacarpal (CMC) joint does not dislocate, the subluxation described is consistent with the instability noted in Blauth Type IIIB thumbs. The photograph shows a thumb with a broad base, which is distracting to the examinee who is not familiar with this disorder. However, the thumb described has significant hypoplasia and pollex abductus. The x-ray study shows the classic finding of a narrowed and underdeveloped metacarpal base, the hallmark of CMC instability.
X-ray study is essentially diagnostic of the Blauth Type IIIB thumb. The most accepted treatment for this type of thumb is ablation/amputation of the existing thumb and replacement with the index finger in the thumb position (pollicization).
In the scenario described, the patient has no significant cortical representation or intentional control of the right thumb. The child picks up objects between the index and long finger, ignoring the thumb. No matter what maneuvers are undertaken to power and stabilize the existing thumb with tendon transfers, the child will still have little to no natural predilection to actually use the thumb. Although opponensplasty and ulnar collateral ligament stabilization are common solutions for Types II and IIIA thumbs, they would not be appropriate. These treatments are often combined with first web space deepening.
Treatment is recommended earlier than age 4 or 5 years to avoid resistance to the thumb ablation and pollicization, which can occur with time on the part of the parents and the child. The younger child will accommodate the pollicized digit better. Treatment of the hypoplastic thumb should be decisive and performed at the appropriate age, if possible.
Flexor pollicis longus reconstruction with a tendon graft will not improve thumb function in the scenario described. This type of surgery is not a standard therapy for hypoplastic thumbs in general. Ulnar collateral ligament stabilization is not recommended because the thumb requires pollicization.
A 2-year-old girl has an unstable carpometacarpal (CMC) joint at the base of the thumb of the left hand. A photograph and x-ray study of the hand are shown. According to Blauth and Manske, which of the following is the most appropriate classification of this hypoplastic thumb?
A ) II
B ) IIIA
C ) IIIB
D ) IV
E ) V
The correct response is Option C.
The Blauth classification of the hypoplastic thumb, as modified by Manske, is a true working classification that can be used for planning treatment (see table). Type IIIB has an unstable CMC joint and is the €œcutoff point € for performing index finger pollicization and ablation of the hypoplastic thumb, versus attempting reconstruction of the original thumb.
A 22-year-old man has had a progressively worsening fixed flexion contracture of the proximal interphalangeal (PIP) joint of the left little finger since birth. There is no history of trauma or illness. The patient has stiffness of the PIP joint but no pain in the finger.
These findings are most consistent with
(A) camptodactyly
(B) clinodactyly
(C) scleroderma
(D) symbrachydactyly
(E) systemic lupus erythematosus
The correct response is Option A.
This 22-year-old man has findings consistent with camptodactyly (“bent finger”), a nontraumatic flexion deformity of the proximal interphalangeal (PIP) joint. This condition can be either sporadic or autosomal dominant and occurs in less than 1% of the population. The little finger is most frequently affected, and nearly two thirds of patients with camptodactyly have bilateral findings. The underlying etiology of this deformity involves volar PIP joint structures and is thought to result from abnormal insertion of either the lumbrical or superficialis tendons. Static or dynamic splinting has been shown to be beneficial in some patients. Surgical repair often yields only partial correction.
Clinodactyly involves either a radial or ulnar curvature of the fingers. This condition is believed to be autosomal dominant, is often bilateral, and is typically associated with some forms of mental retardation, including Down syndrome. Severe clinodactyly is often seen in association with a delta phalanx. Excision and wedge osteotomy are recommended for correction.
Symbrachydactyly is a sporadic, inherited central hand defect characterized by shortened, syndactylous digits. This condition is unilateral. The index, middle, and ring fingers are typically affected.
Systemic conditions such as scleroderma (primary systemic sclerosis) and systemic lupus erythematosus can involve the interphalangeal joints; however, dorsal wounds and flexion contractures are typically associated.
An 18-month-old male infant with an isolated Blauth Type IV thumb (floating) is scheduled to undergo pollicization of the index finger. A photograph is shown. The index finger metacarpal head becomes which of the following structures in the pollicized thumb?
A) Articular surface of the carpometacarpal (CMC) joint
B) Distal articular surface of the proximal interphalangeal (PIP) joint
C) Proximal articular surface of the PIP joint
D) Scaphoid
E) Trapezoid
The correct response is Option A.
Thumb pollicization is a challenging yet functionally rewarding procedure. It is indicated for Blauth Type IIIB or higher thumbs. If done correctly, this technique can greatly enhance the function of the hand and provide a strong, stable thumb analog for grip and pinch. The procedure involves many stages and is technically demanding. Although beyond the scope of this description, the procedure requires shortening of the index finger metacarpal and repositioning of the metacarpal head in hyperextension against the preserved metacarpal base. Thus, the index metacarpal phalangeal joint becomes the new thumb’s carpometacarpal joint, the index proximal interphalangeal joint becomes the new thumb’s metacarpophalangeal joint, and the index distal interphalangeal joint becomes the new thumb’s interphalangeal joint.
A 3-month-old female infant diagnosed with Apert syndrome is referred to the office for evaluation of both hands. Which of the following clinical findings is most likely to be present?
A) Camptodactyly
B) Complex syndactyly
C) Floating thumb
D) Macrodactyly
E) Ulnar clinodactyly of the thumb
The correct response is Option B.
Apert syndrome (acrocephalosyndactyly) is a syndrome associated with an FGFR2 gene mutation and characterized by craniosynostosis, mid-face hypoplasia, and complex syndactyly of the hands and feet. Characteristics of the Apert hand deformity include complex syndactyly of the index, middle, and ring fingers; simple syndactyly of the ring and small fingers; and a varying degree of first web space syndactyly. The Apert hand deformity has been classified into three subtypes on the basis of the increasing degree of thumb involvement and the appearance of the central digital mass. In the Apert hand deformity, the thumb may be short and radially deviated (radial clinodactyly).
The other responses are not associated with Apert syndrome. Floating thumb (“pouce flottant”) is a form of thumb hypoplasia (Blauth Type IV) in which there is a rudimentary digit attached to the hand only by skin and neurovascular bundle.
Camptodactyly is a painless flexion contracture of the proximal interphalangeal joint most commonly involving the small finger.
Macrodactyly is a rare congenital condition in which there is overgrowth of the underlying bone and soft tissue of the finger.
A 1-year-old child is evaluated because of a radial polydactyly deformity with a duplicated distal phalanx of the thumb (Wassel Type II). Excision of the radial-sided thumb and reconstruction of the ulnar-sided thumb are planned. Which of the following is most likely to reestablish stability of the thumb?
A ) Early mobilization of the thumb 3 days after surgery
B ) Excision of the central bone and soft tissue (Bilhaut-Cloquet procedure)
C ) Pollicization of the index finger
D ) Reinsertion of the flexor pollicis brevis and abductor pollicis brevis muscles
E ) Use of a ligamentous and periosteal flap for radial collateral ligament reconstruction
The correct response is Option E.
Careful collateral ligament reconstruction in thumb duplication Types II and IV is critical in achieving stability during reconstruction. This is best done through the technique described by Manske, using a ligamentous and periosteal flap for reconstruction of the radial collateral ligament. In this technique, the radial thumb is excised, with care given to detaching the radial collateral ligament with a periosteal sleeve of tissue. The periosteal sleeve provides additional length to achieve a good repair of the radial collateral ligament.
Early mobilization of the thumb 3 days after surgery would likely be premature and may lead to destabilization of the reconstruction, rather than assisting with final stability. A thumb spica splint is typically used to immobilize such reconstructions for 4 to 6 weeks to aid healing.
Excision of central bone and soft tissue, commonly known as the Bilhaut-Cloquet procedure, can be used in Type II or Type IV duplications but would not be appropriate in the scenario described, in which the surgeon chooses to remove the radial-sided thumb and reconstruct the ulnar-sided thumb.
Pollicization of the index finger would not be appropriate at this level of duplication (Wassel Type II) because a very effective thumb can be made without resorting to the sacrifice of the index finger.
Reinsertion of the flexor pollicis brevis and abductor pollicis brevis muscles is not necessary in a Type II duplication, as the duplication is too distal (distal phalanx) to require any disinsertion or reinsert
A 5-month-old infant presents with nail-patella syndrome. Which of the following is the most likely associated genetic anomaly in this patient?
A) Bone morphogenetic protein (BMP)
B) Engrailed-1 (EN1)
C) Fibroblast growth factor receptor-2 (FGFR2)
D) LIM homeobox transcription factor 1 beta (LMX1B)
E) Sonic hedgehog (SHH)
The correct response is Option D.
The most likely anomaly is in LIM Homeobox transcription factor 1 beta (LMX1B).
This patient presents with nail-patella syndrome, which results in poorly developed nails and kneecaps. Nail-patella syndrome is an autosomal dominant condition associated with mutations in the LMX1B gene. This gene is involved in dorsal and ventral limb patterning during embryology.
Limb development is controlled by signaling pathways that are located within three different signaling centers. These govern the proximal-distal, anterior-posterior, and dorsal-ventral axes of limb development.
Wnt7a from the dorsal ectoderm induces the transcription factor Lmx-1b, which induces the development of dorsal structures. This transcription factor acts within the Wnt signaling pathway, which is responsible for dorsal-ventral limb development. In the ventral portion of the limb, the Engrailed-1 gene product blocks the Wnt pathway, determining the dorsal-ventral boundary.
Mutation in the FGFR2 gene can result in Apert syndrome, which is an autosomal dominant condition that presents with complex syndactyly of hands and feet.
Sonic hedgehog acts within the zone of polarizing activity, which is located in the posterior margin of the limb bud and governs growth in the anterior-posterior axis. The sonic hedgehog protein signals development of the limb into radial and ulnar aspects. This is mediated by the Gli family of transcription factors, most importantly Gli3. Alterations in this pathway can result in mirror duplication.
Bone morphogenetic protein (BMP) is actively involved in multiple areas of upper extremity development, but is not the key anomaly involved in this syndrome. Suppression of BMP is associated with syndactyly.
Which of the following is NOT a cause of the thumb-in-palm deformity in patients with cerebral palsy?
(A) Flaccidity of the extensor and abductor tendons of the thumb
(B) Hypomobility of the metacarpophalangeal joint of the thumb
(C) Skin contracture of the first web space
(D) Spasticity of an adductor tendon of the thumb
(E) Spasticity of a flexor tendon of the thumb
The correct response is Option A.
In patients with cerebral palsy, the thumb-in-palm deformity significantly limits function of the hand. The House classification is used to stratify the thumb-in-palm deformity according to four types. Type I is a simple adduction contracture of the metacarpal that results from spasticity of the adductor and first dorsal interosseous tendons. The type II deformity is similar to type I but also includes a flexion deformity of the metacarpophalangeal (MP) joint that is caused by spasticity of the flexor pollicis longus tendon. Patients with type III deformity have a simple adduction contracture of the metacarpal in conjunction with a hyperextension deformity and/or instability of the MP joint; this deformity results from spasticity of the adductor, first dorsal interosseous, and extensor pollicis brevis tendons and hyperextensibility of the MP joint. A type IV deformity is similar to type I deformity but also includes spasticity of the flexor pollicis longus tendon.
Treatment of the thumb-in-palm deformity involves release of the spastic muscles and stabilization of the joint.
Contracture of the first web space is also likely to exacerbate a thumb-in-palm deformity. Flaccidity of the extensor and abductor tendons of the thumb does not produce this deformity.
A 6 year old boy is brought to the office because of enlargement of the index and long fingers that has been progressing since infancy. A photograph of the fingers is shown. He has not had pain. Two €‘point discrimination is 6 to 8 mm in the affected digits. Which of the following is the most appropriate treatment?
(A) Administration of thyroid supplements
(B) Radiation therapy to the fingers
(C) Ray amputation of the index finger
(D) Surgical debulking and epiphysiodesis
(E) Systemic administration of oral corticosteroids
The correct response is Option D.
The photograph shows a case of macrodactyly of both the index and long fingers. This deformity is caused by the development of a lipomatous hamartoma usually within the digital nerves with resulting overgrowth of the hand and fingers within the distribution of the tumor. If the affected fingers are sensate, then debulking procedures, in addition to epiphysiodesis (premature closure of the growth plates), at the distal interphalangeal, proximal interphalangeal, and metacarpophalangeal joints may slow progression of the disease process. Epiphysiodesis should be performed when the fingers are at the adult length.
Radiation and thyroid supplementation are not known to affect the growth of such tumors and carry significant side effects. The affected digits are often insensate and stiff with cold intolerance. When indicated by painful, functionally massive overgrowth, amputation is an option, although generally not initially. Systemic administration of corticosteroids is the treatment for some forms of congenital hemangiomas.
The lower extremity difference known as mirror foot is most likely linked to which of the following derangements in embryologic development?
A) Duplication of the apical ectodermal ridge
B) Duplication of the zone of polarizing activity
C) Loss of the apical ectodermal ridge
D) Loss of the signal from ventral ectoderm
E) Loss of the zone of polarizing activity
The correct response is Option B.
The zone of polarizing activity (ZPA) is responsible for differentiation in the anteroposterior axis. Regulation of this entity involves the sonic hedgehog and Hox b-8 proteins. Loss of the ZPA results in absence of posterior elements in the developing limb. Duplication of the ZPA leads to mirror hand and mirror foot type anomalies.
The apical ectodermal ridge (AER) is the primary driver for proximal-distal limb growth. The AER is highly regulated by fibroblast growth factor, and loss of AER function leads to arrested limb development.
Ventral (bone morphogenetic proteins and Engrailed-1) and dorsal (Wnt7) signaling factors are antagonistic; disruption of these signals will affect dorsal-volar patterning but also proximal-distal growth of the limb.
A 2-year-old boy is treated for congenital constriction band of the left upper extremity with distal edema. The child undergoes excision of 50% of the circumferential constriction band with direct closure. This intervention is most likely to have which of the following effects on the edema of the distal limb?
A) Gradual improvement during childhood development
B) Gradual worsening during childhood development
C) Significant improvement within a few weeks of surgery
D) Significant worsening during childhood development
E) No effect
The correct response is Option C.
Congenital constriction band syndrome is a sporadic condition with an incidence varying from 1:1200 to 1:15,000 live births. There is a significant predilection for the upper extremities and distal limbs. The two main objectives for the treatment of congenital constriction band syndrome are improvement of function and improvement of cosmetic appearance. Different surgical techniques, such as Z-plasty, have been described and used for decades; however, direct closure after the excision of the constricting band is a simple yet effective treatment.
With complete circumferential constriction bands, it is recommended that a two-stage correction approach be used. At the first operation, one-half of the circumference is excised; the other half can be excised after 3 to 6 months. This will avoid any problems to the distal circulation in the limb, which may already be compromised. Edema, when present, will significantly improve within a few weeks of the first surgery.
A 2-month-old infant is brought to the office for evaluation of bilateral complex syndactyly of the hands and feet. Which of the following is the most likely gene involved?
a. Engrailed-1 (EN1)
b. Fibroblast growth factor receptor-2 (FGFR2)
c. LIM Homeobox transcription factor-1 beta (LMX1B)
d. Sonic hedgehog (SHH)
e. Wingless type (Wnt)
The correct response is Option B.
This patient presents with complex syndactyly of hands and feet consistent with Apert syndrome. This is an autosomal dominant condition that can be caused by mutation in the fibroblast growth factor receptor-2 gene.
Limb development is controlled by signaling pathways that are located within three different signaling centers. These govern the proximal-distal, anterior-posterior, and dorsal-ventral axes of limb development.
The limb develops in a proximal-distal direction, from shoulder to wrist, which is controlled by the apical ectodermal ridge (AER), a thickened layer of ectoderm over the limb bud. Fibroblast growth factors secreted within the AER signal the underlying mesoderm to differentiate. Disruption of the AER results in truncation of the limb.
Growth in the anterior-posterior (radioulnar) axis is determined by the zone of polarizing activity (ZPA). This is located in the posterior margin of the limb bud. The sonic hedgehog protein (SHH) acts to signal development of the limb into radial and ulnar aspects. Alterations in this pathway can result in mirror duplication.
Dorsal-ventral limb development is signaled by the Wnt signaling pathway, which produces a transcription factor, LMX1B, that induces the development of dorsal structures. Deficiency in LMX1B has been associated with nail-patella syndrome. In the ventral portion of the limb, the Engrailed-1 gene product blocks the Wnt pathway, leading to ventralization.
A variety of other transcription factors encoded by Hox and T-Box genes also govern limb and organ development, and alterations in these can give rise to various developmental differences.
Reference(s)
- Kay SP, McCombe DB, Kozin S. Deformities of the Hand and Fingers. In: Wolfe SW, Hotchkiss RN, Pedersen WC, et al. Green’s Operative Hand Surgery, 7th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2016;36:1217-1288.
- Kozin S. Embryology of the Upper Extremity. In: Wolfe SW, Hotchkiss RN, Pedersen WC, et al. Green’s Operative Hand Surgery, 7th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2016;35:1208-1216.
- Oberg KC, Feenstra JM, Manske P, et al. Developmental Biology and Classification of Congenital Anomalies of the Hand and Upper Extremity. J Hand Surg. 2010;35A:2066-2076.
- Oberg KC, Tonkin MA. Embryology and Classification. In: Weiss APC, Goldfarb CA, Hentz VR, et al. Textbook of Hand and Upper Extremity Surgery. Chicago, IL: American Society for Surgery of the Hand; 2013;53.
- Oda T, Pushman, AG, Chung KC. Treatment of Common Congenital Hand Conditions. Plast Reconstr Surg. 2010;126:121e-133e.
A 7-year-old boy is brought to the emergency department one hour after sustaining a fracture of the small finger of the nondominant left hand when he fell down a flight of stairs. A radiograph of the left hand is shown. Which of the following is the most likely diagnosis?
(A) Extra €‘octave fracture
(B) Fracture-dislocation
(C) Salter €‘Harris type I fracture
(D) Salter €‘Harris type II fracture
(E) Salter €‘Harris type III fracture
The correct response is Option A.
This is an extra €‘octave fracture that does not involve the physis. The fracture line is very close to the physis but is above it. Forty-one percent of pediatric hand fractures involve the physis. Most involve the phalanges, particularly the proximal phalanx. The reason for this high rate is that the collateral ligaments insert into the epiphysis.
All Salter-Harris-type fractures involve the physis. Traditionally, pediatric physeal fractures are described using the Salter-Harris classification system. There are five types of Salter-Harris fractures (see below). Type I fractures are transphyseal. Type II are transphyseal but exit through the metaphysis. Type III are transphyseal fractures that exit the epiphysis and the joint. Type IV fractures traverse both the epiphysis and physis, exiting through the metaphysis. Type V fractures describe crush injuries to the physis.
The joint has not been affected in the fracture described and would therefore not be considered a fracture €‘dislocation. If it had involved the physis, this extra €‘octave fracture would likely have been a Salter €‘Harris Type II fracture, the most common type of fracture in this population.
Which of the following techniques is most commonly used for reconstruction of a Blauth IIIB thumb hypoplasia in the United States?
A) Great toe to thumb transfer
B) Index pollicization
C) Metacarpophalangeal (MCP) joint stabilization with opponensplasty
D) Second toe to thumb transfer
E) Toe wrap around transfer
The correct response is Option B.
Blauth classification of Thumb Hypoplasia:
The most severe forms of thumb hypoplasia (types IIIB, IV, and V) require amputation of the existing thumb and reconstruction, most commonly by index pollicization.
Which of the following factors is NOT associated with an increased risk of developing the condition shown in the photograph?
A ) Family history
B ) Low birth weight (less than 2500 g)
C ) Multigravida mother
D ) Prematurity (less than 37 weeks
E ) Young maternal age (less than 25 years)
The correct response is Option A.
Amniotic band syndrome is a sporadic condition in which rupture of the amnion results in strands of tissue that ensnare the developing fetus. The factors associated with this condition include prematurity, low birth weight, and young multigravida mothers. This condition is sporadic and mechanical in nature. As such, it does not have a genetic basis or identifiable pattern of inheritance.
A 1-year-old infant has the deformity shown in the photographs above. These findings are most consistent with which of the following?
(A) Arthrogryposis
(B) Complete thumb-index syndactyly
(C) Madelung’s deformity
(D) Poland’s syndrome
(E) Radial club hand
The correct response is Option E.
This infant has a radial club hand or radially deficient hand, involving partial or total absence of the radial or preaxial border of the upper extremity. Although radial club hand deformities can range from thumb hypoplasia to varying degrees of absence of the radius, resulting in radial deviation of the hand, most patients have total absence of the radius with absence of the radial carpal bones and thumb. It occurs in one in every 55,000 to 100,000 neonates and can be unilateral or bilateral. Abnormalities associated with radial dysplasia include cardiac septal defects (Holt-Oram syndrome), hematopoietic disorders (Fanconi anemia and TAR (thrombocytopenia-absent radius) syndrome), and gastrointestinal disorders (imperforate anus). Radial dysplasia may also occur as part of VATER syndrome (involving vertebral, anal, tracheoesophageal, and renal defects).
Fanconi aplastic anemia is the most serious condition associated with radial club hand. Affected patients also have pancytopenia, a progressive condition that may not be detected initially. Mitomycin testing should be performed in neonates with radial club hand to detect Fanconi anemia and prevent the development of life-threatening complications.
Arthrogryposis is a congenital disorder characterized by nonprogressive joint contractures present at birth. It is thought to occur secondary to neurogenic or myopathic weakness in utero. Multiple joints are typically affected; the extremities are atrophic and have limited active and passive motion. The wrist has a clublike appearance but is usually flexed and deviated ulnarly. Neurogenic and myopathic disorders are often associated with arthrogryposis.
Although this infant’s deformity may appear similar to thumb-index syndactyly, this is a rare finding and would not be characterized by radial deviation of the carpus and hypoplasia of the thenar eminence, which are seen in this patient.
Madelung’s deformity is a congenital disorder of the wrist that first becomes apparent in late childhood or adolescence. Affected patients have shortening of the radius, apparent palmar subluxation of the carpus, and prominence of the ulnar head. Finger abnormalities are not associated.
Patients with Poland’s syndrome have unilateral findings including absence of the pectoralis major and minor muscles, hypoplasia of the breast, and preaxial deformities.
A 7-year-old girl is brought to the office by her parents for consultation regarding surgical correction of camptodactyly of the small fingers. Which of the following interventions is the most appropriate management of this deformity?
(A) Observation only
(B) Corrective osteotomy of the proximal phalanges
(C) Lengthening of the flexor tendons
(D) Release of the volar plate
(E) Tightening of the extensor mechanism
The correct response is Option A.
Camptodactyly is a congenital flexion deformity of the proximal interphalangeal joints of the small fingers. It is usually not a functional problem because patients with the condition make accommodations to adapt to the deformity. Surgical repair, including corrective osteotomy, lengthening of the flexor tendons, release of the volar plate, and tightening of the extensor mechanism, is usually unsatisfactory and may cause stiffness of the small finger. Although the parents of this patient may try to persuade the surgeon to correct the deformity, the appropriate response for the surgeon is to resist their pressure and reassure them that this is not a functional concern. Surgical correction should be the last possible option.
A neonate has complete absence of the left thumb. Which of the following is the most likely associated finding?
(A) Absent pectoralis major muscle
(B) Arthrogryposis
(C) Hematopoietic abnormalities
(D) Scleroderma
(E) Trisomy 19
The correct response is Option C.
Congenitally absent thumb syndrome has no known cause but may be a genetic anomaly with sporadic occurrence. Other environmental factors, such as viruses, drugs, or exposure to radiation or chemicals, may also cause this condition.
Blauth’s classification of congenital absence of the thumb is explained below.
Type I: Shortened thumb, normal bones and muscles
Type II: Shortened thumb, hypoplasia of the thenar muscles and possible contracture of the first web space, narrowed bones, associated instability of the ulnar collateral ligament
Type III: Shortened thumb, absence of the thenar muscles, resulting in severe adduction contracture, instability of the metacarpophalangeal joint, variable abnormalities of the metacarpal, scaphoid, trapezium, and radial styloid
Type IV: Pouce flottant (floating thumb), absence of the thenar muscles
Type V: Complete absence of the thumb
Conditions associated with congenital absence of the thumb include:
- Spinal abnormalities (VATER [vertebral, anal, tracheoesophageal, radial and renal] syndrome)
- Cardiovascular anomalies (Holt-Oram syndrome)
- Hematopoietic anomalies (Fanconi anemia, thrombocytopenia–absent radius [TAR] syndrome)
- Renal abnormalities (VATER syndrome)
- Gastrointestinal anomalies
- Cornelia de Lange syndrome
- Hand-foot-uterus syndrome
- Trisomy 18
- Brachydactyly
- Rubinstein-Taybi syndrome
- Apert syndrome
- Carpenter syndrome
- Myositis ossificans
A 52-year-old man is evaluated because of a congenital deficiency of the upper extremity. A photograph is shown. This patient’s developmental abnormality most likely occurred during which of the following periods of gestation?
A) 0–4 weeks
B) 5–8 weeks
C) 9–13 weeks
D) 14–18 weeks
E) 19–23 weeks
The correct response is Option B.
The most likely period of time during gestation for this abnormality is 31 to 45 days.
This patient presents with transverse deficiency of the upper limb (phocomelia). This can result from abnormal development of the limb with an interruption in longitudinal growth.
The limb develops with formation of a limb bud at 26 days after gestation, which rapidly enlarges with growth of the embryo until approximately 47 days. At around 52 to 53 days after gestation, the fingers are separate. Embryogenesis is complete by 8 weeks, and all limb structures are present.
Limb development is controlled by signaling pathways that are located within three different signaling centers. These control the proximal-distal, anterior-posterior, and dorsal-ventral axes of limb development.
The limb develops in a proximal-distal direction, from shoulder to wrist, which is controlled by the apical ectodermal ridge (AER), a thickened layer of ectoderm over the limb bud. Fibroblast growth factors secreted within the AER signal the underlying mesoderm to differentiate. Disruption of the AER results in truncation of the limb.
Growth in the anterior-posterior (radioulnar) axis is determined by the zone of polarizing activity (ZPA). This is located in the posterior margin of the limb bud. The sonic hedgehog protein acts to signal development of the limb into radial and ulnar aspects. Alterations in this pathway can result in mirror duplication.
Dorsal-ventral limb development is signaled by the Wnt signaling pathway, which produces a transcription factor, LMX1 that induces the development of dorsal structures. In the ventral portion of the limb, the EN1 gene product blocks the Wnt pathway, leading to ventralization.
A variety of other transcription factors encoded by Hox and T-Box genes also govern limb and organ development, and alterations in these can give rise to various developmental differences.
Most limb abnormalities occur during the period of 4 to 8 weeks. In this case, the transverse deficiency likely occurred earlier in the process of limb outgrowth, while abnormalities of the digit would have taken place towards the end of this period.
A 3-month-old male infant is evaluated for polydactyly and mirror hand. Which of the following is the most likely genetic anomaly in this patient?
A) Engrailed-1 (EN1)
B) Fibroblast growth factor-2 (FGF2)
C) LIM homeobox transcription factor 1-beta (LMX1B)
D) Sonic hedgehog (SHH)
E) Wingless type (WNT)
**The correct response is Option D.
This patient presents with polydactyly and mirror hand. The most likely genetic anomaly is in sonic hedgehog (SHH).
Limb development is controlled by signaling pathways that are located within 3 different signaling centers. These control the proximal-distal, anterior-posterior, and dorsal-ventral axes of limb development.
The limb develops in a proximal-distal direction, from shoulder to wrist, which is controlled by the apical ectodermal ridge (AER), a thickened layer of ectoderm over the limb bud. Fibroblast growth factors secreted within the AER signal the underlying mesoderm to differentiate. Disruption of the AER results in truncation of the limb.
Growth in the anterior-posterior (radioulnar) axis is determined by the zone of polarizing activity (ZPA). This is located in the posterior margin of the limb bud. The sonic hedgehog protein (SHH) acts to signal development of the limb into radial and ulnar aspects. Alterations in this pathway can result in mirror duplication.
Dorsal-ventral limb development is signaled by the Wnt signaling pathway, which produces a transcription factor, Lmx-1 that induces the development of dorsal structures. In the ventral portion of the limb, the Engrailed-1 gene product blocks the Wnt pathway, leading to ventralization.
A variety of other transcription factors encoded by Hox and T-Box genes also govern limb and organ development, and alterations in these can give rise to various developmental differences.
A neonate has thumb hypoplasia and a shortened forearm with radial curvature. The child’s mother has a similar deformity. Which of the following is the most closely associated condition?
(A) Fanconi anemia
(B) Klippel-TrŽnaunay syndrome
(C) Maffucci syndrome
(D) Poland syndrome
(E) Sturge-Weber syndrome
The correct response is Option A.
This neonate has a radial club hand, an anomaly of unknown cause that may possibly be associated with autosomal dominant inheritance. Radial club hand deformities can range from partial underdevelopment to total absence of the radial elements of the upper extremity. Conditions associated with radial dysplasia include VATER syndrome (involving vertebral, anal, tracheoesophageal, and renal defects), Holt-Oram syndrome (involving cardiac septal defects), gastrointestinal disorders, and hematologic abnormalities including Fanconi anemia and thrombocytopenia-absent radius (TAR) syndrome.
Fanconi aplastic anemia is the most serious condition associated with radial club hand. Affected patients also have pancytopenia, a progressive condition that may not be detected initially. Mitomycin testing should be performed in neonates with radial club hand to detect Fanconi anemia and prevent the development of life-threatening complications.
Klippel-TrŽnaunay syndrome is characterized by musculoskeletal limb-length discrepancies involving one extremity, typically the leg, with associated venous and lymphatic malformations. Club hand is not seen.
Maffucci syndrome involves multiple enchondromas and venous and lymphatic anomalies. The limbs are usually foreshortened. Exostoses may be noted on the fingers.
Poland syndrome typically involves preaxial hypoplasia of the chest wall and upper extremity unilaterally. Affected patients have absence of the pectoralis major and minor muscles and limb hypoplasia with syndactyly and brachydactyly.
Patients with Sturge-Weber syndrome have port-wine stains in the distribution of the first and second divisions of the trigeminal nerve (V1and V2) associated with seizures and ipsilateral leptomeningeal calcifications.
Which of the following is the greatest predictive risk factor for birth brachial plexus injury?
A) Cesarean delivery
B) Forceps delivery
C) Macrosomia
D) Multiple gestation
E) Shoulder dystocia
The correct response is Option E.
In multivariate analysis, shoulder dystocia has overwhelmingly been found to be the risk factor most predictive of (most associated with) birth brachial plexus injury. The epidemiological study by Foad showed a 100 times greater risk; another study by DeFrancesco showed an odds ratio of 113.2. While conferring a smaller risk, macrosomia and forceps delivery are far weaker predictive factors, with increases in risk of 14-fold and 9-fold, respectively. Multiple gestation and cesarean delivery are actually protective factors against birth brachial plexus injury.
A 1-year-old infant has the malformation shown in the photograph above. Which of the following is most likely in this infant?
(A) Apert’s syndrome
(B) Carpenter’s syndrome
(C) Pfeiffer’s syndrome
(D) Poland’s syndrome
(E) No other associated syndromes
The correct response is Option E.
This infant with syndactyly will most likely have no other associated syndromes. Syndactyly occurs in one of every 2000 neonates and is typically an isolated deformity, although other malformations have been associated. Syndactyly can be complete or incomplete, reflecting the level of webbing distally to proximally, and complex or simple, reflecting the presence or absence of bony union. Complicated syndactyly implies involvement of other congenital abnormalities such as polydactyly.
Male infants are more commonly affected than female infants. Inheritance is more often sporadic than familial. Approximately 50% of affected patients have bilateral syndactyly. The third web space is affected most frequently.
Patients with Apert’s syndrome have bilateral, symmetric, complex syndactyly with shortened fingers. Craniofacial deformities are characteristic. Carpenter’s syndrome is characterized by simple syndactyly, shortened fingers, preaxial polysyndactyly, broad thumbs, and craniosynostosis. In Pfeiffer’s syndrome, there is mild partial syndactyly, as well as broadened, deviated thumbs and severe midface hypoplasia. Poland’s syndrome is associated with unilateral findings, including absence of the sternocostal portion of the pectoralis major muscle, hypoplasia of the upper extremity, simple syndactyly, and shortened fingers.
A 1-year-old boy is brought to the office by his parents for consultation of a flexion deformity of the right thumb. Physical examination shows fixed flexion of the thumb at the interphalangeal joint. No other abnormalities are noted. Which of the following is the most likely diagnosis?
(A) Camptodactyly
(B) Clinodactyly
(C) Delta phalanx
(D) Macrodactyly
(E) Trigger thumb
The correct response is Option E.
Trigger digit reportedly occurs with an incidence of 1 in 2000 to 3 in 1000 births. Whereas most authorities believe this deformity is a congenital abnormality, there is debate whether trigger digit is an acquired deformity. The congenital trigger finger presents as a flexed digit either at birth or up to 3 years of age. Often it may not be recognized early because of the tendencies of infants to hold their fingers in a flexed position. Before 12 months of age, observation is the standard treatment. After 3 years of age, surgical release is generally recommended. The results of conservative nonoperative treatment and spontaneous recovery have been reported as between 0% and 30%.
Trigger digit can be confused with the diagnosis of camptodactyly, which is a congenital flexion posture most often found in the small finger. Although congenital trigger thumb is related to a nodule in the tendon, the etiology of camptodactyly is less clear, with various etiologies related to skin deficit, volar plate abnormalities, and abnormalities of the lumbrical and superficialis tendons.
Abnormally angulated digits in the radial ulnar plane is clinodactyly. Clinodactyly may be associated with a delta phalanx, which is an abnormally shaped, short tubular bone within the digit.
Macrodactyly refers to an abnormal enlargement of the digit. In true macrodactyly, all structures of the digits are enlarged.
Which of the following hand deformities is commonly associated with a delta phalanx?
(A) Brachydactyly
(B) Camptodactyly
(C) Clinodactyly
(D) Macrodactyly
(E) Symbrachydactyly
The correct response is Option C.
Clinodactyly, or “bent finger,” is most commonly caused by the presence of a delta phalanx. Clinodactyly and triphalangeal thumb are most often associated with the presence of a delta phalanx, which has an angulated, short, tubular base, trapezoidal or triangular in shape. The growth plate is longitudinal, often a reverse C-shape or bracket, rather than transverse. The longitudinally bracketed epiphysis can interfere with normal longitudinal growth. Clinodactyly manifests as a radially or ulnarly curved digit. It is typically bilateral and is often transmitted as an autosomal dominant trait with variable expression. Although any digit can be involved, radial deviation of the small finger in the area of the distal interphalangeal joint is most common. In patients with delta phalanges, appropriate management includes bracket resection, fat grafting, and osteotomies, which can be either closing, opening, or reverse, as indicated by the findings in the affected patient.
The other hand deformities listed above can be associated with abnormally shaped phalanges but not with a delta phalanx.
Brachydactyly is a congenital deformity, typically autosomal dominant, that is characterized by abnormal shortening of the digits.
Patients with camptodactyly have a flexion deformity of the proximal interphalangeal joint, most frequently involving the small finger. Possible causes of camptodactyly include skin deficiencies, shortening of the volar plate, abnormalities of the palmar fascia and Landsmeer’s ligament, deficiencies of the central slip, and shortening of the superficialis tendon. Static and dynamic splinting can be helpful; surgical correction is often incomplete.
Macrodactyly describes enlargement of all of the structures of a digit. Staged bony and soft-tissue reduction procedures can be performed to allow for some control. Attempting to halt digital growth with ligation of digital arteries or elastic compression is typically ineffective. Amputation is indicated for any large, unsightly digit that significantly impairs total hand function.
Symbrachydactyly is a congenital hand deformity characterized by shortened digits with syndactyly. Poland’s syndrome is frequently associated. The digits are foreshortened but not angulated.
A 3-year-old girl has congenital amniotic band syndrome affecting the nondominant left hand. On examination of the hand, the thumb is intact and functional, but there is adactyly of the other digits at the level of the metacarpophalangeal joint. The right hand is unaffected.
In order to improve function of this patient’s left hand, which of the following is the most appropriate management?
(A) Use of digital prostheses
(B) Toe phalangeal grafting
(C) Metacarpal lengthening
(D) Second toe-to-hand transfer
(E) Thumb amputation
The correct response is Option D.
Although there are many options for reconstruction of this patient’s fingers, the second-toe-to-hand transfer will provide the greatest restoration of function. Congenital band syndrome is one of few conditions (along with variations of hypoplasia and aplasia) that can affect the fingers but leave a functional thumb. In fact, children with congenital band syndrome often have better hand function following reconstruction because the structures proximal to the level of the deformity are unaffected (ie, bones, muscles, tendons, and vessels).
Because these recipient structures are normal, a second toe-to-hand transfer will provide the best sensory, motor, and overall hand function. The transferred second toe can be positioned to provide either pincer or grasp functions. The transfer is successful in most cases, and growth of the transferred toe is approximately 90% of the normal toe. Donor site morbidity is rare. The incidence of premature physeal closure is 10%.
Digital prostheses will improve the aesthetic quality of the child’s hand but will not restore function. Toe phalangeal grafting is more appropriate for treatment of aphalangia or hypophalangia. These grafts can be used to improve motion at the metacarpophalangeal joints but have a poorer functional outcome when compared with the second toe transfer. Although metacarpal lengthening can be performed to produce a “post” for the thumb to work against, the resultant digit is also less useful than a transferred second toe. A functioning thumb should never be amputated.
A 4-month-old male infant is brought to the office with the multiple extremity findings shown in the photographs. Which of the following additional clinical findings is most commonly seen with this condition?
A) Absence of the sternocostal head of the pectoralis major
B) Bilateral symmetric anomalies
C) Clubfoot
D) Craniosynostosis
E) Hematopoietic changes
The correct response is Option C.
This child has constriction ring syndrome (CRS). CRS is a rare occurrence, with the incidence reported from 1 in 1200 to 15,000 births. CRS frequently affects multiple extremities asymmetrically, with an average of three extremities involved, most often at the distal aspect of the extremity. Several characteristics are most often seen in the affected extremities including constriction rings, amputations, lymphedema distal to the ring, and acrosyndactyly (digits are fused distally, but proximally have fenestrations as fusion occurred after apoptosis in utero). Amputation or hypoplasia is usually seen distal to the ring, whereas the proximal aspect is intact and usually well-formed. CRS affecting the hands most frequently affects the index, middle, and ring fingers. Associated anomalies include syndactyly, oligodactyly, clubfoot, limb absences, body-wall defects (e.g., gastroschisis), and craniofacial anomalies, particularly facial clefts.
Symbrachydactyly, which is associated with Poland syndrome, is usually present in one limb. There is true hypoplasia of the affected extremity with absent or rudimentary digits with nubbins and frequent syndactyly. Symbrachydactyly usually impacts the central digits. Poland syndrome is defined by the absence of the sternocostal head of the pectoralis major.
Hematopoietic changes can be seen in radial hypoplasia. Fanconi anemia and thrombocytopenia (thrombocytopenia absent radius syndrome) are both associated with radial hypoplasia.
Children with Apert syndrome (acrocephalosyndactyly) have bilateral relatively symmetric complex syndactyly, symphalangism, and craniosynostosis.
A 1-year-old boy is brought to the office by his parents for evaluation and correction of the findings shown in the photograph. The patient is otherwise healthy. Which of the following techniques is most appropriate to reconstruct the apex of the web space in this patient?
A) Bilobed flap from the dorsal hand
B) Cross-finger flap
C) Full-thickness skin grafting
D) Proximally based dorsal rectangular flap
E) Split-thickness skin grafting
The correct response is Option D.
Full-thickness skin grafts are usually used to close the resultant defects of the fingers after release of congenital syndactyly. Several local dorsal flaps have been described to reconstruct the web space with differing shapes to avoid the use of skin grafts, including rectangular, a V-Y island, a dorsal flap interdigitated with a small palmar V and a dorsal V-shape. A bilobed flap has been described for treating web creep in adults, but would not routinely be used.
A 1-year-old boy is brought to the office by his parents for consultation of a flexion deformity of the right thumb. Physical examination shows fixed flexion of the thumb at the interphalangeal joint. No other abnormalities are noted. Which of the following is the most likely diagnosis?
(A) Camptodactyly
(B) Clinodactyly
(C) Delta phalanx
(D) Macrodactyly
(E) Trigger thumb
The correct response is Option E.
Trigger digit reportedly occurs with an incidence of 1 in 2000 to 3 in 1000 births. Whereas most authorities believe this deformity is a congenital abnormality, there is debate whether trigger digit is an acquired deformity. The congenital trigger finger presents as a flexed digit either at birth or up to 3 years of age. Often it may not be recognized early because of the tendencies of infants to hold their fingers in a flexed position. Before 12 months of age, observation is the standard treatment. After 3 years of age, surgical release is generally recommended. The results of conservative nonoperative treatment and spontaneous recovery have been reported as between 0% and 30%.
Trigger digit can be confused with the diagnosis of camptodactyly, which is a congenital flexion posture most often found in the small finger. Although congenital trigger thumb is related to a nodule in the tendon, the etiology of camptodactyly is less clear, with various etiologies related to skin deficit, volar plate abnormalities, and abnormalities of the lumbrical and superficialis tendons.
Abnormally angulated digits in the radial ulnar plane is clinodactyly. Clinodactyly may be associated with a delta phalanx, which is an abnormally shaped, short tubular bone within the digit.
Macrodactyly refers to an abnormal enlargement of the digit. In true macrodactyly, all structures of the digits are enlarged.
A 2-month-old infant is scheduled to undergo staged surgical release of complete syndactyly of every web space. Which of the following web spaces are most appropriately addressed during the first stage of syndactyly release?
A ) 1st and 2nd
B ) 1st and 4th
C ) 2nd and 3rd
D ) 2nd and 4th
E ) 3rd and 4th
The correct response is Option B.
Syndactyly is a condition resulting from failure of the normal separation process during five to eight weeks of gestation. It occurs in approximately one in 2000 births, either spontaneously or as part of a syndrome. Syndactyly is classified as complete or incomplete based on degree of distal to proximal webbing. It is also described as complex or simple, reflecting the presence or absence of bony involvement.
When syndactyly involves multiple digits, a plan must be developed to accomplish as much as safely possible at each operation to minimize the total number of operations. Border digit syndactyly should be addressed between four and six months to minimize tethering effects and abnormal growth. Complete syndactyly of adjacent web spaces should not be performed at the same stage due to the increased risk of vascular compromise to the digit.
In complete syndactyly, the border digits (1st and 4th web spaces) are usually released first. The 2nd and 3rd web spaces are released later in two separate operations. If there is no border digit tethering, complete release can be performed in two operations by first releasing the 1st and 3rd web spaces, followed by the 2nd and 4th web spaces.
A 12-month-old male infant is brought to the office for evaluation of a small right thumb. Physical examination shows instability of the metacarpophalangeal joint and hypoplasia of the first web space. The carpometacarpal joint is stable. The patient has difficulty moving the thumb. Which of the following is the next best step in management?
A) Free toe transfer
B) Metacarpal lengthening
C) Opponensplasty
D) Pollicization
E) Continued observation
The correct response is Option C.
This patient presents with a Blauth Grade 2 or 3A thumb hypoplasia. Surgical management is warranted and includes treatment of the absent or hypoplastic thenar musculature with opponensplasty; release of the first web space; and management of MCP instability.
Pollicization is reserved for Blauth Grade 3B or more severe deficiencies. The distinction between a Blauth 3A and 3b hypoplastic thumb is determined by the stability of the CMC joint.
Blauth classification of Thumb Hypoplasia:
During reconstruction of the split thumb deformity shown above, transfer of which of the following muscles is most effective for long-term skeletal stability of the thumb?
(A) Abductor pollicis brevis
(B) Adductor pollicis
(C) Extensor carpi radialis longus
(D) Extensor indicis proprius
(E) Flexor digitorum superficialis ring
The correct response is Option A.
This patient has a Wassel Type IV split thumb deformity. Surgical reconstruction of this deformity involves transfer of the abductor pollicis brevis muscle from the radial base of the radial duplicate to the radial base of the retained ulnar duplicate. This muscle transfer is crucial to balance the force of the adductor pollicis brevis, which is attached to the proximal ulnar aspect of the proximal phalanx. If the abductor pollicis brevis is not transferred, the thumb will eventually collapse into a Z-deformity, with ulnar deviation of the proximal phalanx and radial deviation of the distal phalanx. Normally, the abductor pollicis brevis tendon is removed from the proximal phalanx with a cuff of periosteum, which facilitates attachment to the radial aspect of the proximal phalanx of the ulnar duplicate. This transfer is protected by a longitudinal Kirschner wire placed through the metacarpophalangeal joint. The thumb is then immobilized in a long arm cast for four weeks to protect the surgical repair.
Reconstruction of any duplicate thumb deformity always requires an inventory of all tendon and muscle units. In general, the ulnar duplicate is retained because of the stability of the ulnar collateral ligament of the metacarpophalangeal joint. Augmentation of the extrinsic flexor or extensor tendons is performed occasionally using the tendon and muscle units that would have been discarded after deletion of the radial duplicate. In addition, these deformities should be examined for eccentrically inserted extrinsic tendons, which must be centralized to ensure skeletal stability.
The adductor pollicis is firmly inserted into the ulnar base of the proximal phalanx of the retained ulnar duplicate and is not transferred. The extensor carpi radialis longus tendon, extensor indicis proprius tendon, and flexor digitorum superficialis tendon to the ring finger are useful in reconstruction of palsy of the median and ulnar nerves but have no role in reconstruction of duplicate thumb deformity.
A 7-year-old girl is brought to the office by her parents because she has a deformity of the left hand. Medical history is unknown because the patient was recently adopted. She is otherwise healthy. Examination of the right hand shows no abnormalities. Her parents say that she is able to play with her toys with both hands and can pick up small objects with the left hand. A photograph of the hands is shown. Which of the following is the most appropriate option for surgical reconstruction?
A) Distraction lengthening of the thumb
B) Microvascular transfer of second and third toes to the index and long finger positions
C) Microvascular transfer of second and third toes to the small and ring finger positions
D) Transfer of toe phalangeal epiphysis to the index and long finger positions
E) No surgical reconstruction
Correct answer is option E.
Congenital hand deformities present a challenge to the patient, parents, and the reconstructive surgeon. Transverse arrest or congenital amputations may present as a failure of formation or arrest of development of the limb. Operative indications for this group of patients are often limited but are driven by the function of the child. The patient described is a very functional child who uses her limb for complex grasping activities; therefore, no surgery is indicated.
Distraction lengthening of the thumb is not appropriate for the patient described since it may impede pulp-to-pulp opposition of the radial and ulnar digits. Microvascular transfer of one or two toes may be a worthwhile procedure in children with no opposable digits and no functional use of their hand. However, in the patient described, this procedure is not appropriate because function is already satisfactory. Toe epiphysis nonvascular transfers have been indicated in congenitally short digits, but for the patient described there are no normal phalanges to warrant this procedure.
A 3-year-old boy is scheduled to undergo the first stage of separation of syndactyly of the right hand. Photographs are shown. Which of the following anatomical structures is most likely to limit how far the digits can be separated proximally?
A) Artery
B) Extensor tendon
C) Flexor tendon
D) Nerve
E) Vein
The correct response is Option A.
Digital veins, due to their larger number and relative redundancy, do not normally limit which tissues can be separated to what level. Division of one branch of the digital artery is not normally a problem when only two digits are involved in syndactyly; the digital artery on the unaffected side is normally sufficient to perfuse the digit. For a central digit when three or more digits are involved, dissection must either stop at the bifurcation of the artery, or revascularization, such as with a vein graft, must be done.
The digital nerve often exists as a single unit at least partially down the length of the joined fingers, but it can be separated into two proper digital units with intrafascicular dissection to a level proximal to the neo-web space.
Flexor and extensor tendons are not involved in syndactyly.
A newborn is brought to the office because of the deformity shown in the photograph. Which of the following findings is most likely associated with this condition?
A ) Autosomal recessive inheritance
B ) High plasminogen levels
C ) Infection during the second trimester
D ) Injury to the subclavian artery
E ) Oligohydramnios
The correct response is Option E.
The patient described is brought to the office with the classic findings of skin banding and acrosyndactyly consistent with amniotic band syndrome (ABS). The incidence of ABS has been reported at 1:15,000 births with equal expression in males and females. No autosomal inheritance pattern has been identified nor has a connection been made to any infectious agent. An association with oligohydramnios may explain the increased frequency of clubfoot deformity; however, this finding is not ubiquitous. Researchers have postulated that an early transient oligohydramnios at the time of amniotic disruption is most likely causative.
Anomalies such as calcaneovalgus, pes valgo planus, congenital hip dislocation, and congenital vertical talus can also be associated with oligohydramnios.
Vasculocutaneous catastrophe of the newborn is associated with an altered fibrinolytic system, including high plasminogen levels and antiplasmin inhibitors. Vascular injury to the subclavian artery has been a suspected cause of symbrachydactyly but not ABS.
A 3-month-old infant is brought to the office for consultation regarding deformity of the right hand (shown). The infant is otherwise healthy and has no other abnormalities. On physical examination, no abnormalities other than those of the right hand are noted. Radiographs show no bony syndactyly. The most appropriate management of this patient’s deformity is release of the syndactyly and which of the following?
A) First dorsal interosseus flap
B) Full-thickness skin grafting
C) Radial artery flap
D) Split-thickness skin grafting
The correct answer is option B.
Syndactyly is the second most common congenital hand abnormality after polydactyly, occurring in 1 in 2000 live births. Syndactyly can be described as complete, when the interdigital web extends to the full length of the digit, or incomplete. Although there have been reports of the use of skin flaps or primary closure after radical subcutaneous tissue debulking, skin grafts are almost always necessary. Full-thickness skin grafting is the appropriate management of syndactyly in a child. Effective grafts for this procedure include the lateral groin crease, plantar foot, antecubital fossa, inner arm, or wrist flexion crease.
Amputation of the digits is almost never required for a simple syndactyly.
Pedicle flaps such as a dorsal interosseus flap or radial artery flap are not required because tissue can be closed with adjacent flaps and skin grafts alone.
A split-thickness skin graft is a poor choice in a young child because it is difficult to obtain and has a significant amount of contracture.
Which of the following failures in embryologic development is most likely to have caused the deformity pictured in the photographs shown?
A) Differentiation of the zone of polarizing activity
B) Formation of the apical ectodermal ridge
C) Inhibition by en-1
D) Longitudinal formation
E) Programmed cell death
The correct response is Option E.
The hand plate initially forms with webbed digits. In order to have separate fingers, the interdigital tissue must undergo programmed cell death/apoptosis. Bone morphogenetic protein (BMP) plays an essential role in this process. A complex interplay creates failure of longitudinal formation (i.e., radial club hand). Removal of the apical ectodermal ridge (AER) results in limb truncation. The zone of polarizing activity (ZPA) is present in the posterior aspect of the developing upper limb and helps direct the anteroposterior axis (radial-ulnar axis). Sonic hedgehog (SHH) is the critical signaling factor. ZPA transplantation or excess SHH results in mirror hand deformity. The dorsoventral axis is another pathway critical for appropriate limb development. The WNT7A signaling molecule is expressed in the developing upper limb dorsal ectoderm, activating the LIM homeodomain, resulting in the expression of LMX1B transcription factor from the dorsal mesenchyme, whereas the ventral ectoderm induces the expression of en-1. These signaling factors are necessary for the formation of dorsal versus palmar structures of the hand.
A 6-year-old boy is brought to the office by his mother because she is concerned about a deformity of the little finger of his right hand. She says the deformity has been present for approximately 3 years but has become progressively pronounced during the past year. On examination, the patient can flex the proximal interphalangeal joint but cannot extend it beyond the position shown in the x-ray. The little finger of his left hand is similarly affected, but the condition is less severe. Which of the following is the most likely diagnosis?
A) Camptodactyly
B) Delta phalanx
C) Kirner deformity
D) Symphalangism
E) Trigger finger
The correct response is Option A.
Camptodactyly is a congenital abnormality accounting for 5% of congenital hand anomalies. There is a flexion deformity that is often noted within the first year of life, but a second, noncongenital group occurs around age 10 years. It generally appears at the proximal interphalangeal (PIP) joint. It may occur as part of a syndrome but is often an individual defect. It is classified by the International Federation as Type II (failure of differentiation). It may be accompanied by subtle radiographic changes seen on the lateral view of the PIP joint with flattening of the circular surface of the proximal phalanx and an indentation in the neck of the proximal phalanx; dorsal positioning of the head of the proximal phalanx into the articulation of the base of the middle phalanx is also present.
A delta phalanx (or bracketed epiphysis) will result in clinodactyly. Clinodactyly is an excessive radial or ulnar angulation of the digit. Involvement of the little finger is common and often inherited as a dominant trait. It may be associated with a delta middle phalanx. If the deformity is severe enough, it may require surgical correction.
Kirner deformity is a progressive palmar and radial curvature of the distal phalanx of the little finger that presents in preadolescence. It is caused by an idiopathic, nontraumatic disruption of the epiphysis of the distal phalanx. It may be caused by cold exposure and frostbite and would affect multiple digits.
Symphalangism describes a congenital clinical stiffness of the PIP joints of the fingers. It is also included in the failure of differentiation classification category. Flexion creases are absent, and the fingers may be longitudinally foreshortened. Multiple digits are affected most commonly.
Trigger digits may occur in children but most commonly affect the thumb with a flexion deformity of the interphalangeal joint. They may occur with a flexion deformity of the PIP joints of the fingers, but the fingers are much less commonly affected than the thumb.
A 3-month-old infant is brought to the office for consultation regarding deformity of the right hand (shown). The infant is otherwise healthy and has no other abnormalities. On physical examination, no abnormalities other than those of the right hand are noted. Radiographs show no bony syndactyly. The most appropriate management of this patient €™s deformity is release of the syndactyly and which of the following?
(A) Amputation of the digits
(B) First dorsal interosseus flap
(C) Full-thickness skin grafting
(D) Radial artery flap
(E) Split-thickness skin grafting
The correct response is Option C.
Syndactyly is the second most common congenital hand abnormality after polydactyly, occurring in 1 in 2000 live births. Syndactyly can be described as complete, when the interdigital web extends to the full length of the digit, or incomplete. Although there have been reports of the use of skin flaps or primary closure after radical subcutaneous tissue debulking, skin grafts are almost always necessary. Full-thickness skin grafting is the appropriate management of syndactyly in a child. Effective grafts for this procedure include the lateral groin crease, plantar foot, antecubital fossa, inner arm, or wrist flexion crease.
Amputation of the digits is almost never required for a simple syndactyly.
Pedicle flaps such as a dorsal interosseus flap or radial artery flap are not required because tissue can be closed with adjacent flaps and skin grafts alone.
A split-thickness skin graft is a poor choice in a young child because it is difficult to obtain and has a significant amount of contracture.
A 7-year-old girl is brought to the office by her parents because she has a deformity of the left hand. Medical history is unknown because the patient was recently adopted. She is otherwise healthy. Examination of the right hand shows no abnormalities. Her parents say that she is able to play with her toys with both hands and can pick up small objects with the left hand. A photograph of the hands is shown. Which of the following is the most appropriate option for surgical reconstruction?
(A) Distraction lengthening of the thumb
(B) Microvascular transfer of second and third toes to the index and long finger positions
(C) Microvascular transfer of second and third toes to the small and ring finger positions
(D) Transfer of toe phalangeal epiphysis to the index and long finger positions
(E) No surgical reconstruction
The correct response is Option E.
Congenital hand deformities present a challenge to the patient, parents, and the reconstructive surgeon. Transverse arrest or congenital amputations may present as a failure of formation or arrest of development of the limb. Operative indications for this group of patients are often limited but are driven by the function of the child. The patient described is a very functional child who uses her limb for complex grasping activities; therefore, no surgery is indicated.
Distraction lengthening of the thumb is not appropriate for the patient described since it may impede pulp-to-pulp opposition of the radial and ulnar digits. Microvascular transfer of one or two toes may be a worthwhile procedure in children with no opposable digits and no functional use of their hand. However, in the patient described, this procedure is not appropriate because function is already satisfactory. Toe epiphysis nonvascular transfers have been indicated in congenitally short digits, but for the patient described there are no normal phalanges to warrant this procedure.
A 2-year-old boy is referred to the office by a pediatrician for surgical correction of a deformity of the right hand. Physical examination shows Wassel Type 4 duplication of the thumb. Which of these is a standard component of the surgical management of the condition?
A) Amputation of the ulnar duplication
B) Maintenance of the ulnar collateral ligament at the metacarpophalangeal joint
C) Repair of the flexor pollicis longus tendon
D) Repair of the nail bed
The correct answer is option B.
There are seven classes of thumb duplication as described by Wassel. Type 4 is the most common. Type 1 involves a duplication of the distal phalanx in which the two are connected at the base. Type 2 duplication occur when the two distal phalanges are separate. Type 3 duplication are of the proximal phalanx and are connected at the base. Type 4 duplication are of the distal and proximal phalanxes when there are four distal and proximal phalanges. Type 5 are duplication of the distal and proximal phalanxes with a duplication of the metacarpal still fused at the base. Type 6 duplication result in six separate bones, two distal phalanges, two proximal phalanges, and two metacarpals that are separate.
In the correction of Type 4 duplication, it is most critical to preserve the ulnar collateral ligament to stabilize pinch. Typically, the radial thumb is less functional and less developed. The radial collateral ligament (RCL) is reconstructed with a ligament-periosteal flap. The abductor pollicis brevis is included in this RCL reconstruction. Most often, the flexor pollicis longus in the ulnar element is intact and does not require repair or reconstruction. As seen in the photograph of the thumb duplication in the patient described, the nail complex does not require intervention.
A 12-month-old boy comes to the office for evaluation of a congenital thumb deformity. A photograph is shown. Which of the following is the most appropriate management of the thumb?
A) First metacarpal distraction osteogenesis
B) First web space deepening
C) Flexor digitorum superficialis opponensplasty
D) Free great toe transfer
E) Index finger pollicization
The correct response is Option E.
This patient has a type IV (floating thumb or pouce flottant) thumb hypoplasia best managed with thumb ablation and index finger pollicization. Thumb hypoplasia can range from a minor decrease in size to complete absence. Thumb hypoplasia may also be associated with VACTERL (vertebral abnormalities, anal atresia, cardiac abnormalities, tracheoesophageal fistula or esophageal atresia, renal agenesis and dysplasia, and limb defects), TAR syndrome, Fanconi anemia, and Holt-Oram syndrome. Given the possible association with these conditions, a workup of all potentially affected organ systems should be performed. This includes a renal ultrasound, an echocardiogram, spine x-ray studies, a complete blood count, and a chromosomal challenge test.
Thumb hypoplasia may occur in an isolated fashion or in combination with radial hypoplasia, as seen in this case. The most important and difficult distinction is between types IIIa and IIIb hypoplastic thumbs. A type IIIa thumb has a stable thumb carpometacarpal (CMC) joint, whereas a type IIIb thumb does not. If the child uses the thumb for integrated pinch, the CMC joint is deemed stable. If the thumb is bypassed in favor of scissor pinch between the index and middle fingers, the CMC joint is either unstable or absent; in this case, a pollicization is recommended.
A free great toe transfer is not indicated in children with thumb hypoplasia because the existing thumb CMC is not stable and pollicization would provide a better functional outcome. Flexor digitorum superficialis or abductor digiti minimi opponensplasty are both options for thumb hypoplasia reconstruction in the presence of a stable CMC joint. A first webspace deepening is typically combined with opponensplasty and metacarpophalangeal joint stabilization in children with reconstructible hypoplastic thumbs, but not for children undergoing pollicization. The patient in the image does not have a first metacarpal, and therefore cannot undergo distraction osteogenesis.
A 6-month-old male infant presents with bilateral radial longitudinal deficiency and thumb hypoplasia. X-ray study is shown. Which of the following studies is most likely to rule out Fanconi anemia in this patient?
A) Bone marrow biopsy
B) Chromosomal breakage testing
C) Complete blood count with differential
D) Peripheral blood smear
E) Renal ultrasonography
The correct response is Option B.
All children with radial longitudinal deficiency (RLD) should undergo a thorough physical examination because of the frequency of associated syndromes. Common conditions associated with RLD include thrombocytopenia-absent radius (TAR) syndrome, Holt-Oram syndrome, VACTERL syndrome and Fanconi anemia.
Thrombocytopenia-absent radius (TAR) syndrome is an autosomal recessive disorder characterized by an absent radius with a relatively normal thumb. Holt-Oram syndrome is an autosomal-dominant disorder in which RLD is accompanied by either an atrial or ventricular cardiac septal defect. Fanconi anemia is an autosomal-recessive pancytopenia, once invariably fatal, that is now routinely treated with bone marrow transplantation. One should consider further screening with spinal x-ray studies, cardiac echocardiography, renal ultrasonography, and complete blood count.
Because children with Fanconi anemia often do not manifest aplastic anemia on routine blood testing until after age 3 years, it is also recommended that patients with RLD undergo a chromosomal breakage test for earlier detection of this potentially fatal disease. Routine genetic counseling is also recommended. A peripheral blood smear and bone marrow biopsy would not be helpful in making this diagnosis.
A 2-year-old boy is referred to the office by a pediatrician for surgical correction of a deformity of the right hand. Physical examination shows Wassel Type 4 duplication of the thumb. In surgical management of this patient €™s condition, which of the following is the most critical point?
(A) Amputation of the ulnar duplication
(B) Maintenance of the ulnar collateral ligament at the metacarpophalangeal joint
(C) Reattachment of the abductor pollicis brevis
(D) Repair of the flexor pollicis longus tendon
(E) Repair of the nail bed
The correct response is Option B.
There are seven classes of thumb duplication as described by Wassel. Type 4 is the most common. Type 1 involves a duplication of the distal phalanx in which the two are connected at the base. Type 2 duplications occur when the two distal phalanges are separate. Type 3 duplications are of the proximal phalanx and are connected at the base. Type 4 duplications are of the distal and proximal phalanxes when there are four distal and proximal phalanges. Type 5 are duplications of the distal and proximal phalanxes with a duplication of the metacarpal still fused at the base. Type 6 duplications result in six separate bones, two distal phalanges, two proximal phalanges, and two metacarpals that are separate.
In the correction of Type 4 duplications, it is most critical to preserve the ulnar collateral ligament to stabilize pinch. Typically, the radial thumb is less functional and less developed. The radial collateral ligament (RCL) is reconstructed with a ligament-periosteal flap. The abductor pollicis brevis is included in this RCL reconstruction. Most often, the flexor pollicis longus in the ulnar element is intact and does not require repair or reconstruction. As seen in the photograph of the thumb duplication in the patient described, the nail complex does not require intervention.
A 2-year-old male infant presents with a congenital deformity of the ring finger. A photograph and x-ray study are shown. The patient’s parents report that the condition limits his ability to make a full fist but is otherwise painless. Which of the following is the most likely diagnosis in this patient?
A) Amniotic band syndrome
B) Camptodactyly
C) Congenital trigger finger
D) Macrodactyly
E) Syndactyly
The correct response is Option A.
Amniotic band syndrome (ABS) has an incidence of 1/1200 to 1/15,000 births. Some congenital anomalies have been associated with ABS including cleft palate, imperforate anus, equinovarus, and body wall defects.
The etiology of ABS has two theories. The intrinsic defect theory endorses genetic abnormalities which lead to mesenchymal hypoplasia and scarring. The extrinsic theory endorses amniotic tissue which entangles fetal parts leading to constriction.
Constriction varies leading to a spectrum of clinical manifestations from skin dimpling to digital amputation. Neurovascular injury can manifest as peripheral nerve palsy, lymphedema and arterial insufficiency. Syndactyly is common, and acrosyndactyly is pathognomonic of ABS. The Patterson classification system has four subtypes. The first is a simple constriction ring. The second has a constriction ring that affects the digit distal to the ring, with or without lymphedema. The third consists of constriction rings with acrosyndactyly. The fourth is characterized by amputation at any level.
Camptodactyly is defined as a painless and progressive non-traumatic contracture of the proximal interphalangeal (PIP) joint. It affects around 1% of the population and the great majority of the cases are extremely mild and asymptomatic. The cause of the contracture is controversial. There have been descriptions of malformations of the superficial flexor of the fingers, lumbrical muscles, and the transverse and oblique retinacular ligaments. There may also be alterations to the configurations of the PIP joint.
Congenital trigger finger differs from congenital trigger thumb. Congenital trigger finger is rare and presents more commonly in the ulnar digits with associated malformations of the superficial and deep flexors. It presents with sporadic locking. Release of the A1 pulley alone is not adequate, with tenoplasty of the chiasm and partial opening of the A2 pulley generally necessary.
Syndactyly is a variable fusion between two adjacent fingers, and is one of the most common congenital
deformities, occurring in 1:2000 live births.
Classification includes:
Simple: fusion only through the skin
Complex: bone connection.
Complete: the entire commissure is involved, including the nail bed
Incomplete: the nail bed is not involved.
Complicated: involvement of vascular tissues, tendons or nerves.
It can occur separately or as a manifestation of a syndrome, such as Streeter, Apert or Poland, in which the severity of the syndactyly is more significant.
Macrodactyly is a congenital overgrowth disorder and represents 0.9% of upper extremity congenital anomalies. Digital enlargement involves all tissue types and maintains patterns of growth and anatomic relationships within the affected portion of the hand.
The term “macrodactyly” is reserved for nonsyndromic, congenital enlargement of a digit or digits that occurs in isolation without associated limb hemihypertrophy or vascular anomaly.
A 14-month-old girl is evaluated for surgical management of the condition shown in the photograph. Which of the following is the most appropriate classification of this congenital difference?
A) Duplication
B) Failure of differentiation
C) Failure of formation
D) Overgrowth
E) Undergrowth
The correct response is Option C.
The image shown is a patient with a typical cleft hand, or ectrodactyly. This is classified as a Swanson type I (failure of formation) congenital difference of the upper extremity. This deformity is caused by a longitudinal growth deficiency of one or more central digits. This condition may have a genetic underpinning and is most commonly inherited in autosomal dominant fashion with approximately 70% penetrance.
Ectrodactyly presents with significant heterogeneity. Many patients with cleft hand do not require any type of surgical management. The most important determinants of surgical management are establishment of an appropriate thumb to index webspace for gripping and grasping and release of syndactyly. Surgical management includes elevation of skin flaps, transposition of the index finger to the ulnar side of the cleft, and creation of a web space between the thumb and index finger.
Cleft hand is classified with the Thumb-Index Classification of Central Deficiency proposed by Manske. This generally guides the treatment approach in conjunction with management of syndactyly. A myriad of techniques have been employed based upon the severity of the webspace contraction and the presence of syndactyly adjacent to the cleft.
A male newborn has the isolated congenital deformities of the left hand shown in the photographs. Which of the following procedures is most likely to provide optimal function of the hand?
(A) Amputation of the long, ring, and small fingers
(B) Full-thickness matrix grafting
(C) Phalangeal lengthening of the small and ring fingers
(D) Radial metacarpal lengthening of the index and long fingers
(E) Toe-to-hand transplantation
The correct response is Option C.
The patient described has an isolated congenital anomaly of the left hand known as shortened fingers or brachydactyly. The most functional improvement is to lengthen the small and ring fingers to facilitate power grip and opposition. One method is nonvascularized toe phalanx grafting; another is distraction lengthening. This procedure should be performed when the patient is between 8 and 12 months of age.
Amputation would not add to the patient €™s function. Full-thickness matrix grafting is for reconstruction of the nail matrix complex. Lengthening the second and third metacarpals would not address the functional deficit. The patient €™s thumb appears to be quite functional, so toe-to-hand transplantation is not appropriate.
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.
A 12-year-old female is referred to the clinic for evaluation of bilateral thumb abnormalities noted since birth. She reports no pain or functional limitations but is self-conscious about the appearance of her thumbs. On examination, both thumbs have short, broad distal phalanges with corresponding short and broad nails. The proximal phalanges and carpometacarpal joints are normal. There are no associated abnormalities of the thenar muscles or the first web space. Family history reveals that her father has similar thumb abnormalities. What is the most likely diagnosis for this patient?
A. Brachydactyly type D (BDD)
B. Thumb hypoplasia (modified Blauth type II)
C. Clinodactyly
D. Ectrodactyly
E. Camptodactyly
Correct Answer: A. Brachydactyly type D (BDD)
The patient’s clinical findings of short, broad distal phalanges in the thumbs with normal proximal phalanges and carpometacarpal joints are classic for Brachydactyly type D (BDD). This condition, also known as “stub thumb,” is associated with HOXD13 gene mutations and has an autosomal dominant inheritance pattern with incomplete penetrance. The absence of functional deficits and the family history support the diagnosis.
• Option B: Thumb hypoplasia (type II) involves hypoplasia of the thenar muscles and narrowing of the first web space, which are not present here.
• Option C: Clinodactyly refers to a curvature of a digit in the plane of the hand, most commonly affecting the small finger.
• Option D: Ectrodactyly, or split hand/foot malformation, is characterized by the absence or hypoplasia of digits, which is not seen in this patient.
• Option E: Camptodactyly describes a flexion deformity, typically involving the proximal interphalangeal joint, which is also not present in this case.
