Congenital Disorders of the Pediatric Thumb

Abstract

» Surgical timing for pediatric trigger thumb treatment is controversial for numerous reasons including the potential for spontaneous resolution, the possibility of bilateral involvement, and anesthesia concerns regarding the developing brain. Hence, a reasonable approach is to delay the surgical procedure until the patient is ≥3 years of age.» Preaxial polydactyly is usually unilateral and sporadic, with the most common reconstruction method consisting of excision of the diminutive thumb with preservation and soft-tissue reconstruction of the dominant thumb. The surgical procedure is typically performed around the patient age of 1 year to decrease the risks of anesthesia but allow reconstruction prior to the development of a tip-to-tip pinch.» Triphalangeal thumb and thumb hypoplasia are often found in the setting of systemic anomalies such as Holt-Oram syndrome, thrombocytopenia absent radius syndrome, Fanconi anemia, VACTERL (vertebral anomalies, anal atresia, cardiac anomalies, tracheoesophageal fistula, renal defects, and limb anomalies), and/or Blackfan-Diamond anemia. As such, patients should receive adequate workup for these entities. A surgical procedure should be performed only once patients have been medically cleared.» The status of the carpometacarpal joint in thumb hypoplasia determines whether reconstruction with first web space deepening, collateral ligament stabilization, and opponensplasty compared with index pollicization is performed.

Common Pediatric Hand Anomalies

“…35,36 ►Table 4 details the structural and functional changes that occur during pollicization. 26 Overall, both thumb hypoplasia reconstruction and index pollicization do well. One review of ADM opponensplasty showed mean postoperative key pinch strength of 40% when compared with normal age-matched controls.…”

“…25 It is important to screen these patients for associated syndromes, the most common being Fanconi anemia, thrombocytopenia absent radius syndrome, Holt–Oram syndrome, and vertebral anomalies, anal atresia, cardiac anomalies, tracheoesophageal fistula, renal defects, and limb anomalies association ( Table 2 ). 26 Initial workup should include spinal radiographs, echocardiogram, complete blood-cell count, abdominal ultrasound, and possibly chromosomal breakage test (i.e., diepoxybutane testing) to rule out Fanconi anemia. 25 27 Surgical reconstruction of the hypoplastic thumb should only be performed after obtaining appropriate medical clearance.…”

Genetics of congenital anomalies of the hand

“…It follows an autosomal dominant inheritance model with reduced penetrance[ 4 ]. Thumb polydactyly has been further subdivided into six subtypes by Wassel according to the level of (metacarpal, proximal, or distal phalange) and the extent of duplication (partial and complete)[ 5 , 6 ]. Next generation sequencing (NGS) analysis in a patient with Wassel III polydactyly identified three gene mutations as follows: (1) Substitution c.1639 G>T in RPGRIP1 gene; (2) Insertion of adenine in TMEM216 gene; and (3) A>G nucleotide substitution (c.490) in FBN1 gene.…”

Surgical Reconstruction for the Triphalangeal Thumb

“…16 Hypoplastic variations are more often seen with congenital malformations and in the setting of Holt-Oram syndrome, Blackfan-Diamond syndrome, and Fanconi anemia. 7,17,18 With profound variability in clinical presentation, many authors have sought to delineate classification schemes, but without substantial success in attaining uniform use. Published classification systems focus on the clinical features of the triphalangeal thumb, such as the shape of the accessory phalanx, [20][21][22] opposition, [23][24][25] syndactyly and polydactyly, 7 and type of polydactyly present.…”