PMC6968632_01
Thumb polydactyly Type IV S u (Rotterdam classification) with radial metacarphophalangeal joint synostosis.
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A 14-year old healthy boy of Ethiopian descent presented with a duplicated thumb on his right hand consisting of a non-functioning hypoplastic radial and a fully developed functional ulnar component (Figure 2). X-Rays of his right hand showed a Wassel Type IV resembling polydactyly with radial synostosis at the metacarpophalangeal joint and a slightly hypoplastic distal phalanx as well as a normally developed ulnar component with a proximal and distal phalanx (Figure 2).
Intraoperative findings, bold white arrow: accessory FPL; bold black arrow: accessory APL; empty white arrow: FPL; empty black arrow: APL; black star: accessory proximal phalanx.
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During surgery (Figure 3) the hypoplastic bony radial component was resected with an oscillating saw cutting from distal to proximal at the level of the metacarpophalangeal joint and the metacarpal head reduced to match the proximal ulnar phalanx.
Clinical and radiological result at 1 year postoperative.
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At three months and one year follow-up the patient showed no metacarpophalangeal joint instability, a satisfying motion of the thumb (Figure 4) as well as intact sensation.