Congenital and Pediatric Hand Conditions
Framing the problem
Congenital differences are approached with three questions: is the anomaly isolated or syndromic, is the limb growing normally, and does function (or the growth of adjacent parts) demand early surgery?
Syndactyly. Simple (skin only) versus complex (bone/fascia), complete versus incomplete. Border-digit webs (thumb–index, ring–small) are released early, around 6 months, because the longer digit tethers the shorter one; central webs are usually released at 12–18 months. The most tested rule is that only one side of a digit is released per stage, leaving the digit an intact blood supply from the other side; full-thickness grafts cover the defects created.
Polydactyly. Preaxial thumb duplication is classified by Wassel (I distal phalanx through VII triphalangeal); Wassel IV is most common. Reconstruction aims at a stable, aligned thumb with a shared, centrally placed nail and a preserved ulnar collateral ligament.
Thumb hypoplasia. Blauth I–V. Types I–II are reconstructable; IIIB (absent CMC or severe metacarpal deficiency), IV (absent thumb), and V (absent thumb and radius) are best treated by index pollicization.
Radial longitudinal deficiency. Screen for VACTERL (renal ultrasound, echocardiogram, spine films), Holt–Oram (TBX5, cardiac), and Fanconi anemia (chromosome breakage studies, CBC) before any surgery.
Traps: assuming every pediatric trigger thumb needs release (most resolve by about 1 year), confusing trigger thumb with thumb hypoplasia, mismatching Blauth IIIA versus IIIB, and splinting a radial deficiency instead of working it up.
Rule of thumb: 'one side per digit' when staging syndactyly release.