Treatment of Blauth Type IIIB Thumb Hypoplasia Using a Nonvascularized Toe Phalanx

The purpose of this study was to evaluate surgical outcomes of thumb preservation surgery for Blauth type IIIB hypoplastic thumbs using a nonvascularized toe phalanx to reconstruct the carpometacarpal joint. We reviewed the records of 12 patients with Blauth type IIIB thumb hypoplasia who underwent nonvascularized toe proximal phalanx transfer from the fourth toe. Stability and mobility of the thumb, lateral pinch power, and the percentage of the thumb length relative to the index finger proximal phalanx were evaluated. Outcomes were also assessed with the Functional Dexterity Test, a visual analog scale for daily use of the operated thumb, and for overall functional and appearance satisfaction of the parents. Age at operation ranged from 0.9 to 11 years (mean, 3.0 years; median, 1.5 years). The mean follow-up period was 7.6 years (minimum, 3 years). Secondary reconstruction was planned in all 12 patients, but 2 families did not desire a second surgery. Secondary reconstruction consisted of tendon transfer for opposition, adduction, and/or extension of the reconstructed thumb and/or realignment surgery of the thumb axis by arthrodesis or corrective osteotomy. Eleven patients had good carpometacarpal joint stability. Thumb opposition was possible to the little finger in 7, to the middle finger in 3, and not possible in 2 patients. The mean lateral pinch strength was 18% of the contralateral normal side. The relative length of the thumb was 57% of the index finger. Time in seconds to complete Functional Dexterity Test was 83 seconds in the affected side and 38 seconds for the contralateral side. The visual analog scale suggested parental satisfaction for both the appearance and the function. The parents felt that their child used the reconstructed thumb more frequently when manipulating large objects than when manipulating small objects. Nonvascularized toe phalanx transfer is a useful procedure to preserve the thumb in Blauth type IIIB thumb hypoplasia. It provides a mobile, stable thumb that is functionally useful for the child and satisfying for the family. Therapeutic IV.