Improvement of thenar bulk appearance in index finger pollicization with adipofascial flap fashioned from pouce flottant/rudimentary thumb.

Abstract

Purpose: Index finger pollicization is a surgical technique used for Blauth Types IIIB and IV thumb hypoplasia reconstruction. Traditionally, index finger pollicization techniques have not addressed management of the rudimentary thumb/pouce flottant; with no improvements made to the thenar eminence, it often remains flat and hypoplastic. This case series aims to contribute to the body of literature supporting the technique of index finger pollicization with use of the pouce flottant to create a vascularized adipofascial flap for reconstruction of the thenar eminence.

Methods: From 2018 to 2024, a single surgeon performed a modified index finger pollicization technique on seven patients with Blauth Type IIIB and IV thumb hypoplasia. The skin incision technique incorporates the vascular pedicle to the pouce flottant to allow for creation of a vascularized adipofascial flap. This approach utilizes the soft tissue components of the remnant thumb to reconstruct the thenar eminence with a filet flap derived from portions of the typically discarded hypoplastic thumb. Cosmetic and functional outcomes were evaluated by the surgeon, the occupational therapist and the patients' parents. Functional outcomes assessed include evaluation of thumb opposition, stability, and pinch.

Results: The use of an adipofascial flap from the rudimentary thumb provided sufficient bulk to improve the appearance of the thenar eminence and hand without complications. All patients achieved satisfactory cosmetic results. All the parents were satisfied with the appearance of the hand. Two patients initially showed disfavor to utilizing the newly created thumb and restraint therapy was successfully employed to encourage use of the new thumb. The thenar eminence was maintained at latest follow-up for all patients. At one-year follow-up, all seven patients demonstrated opposition, strong pinch, flexion, and extension with continued satisfactory cosmetic results.

Conclusion: For patients with Type IIIB and IV thumb hypoplasia, soft tissue components of the remnant thumb/pouce flottant can be used as an adipofascial flap to improve the cosmetic result of pollicization. All patients demonstrated satisfactory functional and cosmetic results with improved appearance of the thenar eminence. The technique was reproducible, suggesting its implementation should be incorporated into standard practice for treatment of Types IIIB and IV thumb hypoplasia.