Review Question - QID 4508

The clinical vignette is consistent with an oblique amputation of the distal phalanx of a thumb with a defect measuring >2.5 cm. Island volar advancement flaps are a safe and effective procedure for single-stage closure of considerably large thumb defects measuring up to 3.5 cm in length.

The operative technique chosen for reconstruction of distal volar thumb defects depends largely on the size of the defect. Island volar advancement flaps used for defects up to 3.5 cm are pure island flaps in which all of the proximal attachments, with the exception of the neurovascular bundles, are divided to provide maximal advancement. Mobility up to 4 cm can be achieved with elevation of the entire volar skin of the thumb from the underlying tendon sheath providing a considerable advantage in thumb reconstruction. The island volar advancement flap is useful for coverage of the entire distal phalanx from the IP joint crease to the nail bed.

Foucher et al. reviewed long-term clinical results of 13 neurovascular palmar advancement flaps for thumb tip coverage. Specifically, they reported on Moberg and O’Brien flaps. The Moberg flap is a pedicled advancement flap proximally-based on an intact skin pedicle of the thumb including both neurovascular bundles. The O’Brien flap is a modification of the Moberg technique which advances a volar flap based on a subcutaneous pedicle including both neurovascular bundles by incising the proximal skin and skin grafting the donor site. The study found that both flaps preserved near-normal pulp sensibility, MP and IP joint motion, and grasp and pinch strength. They suggested that Moberg and O’Brien flaps remain the first choice for coverage of 1-2 cm thumb pulp defects.

Baumeister et al. reported on the functional outcomes of 25 patients that underwent thumb pulp reconstructions utilizing Moberg volar advancement flaps. They found that 72% of patients had no or only minor subjective complaints, 74% had normal sensitivity, DASH scores showed only minor impairments, no flaps resulted in decreased grip strength, and only minor restrictions were identified in active IP joint motion. All defects with a length less than or equal to 2 cm were successfully reconstructed, whereas, patients presenting with defects >2 cm developed complications.

Mutaf et al. reviewed outcomes of 12 patients that underwent thumb reconstruction utilizing an island volar advancement flap for traumatic distal thumb injuries measuring 3 to 3.5 cm in length. Their results showed that none of the flaps failed, no patients had limited mobility or scar contractures, near-normal sensation was achieved, excellent recovery of pinch strength occurred, and maximal preservation of thumb length was possible in all patients.

Figure A and Illustrations A through C represent a case example presented by Mutaf et al. Figure A depicts an oblique amputation of the distal phalanx of a right thumb. Illustration A reveals elevation of an island volar advancement flap on both sides of the digital neurovascular bundles in the same thumb. Illustration B reveals flap advancement and Illustration C reveals a postoperative image of the same thumb 4 months after surgery.

Incorrect Answers:
Answers 1 & 2: Small or superficial defects may be amenable to conservative treatment or local flaps depending on the location of the defect.
Answers 3 & 4: The Moberg flap with modifications to lengthen distal advancement as necessary is considered a standard option for medium-sized defects of the thumb pulp less than or equal to 2 cm.