|
Year |
2005 |
|---|---|
|
Question Number |
91. |
|
Category |
Hand |
Question
A 35-year-old meat cutter sustains a fingertip injury to his ring finger in a meat slicing machine. Examination reveals an oblique wound beginning at the distal interphalangeal joint flexion crease with loss of volar tissue only. There is no exposed bone or tendon. Primary coverage is best achieved with a
1- V-Y advancement flap.
2- thenar flap.
3- axial flag flap.
4- cross-finger flap.
5- split-thickness skin graft.
Figures
Answer (click for answer)
PREFERRED RESPONSE: 4
The cross-finger flap (#4) is based on the dorsal aspect of the middle phalanx of the adjacent finger (usually the finger radial to the injured digit, the middle finger in this case) and is tailored to fit a volar tissue defect like in this question. Therefore, #4 is correct. #1 is wrong because V-Y advancement flaps are typically used to cover defects with dorsal tissue loss. Thenar flaps (#2) can also be used for volar tissue loss, but may be more difficult to reach for coverage in this patient with a ring finger injury, compared to a cross-finger flap. Axial flag flaps (#3) are used to cover the volar or dorsal aspect of the proximal phalanx of the index finger or the MP joint of the index or long finger, neither of which are the defect areas described here. Finally, #5 is also incorrect because split-thickness skin grafts are typically used to cover dorsal defects, not volar defects, due to their propensity for contracture. This would be less than ideal over a defect starting at the DIP joint flexion crease, as in this case.
V-Y advancement flaps are useful for covering exposed bone. This is essentially a full-thickness local skin graft that is elevated and advanced to cover the fingertip with the skin closed behind it. This is not necessary in this case as there is no bone exposed.
The cross-finger flap is used for a palmar oblique amputation to the index or ring finger, and maintains digit length. A full thickness skin flap is elevated on three sides from the dorsum of the middle finger at the middle phalanx. The flap is then opened up and sewn to the volar area of pulp loss on the injured finger. This is then a vascularized flap that stays in place for 2-3 weeks, after which the bridge is separated from the middle finger once it has taken onto the injured digit. (STSG is used to cover the dorsum of the middle finger where the flap was elevated.) Note this restores protective sensation to the tip of the injured finger.
The thenar flap is the same concept as the cross-finger flap, with skin elevated from the thenar eminence of the palm, but only works for the index and middle fingers.
Split-thickness skin graft (STSG) is not feasible as the exposed fat of the injured pulp is poorly vascularized, and STSG requires a well-vascularized tissue bed to adhere to. Usually full-thickness skin grafts are used for palmar defects, and split-thickness for dorsal defects.
The axial flag flap is raised on a vascularized pedicle based on the first dorsal metacarpal artery, and is ideal for coverage of a volar thumb tip wound. Inherently sacrifices the radial digital nerve and artery to the index, but in turn provides sensation to the covered area of the thumb. The flap is raised from the dorsum of the index proximal phalanx, which is then covered with STSG.
Reference: RECOMMENDED READINGS: Trumble TE (ed): Hand Surgery Update 3: Hand, Elbow, & Shoulder. Rosemont, IL, American Society for Surgery of the Hand, 2003, pp 479-492.