Keywords finger injuries - perforator flap - hand injuries
Introduction
Covering the soft-tissue defect of the digits requires various surgical techniques
incarnating flaps. These include the transposition flap, rotation flap, cross-finger
flap, and vascular island flap methods for using nonmicrosurgical flaps for soft-tissue
defects in the digits. Among them, the vascular island flap is used when there is
not enough soft tissue around the defect, the defect has a large size, or it requires
a one-stage procedure or an early mobilization.[1 ]
In 1990, Quaba and Davision first described the dorsal metacarpal artery (DMCA) perforator
flap; it consists of an axial patterned vascular island flap that rises from the hand
dorsum.[2 ] Owing to its reliability and versatility, this flap is used as a workhorse for soft-tissue
defects of the finger in various locations, such as the dorsal area of the finger,
palmar side of the proximal phalanx, and web spaces, to name a few.
The DMCA perforator flap is mainly used to cover defects from the index finger to
the little finger using the second to fourth DMCA.[1 ] In particular, the flap using the first dorsal metacarpal artery (FDMA) is called
the FDMA flap; this is mainly used for reconstructing thumb defects.[3 ] However, to cover the radial-volar defect of the proximal interphalangeal joint
(PIPJ) of the index finger, a longer flap is required. Here, we introduced the oblique
extended reverse FDMA perforator flap to cover the radial-volar aspect defect of the
index finger.
Case
A 45-year-old man came to the emergency room with an injury to the radial-volar defect
of the PIPJ of the left index finger caused by a thermal press machine ([Fig. 1 ]). The wound was 2 × 1 cm in size, and the joint and bone were exposed. He did not
want a long operation time and a scar in areas other than the hand; hence, we decided
to perform an oblique extended reverse FDMA perforator flap to cover up the volar
defect of the PIPJ.
Fig. 1 The radial-volar defect of the proximal interphalangeal joint of the left index finger
was caused by a thermal press machine. It was 2 × 1 cm in size and had exposed the
joint and bone.
Under general anesthesia, a pinch test of the hand dorsum was performed to confirm
that there was sufficient laxity of the skin. Then, the width of the flap was determined
enough to close primarily of the donor site. The FDMA perforator at the neck of the
second metacarpal bone where the palmar metacarpal artery (PMCA) and FDMA anastomoses
was set as the pivot point, and the flap length was determined as the length from
the pivot point to the PIPJ defect. The flap size was 11 × 1.5 cm and was obliquely
designed from the second metacarpal neck to the fourth metacarpal base, and the proximal
margin did not exceed the wrist crease.
A pneumatic tourniquet was inflated, and an incision was made from the proximal of
flap. FDMA originated directly from the radial artery, just distal to the extensor
pollicis longus tendon. It passes deeper than the second extensor digitorum communis
tendon and more superficially than the deep interosseous muscle fascia. After ligation
of the FDMA origin, the elevation of the cutaneous adipofascial flap was performed,
including the deep interosseous muscle fascia, to prevent damage to the venous outflow
([Fig. 2 ]). The perforator of FDMA was found within the vicinity of the second metacarpal
neck, and the flap was elevated by attaching sufficient adipose tissue without skeletonization.
Then, the flap was rotated in the counterclockwise direction to release tension and
prevent twists. The distal flap was fully covered with the radial-volar defect of
the index finger ([Fig. 3 ]). The donor site was then primarily closed.
Fig. 2 Schematic diagram showing intraoperative oblique extended reverse first dorsal metacarpal
artery perforator flap elevation. The distal first dorsal metacarpal artery (FDMA)
was preserved, and its perforator worked as a single pedicle in the flap. The fascia
was included in the flap. PMCA, palmar metacarpal artery; RA, radial artery.
Fig. 3 Immediate postoperative clinical photo. The flap was elevated by oblique extension
to the fourth metacarpal base level, and the defect was fully covered.
After reconstruction, the flap remained stable without venous congestion. One year
after surgery, the metacarpophalangeal joint had a full range of motion, and the aesthetic
result was acceptable ([Fig. 4 ]).
Fig. 4 After 12 months of operation, the flap was stable without complications.
Discussion
The DMCA perforator flap is a flap that uses the DMCA as the pedicle and covers the
defect in the finger by elevation from the hand dorsum. The hand dorsum is an appropriate
donor site with appropriate color and tissue match for covering soft-tissue defects
in the fingers. The DMCA flaps can be performed as a one-stage operation, and the
donor is usually capable of primary closure; early mobilization is also possible after
the operation.
The use of the first reverse DMCA flap was mentioned in Maruyama's study on eight
flaps.[4 ] Quaba and Davison reported flap elevation using the anastomosed artery between the
PMCA and DMCA around the second to fourth metacarpal neck area.[2 ] Several anatomic studies regarding the DMCA confirmed its constancy and branch variation.[5 ]
[6 ]
The FDMA has been well identified in Sherif's work as the most anatomically constant
vessel in the whole DMCA.[7 ] It originates from the radial artery and usually has three branches. The flap using
the FDMA perforator has only been recently studied. di Summa et al introduced the
first web space defect as a propeller flap using an FDMA perforator.[8 ] However, it does not reach the PIPJ or more distal defect since its flap length
was too short. Aizawa et al conducted a study to find the FDMA perforator in 29 cadavers.[9 ] FDMA was found in 27 specimens, and the most distal perforator of FDMA was located
mainly in the metacarpal head and neck area.
Unlike soft-tissue defects of the other digits that conventionally use DMCA perforator
flaps and FDMA flaps, the radial-volar defect of the PIPJ in the index finger has
limited options in nonmicrosurgical flaps because there is no adjacent finger other
than the thumb, which is the most important finger in hand function. Hence, this is
rarely used as a donor site. In previous studies, Chen et al performed the dorsal
homodigital island flap with the dorsal branch of the proper digital artery as the
pedicle to cover pulps or tip defects of the index finger.[10 ] Similarly, Zhang et al used the transposition flap from the dorsum of the proximal
phalanx to cover the volar soft-tissue defects of the PIPJ in five cases.[11 ]
In our case, unlike the aforementioned reverse DMCA flap, the oblique extended reverse
FDMA perforator flap is elevated oblique proximally, and the flap spans the second
to fourth metacarpal bone. Through this method, it is possible to reach the PIPJ defect
that is far from the FDMA perforator of the metacarpal neck area compared with the
previously introduced FDMA perforator flaps.[8 ]
[9 ] Venous congestion was prevented through elevation of the fascia. By choosing the
perforator at the metacarpal neck area rather than the proximal phalanx level, the
arterial supply is also more stable, and the flap is easier to elevate and has fewer
complications. Proximal scars of the donor site were covered by the relaxed skin tension
lines of the wrist crease, and the vertical scar and flap were biased toward the radial
side of the hand; hence, the overall scar was not visible on the front dorsal view,
which was aesthetically acceptable.
The oblique extended reverse FDMA perforator flap is a reliable method for covering
the radial-volar defect of the PIPJ of the index finger. It could reach a more distal
wound than the conventional reverse FDMA flaps. This flap, which also has an aesthetic
advantage, will be a good choice for hand surgeons who want to cover the PIPJ defect
of the index finger using a nonmicrosurgical option.
