Download Sensate First Dorsal Metacarpal Artery Flap for Resurfacing

ORIGINAL ARTICLE
Sensate First Dorsal Metacarpal Artery Flap for Resurfacing
Extensive Pulp Defects of the Thumb
Shun-Cheng Chang, MD, Shao-Liang Chen, MD, Tim-Mo Chen, MD, Chia-Jueng Chuang, MD,
Tian-Yeu Cheng, MD, and Hsian-Jenn Wang, MD
Abstract: Finding an appropriate soft-tissue grafting material to
close a wound located over the distal phalanx of the thumb, especially the pulp region, can be a difficult task. A sensate first dorsal
metacarpal artery flap, mobilized from the dorsum of the adjacent
index finger and used as an island pedicle skin flap, can be useful for
this purpose. The pedicle includes the ulnar branch of the first dorsal
metacarpal artery, the dorsal veins, and the cutaneous branch of the
radial nerve. Although this tiny artery is anatomically variable, safe
dissection can be achieved by including the radial shaft periosteum
of the secondary metacarpal bone and the ulnar head fascia of the
first interosseous muscle.
This approach has been used for 8 individuals with extensive
pulp defects of the thumb over the past 3 years. Skin defects in all
patients were combined with bone, joint, or tendon exposure. All flaps
survived completely. This 1-stage procedure is reliable and technically
simple. It provides sensate coverage to the pulp of the thumb but also
avoids nerve repair or more complicated microsurgery.
Key Words: first dorsal metacarpal artery flap, pulp defect of
thumb
(Ann Plast Surg 2004;53: 449 – 454)
E
xtensive pulp defects of the thumb, with the exposure of
tendon or bone, are challenging reconstructive problems
because of the lack of locally available tissue. Surgical
treatment includes the use of local, regional, and free flaps.
The use of local flaps, including transposition and
advancement flaps with random vascularity, is restricted
because of the limited range of flap mobility and the limited
amount of tissue movable from nearby areas.1 The use of a
skin flap mobilized from an adjacent finger, such as the
cross-finger flap, requires a staged approach and has limitations, including a considerable period of immobilization, with
the risk of subsequent joint stiffness and a limited arc of
transposition.2
The heterodigital neurovascular island flap formed
from the ulnar pulp of the middle finger or the radial pulp of
the ring finger, based on the proper palmar digital artery and
nerve, is another option. However, with this flap, 2 major
digital arteries are killed and extensive digital and palmar
dissection is needed.3 Microvascular transfer of a free flap,
like free partial toe transfer, can be used to remedy these
problems, but such a technique requires microsurgical experience and prolonged operation.4
Since Foucher and Braun5 demonstrated that a sensate
skin island flap created from the dorsum of the index finger
could be raised and based upon the first dorsal metacarpal
artery and sensory branch of the radial nerve, similar flaps
have been reported subsequently and have been shown to be
appropriate for resurfacing the defects of the dorsal thumb or
the first web space.6 –9 Reports seldom comment on its use for
pulp loss from the thumb. Here we report 8 cases of extensive
pulp loss extending to the tip of the thumb, which were
resurfaced with a sensate first dorsal metacarpal artery
(FDMA) flap in a single stage procedure.
Vascular Anatomy
Received February 9, 2004; accepted for publication March 15, 2004.
From the Division of Plastic Surgery, Department of Surgery, Tri-Service
General Hospital, National Defense Medical Center, Taipei, Taiwan,
R.O.C.
Presented at the Annual Meeting of the Taiwan Association of Surgery,
Taipei, March 28, 2003.
Reprints: Shao-Liang Chen, Division of Plastic Surgery, Tri-Service General
Hospital, 3F, No25, Alley 4, Lane 154, Yung-Chun Street, Taipei 100,
Taiwan, R.O.C. E-mail: [email protected]
Copyright © 2004 by Lippincott Williams & Wilkins
ISSN: 0148-7043/04/5305-0449
DOI: 10.1097/01.sap.0000137134.15728.dd
The FDMA is a constant vessel arising from the radial
artery just distal to the tendon of the extensor pollicis longus
and proximal to the point at which the radial artery pierces
between the radial and ulnar heads of the first dorsal interosseous muscle.10 The artery runs over the fascial layer of
the first dorsal interosseous muscle and divides into the radial
branch to the thumb, the intermediate branch to the first web
space, and the ulnar branch to the index finger. The ulnar
branch usually courses distally within the musculo-osseous
groove, between the ulnar head of the first dorsal interosseous
muscle and the radial shaft of the second metacarpal bone,
Annals of Plastic Surgery • Volume 53, Number 5, November 2004
449
Annals of Plastic Surgery • Volume 53, Number 5, November 2004
Chang et al
until it reaches the metacarpophalangeal (MP) joint. Here a
nutrient branch from the second palmar metacarpal artery
joins the artery before it divides into a number of small
vessels, which supply a rich subdermal plexus over the
dorsum of the proximal phalanx (Fig. 1A).11
PATIENTS AND METHODS
The FDMA flap was used to reconstruct the pulp defects
of the thumbs in 8 patients over 3 years. The patients included 6
men and 2 women, ranging in age from 20 to 56 years. They all
had avulsion injury or painful scar needing reconstruction. Tissue grafting was contraindicated for all patients because of the
exposure of tendons or bones at the wound site. The flap was
used in the acute stage for wound coverage in 7 patients, and 1
was performed in the late reconstructive stage.
Operative Technique
A skin marking, with its size determined by the defect
of the thumb, is made over the dorsum of the proximal
phalanx of the adjacent index finger. The flap margins are
outlined proximally and distally to preserve the dorsal skin of
the MP joint and the proximal interphalangeal (PIP) joint
respectively. The width of the flap is designed so that it does
not to extend beyond the radial and ulnar midaxial lines of the
proximal phalanx. The estimated pivotal point is then marked
on the site of origin of the FDMA.
Operation is performed with the patient under general,
axillary block, or regional anesthesia, with the aid of tourniquet control and loupe magnification. The flap is raised from
the distal to the proximal side and from the ulnar to the radial
side. Care is taken to leave the paratenon undisturbed to
FIGURE 1. A, The first dorsal metacarpal artery (FDMA) divides into the
FDMAr to the thumb, the FDMAi to
the first web space, and the FDMAu
to the index finger. The flap territory
is limited between the MP joint and
the proximal interphalangeal joint.
The cutaneous branch of the radial
nerve is included in the flap. The
dotted line means the radial shaft
periosteum of the secondary metacarpal bone will be included in the
pedicle. B, FDMAu usually courses
within the musculo-osseous groove,
between the ulnar head of the first
dorsal interosseous muscle and the radial shaft of the secondary metacarpal
bone. C, After raising the flap, the
FDMAu (arrows) sticks to the fascia of
the musculo-osseous groove. The radial shaft periosteum (arrowheads)
of the secondary metacarpal bone is
included in the pedicle for safe dissection of this tiny artery. FDMAi, intermediate branch of FDMA; FDMAr, radial branch of FDMA; FDMAu, ulnar
branch of FDMA; MC I, first metacarpal bone; MC II, second metacarpal
bone; RA, radial artery; RN, radial
nerve.
450
© 2004 Lippincott Williams & Wilkins
Annals of Plastic Surgery • Volume 53, Number 5, November 2004
ensure the “take” of a skin graft and the free gliding of the
tendon. The fascia pedicle will be taken through a zigzag
skin incision and subdermal dissection along the radial
border of the MP joint toward the pivot point; thus, the
maximal potential length of the flap pedicle can be
achieved, allowing it to reach the thumb tip without
tension. The pedicle includes the fascia of the first dorsal
interosseous muscle, the dorsal veins, and the sensory
branch of the radial nerve (Fig. 1B).
Although the ulnar branch of the FDMA is tiny and
courses deeply within the musculo-osseous groove, no attempt is made to visualize the artery. Instead, safe dissection
can be achieved by including the radial shaft periosteum of
the second metacarpal bone, continued by the ulnar head
fascia of the first dorsal interosseous muscle (Fig. 1C).
Another key point for successful flap dissection is near the
MP joint, where the nutrient branch needs to be carefully
identified and divided. Also, distal to this critical area, the
FDMA starts to ramify into small vessels. If the fascia
overlying the first dorsal interosseous muscle is not included, dissection will be difficult. After raising the flap,
the tourniquet is released and vascular flow to the flap is
ascertained. A subcutaneous tunnel is made, and the flap is
transferred by gentle traction into the pulp defect of the
thumb. The donor site is grafted with either a splitthickness or full-thickness skin graft, depending on convenience during surgery.
RESULTS
Clinical data were summarized in Table 1. The flap
sizes ranged from 3 ⫻ 1.5 cm to 5 ⫻ 3 cm, and all survived
completely. The eventual static 2-point discrimination of
the flap ranged from 6 to 14 mm, and the patients needed
4 to 8 months to reorient the flap in the new location. The
skin grafts applied to the donor area were satisfactory, and
full recovery of flexion and extension of the index finger
Metacarpal Artery Flap for Resurfacing Pulp Defects
was also obtained. The only complaint from the patients
was graft discoloration.
CASE REPORTS
Case 2
A 28-year-old man experienced a crushing injury with
soft tissue loss and joint exposure over the pulp of his left
thumb. A sensate FDMA flap, 3 ⫻ 1.5 cm in size, was raised
to cover the defect. The flap was completely viable following
surgery, and its static 2-point discrimination was 8 mm, as for
the contralateral side of the dorsal index finger (Fig. 2A-D).
Case 7
A 37-year-old man sustained an electric saw injury with
extensive pulp loss and bone exposure to his right thumb. A
sensate FDMA flap, 5 ⫻ 3 cm in size, was raised to restore
the pulp defect. The vascular pedicle, including the radial
shaft periosteum of the second metacarpal bone, was dissected to the origin of the FDMA. The flap survived well and
the contour of the thumb appeared to be nicely restored. The
static 2-point discrimination of the flap was 9 mm (Fig.
3A-D).
DISCUSSION
As an island sensory flap, the FDMA flap has a pedicle
length up to 7 cm, allowing a wide arc of rotation, and has
proved to be very useful in resurfacing pulp defects of the
thumb.12 Although there are some variations of the FDMA
and its ulnar branch is tiny and fragile, the vascularity of the
FDMA flap can be maintained if the fascia overlying the
musculo-osseous groove is included in the pedicle. Because
the ulnar branch of the FDMA usually sticks to the fascia
within the groove, this modified method avoids the need for
meticulous dissection of the artery or raising the flap on a
nondominant arterial branch.
TABLE 1. Patient Data
Patient
Sex/age
(y)
Cause
Flap Size
(cm)
Complication
Static 2-PD
(mm)
Reorientation
(months)
1
2
3
4
5
6
7
8
M/20
M/28
M/21
F/42
M/20
F/56
M/37
M/40
Avulsion
Avulsion
Avulsion
Avulsion
Avulsion
Scar contracture
Avulsion
Avulsion
3.5 ⫻ 3
3 ⫻ 1.5
3.5 ⫻ 2
3.5 ⫻ 2.5
4⫻2
4⫻2
5⫻3
4 ⫻ 2.5
Flap congestion
Nil
Nil
Nil
Nil
Nil
Nil
Nil
14
8
7
8
6
6
9
7
8
4
6
4
6
4
5
6
F, female; M, male; 2-PD, 2-point discrimination.
© 2004 Lippincott Williams & Wilkins
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Chang et al
Annals of Plastic Surgery • Volume 53, Number 5, November 2004
FIGURE 2. A, A pulp defect of the
left thumb with joint exposure. B, A
sensate FDMA flap, 3 ⫻ 1.5 cm in
size, was designed on the dorsum of
the proximal index finger. C, Immediately after the operation, the pulp
has been nicely restored. D, View at
2-year follow-up. The static 2-point
discrimination was 8 mm, as on the
contralateral side of the index finger.
The dorsal cutaneous branch from the radial nerve is
included in the flap for obtaining sensory restoration.13 The
nerve enters the flap lateral to the MP joint and superficial to
the extensor apparatus. It is easily identified. All cases in our
series recovered good or excellent tactile gnosis, while the
eventual static 2-point discrimination was in the order of 6 to
14 mm. Although the sensation pattern of this flap in the new
452
location of thumb pulp was still felt as if it was at the donor
site—the dorsum of the proximal index finger—most patients
adapted it to well within 4 to 8 months.
Size limitation is a restricting factor for the FDMA flap,
which can extend distally to the PIP joint and proximally to
the MP joint.14 –16 There is no single artery that traverses the
dorsal skin of the proximal phalanx after the ulnar branch of
© 2004 Lippincott Williams & Wilkins
Annals of Plastic Surgery • Volume 53, Number 5, November 2004
Metacarpal Artery Flap for Resurfacing Pulp Defects
FIGURE 3. A, Extensive pulp loss of
the right thumb with bone exposure. B, A large sensate first dorsal
metacarpal artery flap, 5 ⫻ 3 cm in
size, was raised from the dorsum of
the index finger. C, The flap resurfaced the pulp defect completely
and the donor site was covered with
skin graft. D, View at 1-year followup. The contour of the pulp has
been restored and the static 2-point
discrimination was 9 mm. Free joint
motion of the index finger was also
noted.
the FDMA ramifies into small branches distal to the MP joint,
so the flap is a random flap, and its length should be confined
within the dorsum of the proximal phalanx. If the flap extends
beyond the PIP joint, the viability of its distal part and scar
contracture of the donor region will be the major concerns. In
our series, there was no morbidity related to the donor area on
the dorsum of the index finger. Good take of the skin graft on
preserved paratenon and maintaining the specialized skin
© 2004 Lippincott Williams & Wilkins
over the MP and PIP joints intact were factors contributing
to this.
The main goal of the plastic surgeon facing a complex
soft-tissue defect is to replace “like with like” tissue at
minimal donor site cost and with maximal efficacy. The
FDMA flap, which allows the surgeon to accomplish the goal
better, should serve as a valuable alternative for sensory
resurfacing in the thumb.
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Chang et al
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© 2004 Lippincott Williams & Wilkins