First Dorsal Metacarpal Artery Flap Versus Reverse Homodigital Dorsoradial Flap in Soft Tissue Reconstruction of Post-Traumatic Deep Thumb Defects

INTRODUCTION
In complex thumb injuries with large skin and
soft tissue substance loss, exposure of deep vital
structures such as bone, tendon, and nerve could
happen [1]. These skin defects could not be left for
healing by secondary intention and are not amenable
to simple closure or skin graft coverage [2], in
this situation the need of immediate coverage with
a flap is mandatory to preserve the deep vital
structures [3].
Several flaps have been proposed for thumb
defect resurfacing ranging from local, regional to
free flaps [3,4]. the choice of a particular flap must
fulfill the unique reconstruction goals concerning
with soft tissue coverage of thumb defect, which
should be stable, pliable to the extent not to hinder
mobility of both donor and recipient site, maintain
length without bone shortening [5.6], beside obtaining
a proper soft tissue padding with restoration
of the contour and protective sensibility in reconstructed
pulp injuries [2,4].
First dorsal metacarpal artery flap (1st DMCA)
has stood the test of time and is considered as the
workhorse for partial thumb defect reconstruction,
but in certain situations it could be not selected
such as; this flap is no longer available due to
associated injury to its vascular pedicle, or it is
blamed as it is a heterodigital flap with tethering
and morbidity to adjacent index finger [4].
An alternative flap may be needed, many anatomical
studies have defined the dorsal blood
supply of the thumb, revealed a constant anatomy
of dorsoradial digital artery of the thumb; this led
to the development of a reverse homodigital dorsoradial
fasciocutaneous flap from the dorsum of
the thumb metacarpal area [7].
The purpose of this study was to compare the
use of two regional flaps; first dorsal metacarpal
artery [1st DMCA], and reverse homodigital dorsoradial
artery flap [RHDRA] for reconstruction
of partial soft tissue defects of the thumb, by
assessing wound healing of donor and reconstructed
sites, sensibility recovery in reconstructed pulp
Egypt, J. Plast. Reconstr. Surg., Vol. 42, No. 2, July: 367-374, 2018
First Dorsal Metacarpal Artery Flap Versus Reverse Homodigital
Dorsoradial Flap in Soft Tissue Reconstruction of Post-Traumatic
Deep Thumb Defects
AYMAN FIKRY MEHANNA, M.D.; MOHAMED ALI NASR, M.D. and MOHAMED WAHSH, M.D.
The Department of General Surgery, Plastic & Reconstructive Surgery Unit, Faculty of Medicine, Zagazig University
367
area, and functional outcome of the reconstructed
thumb.
PATIENTS AND METHODS
From September 2016 to October 2017, Random
sample of eighteen patients having partial
thumb soft tissue defect were included in this study.
The patients were equally divided into two groups;
nine patients were representing the odd numbers,
were operated by 1st dorsal metacarpal artery flap
and described as group A and nine patients were
represented the even numbers, were operated by
reverse homodigital dorsoradial artery flap and
described as group B.
This study was conducted in plastic surgery
unit, general surgery department, Zagazig University
after approval of The Ethical Committee in
Zagazig University; all participating patients were
informed about the steps of the procedure and
possible complications and were consented. Patient's
details are summarized in Table (1).
The patients with a mutilating hand trauma, in
which there is an associated injury that may compromise
the vascular pedicle or the cutaneous
territory of both flaps, were excluded from the
study.
In both groups; all patients received perioperative
antibiotic, the surgical procedures were done
under general anesthesia. After wound debridement
of the thumb defect or (post burn-post traumatic)
contracture scar release, flap harvesting and mobilization
of the pedicle was performed under tourniquet
control and loupe magnification.
368 Vol. 42, No. 2 / First Dorsal Metacarpal Artery Flap
Table (1): Patients data.
Site
Rt Palmer+1st
web
Lt Pulp space
Dorsal
Palmer
Lt Pulp space
Rt Pulp space
Palmer
Dorsal
Palmer
Half of Lt distal
phalanx
Half of Rt distal
phalanx
Lt finger tip
Lt Palmer+1st
web
Dorsal
Lt Pulp space
Dorsal
Palmer
Lt Pulp space
Patient
1
23456789
10
11
12
13
14
15
16
17
18
Sex/Age
(yr)
M/27
M/33
M/25
M/36
F/32
M/46
M/19
M/50
M/59
M/57
M/55
M/44
F/6
M/33
M/43
M/27
F/31
M/18
Cause
Post traumatic
contracture
Traumatic
Traumatic
Infection
Traumatic
Traumatic
Traumatic
Avulsion
Traumatic
Traumatic
amputation
Avulsion
Traumatic
Post burn
contracture
Traumatic
Avulsion
Traumatic
Traumatic
Avulsion
118
122
115
118
120
115
115
118
117
90
95
90
100
85
100
85
90
100
Operative
time
(minutes)
No
No
Venous congestion
-------
-------
-------
Distal partial necrosis
-------
-------
Venous congestion
Distal partial necrosis
---------
---------
Venous congestion
---------
---------
---------
Venous congestion
Complications
Flap
Dimension
(cm)
4x2.5
4x2.6
3.9x2.5
3.8x2.5
4.2x2.6
4.2x2.4
3.9x2.6
3.7x2.4
3.9x2.4
5.6x3.5
6x3.8
6.1x3.8
3x1.5
5.5x3.8
6x4.2
5x3
4x3
5.2x3.2
Donor-Site
Repair
Skin graft
Skin graft
Skin graft
Skin graft
Skin graft
Skin graft
Skin graft
Skin graft
Skin graft
Primary closure
Primary closure
Primary closure
Primary closure
Primary closure
Primary closure
Primary closure
Primary closure
Primary closure
RHDRF 1st DMCA
First dorsal metacarpal artery (DMCA) flap:
Surgical anatomy:
It is a pedicled neurovascular flap based on 1st
dorsal metacarpal artery with its concomitant veins
and a branch of the superficial radial nerve [8].
This artery constantly originates from the radial
artery just distal to the extensor pollicis longus
tendon and proximal to the point at which the radial
artery pierces between the two heads of the first
dorsal interosseous muscle, and then it runs distally
either in fascial, subfascial, or mixed course in
relation to the fascial layer of the first dorsal
interosseous muscle.
It divides at the middle of the second metacarpal
bone into three terminal branches; The radial branch
goes to the thumb, while the intermediate branch
runs to the first web space, and the ulnar branch
to the index finger which runs distally within a
musculo-osseous groove, between the ulnar head
of the 1st dorsal interosseous muscle and the radial
shaft of the 2nd metacarpal bone, it usually terminates
at the level of the metacarpo-phalangeal joint
and then arborizes into the dorsal skin of the index
finger after giving off a perforating branch at the
level of the metacarpal neck to join the second
palmar metacarpal artery [9,10].
Surgical procedure:
With the aid of Doppler 8MHz the origin and
the course of the artery is marked, then the flap
cutaneous territory is outlined between the MP
joint and the proximal interphalangeal joint. Start
raising of the skin paddle from the distal to the
proximal direction, cautiously leaving the paratenon
of extensor tendon undisturbed to guarantee skin
graft take and the allowing free gliding of the
tendon. A lazy S skin incision is done over the
fascial pedicle with skin subdermal dissection,
Safe dissection of the fascial pedicle can be
achieved by including the radial side of the periosteum
of the shaft 2nd metacarpal bone, and then
continuing the flap raising in the subfascial plane
with including a strip of the interosseous muscle
fascia and the sensory branch of the radial nerve
with the pedicle, the tourniquet is deflated to check
flap vascularity, Figs. (1,2,3).
A wide subcutaneous tunnel is made, and the
flap is transferred by gentle traction into the defect
area of the thumb and in sited. The donor site is
grafted with full-thickness skin graft. Finally thumb
is splinted for 2 weeks.
Reversed homodigital dorsoradial artery (RHDRA)
flap:
Surgical anatomy:
It is based on the dorsal radial digital collateral
artery, it originates from the radial artery at the
level of the anatomical snuffbox; it passes under
the extensor pollicis brevis tendon, then it has a
straight and regular course on a subcutaneous plane
along the radial side of the thumb, it constantly
communicates with the palmar circuit at the level
of the middle third of the proximal phalanx. In its
course along the diaphysis of the 1st metacarpal
bone, it accompanies the dorsal collateral branch
of the radial nerve [3].
Surgical procedure:
With the aid of Doppler 8MHz the origin and
the course of the artery is identified till the pivot
point at the middle of the proximal phalanx, a line
is drawn along its course. The predicted skin island
is centered on that line; its dimensions nearly equal
the defect size. Skin incision is done at the periphery
of the skin island, and at the site of anticipated
subcutaneous pedicle; a very superficial lazy-S
skin incision is done extending from the distal end
of skin island to the pivot point with sub-dermal
dissection is done to expose the pedicle, and enough
quantity of soft tissue is left around the pedicle to
protect the vascular axis and allows venous outflow.
Then the flap is raised in a proximal to distal
direction, during raising the flap, the extensor
pollicis brevis is identified, and it is gently spread
away. The sensory collateral nerve is identified,
and it enclosed in the flap. The pedicle is dissected
from the deep tissues; it stopped near to the pivot
point to protect the anastomosis with the perforating
digital palmar vessels.
The bridging skin between the pivot point and
the edge of the defect is incised and elevated; the
tourniquet is released to ensure proper blood flow
to the flap, then the flap can be transposed and
sutured at the tissue defect site. The skin above
the pedicle is left partially opened without stitches
to avoid any tension on the pedicle. Finally the
donor site can be primarily closed directly and the
thumb is immobilized for two weeks, Figs. (4,5,6).
Follow-up: all patients were followed-up at a
period ranging at least from 6 weeks up to 6 months.
During the follow-up period the flaps were examined
for sensation, thumb movement (flexion,
extension and opposition), and post-operative
cosmetic results in both donor and recipient sites.
RESULTS
All flaps in both groups were survived, with
minimal venous congestion in only one case in
group A (compression by a narrow tunnel), and
three cases in group B; nothing was done more
than removal of stitches over the pedicle to relive
the compression, and one case in each group with
partial marginal necrosis which eventually healed
spontaneously. Otherwise all patients had maintained
full flexion and extension of the thumb, and
the outcome was satisfactory in all cases but the
redial scars were more appealing in group B than
A.
Egypt, J. Plast. Reconstr. Surg., July 2018 369
There was statistically significant difference
between group A and group B regarding flap dimensions
(cm) with (p-value 0.008), the mean
value was [3.9x2.5] in 1st DMCA flap group while
it was [5.2x3.3] with RHDRA flap group. Also
there was statistically significant difference between
the two studied groups regarding operative time
(minutes) with (p-value 0.000), the mean value
was [117.56] in group A while it was shorter [92.78]
with group B.
The Static Two-Point Discrimination testing
was done in reconstructed pulp space cases at 6
weeks postoperatively by using drawing compass;
3 cases in group A with mean value was 10.66 mm,
and 5 cases in group B with mean value was 12.61
mm with reported dual location in all cases of 1st
DMCA flaps. In both groups there was limited
period of immobilization in an appropriate position
(2 weeks) with minimal time off work.
370 Vol. 42, No. 2 / First Dorsal Metacarpal Artery Flap
Fig. (1): (A) Preoperative marking,
(B) The post traumatic contracture,
(C) Post-operative view of donor
scar 3 months later, (D) Postoperative
view of recipient site 3
months later.
Fig. (2): (A) 1st DMCA Skin
island an pedicle harvesting, (B)
Skin island at the recipient area, (C)
Subfascial dissection of the pedicle,
(D) Flap insitting.
Egypt, J. Plast. Reconstr. Surg., July 2018 371
Fig. (3): (A) Preoperative fingertip injury, (B) Post-operative view of 1st DMCA flap, (C) Opposition
of the thumb, (D) Full function of thumb.
Fig. (4): (A) Preoperative fingertip injury, (B) Preoperative marking of RHDRA flap, (C) Flap raising,
(D) Postoperative view 3 weeks later.
DISCUSSION
Reconstruction of hand soft tissue defects, and
in particular in the thumb, presents a challenging
task in relation to the restricted availability of local
tissues. Recent evolves in anatomical research
studies and continuous refinements in flap design
and harvesting techniques have led to considerable
improvement in aesthetic and functional results in
thumb soft tissue reconstruction [4,11].
Both of 1st DMCA and RHDRA flaps can provide
a versatile, sensate, moderately sized skin
paddle on a reliable vascular axis, allowing onestage
reconstruction for thumb defects without
prolonged immobilization in an inappropriate position
and without the need for free flap microsurgical
anastomosis [11,12].
The major advantage of the RHDRA flap is its
independence from other fingers with inconspicu-
372 Vol. 42, No. 2 / First Dorsal Metacarpal Artery Flap
Fig. (5): (A) Fingertip injury with exposed tendon, (B) Postoperative view 3 months later of RHDRA
flap, (C) Flap raising, (D) Flap insitting.
Fig. (6): (A) 1st web space contracture [post burn], (B) Flap raising and contracture release,
(C) Intraoperative flap insitting, (D) Postoperative view 2 weeks later.
ous donor-site morbidity, often without skin graft
at the donor site. This is critically important in
case of mutilating hand trauma which might involve
the neighboring index finger, thus reducing the
availability of the donor site of heterodigital 1st
DMCA [1]. Also the major inconvenience of 1st
DMCA flap harvesting; it probably leaves an obvious
scar on the dorsum of the hand with mandatory
skin graft at the donor site, which may be
undesirable, particularly in female patients [12].
As regard the complication; the problem of
venous congestion was the mostly occurring one,
in only one case in group A and 3 cases in group
B. this can be explained as the venous drainage of
the concomitant veins of the 1st DMCA is very
reliable [8], on the other hand venous outflow in
group B takes a random pattern rather than a defined
one after the dorsal radial artery in several anatomical
dissections [1], we took enough soft tissue
around the pedicle to overcome this problem. Also
in both group we did not try to identify or skeletonize
the vascular pedicle to avoid flap vascularity
impairment.
The skin island dimensions [width and length]
was statistically larger with the reversed flap than
1st DMCA flap, beside the versatility of the pivot
point, this is allowed coverage of wider and distal
thumb defects [8], to overcome this problem, El-
Khatib [13] and Gebhart and Meissl [14] had reported
in a small number case series; the use of an extended
skin island 1st DMCA flap that included the
dorsal skin from both the proximal and middle
phalanges of the index finger.
In our cases, good recovery of protective sensibility
was obtained in both groups, the mean
value of static two-point discrimination in group
A was 10.66, which agreed with other searchers
such as; with Chang et al., [15] it was 8.12, Muyldermans
and Hierner [8] it was 10.57, and with
Ege et al., [12] it was 10.8. While in group B, it
was 12.6 relatively higher than reported by Moschella,
and Cordova [3] which was 9.7, this perhaps
because we did the test in the early postoperative
period after 6 weeks.
We agreed with the work of Tränkle et al., [16],
that the innervated 1st DMCA flap provides immediate
sensation, but the main concern was about
the dual location phenomenon, and the problem of
cortical reorientation. Muyldermans and Hierner
[8] mentioned that cortical reorientation takes some
time, but is usually complete after 2 years. The
incomplete reorientation was reported not to be
disturbing and did not interfere with patient's daily
activities. If however, on patient demand Foucher
[17] had corrected this situation surgically with a
technique (débranchement-rébranchement) by dividing
the transferred nerve and resuturing it to
the original nerve of the thumb.
Moschella, and Cordova [3] also reported that
epineural suturing between the cutaneous branch
of the radial nerve, enclosed in the flap, and a
digital nerve, identified at the recipient site did not
improved the sensitivity, they no longer recommended
this step.
Conclusion:
The 1st dorsal metacarpal artery flap had been
recognized as a keystone in the reconstruction of
thumb defects, on the other hand the reverse homodigital
dorsoradial artery flap could be considered
another useful alternative reconstructive tool
in thumb reconstruction. Both flaps have a constant
vascular anatomy with straightforward and easy
harvesting technique, and sensate reconstructed
pulp area. The RHDRA flap has relatively larger
skin island with inconspicuous residual scar at
donor site, and less operative time compared to 1st
DMCA flap.