Research Article
The Dorso-Radial Flap. A Useful Skin Flap for Hand Reconstruction
Joseph Bakhach, Dimitri Bakhach and Elias Zgheib*
Department of Plastic and Reconstructive Surgery, Hand and Microsurgery, American University of Beirut Medical
Centre, Lebanon
*Corresponding author: Elias Zgheib, Department of Plastic & Reconstructive Surgery, Hand & Microsurgery, American University of Beirut Medical Centre, Riad el-Solh 1107 2020, Beirut, Lebanon
Published: 02 Aug, 2017
Cite this article as: Bakhach J, Bakhach D, Zgheib E. The
Dorso-Radial Flap. A Useful Skin Flap
for Hand Reconstruction. Clin Surg.
2017; 2: 1574.
Abstract
Background: Soft tissue defects on the dorsum of the hand are challenging to reconstruct and
regional options with similar characteristics are limited. We thus report an original alternative, the
dorso-radial flap, harvested from the distal quarter of the forearm dorsum and used to cover defects
of the dorsum of the hand, first web space and thumb.
Methods: Anatomic studies showed a direct cutaneous branch of the radial artery arising constantly
at the level of the first intermetacarpal space’s apex, emerging directly or through a common trunk
with the first dorsal metacarpal artery. These variations do not influence the operative technique or
flap survival. A series of 12 clinical cases is reported. Four flaps were used to cover the MCP joint of
the thumb, three were applied to resurface the first web space and the remaining five used to cover
the hand dorsum and the MCP joints. The sizes of the dorso-radial flaps ranged from 4 to 7 cm in
length and from 2 to 5 in width.
Results: Follow-up ranged from three to six months with a mean of 4.8 months. All flaps survived
and allowed enough skin coverage for the hand dorsum, underlying bones, joints and reconstructed
tendons. Donor sites were closed primarily in two cases and grafted in the remaining ten. Functional
outcomes were related to the associated bony and tendinous injuries.
Conclusion: The dorso-radial flap is a direct anterograde flap. It is simple, reliable and useful in
reconstructing soft tissue defects of the hand dorsum.
Keywords: Hand defect; Hand; Thumb; Forearm; Reconstruction; Skin flap
Introduction
The management of soft tissue defects of the hand still remains a challenge in hand surgery. Various types of distally based island flaps have been reported, most notably the reverse flow radial forearm flap, the distally based ulnar forearm flap and the posterior interosseous flap [1-4]. However, for coverage of relatively small defects of the hand and thumb, these flaps appear to be too bulky and sometimes may be related to significant donor site morbidity. We thus report a cutaneous direct island flap, which is harvested from the dorsal aspect of the distal quarter of the forearm, and is useful in covering skin defects of the hand, the thumb and the first web space.
Material and Methods
Anatomical studies
Anatomical work was carried out on 36 fresh upper limb cadavers, focusing on the cutaneous
vascularity of the dorsal aspect of the distal quarter of the forearm and wrist. This was done and
published previously by the main author [5]. It aimed to demonstrate the consistency of the dorsoradial
artery which is a branch of the radial artery, to delineate its cutaneous supply, and to define
the operative technique used to dissect it and elevate the corresponding flap [5].
We focused on two branches in particular: the first dorsal metacarpal artery, which supplies the
“kite” flap described by Foucher and Braun [6], and the dorso-radial branch corresponding to the
feeding artery of the dorso-radial flap, subject of the present work.
Our anatomic dissections showed that the dorso-radial artery is a constant cutaneous
branch of the radial artery, which arises at the apex of the first intermetacarpal space and enters
the subcutaneous tissues, passing between the tendons of the extensor pollicis longus (EPL) and
extensor carpi radialis longus (ECRL). More specifically, this artery runs proximally, parallel and medial to the tendon of the extensor pollicis longus towards the distal radio-ulnar joint. It passes above the medial branch of the superficial
radial nerve, crosses the fascia and enters the subcutaneous tissue of
the dorsum of the wrist at the medial border of the ECRL tendon. It
eventually divides into multiple fine cutaneous branches supplying
the subcutaneous arterial network of the wrist dorsum and distal
quarter of the forearm, an area which corresponds to the skin paddle
of the dorso-radial flap.
In regards to the origin of this artery, two anatomical variants
were recorded. Type I (84%) with the vessel arising directly from
the radial artery, 3 to 4 mm proximal to the origin of the first dorsal
metacarpal artery (Figure 1A), and Type II (16%) with both the
dorso-radial artery and the first dorsal metacarpal artery arising from
a common arterial trunk about 5 mm long and running vertically
before it divides into its two terminal cutaneous branches (Figure 1B)
[5]. These variations have no effect on the elevation and use of the
flap. The pivot point of the pedicle is always located over the apex of
the first intermetacarpal space, allowing a rotational arc that covers
the dorsal aspect of the hand, the thumb and the first web space, even
allowing the flap to reach the palmar aspect of the wrist if needed. In
all specimens, two accompanying venae comitantes, draining into the
radial venae comitantes were present.
Operative procedure
The skin island is designed over the distal quarter of the dorsal
aspect of the forearm according to the size and location of the skin
defect (Figure 2), although it can be extended to the entire width of
the distal forearm dorsum. We recommend orienting the longitudinal
axis of the skin paddle parallel to the EPL with its axis at the medial
border of this tendon, in order to respect the main orientation of the
dorso-radial artery.
The surgical procedure is carried out using a tourniquet. We
prefer to empty the veins by simple elevation of the arm, as this
method avoids complete exsanguination of the upper limb and
aids in the visualization of the vascular structures. The pedicle is
exposed using a skin incision in a lazy S-shaped fashion over the
apex the first web space, allowing skin elevation with preservation
of the superficial venous network. The flap is then raised from
proximal to distal including the forearm fascia and passing close to
the extensor retinaculum. The medial branch of the superficial radial
nerve should be identified and respected. At the distal border of the
dorsal retinaculum, the EPL and ECRL tendons are identified and
retracted. The pedicle is dissected with its surrounding subcutaneous
tissue in order not to harm the vessels (Figure 3). At the apex of the
first intermetacarpal space, the dissection continues palmarly to the
origin of the dorso-radial vessels, obtaining a pedicle length of 5 cm.
After completing the dissection, we prefer to place the flap back on
its donor site and release the tourniquet to allow revascularization
of the cutaneous paddle before transferring it to the recipient area
(Figure 4). When the skin paddle does not exceed 3 cm in width, the
donor area can be directly closed. If larger flaps are used, a skin graft is
applied, either primarily or secondarily, to cover the donor site defect.
Figure 1A
Figure 1A
Type I. The dorso-radial artery and the first dorsal metacarpal
artery arise independently from the radial artery, in 84% of the cases.
Figure 1B
Figure 1B
Type II. The dorso-radial artery and the first dorsal metacarpal
artery arise from a common arterial trunk, in 16% of the cases.
Figure 2
Figure 2
The EPL tendon is marked, the dorso-radial pedicle is drawn
parallel to it and at 4 mm from its medial border. The cutaneous paddle is
designed over the dorsal aspect of the distal quarter of the forearm and the
pivot point is placed at the apex of the first webspace.
Figure 3
Figure 3
The EPL and ECRB tendons are identified and retracted. The
dorso-radial pedicle with the whole surrounding fatty tissue is harvested and
dissection is conducted volarly towards the apex of the first web space.
Figure 4
Figure 4
The dorso-radial flap is placed back on its donor site and the
tourniquet is released in order to allow the revascularization of the skin flap
before transferring and spreading the flap on the recipient site.
Figure 5A
Figure 5A
Penatrating gunshot injury to the left hand involving bones,
extensor tendons, MCP joints and skin over the base of the middle and ring
fingers.
Figure 5B
Figure 5B
After extensor tendon repair and temporary bone stabilization
with K-wires, a dorso-radial flap of 6 x 4 cm is designed.
Figure 5C
Figure 5d
Table 1
Clinical Series
Twelve patients presented to us with deep lacerations to their
hands combining soft tissue defects of the hand dorsum and the MCP
joints, extensor tendon rupture and/or exposure and bone defect
with comminuted joint fractures. After debridement, fixation of bone
fractures and repair of extensor tendon lacerations, all patients were
reconstructed using a dorso-radial skin flap.
Nine patients were male and three patients were female with
their ages raging from 16 to 53 years old (mean, 36 year old). In four
patients, the right hand was injured while in the remaining eight
patients the left hand was involved. Six cases resulted from crush
injuries with two from road traffic accidents (RTA). Three cases
resulted from avulsion injuries, two cases of contracture of the first
web space after electrical burn and one case of gunshot injury to the
hand dorsum.
In four cases the injury was compound, involving the different
structures around the MCP joint of the thumb with comminuted
fractures, exposed joints and extensor tendon ruptures. These
underwent an MCP fusion for thumb stabilization. Three patients
presented with a contracture of the first web space; two resulting from
electrical burns and one from a crush injury. One patient presented with an isolated skin defect of the dorsum of the hand exposing the
underlying tendons. The remaining four cases consisted of a defect
located on the dorsal aspect of the finger MCP joints with extensor
tendon exposure and/or rupture. The sizes of the dorso-radial flaps
ranged from 4 to 7 cm in length and from 2 to 5 cm in width (Table 1).
Results
THe follow-up period ranged from three to six months (mean, 4.8
months). All dorso-radial flaps achieved complete wound coverage.
No flap failure was noted. Wounds healed uneventfully and no donor
site complications were noted. The donor site was closed primarily
in one case (the width of the flap did not exceed 2 cm), left to heal
secondarily in another, grafted primarily in three cases, and was
grafted secondarily after few days of wound stabilization and bed
granulation in the remaining seven cases.
The functional result in terms of range of motion of the injured
hand and fingers was determined by the extent of the injury and the
structures involved. Among the four patients (2, 4, 8 and 10) who
benefited from thumb stabilization with fusion of the MCP joint, two
of them recovered with an opposition scale 7 over 10 according to
Kapandji classification while the two others scored 8 over 10 on the
opposition scale [7]. The three patients (6, 9 and 11) who benefited
from a release of the first web space contracture showed a near normal
thumb abduction with a limited thumb opposition of 6 over 10 due to
the weakness of the adductor and thenar muscles. Of the three patients
(1, 3 and 5) who presented with rupture of the extensor tendons and
exposure of the MCP joints of the fingers, one scored an excellent
result whereas the other two had a good result according to Strickland
classification [8]. These patients benefited from a teno-arthrolysis of
the extensor tendons and the involved MCP joints. Patient 7 who had
an exposure of the extensor tendons on the dorsal aspect of his hand
scored an excellent result on the Strickland classification [8]. Finally,
patient 12 presented with a total loss of the ring finger and a near total
destruction of the middle finger MCP joints as a result of a gunshot
injury. The dorso-radial flap outcome was successful but this patient
could not be assessed functionally as he still needed bone and joint
reconstructions.
Discussion
The cutaneous vascularity of the dorsal aspect of the upper
extremity has been the subject of multiple anatomic studies [9,10].
At the level of the hand, it is supplied by the dorsal intermetacarpal
arteries originating from the dorsal arterial arcades of the wrist;
whereas at the forearm, the cutaneous blood supply depends mainly
on two arterial axes: the anterior and posterior interosseous arteries.
Fasciocutaneous flaps vascularized in a retrograde fashion
were first described by Song et al. [1] in 1982 and their use has
radically changed the reconstructive options of the upper extremity,
particularly the hand. These flaps, raised on the radial, ulnar,
posterior interosseous or anterior interosseous vascular pedicle,
receive a reverse flow blood supply. Enforced by the rich anastomotic
arterial network of the hand, these flaps have been widely used to
cover distally located soft tissue defects [2-4,11]. However, drawbacks
resulting from the use of these flaps should be seriously considered;
i.e., they may require the sacrifice of one of the main vascular axes of
the hand as in the distally based radial forearm flap or the reserve flow
ulnar forearm flap [1,2]. They may also consist of a bulky skin paddle
which does not always correspond to the contour of hand defects.
In addition, their dissection, especially for the posterior and anterior
interosseous flap, is a technically demanding procedure requiring
previous experience [3,4,11]. Even, if the radial forearm flap can be
transferred to the hand based only on the distal perforators without
scarifying the radial artery, it cannot compete with the dorso-radial
flap particularly by its bulkiness when used to the hand dorsum.
The dorso-radial flap, described herein, is an original alternative
flap, simple to perform, and useful for covering various skin defects
of the hand. The vascularity of the flap is reliable and the anatomy of
its pedicle is constant. The dorso-radial artery has a mean diameter
of 1 mm, arising in most cases (84%) directly from the radial artery
(Type I). However, the artery emerged from a common arterial trunk
with the first dorsal metacarpal artery in 16% of the cases (Type II),
but its course remained the same. Hence, the operative steps of the
procedure were maintained regardless of anatomic variance, making
it an easy flap to learn and master, with a relatively easy learning
curve. In cases where Type II anatomic variation is present, a further
lengthening of the vascular pedicle might be obtained, according to
the Y-V technique described by Martin et al. [12] which allowed the
pivot point of this extended pedicle to be located more distally over
the head of the second metacarpal. This provides for a wider rotation
arc that covers the dorsal aspect of the long fingers, but its presence in
only 16% of the situations do not make it a reproducible and constant
procedure.
As has been already mentioned, the skin island of the flap should
overlie the course of the dorso-radial artery. This runs proximally
and medially, from the apex of the first intermetacarpal space to the
inferior radio-ulnar joint, parallel and at 4 mm medial to the EPL
tendon, supplying the skin of the dorso-radial aspect of the wrist and
distal forearm. Paired venae comitantes accompany the artery and
ensure an adequate venous outflow from the skin island. Although,
flap dissection also includes the forearm fascia, its elevation is not
mandatory for the vascularity of the skin paddle; we perform the
dissection under the fascia, only to facilitate the raising of the flap and
protect the overlying vascular structures. Therefore, the dorso-radial
flap belongs to the group of direct axial cutaneous flaps.
The flap can be mobilized to reach the dorsal aspect of the hand
including the MCP joints of the long fingers, the first web space,
the thumb and the palmar aspect of the wrist (Figure 5A-5D).
As the rotation point of the pedicle is located distal to the carpus,
postoperative immobilization of the wrist is not required and
rehabilitation may start immediately after surgery.
The fact that the dorso-radial artery shares its origin with the
first dorsal metacarpal artery enables us to raise a “chimeric” flap,
including a piece of cortical bone from the second metacarpal bone,
as it has already been performed in patient number 8, allowing for
composite tissue reconstruction (Figure 6A-6G).
The donor site management is easy and simple. It is closed
primarily if the width of the flap does not exceed 3 cm, or left for
secondary healing. A skin graft can also be applied primarily or
secondarily after obtaining a granulation of the donor site. This late
option is chosen when a thick layer of subcutaneous tissue is present
in order to avoid a depression of the donor site. In the situations
when a direct closure cannot be achieved, approximation stitches are
applied in order to decrease as much as possible the donor site defect
while waiting the wound to granulate before being grafted. In all cases,
the mobility of the wrist particularly in flexion was not disturbed as
the flap was designed and harvested from the distal quarter of the
forearm dorsum far from the dorsal crease of the wrist. The main
problem in the donor site is still the scar left by the skin grafts in a
social exposed part of the body.
Figure 6A
Figure 6A
Subtotal amputation of the right thumb with bone and MCP defect
associated with skin loss.
Figure 6B
Figure 6C
Figure 6D
Figure 6E
Figure 6F
Figure 6G
Conclusion
In conclusion, we believe that the dorso-radial flap certainly deserves to be added to the armamentarium of the reconstructive surgeon. It is a reliable and simple method for covering soft tissue defects of the hand, offering a fine reconstruction of the hand contour with similar tissues and acceptable donor site morbidity.
References
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