Case Report
Resurfacing of Two Separate Digital Defects using a Radial Forearm Fascial Free Flap with Neosyndactylization
Herrera FA Jr1,2*, Horton KM1, Brennan R1, Buntic RF1 and Buncke GM1
1Division of Microsurgery, California Pacific Medical Center, USA
2Division of Plastic and Hand Surgery, Medical University of South Carolina, USA
*Corresponding author: Fernando A. Herrera Jr, Division of Plastic and Hand Surgery, Medical University of South Carolina Charleston, SC, 29425, USA
Published: 09 Aug, 2016
Cite this article as: Herrera FA Jr, Horton KM, Brennan R, Buntic RF, Buncke GM. Resurfacing of Two Separate Digital Defects using a Radial Forearm Fascial Free Flap with Neosyndactylization. Clin Surg. 2016; 1: 1077.
Abstract
We report a case of a 20-year-old patient who sustained a mutilating crush injury to the left hand. After thorough debridement and stabilization of the skeletal injury, a radial forearm fascial free
flap was used to resurface the distal soft tissue volar defect of two adjacent digits. This thin fascial
flap allows for stable soft tissue coverage and provides a gliding surface for the exposed tendons.
The neosyndactylized digits were safely divided at 3-months follow-up, excellent functional and
aesthetic results were achieved. The radial forearm fascia is a thin, durable, and pliable tissue that is
based on the radial artery as a vascular pedicle. We consider this free fascial flap as a valuable option
for coverage of multiple complex distal digit injuries using a single flap and highly recommend its
use.
Keywords: Free fascia flap; Neosyndactyly; Digital resurfacing
Introduction
Traumatic hand and digit injuries resulting in soft tissue loss pose many challenges for the reconstructive surgeon. These injuries may result in composite tissue loss to digits and require soft tissue coverage as well as bone, tendon, and nerve grafts. Coverage of exposed structures such as tendons, bones, vessels, or nerves at the dorsal and palmer surfaces of the hand requires thin, supple tissue to provide adequate range of motion and a satisfying aesthetic result. The use of local and regional flaps when possible to treat these injuries is a popular choice [1-4]. However, due to the limited amount of expendable tissue in the hand, this may result in a functional limitation at the donor site or simply may not be possible due to the surrounding zone of injury (multiple digit crush, avulsion injuries). Advancements in microsurgical techniques have allowed the use of free tissue transfers to treat these defects in the distal hand and fingers, allowing for improved range of motion and a more aesthetically pleasing appearance of the traumatized upper extremity [5-7]. We discuss a case of simultaneous coverage of two digital defects with a single fascial free flap with neosyndactylization.
Case Presentation
A 20-year-old, right hand dominant male sustained a significant crush injury to his left hand
after a motor vehicle rollover collision. Initial evaluation of his injuries revealed a complex avulsion
injury of the volar surface of his left middle and ring finger with open fractures of the distal phalanx
of the middle finger and avulsion of the digital nerves to the middle and ring fingers (Figure 1). He
underwent immediate irrigation and open reduction, percutaneous pinning of the phalanx fracture,
and placement of a vacuum closure device to temporarily cover the soft tissue defect. The patient
was taken back to the operating theatre 2 days later for definitive closure of this complex defect.
Given the unique location involving the volar surface of multiple digits, the decision to perform a
free radial fascial flap with split thickness skin graft and neosyndactylization of the affected digits
was made.
An Allen test was performed preoperatively to verify that there was indeed a patent arch with
retrograde flow to the hand through the ulnar artery. The volar wounds were then debrided and
the incision was extended proximally to isolate the common digital artery for our microvascular
anastomosis. The neurovascular bundles were carefully identified while the ulnar digital nerve to
the middle finger and the radial digital nerve to the ring finger were transected with roughly a 2 cm
segment loss at the level of the middle phalanx. These nerves were isolated and prepared for nerve
grafting. A nearby dorsal vein was also isolated and prepared for our venous anastomosis.
Once the hand was prepared, we then turned our attention to
harvesting the ipsilateral radial forearm fascial flap. The skin incision
was designed in a straight line over the proximal volar forearm
ending in a curvilinear fashion at the distal forearm (Figure 2A). Skin
flaps were elevated medially and laterally, taking care to identify and
preserve both the lateral antebrachial nerve and dorsal branches of
the radial nerve in the subcutaneous tissue. Following elevation of
skin and subcutaneous tissue, the radial forearm fascia was incised
creating a 7 cm x 6 cm flap to cover both volar defects to the middle
and ring fingers (Figure 2B). Perforators into the fascia from the radial
artery were preserved. The radial artery and its venae comitantes
were identified proximally and distally and protected throughout the
dissection. The fascial flap was elevated off the muscle bellies below,
taking care to preserve some paratenon over the underlying tendons.
Once the fascia and vessels were raised, the vessels were divided
distally and a proximal pedicle of roughly 8 cm was isolated and ready
for division.
Interposition nerve grafting of the ulnar digital nerve of the long
finger and the radial digital nerve of the ring finger using a segment
of the lateral antebrachial cutaneous nerve from the forearm was
performed prior to insetting the flap. The pedicle of the radial forearm
fascial flap was then divided and the flap was partially inset using
4-0 chromic sutures to cover the exposed vital structures. The radial
artery was anastomosed to the common digital artery in an end-toside
fashion using 8-0 nylon sutures in an interrupted fashion. After
completion of the microvascular anastomosis all the digits were noted
to be perfused and pink with flow across the anastomosis. A primary,
hand sewn, end-to-end microanastomosis was then performed
from the venae comitantes of the radial artery to a dorsal vein in the
third web space. An implantable venous doppler probe was placed
(Cook Vascular Inc, Vandergrift, Pennsylvania) around the venous
anastomosis. The fascial flap was then covered using a very thin split
thickness skin graft harvested from the right thigh. Primary closure
of the forearm donor site was easily performed (Figure 3). The patient
was placed in a bulky dressing and a dorsal extension blocking
splint to avoid tension across the nerve and vessels repairs. The flap
survived without complications and the patient underwent division
of the neosyndactylized digits at 89 days from the original procedure
without further complications or secondary procedures needed.
Figure 1
Figure 1
Left hand multiple crush/avulsion injuries to volar middle and ring
fingers distal to the proximal inter-phalangeal joint.
Figure 2
Figure 2
Intra-operative dissection. (a) Design of volar skin incision. (b)
Harvesting of the radial forearm fascia.
Figure 3
Figure 3
(a) Completion of insetting and skin grafting with closure of donor
site. (b) 3 months postoperative with well healed donor site.
Discussion
Free flap transplantation allows for rapid closure of difficult
wounds, provides a robust blood supply to the zone of injury,
and facilitates clearing of infected wounds. Coverage of an upper
extremity wound can be very challenging as it requires tissue that
easily conforms to the contour of the forearm and hand, protects the
underling structures, and provides a surface for tendon gliding. In our
case the volar surfaces of the left middle and ring fingers distal to the
proximal interphalangeal joints were extensively damaged secondary
to a crush/avulsion injury. Loco-regional flaps such as cross finger
flaps were not possible due to defect size and injury to neighboring
digits [1]. Heterodigital or homodigital flaps may be of use in single
injured digits with small defects. The reverse radial forearm flap is
indicated for moderate-sized defects of the palmar and dorsal aspects
of the wrist and hand out to the level of the proximal interphalangeal
joints [6]. However, our defects extended beyond this level and any
pedicled reverse radial forearm fasciocutaneous or adipofascial flaps
would not likely be of adequate length. The free radial forearm flap
has been used extensively for head and neck and upper extremity
reconstruction [8]. The disadvantage of this flap is significant donor
site morbidity due to the inability to directly close the donor wound,
thus requiring split thickness skin grafting. However, given the
location and complexity of this injured region we needed soft tissue
coverage to be thin, pliable, and allow for gliding of the underlying
tendons. Ismail et al. described a modification of this flap using only
the forearm fascia as a free flap in 8 cases [9]. This modification not
only allows for ease of donor site closure but also allows for the use of
a fascia-only free flap to resurface the distal volar digits. Our case was
further complicated due to the multiple injured digits requiring soft
tissue coverage. When multiple adjacent fingers require soft tissue
coverage, fascial flaps can be placed over the entire defect creating
iatrogenically syndactylized digits. This allows for complete coverage
of all defects using a single free flap. This requires a second procedure
to divide the flap after adequate neovascularization has occurred.
Although many papers have been written on the subject, the exact
timing at which free flaps become independent of their vascular
pedicle remains unclear. Oswald et al. [10] showed that occlusion of
the vascular pedicle in microvascular free flaps on the 5th day resulted
in survival of the flap in rats. With the exception of anecdotal reports,
most of the published literature suggests that free flaps in humans
are dependent on their pedicle for at least 15 to 17 days [11-15]. The
condition and quality of the recipient site plays a large role in survival
of these flaps. Ischemic, irradiated, and scarred beds are inadequate in
providing late flap neovascularization compared to healthy recipient
sites and therefore would be dependent on the vascular pedicle for
longer periods of time [16,17]. In our patient the decision and timing
of flap division was altered by the patient’s unavailability.
In conclusion, the Radial Forearm free Fascia (RFF) is a reliable
flap with consistent vascular anatomy and low donor-site morbidity.
This thin and pliable flap allows for its use in locations where contour
and gliding are critical. The fascia is also ample so one can modify
the size of this flap to cover several neighboring defects with a single
arterial anastomosis. Our case underscores the utility of the RFF free
flap in the management of complex hand and digital injuries and its
use as a single flap for multiple defects. We highly recommend its
use and believe that it should be part of the armamentarium of the
reconstructive surgeon.
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